View MAX2822ETM_1272888.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-2884; Rev 0; 7/03
KIT ATION EVALU ILABLE AVA
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
General Description Features
2.4GHz to 2.5GHz ISM Band Operation 802.11b (11Mbps CCK and 22Mbps PBCC) PHY Compatible Integrated +17dBm PA Integrated PA Power Detector Integrated Transmit/Receive Switch Complete RF-to-Baseband Transceiver Direct Up/Down Conversion Monolithic Low-Phase-Noise VCO Integrated Baseband Lowpass Filters Integrated PLL with 3-Wire Serial Interface Digital Bias Control for PA Transmit Power Control Receive Baseband AGC Complete Baseband Interface Digital Tx/Rx Mode Control -95dBm Rx Sensitivity at 1Mbps -85dBm Rx Sensitivity at 11Mbps Single +2.7V to +3.0V Supply 2A Shutdown Mode Very Small 48-Pin QFN Package
MAX2822
The MAX2822 single-chip transceiver is designed for 802.11b (11Mbps) applications operating in the 2.4GHz to 2.5GHz ISM band. The transceiver includes all the circuitry required to implement an 802.11b RF-to-baseband transceiver solution, including the power amplifier, transmit/receive switch, and 50 matching. The fully integrated receive path, transmit path, VCO, frequency synthesis, and baseband/control interface provide all the required active RF circuitry. Only a small number of passive components are needed to form the complete radio front-end solution. The IC eliminates the need for external IF SAW and RF image-reject filters by utilizing a direct-conversion radio architecture and monolithic baseband filters for both receiver and transmitter. It is specifically optimized for 802.11b (11Mbps CCK) and 22Mbps PBCCTM applications. The baseband filtering and Rx and Tx signal paths support the CCK modulation scheme for BER = 10-5 at the required sensitivity levels. The transceiver is suitable for the full range of 802.11b data rates (1Mbps, 2Mbps, 5.5Mbps, and 11Mbps) as well as the higher-rate 22Mbps PBCC standard. The MAX2822 is available in the very small 7mm x 7mm 48lead QFN or thin QFN packages. The small solution size makes it ideal for small form-factor 802.11b applications such as PDAs, SmartPhones, and embedded modules.
Applications
802.11b PDAs and SmartPhones 802.11b Embedded Modules 802.11b PC Cards, Mini-PCI Cards
PART MAX2822EGM MAX2822ETM
Ordering Information
TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 48 QFN 48 Thin QFN
Pin Configuration/Functional Diagram appears at end of data sheet. PBCC is a trademark of Texas Instruments, Inc.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
ABSOLUTE MAXIMUM RATINGS
VCC Pins to GND ...................................................-0.3V to +3.6V RF I/O: RFP, RFN (current into pin).....................................50mA Baseband Inputs: TX_BBIP, TX_BBIN, TX_BBQP, TX_BBQN to GND ..................................-0.3V to (VCC + 0.3V) Baseband Outputs: RX_BBIP, RX_BBIN, RX_BBQP, RX_BBQN to GND ..................................-0.3V to (VCC + 0.3V) Analog Inputs: RX_AGC, TX_GC, TUNE, ROSCN, ROSCP to GND ......................................-0.3V to (VCC + 0.3V) Analog Outputs: PWR_DET, CP_OUT to GND....................................................-0.3V to (VCC + 0.3V) Digital Inputs: RX_ON, TX_ON, SHDNB, CSB, SCLK, DIN, RF_GAIN, RX_1K to GND...............-0.3V to (VCC + 0.3V) Bias Voltages: RBIAS, BYP ..................................+0.9V to +1.5V Short-Circuit Duration Digital Output: DOUT ..........................10s RF Input Power ...............................................................+10dBm Continuous Power Dissipation (TA = +70C) 48-Lead QFN (derate 27.0mW/C above +70C) ......2162mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(MAX2822 EV kit: VCC = +2.7V to +3.0V, RF_GAIN = VIH, 0V VTX_GC +2.0V, 0V VRX_AGC +2.0V, RBIAS = 12k, no input signals at RF and baseband inputs, RF I/O terminated into 50 though a 2:1 balun, receiver baseband outputs are open, transmitter baseband inputs biased at +1.2V, registers set to default power-up settings, TA = -40C to +85C, unless otherwise noted. Typical values are for VCC = +2.7V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETERS Supply Voltage Shutdown Current Standby-Mode Supply Current Receive-Mode Supply Current SHDNB = VIL, RX_ON = VIL, TX_ON = VIL SHDNB = VIH, RX_ON = VIL, TX_ON = VIL SHDNB = VIH, RX_ON = VIH, TX_ON = VIL SHDNB = VIH, RX_ON = VIL, TX_ON = VIH, bias registers set as in Table 9 POUT = +3dBm POUT = +12dBm POUT = +17dBm TA = +25C TA = -40C to +85C 220 TA = +25C TA = -40C to +85C TA = +25C TA = -40C to +85C 98 157 175 185 mA 80 CONDITIONS MIN 2.7 2 25 TYP MAX 3.0 50 35 40 100 110 UNITS V A mA mA
Transmit-Mode Supply Current
LOGIC INPUTS: SHDNB, RX_ON, TX_ON, SCLK, DIN, CSB, RF_GAIN Digital Input Voltage High (VIH) Digital Input Voltage Low (VIL) Digital Input Current High (IIH) Digital Input Current Low (IIL) LOGIC OUTPUT: DOUT Digital Output Voltage High (VOH) Digital Output Voltage Low (VOL) ANALOG OUTPUT: PWR_DET Power-Detector Output Impedance 400 Sourcing 100A Sinking 100A VCC 0.5 0.5 V V -5 -5 VCC 0.5 0.5 +5 +5 V V A A
2
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
DC ELECTRICAL CHARACTERISTICS (continued)
(MAX2822 EV kit: VCC = +2.7V to +3.0V, RF_GAIN = VIH, 0V VTX_GC +2.0V, 0V VRX_AGC +2.0V, RBIAS = 12k, no input signals at RF and baseband inputs, RF I/O terminated into 50 though a 2:1 balun, receiver baseband outputs are open, transmitter baseband inputs biased at +1.2V, registers set to default power-up settings, TA = -40C to +85C, unless otherwise noted. Typical values are for VCC = +2.7V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETERS RX BASEBAND I/O RX_AGC Input Resistance Rx I/Q Common-Mode Voltage Rx I/Q Output DC Offsets TX BASEBAND I/O TX BB Input Common-Mode Range TX BBI and BBQ Input Bias Current TX BB Input Impedance TX_GC Input Bias Current TX_GC Input Impedance Reference Oscillator Input Impedance VOLTAGE REFERENCE Reference Voltage ILOAD = 2mA 1.10 1.20 1.30 V Differential resistance 0V VTX_GC +2.0V Resistance 1.0 1.2 -10 100 10 250 1.4 V A k A k 3 limit 0V VRX_AGC +2.0V 50 1.25 15 k V mV CONDITIONS MIN TYP MAX UNITS
MAX2822
REFERENCE OSCILLATOR INPUT 20 k
AC ELECTRICAL CHARACTERISTICS--RECEIVE MODE
(MAX2822 EV kit: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, receive baseband output levels = 500mVP-P, VSHDNB = VRX_ON = VIH, VTX_ON = VIL, VCSB = VIH, VSCLK = VDIN = VIL, VRF_GAIN = VIH, 0V VRX_AGC +2.0V, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, registers set to default power-up settings, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER RF Frequency Range LO Frequency Range RF_GAIN = VIH, VRX_AGC = 0V Voltage Gain (Note 3) TA = +25C TA = -40C to +85C CONDITIONS MIN 2400 2400 97 95 35 75 3 32 dB dB 105 TYP MAX 2499 2499 UNITS MHz MHz
RECEIVER CASCADED PERFORMANCE (RF INPUT TO BASEBAND OUTPUT)
RF_GAIN = VIH, VRX_AGC = +2.0V RF_GAIN = VIL, VRX_AGC = 0V RF_GAIN = VIL, VRX_AGC = +2.0V
RF Gain Step
From RF_GAIN = VIH to RF_GAIN = VIL
_______________________________________________________________________________________
3
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
AC ELECTRICAL CHARACTERISTICS--RECEIVE MODE (continued)
(MAX2822 EV kit: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, receive baseband output levels = 500mVP-P, VSHDNB = VRX_ON = VIH, VTX_ON = VIL, VCSB = VIH, VSCLK = VDIN = VIL, VRF_GAIN = VIH, 0V VRX_AGC +2.0V, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, registers set to default power-up settings, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER DSB Noise Figure (Note 4) Adjacent Channel Rejection Input Third-Order Intercept Point (Note 6) Input Second-Order Intercept Point (Note 7) LO Leakage Input Return Loss RECEIVER BASEBAND BASEBAND FILTER RESPONSE -3dB Frequency Default bandwidth setting BW(2:0) = (010) At 12.5MHz Attenuation Relative to Passband At 16MHz At 20MHz At 25MHz BASEBAND OUTPUT CHARACTERISTICS Rx I/Q Gain Imbalance Rx I/Q Phase Quadrature Imbalance Rx I/Q Output 1dB Compression Rx I/Q Output THD BASEBAND AGC AMPLIFIER AGC Range AGC Slope AGC Response Time VRX_AGC = 0 to +2.0V Peak gain slope 20dB gain step (80dB to 60dB), settling to 1dB 70 60 2 dB dB/V s 3 limit 3 limit Differential voltage into 5k VOUT = 500mVP-P at 5.5MHz, ZL = 5k||5pF 1 5 1 -35 dB Degrees VP-P dBc 7 40 65 70 85 dB MHz CONDITIONS RF_GAIN = VIH, RX gain 80dB RF_GAIN = VIH, RX gain = 50dB RF_GAIN = VIL, RX gain = 50dB RX gain = 70dB (Note 5) RF_GAIN = VIH, RX gain = 80dB RF_GAIN = VIL, RX gain = 50dB RF_GAIN = VIH, RX gain = 80dB RF_GAIN = VIL, RX gain = 50dB At balun input MIN TYP 5.5 8 35 45 -13 +19 +23 +60 -65 15 dB dBm dBm dBm dB MAX 6.0 dB UNITS
4
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
AC ELECTRICAL CHARACTERISTICS--TRANSMIT MODE
(MAX2822 EV kit, characteristics relative to RFP/RFN: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, transmit baseband input signal: 500mVP-P at 5.5MHz, VSHDNB = VRX_ON = VIL, VTX_ON = VIH, VCSB = VIH, VSCLK = VDIN = VIL, VRF_GAIN = VIH, 0V VTX_AGC +2.0V, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, baseband inputs DC biased to +1.2V, registers set to default power-up settings, measurements taken within 1s of TXON rising edge, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER RF Output Frequency Range LO Output Frequency Range 11Mbps CCK signal, ACPR (adj) -30dBc, ACPR (alt) -50dBc (Note 4) TA = +25C TA = -40C to +85C CONDITIONS MIN 2400 2400 +16.5 +15.5 +17.5 dBm TYP MAX 2499 2499 UNITS MHz MHz
MAX2822
TRANSMIT SIGNAL PATH: BASEBAND INPUT TO RF OUTPUT
Tx RF Output Power
Adjacent (adj): -22MHz fOFFSET -11MHz, 11MHz fOFFSET 22MHz, POUT = +16.5dBm Tx RF ACPR (Note 8) Alternate (alt): -33MHz fOFFSET < -22MHz, 22MHz < fOFFSET 33MHz, POUT = +16.5dBm In-Band Spurious Signals Relative to Carrier fRF = 2400MHz to 2483MHz (Note 9) 11Mbps CCK at +16.5dBm < 2400MHz 2500MHz to 3350MHz > 3350MHz fOFFSET 22MHz, 0V VTX_GC +2.0V 100 balanced output impedance, POUT = +17dBm Unwanted sideband LO signal Spurs > 22MHz 2 x fRF 3 x fRF
-33 dBc -56
-40 -30 -80 -45 -30 -50 -35 -40 -125 10 dBm/Hz dB dBm dBm dBc
Tx RF Harmonics Tx RF Spurious Signal Emissions (Outside 2400MHz to 2483.5MHz) Nonharmonic Signals Tx RF Output Noise Tx RF Output Return Loss Tx BASEBAND FILTER RESPONSE -3dB Frequency Attenuation Relative to Passband Tx GAIN-CONTROL CHARACTERISTICS Gain-Control Range Gain-Control Slope Gain-Control Response Time
10 At 22MHz At 44MHz 0V VTX_GC +2.0V Peak gain slope VTX_GC = +2.0V to 0V step, settled to within 1dB 25 50 20 30 0.3
MHz dB
dB dB/V s
_______________________________________________________________________________________
5
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
AC ELECTRICAL CHARACTERISTICS--TRANSMIT MODE (continued)
(MAX2822 EV kit, characteristics relative to RFP/RFN: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, transmit baseband input signal: 500mVP-P at 5.5MHz, VSHDNB = VRX_ON = VIL, VTX_ON = VIH, VCSB = VIH, VSCLK = VDIN = VIL, VRF_GAIN = VIH, 0V VTX_AGC +2.0V, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, baseband inputs DC biased to +1.2V, registers set to default power-up settings, measurements taken within 1s of TXON rising edge, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER POWER DETECTOR Power-Detection Range Power-Detection Error (3 Limit) Power-Detection Error Variation with Temperature 0.1V VPWR_DET 1.5V Fixed VPWR_DET, TA = +25C POUT = +3dBm POUT = +17dBm 17 0.7 0.5 0.3 dB dB dB CONDITIONS MIN TYP MAX UNITS
TA = -40C to +85C, relative to TA = +25C
AC ELECTRICAL CHARACTERISTICS--SYNTHESIZER
(MAX2822 EV kit: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, SHDNB = VIH, CSB = VIH, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, registers set to default power-up settings, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER FREQUENCY SYNTHESIZER LO Frequency Range Reference Frequency Minimum Channel Spacing Charge-Pump Output Current Charge-Pump Compliance Range -11MHz fOFFSET 11MHz Reference Spur Level (Note 10) -22MHz fOFFSET < -11MHz, 11MHz < fOFFSET 22MHz fOFFSET < -22MHz, fOFFSET > 22MHz Closed-Loop Phase Noise Closed-Loop Integrated Phase Noise Reference Oscillator Input Level VOLTAGE-CONTROLLED OSCILLATOR VCO Tuning Voltage Range VCO Tuning Gain fLO = 2400MHz fLO = 2499MHz fLO = 2400MHz fLO = 2499MHz 170 130 0.4 2.3 V MHz/V fOFFSET = 10kHz fOFFSET = 100kHz Noise integrated from 100Hz to 10MHz, measured at the TX_RF output AC-coupled sine wave input 200 0.4 -41 -75 -90 -80 -87 2.5 300 500 dBc/Hz RMS mVP-P dBc SYNTH:R(0) = 0 SYNTH:R(0) = 1 2400 22 44 1 2 VCC 0.4 2499 MHz MHz MHz mA V CONDITIONS MIN TYP MAX UNITS
6
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
AC ELECTRICAL CHARACTERISTICS--SYSTEM TIMING
(MAX2822 EV kit: VCC = +2.7V to +3.0V, fRF and fLO = 2400MHz to 2499MHz, fOSC = 22MHz or 44MHz, SHDNB = VIH, CSB = VIH, RBIAS = 12k, ICP = +2mA, BWPLL = 45kHz, registers set to default power-up settings, TA = +25C, unless otherwise noted. Typical values are for VCC = +2.7V, fLO = 2437MHz, fOSC = 22MHz, unless otherwise noted.) (Note 2)
PARAMETER Channel-Switching Time CONDITIONS fLO = 2400MHz 2499MHz, fLO settles to 10kHz (Note 11) Rx to Tx, fLO settles to within 30kHz, relative to the rising edge of TX_ON Rx/Tx Turnaround Time Tx to Rx, fLO settles to within 30kHz, relative to the rising edge of RX_ON Standby-to-Receive Mode Standby-to-Transmit Mode Standby to Rx, fLO settles to within 30kHz, relative to the rising edge of RX_ON Standby to Tx, fLO settles to within 30kHz, relative to the rising edge of TX_ON 10 10 5 s s MIN TYP 150 MAX 200 5 s UNITS s
MAX2822
AC ELECTRICAL CHARACTERISTICS--SERIAL INTERFACE TIMING
(MAX2822 EV kit: VCC = +2.7V to +3.0V, registers set to default power-up settings, TA = +25C, unless otherwise noted.) (Note 2)
PARAMETER SERIAL INTERFACE TIMING (SEE FIGURE 1) tCSO tCSS tDS tDH tCH tCL tCSH tCSW tCS1 fCLK SCLK rising edge to CSB falling edge wait time Falling edge of CSB to rising edge of first SCLK time Data-to-serial clock setup time Data-to-clock hold time Serial clock pulse-width high Clock pulse-width low Last SCLK rising edge to rising edge of CSB CSB high pulse width Time between the rising edge of CSB and the next rising edge of SCLK Clock frequency 5 5 5 10 10 10 5 10 5 50 ns ns ns ns ns ns ns ns ns MHz CONDITIONS MIN TYP MAX UNITS
Note 1: Note 2: Note 3: Note 4: Note 5:
Parameters are production tested at +25C only. Min/max limits over temperature are guaranteed by design and characterization. Guaranteed by design and characterization. Defined as the baseband differential RMS output voltage divided by the RMS input voltage (at the RF balun input). Specification excludes the loss of the external balun. The external balun loss is typically ~0.5dB. CCK interferer at 25MHz offset. Desired signal equals -73dBm. Interferer amplitude increases until baseband output from interferer is 10dB below desired signal. Adjacent channel rejection = PINTERFERER - PDESIRED . Note 6: Measured at balun input. Two CW tones at -43dBm with 15MHz and 25MHz offset from the MAX2822 channel frequency. IP3 is computed from 5MHz IMD3 product measured at the Rx I/Q output. Note 7: Two CW interferers at -38dBm with 24.5MHz and 25.5MHz offset from the MAX2822 channel frequency. IP2 is computed from the 1MHz IMD2 product measured at the RX I/Q output. Note 8: VTXGC adjusted for +16.5dBm output power; adjacent and alternate channel power relative to the desired signal. Power measured with 100kHz video BW and 100kHz resolution BW. Note 9: CW tone at 2.25MHz offset from carrier with VTXGC set for maximum modulated POUT at -30dBc/-50dBc (ADJ/ALT) ACPR limits. Unwanted sideband refers to suppressed image resulting from I/Q baseband input tones. Note 10: Relative amplitude of reference spurious products appearing in the Tx RF output spectrum relative to a CW tone at 2.25MHz offset from the LO. Note 11: Time required to reprogram the PLL, change the operating channel, and wait for the operating channel center frequency to settle within 10kHz of the nominal (final) channel frequency. _______________________________________________________________________________________ 7
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Typical Operating Characteristics
(MAX2822 EV kit, VCC = +2.7V, fBB = 1MHz, fLO = 2437MHz, receive baseband outputs = 500mVP-P, transmit baseband inputs = 400mVP-P, ICP = +2mA, BWPLL = 45kHz, differential RF input/output matched to 50 through a balun, baseband input biased at +1.2V, registers set to default power-up settings, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
100 90 80 RX AND STBY ICC (mA) 70 60 50 40 30 20 10 0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C) STBY TX (POUT = +17dBm) RX, LNA LOW GAIN
MAX2822 toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
260 250 240 RX AND STBY ICC (mA) 230 TX ICC (mA) 220 210 200 190 180 170 160 100 90 80 70 60 50 40 30 20 10 0 2.70 2.75 2.80 STBY TX, FIXED, POUT = +17dBm
MAX2822 toc02
SUPPLY CURRENT vs. TX OUTPUT POWER
250 240 230 ICC (mA) 220 210 200 190 180 170 120 100 +3dBm APPLICATION 80 -4 -2 0 2 4 6 8 10 12 14 16 18 20 OUTPUT POWER (dBm) TX ICC (mA) 200 180 160 140 +12dBm APPLICATION +17dBm APPLICATION 220 TRACES END AT LINEARITY LIMITS (-30dBc/-50dBc)
MAX2822 toc03
RX, LNA HIGH GAIN
RX, LNA HIGH GAIN
260
240
RX, LNA LOW GAIN
2.85 VCC (V)
2.90
2.95
160 3.00
RECEIVER GAIN vs. GAIN-CONTROL VOLTAGE
MAX2822 toc04
RECEIVER VOLTAGE GAIN vs. FREQUENCY
MAX2822 toc05
RECEIVER NOISE FIGURE vs. GAIN
45 40 NOISE FIGURE (dB) 35 30 25 20 15 10 HIGH-GAIN LNA LOW-GAIN LNA fBB = 2.25MHz fLO = 2437MHz
MAX2822 toc06 MAX2822 toc09
110 100 90 RECEIVER GAIN (dB) 80 70 60 50 40 30 20 10 0 0 LNA HIGH GAIN LNA LOW GAIN
RX GAIN, HIGH-GAIN LNA (dB)
VOUT = 500mVP-P fBB = 1MHz fLO = 2437MHz
40 HIGH-GAIN LNA 35 30 25 20 15 10 5 0 LOW-GAIN LNA VRX_AGC = 2.0V
50
5 0 2440 2460 2480 2500 0 10 20 30 40 50 60 70 80 90 100 110 RX GAIN (dB)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 VRX_AGC (V)
2400
2420
FREQUENCY (MHz)
RECEIVER BLOCKER REJECTION vs. RF FREQUENCY
MAX2822 toc07
RECEIVER BLOCKER REJECTION vs. CARRIER OFFSET
MAX2822 toc08
RECEIVER FILTER RESPONSE (1kHz TO 1MHz)
10 0 NORMALIZED RESPONSE (dB) -10 -20 -30 -40 -50 -60 -70 -80 -90 50 1 10 100 1000 RX_1K = VIL RX_1K = VIH
10 0 INTERFERER LEVEL (dBm) -10 -20 -30 -40 -50 -60 LO/2 GAIN = 80dB PINT (MAX) FOR SNR DEGRADED TO 10dB (PER = 8%) 2LO/3 LO/3
0 -10 INTERFERER LEVEL (dBm) -20 -30 -40 -50 -60 -70 -80 10 15 20 25 30 GAIN = 80dB PINT (MAX) FOR SNR DEGRADED TO 10dB (PER = 8%) 35 40 45
800 1000 1200 1400 1600 1800 2000 2200 2400 RF FREQUENCY (MHz)
OFFSET FROM CARRIER (MHz)
FREQUENCY (kHz)
8
_______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Typical Operating Characteristics (continued)
(MAX2822 EV kit, VCC = +2.7V, fBB = 1MHz, fLO = 2437MHz, receive baseband outputs = 500mVP-P, transmit baseband inputs = 400mVP-P, ICP = +2mA, BWPLL = 45kHz, differential RF input/output matched to 50 through a balun, baseband input biased at +1.2V, registers set to default power-up settings, TA = +25C, unless otherwise noted.)
RECEIVER FILTER RESPONSE (1MHz TO 100MHz)
MAX2822 toc10
RECEIVER LEAKAGE SPECTRUM
MAX2811 toc11
RECEIVER BASEBAND OUTPUT SPECTRUM (SINGLE TONE)
-10 -20 -30 -40 -50 -60 -70 -80 POUT IS 50 REFERRED (SINGLE ENDED) RBW = 100kHz fLO = 2437MHz LNA HIGH GAIN
MAX2822 toc12 MAX2822 toc18
10 0 NORMALIZED RESPONSE (dB) -10 -20 -30 -40 -50 -60 -70 -80 -90 1 10 FREQUENCY (MHz) f-3dB = 7.5MHz f-3dB = 8.5MHz
-10 -20 -30 LEAKAGE POWER (dBm) -40 -50 -60 -70 -80 -90 -100 -110 POUT IS 50 REFERRED (SINGLE ENDED) RBW = 100kHz fLO = 2437MHz LNA HIGH GAIN
0 BASEBAND OUTPUT POWER (dBm)
100
0
1
2
3
4
5
6
7
8
0
5
10
15
20
25
30
35
40
FREQUENCY (GHz)
BB FREQUENCY (MHz)
RECEIVER BASEBAND OUTPUT SPECTRUM (MODULATED)
MAX2822 toc13
TRANSMITTER OUTPUT POWER vs. SUPPLY VOLTAGE
MAX2822 toc14
TRANSMITTER OUTPUT POWER vs. FREQUENCY
TRANSMITTER OUTPUT POWER (dBm) 18.5 18.0 17.5 17.0 16.5 16.0 15.5 15.0 14.5 14.0 2400 2420 TA = +85C VIN = 400mVP-P 802.11b SIGNAL VTX_GC FOR +17.0dBm OUTPUT POWER AT 2437MHz, +25C 2440 2460 2480 2500 RF FREQUENCY (MHz) TA = +25C TA = -40C
MAX2822 toc15
0 BASEBAND OUTPUT POWER (dBm) -10 -20 -30 -40 -50 -60 -70 -80 0 5 10 15 20 25 30 35 SIGNAL APPLIED POUT IS 50 REFERRED (SINGLE ENDED) RX GAIN = 50dB RBW = 100kHz fLO = 2437MHz LNA HIGH GAIN
20 TRANSMITTER OUTPUT POWER (dBm) 19 TA = -40C 18 17 16 15 14 13 12 2.70 2.75 VIN = 400mVP-P 802.11b SIGNAL VTX_GC FOR +17.0dBm OUTPUT POWER AT 2437MHz, +25C 2.88 2.85 VCC (V) 2.90 2.95 TA = +25C TA = +85C
19.0
NO SIGNAL APPLIED 40
3.00
BB FREQUENCY (MHz)
ACPR vs. OUTPUT POWER
-26 +3dBm APP. -28 ACPR, ADJACENT (dBc) -30 -32 802.11b SPEC LIMITS ALT ALT +12dBm APP.
MAX2822 toc16
TRANSMITTER OUTPUT SPECTRUM
-48 ACPR, ALTERNATE (dBc) -50 -52 -54 -56 -58 NORMALIZED TRANSMITTER GAIN (dB) 10 0 -10 POWER (dBm) -20 -30 -40 -50 -60 -60 fLO = 2437MHz fBB = 1MHz RBW = 100kHz
MAX2822 toc17
TRANSMITTER GAIN vs. GAIN-CONTROL VOLTAGE
5 0 -5 -10 -15 -20 -25 -30 NORMALIZED TO +25C VTX_GC = 0V 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 VTX_GC (V) TA = +85C TA = +25C TA = -40C
-46
+17dBm APP.
20
-34 ALT -36 -38 -40 -42 0 2 4 6 8 ADJ
ADJ
ADJ -62
-70 -80 0 1 2 3 4 5 6 7 8 FREQUENCY (GHz)
10 12 14 16 18 20
OUTPUT POWER (dBm)
_______________________________________________________________________________________
9
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Typical Operating Characteristics (continued)
(MAX2822 EV kit, VCC = +2.7V, fBB = 1MHz, fLO = 2437MHz, receive baseband outputs = 500mVP-P, transmit baseband inputs = 400mVP-P, ICP = +2mA, BWPLL = 45kHz, differential RF input/output matched to 50 through a balun, baseband input biased at +1.2V, registers set to default power-up settings, TA = +25C, unless otherwise noted.)
TRANSMITTER BASEBAND FILTER RESPONSE
MAX2822 toc19
LO FREQUENCY vs. TUNING VOLTAGE
MAX2822 toc20
SYNTHESIZER CLOSED-LOOP PHASE NOISE
-50 PHASE NOISE (dBc/Hz) -60 -70 -80 -90 -100 -110 -120 fOSC = 2437MHz ICP = 2mA PLL BW = 45kHz TTL INTEGRATED PHASE NOISE = 2.0RMS
MAX2822 toc21
5 0 NORMALIZED RESPONSE (dB) -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 0 5
NORMALIZED TO 1MHz
2.65 2.60 2.55 LO FREQUENCY (GHz) 2.50 2.45 2.40 2.35 2.30 2.25 2.20 +85C -40C +25C
-40
10 15 20 25 30 35 40 45 50 BASEBAND FREQUENCY (MHz)
0
0.5
1.0
1.5
2.0
2.5
1
10 fOFFSET (kHz)
100
1000
VTUNE (V)
VCO/PLL SETTING TIME
MAX2822 toc22
RX/TX TURNAROUND TIME
MAX2822 toc23
PA POWER-DETECTOR OUTPUT VOLTAGE vs. OUTPUT POWER
1.8 DETECTOR OUTPUT VOLTAGE (V) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 MODULATED BASEBAND INPUT SIGNAL
MAX2822 toc24
50 40 FREQUENCY ERROR (kHz) 30 20 10 0 -10 -20 -30 -40 -50 0 BWLOOP = 45kHz fLO = 2499MHz TO 2400MHz
50 40 FREQUENCY ERROR (kHz) 30 20 10 0 -10 -20 -30 -40 -50 TRIGGERED ON RISING EDGE OF TXON SYNTHESIZER SETTINGS DO NOT CHANGE
2.0
40 80 120 160 200 240 280 320 360 400 TIME (s)
0
2
4
6
8
10 12 14 16 18 20
0
2
4
6
8
10 12 14 16 18 20
TIME (s)
OUTPUT POWER (dBm)
10
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Pin Configuration/Functional Diagram
MAX2822
VCC_RMX
VCC_BUF
RX_BBQN
RX_BBQP
RX_BBIN
RX_BBIP
RX_AGC
RX_ON
TX_ON
RX_1K
38
48 VCC_LNA 1
47
46
45
44
43
42
41
40
39
37 36 SHDNB 35 VCC_RXF 34 VCC_LO
PROGRAMMING AND MODE CONTROL
VREF 2 RF_GAIN VCC_REF GND RFP RFN GND VCC_PA 3 4 5 6 7 8 9 PWR DET PWR_DET OUTPUT MATCH 90 0 INTEGER-N SYNTHESIZER INPUT MATCH
DOUT
33 VCC_VCO 32 BYP 31 TUNE 30 GND_VCO 29 GND_CP 28 CP_OUT 27 VCC_CP 26 CSB 25 SCLK 24
N.C.
MAX2822
T/R SWITCH 90 0
VCC_DRVR 10 BIAS 11 TX_GC 12 13 14 15 16 17 18 19 20 21 22 23 VOS COMP SERIAL INTERFACE
PWR_DET
ROSCP
VCC_TMX
TX_BBIN
TX_BBIP
TX_BBQP
TX_BBQN
VCC_TXF
GND_DIG
VCC_DIG
ROSCN
______________________________________________________________________________________
DIN
11
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Pin Description
PIN 1 2 3 4 5, 8 6 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NAME VCC_LNA VREF RF_GAIN VCC_REF GND RFP RFN VCC_PA BIAS TX_GC VCC_TMX TX_BBIN TX_BBIP TX_BBQP TX_BBQN VCC_TXF GND_DIG VCC_DIG PWR_DET ROSCP ROSCN DIN SCLK FUNCTION Supply Voltage Connection for LNA. Bypass with a capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Voltage Reference Output for Baseband IC. Requires external RF bypass to GND. LNA Gain-Select Logic Input. Logic high for LNA high-gain mode, logic low for LNA low-gain mode. Supply Voltage for Bias Circuitry and Autotuner. Bypass with a capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Ground RF Balanced I/O Port (Positive). On-chip matched for 100 balanced. RF Balanced I/O Port (Negative). On-chip matched for 100 balanced. Supply Voltage Connection for Power Amplifier. Requires external RF bypass to GND. Precision Bias Resistor Pin. Connect a 12k precision resistor ( 2%) to GND. Transmit Gain-Control Input. Analog high-impedance input. Connect directly to baseband IC DAC output. See Figure 3 for transmitter gain vs. gain-control voltage. Supply Voltage for Transmit Mixer and VGA. Bypass with a capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Transmit Negative In-Phase Baseband Input. Analog high-impedance differential input. Connect directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage. Transmit Positive In-Phase Baseband Input. Analog high-impedance differential input. Connect directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage. Transmit Positive Quadrature Baseband Input. Analog high-impedance differential input. Connect directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage. Transmit Negative Quadrature Baseband Input. Analog high-impedance differential input. Connect directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage. Supply Voltage for Transmit Baseband Filter. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Digital Ground Supply Voltage for Digital Circuitry. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Transmitter Power-Detector Output Reference Oscillator Positive Input. Analog high-impedance differential input. DC-coupled. Requires external AC-coupling. Connect an external reference oscillator to this analog input. Reference Oscillator Negative Input. Analog high-impedance differential input. DC-coupled. Requires external AC-coupling. Bypass this analog input to ground with capacitor for single-ended operation. 3-Wire Serial Interface Data Input. Digital high-impedance input. Connect directly to baseband IC serial interface CMOS output (SPITM/QSPITM/MICROWIRETM compatible). 3-Wire Serial Interface Clock Input. Digital high-impedance input. Connect this digital input directly to baseband IC serial interface CMOS output (SPI/QSPI/MICROWIRE compatible).
VCC_DRVR Supply Voltage Connection for PA Driver. Requires external RF bypass to GND.
SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp. 12 ______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Pin Description (continued)
PIN 26 27 28 29 30 31 32 33 34 35 36 37 38 NAME CSB VCC_CP CP_OUT GND_CP GND_VCO TUNE BYP VCC_VCO VCC_LO VCC_RXF SHDNB DOUT RX_1K FUNCTION 3-Wire Serial Interface Enable Input. Digital high-impedance input. Connect directly to baseband IC serial interface CMOS output (SPI/QSPI/MICROWIRE compatible). Supply Voltage for PLL Charge Pump. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. PLL Charge-Pump Output. Analog high-impedance output. Current source. Connect directly to the PLL loop filter input. PLL Charge-Pump Ground. Connect to PC board ground plane. VCO Ground. Connect to PC board ground plane. VCO Frequency Tuning Input. Analog high-impedance voltage input. Connect directly to the PLL loop filter output. VCO Bias Bypass. Bypass with a 2000pF capacitor to ground. Supply Voltage for VCO. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Important note: Operate from separate regulated supply voltage. Supply Voltage for VCO, LO Buffers, and LO Quadrature Circuitry. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Supply Voltage for Receiver Baseband Filter. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Active-Low Shutdown Input. Digital high-impedance CMOS input. Connect directly to baseband IC modecontrol CMOS output. Logic low to disable all device functions. Logic high to enable normal chip operation. Serial Interface Data Output. Digital CMOS output. Optional connection. Receiver 1kHz Highpass Bandwidth Control. Digital CMOS input. Connect directly to baseband IC CMOS output. Controls receiver baseband highpass -3dB corner frequency; logic low for 10kHz, logic high for 1kHz. See the Applications Information section for proper use of this function. Receive Positive Quadrature Baseband Output. Analog low-impedance differential buffer output. Connect output directly to baseband ADC input. Internally biased to 1.2V common-mode voltage and can drive loads up to 5k || 5pF. Receive Negative Quadrature Baseband Output. Analog low-impedance differential buffer output. Connect output directly to baseband ADC input. Internally biased to 1.2V common-mode voltage and can drive loads up to 5k || 5pF. Receive Negative In-Phase Baseband Output. Analog low-impedance differential buffer output. Connect output directly to baseband ADC input. Internally biased to 1.2V common-mode voltage and can drive loads up to 5k || 5pF. Receive Positive In-Phase Baseband Output. Analog low-impedance differential buffer output. Connect output directly to baseband ADC input. Internally biased to 1.2V and can drive loads up to 5k || 5pF. No Connection. Make no connections to this pin. Supply Voltage for Receiver Baseband Buffer. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches.
MAX2822
39
RX_BBQP
40
RX_BBQN
41
RX_BBIN
42 43 44
RX_BBIP N.C. VCC_BUF
______________________________________________________________________________________
13
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Pin Description (continued)
PIN 45 46 47 48 Exposed Paddle NAME RX_ON VCC_RMX TX_ON RX_AGC GND FUNCTION Receiver-On Control Input. Digital CMOS input. Connect to baseband IC mode-control CMOS output. Supply Voltage for Receiver Downconverter. Bypass with capacitor as close to the pin as possible. Do not share the bypass capacitor ground vias with other branches. Transmitter-On Control Input. Digital CMOS input. Connect directly to baseband IC mode-control CMOS output. Receive AGC Control. Analog high-impedance input. Connect directly to baseband IC DAC voltage output. See Figure 2 for gain vs. VRX_AGC. DC and AC Ground Return for IC. Connect to PC board ground plane using multiple vias.
Table 1. Operating Mode Truth Table
OPERATING MODE Shutdown Standby Receive Transmit Not Allowed MODE-CONTROL INPUTS SHDNB 0 1 1 1 1 TX_ON X 0 0 1 1 RX_ON X 0 1 0 1 RX_PATH OFF OFF ON OFF -- CIRCUIT BLOCK STATES TX_PATH OFF OFF OFF ON -- PLL/VCO/LO GEN OFF ON ON ON --
Detailed Description
Operating Modes
The MAX2822 has four primary modes of operation: shutdown, standby, receive active, and transmit active. The modes are controlled by the digital inputs SHDNB, TX_ON, and RX_ON. Table 1 shows the operating mode vs. the digital mode-control inputs. Shutdown Mode Shutdown mode is enabled by driving SHDNB low. In shutdown mode, all circuit blocks are powered down, except for the serial interface circuitry. While the device is in shutdown, the serial interface registers can still be loaded by applying VCC to the digital supply voltage (VCC_DIG). All previously programmed register values are preserved during the shutdown mode, as long as VCC_DIG is applied. Standby Mode Standby mode is achieved by driving SHDNB high, and RX_ON and TX_ON low. In standby mode, the PLL, VCO, LO generation circuitry, and filter autotuner are powered on by default. The standby mode is intended to provide time for the slower-settling circuitry (PLL and autotuner) to turn on and settle to the correct frequency before making Rx or Tx active. The 3-wire serial inter14
face is active and can load register values at any time. Refer to the serial interface specifications for details. Receive Mode Receive mode is enabled by driving SHDNB high, RX_ON high, and TX_ON low. In receive mode, all receive circuit blocks are powered on and all VCO, PLL, and autotuner circuits are powered on. None of the transmit path blocks are active in this mode. Although the receiver blocks turn on quickly, the DC offset nulling requires ~10s to settle. The receiver signal path is ready ~10s after a low-to-high transition on RX_ON. Transmit Mode Transmit mode is enabled by driving the digital inputs SHDNB high, RX_ON low, and TX_ON high. In transmit mode, all transmit circuit blocks are powered on and all VCO, PLL, and autotuner circuits are powered on. None of the receive path blocks are active in this mode. Although the transmitter blocks turn on quickly, the baseband DC offset calibration requires ~2.2s to complete. In addition, the Tx driver amplifier is ramped from the low-gain state (minimum RF output) to highgain state (peak RF output) over the next 1s to 2s. Also, the LO takes a few microseconds after TX_ON rises to resettle. The transmit signal path is ready ~5s after a low-to-high transition on TX_ON.
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Programmable Registers
The MAX2822 contains programmable registers to control various modes of operation for the major circuit blocks. The registers can be programmed through the 3-wire SPI/QSPI/MICROWIRE-compatible serial port. The MAX2822 includes five programmable registers: 1) Block-enable register 2) Synthesizer register 3) Channel frequency register 4) Receiver settings register 5) Transmitter settings register Each register consists of 16 bits. The four most significant bits (MSBs) are the register's address. The twelve least significant bits (LSBs) are used for register data. Table 2 summarizes the register configuration. A detailed description of each register is provided in Tables 4-8. Data bits are shifted in the MSB first. The data sent to the MAX2822, in 16-bit words, is framed by CSB. When CSB is low, the clock is active and data is shifted with the rising edge of the clock. When CSB transitions to high, the shift register is latched into the register selected by the contents of the address bits. Only the last 16 bits shifted into the MAX2822 are retained in the shift register. No check is made on the number of clock pulses. Figure 1 documents the serial interface timing for the MAX2822.
Power-Up Default States
The MAX2822 provides power-up loading of default states for each of the registers. The states are loaded on a VCC_DIG supply voltage transition from 0V to V CC . The default values are retained until reprogrammed through the serial interface or the power-supply voltage is taken to 0V. The default state of each register is described in Table 3. Note: Putting the IC in shutdown mode does not change the contents of the programming registers.
MAX2822
Block-Enable Register
The block-enable register permits individual control of the enable state for each major circuit block in the MAX2822. The actual enable condition of the circuit block is a logical function of the block-enable bit setting and other control input states. Table 4 documents the logical definition of state for each major circuit block.
Synthesizer Register
The synthesizer register (SYNTH) controls the reference frequency divider and charge-pump current of the PLL. See Table 5 for a description of the bit settings.
Channel Frequency Register
The channel frequency register (CHANNEL) sets the RF carrier frequency for the MAX2822. The channel is programmed as a number from 0 to 99. The actual frequency is 2400 + channel in MHz. The default setting is 37 for 2437MHz. See Table 6 for a description of the bit settings.
CSB tCSO tCSS SCLK tDS tDH tCH tCL DIN BIT 1 tDV tDO DOUT BIT 1 BIT 2 BIT 6 BIT 7 BIT 8 BIT 14 BIT 15 BIT 2 BIT 6 BIT 7 BIT 8 BIT 14 BIT 15 BIT 16 tTR tCS1 tCSH tCSW
BIT 16
Figure 1. MAX2822 Serial Interface Timing Diagram ______________________________________________________________________________________ 15
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Receiver Settings Register
The receiver settings register (RECEIVE) controls the receive filter -3dB corner frequency and VGA DC offset nulling parameters. The defaults are intended to provide proper operation. However, the filter frequency and detector can be modified if desired. Do not reprogram VGA DC offset nulling parameters. These settings were optimized during development. See Table 7 for a description of the bit settings.
Transmitter Settings Register
The transmitter settings register (TRANSMIT) provides a 6-bit digital control of the PA bias and 1-bit enable for the transmit power detector. Bits D0:D3 control the PA output stage bias current (0000 lowest, 1111 highest) and PA driver stage bias current (00 lowest, 11 highest). The appropriate values vs. target output power are given in Table 9. The detector enable bit allows independent turn-on of the detector for testing purposes.
Table 2. Programming Register Definition Summary
4 ADDRESS BITS REGISTER NAME ENABLE SYNTH CHANNEL RECEIVE TRANSMIT A3 MSB 0 0 0 0 0 A2 15 0 0 0 1 1 A1 14 0 1 1 0 0 A0 13 1 0 1 0 1 D11 12 E11 X X 2C2 X D10 11 E10 X X 2C1 X D9 10 E9 X X 2C0 X D8 9 E8 X X 1C2 X D7 8 E7 0 X 1C1 X 12 DATA BITS D6 7 E6 1 CF6 1C0 DE D5 6 E5 0 CF5 DL1 DR1 D4 5 E4 0 CF4 DL0 DR0 D3 4 E3 0 CF3 SF PA3 D2 3 E2 0 CF2 BW2 PA2 D1 2 E1 0 CF1 BW1 PA1 D0 LSB E0 R0 CF0 BW0 PA0
X = Don't care.
Table 3. Register Power-Up Defaults States
REGISTER ENABLE SYNTH CHANNEL RECEIVE ADDRESS 0001 0010 0011 0100 DEFAULT 0000 0001 1110 0000 0100 0000 0000 0010 0101 1111 1101 0010 Synthesizer Settings: * Reference frequency (R) Channel frequency settings (CF) Receiver Settings: * -3dB lowpass filter bandwidth (BW) * Detector midpoint level (DL) Transmit Settings: * PA bias (PA) * PA driver bias (D) * PA driver enable (DE) FUNCTION Block-Enable Control Settings (E)
TRANSMIT
0101
0000 0010 1101
16
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Table 4. Block-Enable Register (ENABLE)
ADDRESS DATA BIT CONTENT DEFAULT D11 D10 D9 D8 D7 D6 0001 D5 D4 D3 D2 D1 D0 E(11) E(10) E(9) E(8) E(7) E(6) E(5) E(4) E(3) E(2) E(1) E(0) 0 0 0 0 0 0 0 1 1 1 1 0 Reserved PA Bias-Control Enable (PAB_EN) PAB_EN = SHDNB * (E(10) + TX_ON) Transmit Baseband Filters Enable (TXFLT_EN) TXFLT_EN = SHDNB * (E(9) + TX_ON) Tx Upconverter + VGA + Driver Amp Enable (TXUVD_EN) TXUVD_EN = SHDNB * (E(8) + TX_ON) Reserved Rx Downconverter + Filters + AGC Amps Enable (RXDFA_EN) RXDFA_EN = SHDNB * (E(6) + RX_ON) Receive LNA Enable (RXLNA_EN) RXLNA_EN = SHDNB * (E(5) + RX_ON ) Autotuner Enable (AT_EN) AT_EN = SHDNB * (E(4) + RX_ON + TX_ON) PLL Charge-Pump Enable (CP_EN) CP_EN = SHDNB * E(3) PLL Enable (PLL_EN) PLL_EN = SHDNB * E(2) VCO Enable (VCO_EN) VCO_EN = SHDNB * E(1) Reserved DESCRIPTION AND LOGICAL DEFINITION
MAX2822
Table 5. Synthesizer Settings Register (SYNTH)
ADDRESS DATA BIT D11:D8 D7 0010 D6 D5:D0 CONTENT X -- -- R(5:0) DEFAULT 0000 0 1 000000 Reserved Must be 0 for proper operation Must be 1 for proper operation Reference Frequency Divider: * 000000 = 22MHz * 000001 = 44MHz DESCRIPTION
Table 6. Channel Frequency Register (CHANNEL)
ADDRESS DATA BIT D11:D7 CONTENT X DEFAULT 00000 Reserved Channel Frequency Select: fLO = (2400 + CF(6:0))MHz * 0000000 = 2400MHz * 0000001 = 2401MHz * ............ * 1100010 = 2498MHz * 1100011 = 2499MHz DESCRIPTION
0011
D6:D0
CF(6:0)
0100101
______________________________________________________________________________________
17
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Table 7. Receiver Settings Register (RECEIVE)
ADDRESS DATA BIT D11:D4 D3 CONTENT -- -- DEFAULT 11111111 0 DESCRIPTION Must be 11111111 for proper operation Must be 0 for proper operation Receive Filter -3dB Frequency Select (frequencies are approximate): * 000 = 8.5MHz * 001 = 8.0MHz * 010 = 7.5MHz * 011 = 7.0MHz * 100 = 6.5MHz * 101 = 6.0MHz
0100 D2:D0 BW(2:0) 010
Table 8. Transmit Settings Register (TRANSMIT)
ADDRESS DATA BIT D11:D7 D6 CONTENT X DE DEFAULT X 0 Reserved Transmit Power-Detector Enable PA Predriver Bias: * 11 = Highest predriver bias * ............ * 00 = Lowest predriver bias PA Bias Select: * 1111 = Highest PA bias * ............ * 0000 = Lowest PA bias DESCRIPTION
D5:D4 0101
D(1:0)
10
D3:D0
PA(3:0)
1101
Applications Information
RF I/O and Tx/Rx Switching
The MAX2822 completely integrates the power amplifier, low-noise amplifier, transmit/receive (Tx/Rx) switch, as well as all matching components, to allow direct connection to the antenna through a balun or combination balun/filter. This single RF interface (RFP and RFN) is internally matched to form a 100 balanced port--no additional components are required to impedancematch the I/O. Most applications employ a 100 balanced to 50 single-ended RF bandpass filter between the RF port and the antenna.
Receive Path
LNA Given the LNA input is internally matched to 100 differential, it is important that the differential pair from RFP/RFN to the RF BPF be an identical pair of transmission lines to present a 100 differential impedance to the balun. Identical line layout on the differential input traces is important in maintaining good IP2 performance and RF common-mode noise rejection. The MAX2822 has two LNA gain modes that are digitally controlled by the logic signal applied to RF_GAIN. RF_GAIN high enables the high-gain mode, and RF_GAIN low enables the low-gain mode. The LNA gain step is nominally 32dB. In most applications, RF_GAIN is connected directly to a CMOS output of the baseband IC, and the baseband IC controls the state of the LNA gain based on the detected signal amplitude.
18
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Receiver Baseband Lowpass Filtering The MAX2822 on-chip receive lowpass filters provide the steep filtering necessary to attenuate the out-ofband (> 11MHz) interfering signals to sufficiently low levels to preserve receiver sensitivity. The filter frequency response is precisely controlled on-chip and does not require user adjustment. However, a provision is made to permit the -3dB corner frequency and entire response to be slightly shifted up or down in frequency. This is intended to offer some flexibility in trading off adjacent channel rejection vs. passband distortion. The filter -3dB frequency is programmed through the serial interface. The specific bit setting vs. -3dB frequency is shown in Table 7. The typical receive baseband filter gain vs. frequency profile is shown in the Typical Operating Characteristics. Default filter settings are optimal (-3dB corner at 7.5MHz)--this provides the best trade-off between noise filtering and baseband distortion to obtain best receive sensitivity. No user adjustment is required. Receive Gain Control The MAX2822 receive path gain is varied through an external voltage applied to the pin RX_AGC. Maximum gain is at V RX_AGC = 0V and minimum gain is at VRX_AGC = 2V. The RX_AGC input is a high-impedance analog input designed for direct connection to the RX_AGC DAC output of the baseband IC. The gaincontrol range, which is continuously variable, is typically 70dB. The gain-control characteristic is shown in the Typical Operating Characteristics Receiver Voltage Gain vs. Gain-Control Voltage graph and again as a full-page plot in Figure 2. Some local noise filtering through a simple RC network at the input is permissible. However, the time constant of this network should be kept sufficiently low to not limit the desired response time of the Rx gain-control function. Receiver Baseband Amplifier Outputs The MAX2822 receiver baseband outputs (RX_BBIP, RX_BBIN, RX_BBQP, and RX_BBQN) are differential low-impedance buffer outputs. The outputs are designed to be directly connected (DC-coupled) to the in-phase (I) and quadrature-phase (Q) ADC inputs of the baseband IC. The Rx I/Q outputs are internally biased to +1.2V common-mode voltage. The outputs are capable of driving loads up to 5k || 5pF with the full bandwidth baseband signals at a differential amplitude of 500mVP-P. Proper board layout is essential to maintain good balance between I/Q traces. This provides good quadrature phase accuracy.
Transmit Path
Transmitter Baseband Inputs The MAX2822 transmitter baseband inputs (TX_BBIP, TX_BBIN, TX_BBQP, and TX_BBQN) are high-impedance differential analog inputs. The inputs are designed to be directly connected (DC-coupled) to the in-phase (I) and quadrature-phase (Q) DAC outputs of the baseband IC. The inputs must be externally biased to +1.2V common-mode voltage. Typically, the DAC outputs are current outputs with external resistor loads to ground. I and Q are driven by a 400mVP-P (nominal) differential baseband signal. Proper board layout is essential to maintain good balance between I/Q traces. This provides good quadrature phase accuracy by maintaining equal parasitic capacitance on the lines. In addition, it is important not to expose the Tx I/Q circuit board traces going from the digital baseband IC to the MAX2822. The lines should be shielded on an inner layer to prevent coupling of RF to these Tx I/Q inputs and possible envelope demodulation of the RF signal. Transmit Path Baseband Lowpass Filtering The MAX2822 on-chip transmit lowpass filters provide the filtering necessary to attenuate the unwanted higherfrequency spurious signal content that arises from the DAC clock feedthrough and sampling images. In addition, the filter provides additional attenuation of the second sidelobe of signal spectrum. The filter frequency response is set on-chip. No user adjustment or programming is required. The Typical Gain vs. Frequency profile is shown in the Typical Operating Characteristics. Transmitter DC Offset Calibration In a zero-IF system, the DC offset of the Tx baseband signal path must be reduced to as near zero as possible to minimize LO leakage at the RF output. Given that the amplifier stages, baseband filters, and Tx DAC possess some finite DC offset that is too large for the required LO leakage specification, it is necessary to null the DC offset. The MAX2822 accomplishes this through an on-chip calibration sequence. During this sequence, the net Tx baseband signal path offsets are sampled and cancelled in the baseband amplifiers. This calibration occurs in the first ~2.2s after TX_ON is taken high. The calibration corrects for any DC offset from the DAC, but this DC offset must not change after this cal sequence. Be sure the DAC outputs are set to zero state before taking TX_ON high.
MAX2822
______________________________________________________________________________________
19
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
RECEIVER GAIN vs. GAIN-CONTROL VOLTAGE
110
VOUT = 500mVP-P fBB = 1MHz fLO = 2437MHz
100
90
80
LNA HIGH GAIN
70
RECEIVER GAIN (dB)
60
LNA LOW GAIN
50
40
30
20
10
0 0 0.2 0.4 0.6 0.8 1.0 VRX_AGC (V) 1.2 1.4 1.6 1.8 2.0
Figure 2. Receiver Gain vs. VRX_AGC 20 ______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
TRANSMITTER GAIN vs. GAIN-CONTROL VOLTAGE
5 NORMALIZED TO +25C VTX_GC = 0V 0
-5 NORMALIZED TRANSMITTER GAIN (dB)
-10
TA = +85C TA = +25C
-15
TA = -40C
-20
-25
-30 0 0.2 0.4 0.6 0.8 1.0 VTX_GC (V) 1.2 1.4 1.6 1.8 2.0
Figure 3. Transmitter Gain vs. VTX_GC
______________________________________________________________________________________
21
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
The DC offset circuitry uses a sample-and-hold technique to accomplish this DC offset nulling. Over time (many seconds), the sample-and-hold storage cap slowly discharges, causing the DC value at the Tx BB to slowly increase, and the LO level in the RF output to slowly increase. This can be seen on the bench during evaluation, when the transceiver is left in Tx mode for more than 30 to 60 seconds. Even under worst-case conditions, however, the DC null value changes very little during the longest 802.11b Tx burst of 20ms--LO suppression in 802.11b applications always remains around the -30dBc typical level specified in the Electrical Characteristics table. Transmit Gain Control The transmit gain-control input provides a direct analog control over the transmit path gain. The transmit gain of the MAX2822 is controlled by an external voltage at pin TX_GC. The typical gain-control characteristic is provided in the Typical Operating Characteristics Transmitter Gain Control vs. Gain-Control Voltage graph and again as a full-page plot in Figure 3. The input is a high-impedance analog input designed to directly connect to the DAC output of the baseband IC. Some local noise filtering through a simple RC network at the input is permissible. However, the time constant of this network should be kept sufficiently low so the desired response time of the Tx gain-control function is not limited. During the Tx turn-on sequence, internally the gain is set at the minimum while the Tx baseband offset calibration is taking place. The RF output is effectively blanked for the first 2.2s after TX_ON is taken high. After 2.2s, the blanking is released, and the gain-control amplifier ramps to the gain set by the external voltage applied to the TX_GC input.
MAX2822
idle current based on the output power level of the PA. See Table 8 for a description of the TRANSMIT control bits, and the corresponding PA predriver and PA bias currents. These two bias current settings significantly affect both efficiency and linearity. They should be chosen based on the target output power for the application. Table 9 shows the recommended register settings for three target output powers.
Synthesizer
Channel Frequency and Reference Frequency The synthesizer/PLL channel frequency and reference settings establish the divider/counter settings in the integer-N synthesizer of the MAX2822. Both the channel frequency and reference divider are programmable through the serial interface. The channel frequency is programmed as a channel number 0 to 99 to set the carrier frequency to 2400MHz to 2499MHz (LO frequency = channel + 2400). The reference divider is programmable to allow for 22MHz or 44MHz reference oscillators. These settings are intended to cover only the required 802.11b channel spacing and the two typical crystal oscillator options used in the radios. Reference Oscillator Input The reference oscillator inputs ROSCP and ROSCN are high-impedance analog inputs. They are designed to be connected to the reference oscillator output through a coupling capacitor. The input amplitude can range from 200mVP-P to 500mVP-P; therefore, in the case of a reference oscillator with a CMOS output, the signal must be attenuated before being applied to the ROSC inputs. The signal can be attenuated with a resistor- or capacitor-divider network. Loop Filter The PLL uses a classical charge pump into an external loop filter (C-RC) in which the filter output connects to the voltage tuning input of the VCO. This simple thirdorder lowpass loop filter closes the loop around the synthesizer. The Typical Application Circuit shows the loop filter elements around the MAX2822. The capacitor and resistor values are set to provide the loop bandwidth required to achieve the desired lock time while also maintaining loop stability. Refer to the MAX2822
Power Amplifier
The MAX2822 provides two programmable analog current sources for internally biasing the on-chip RF power amplifier and the PA predriver. The PA predriver current is controlled by two bits in the TRANSMIT control register (TRANSMIT:D5, D4). The value of the PA bias current is determined by four bits (TRANSMIT:D3-D0). This programmability permits optimizing of the power amplifier
Table 9. Suggested PA and PA Driver Bias Current Settings
TARGET OUTPUT POWER (dBm) +3 +12 +17 PA DRIVER BIAS SETTING (TRANSMIT: D5, D4) 00 01 10 PA BIAS SETTING (TRANSMIT: D3-D0) 0011 0111 1101
22
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
EV kit schematic for component values. A 45kHz loop bandwidth is recommended to ensure the loop settles quickly enough to achieve 5s Tx turnaround time and 10s Rx turnaround time. This is the loop filter on the EV kit. Narrowing the loop bandwidth increases the settling time and results in unacceptable Tx/Rx turnaround time performance. Application Circuit, connect the ground side of C30 and C52 to the ground path for GND_CP, and connect the ground side of C31 to the ground path for GND_VCO. Keeping the charge-pump return currents from bouncing the VCO's ground minimizes the LO comparison frequency spurs. * BYP: This bypass capacitor is directly connected to the VCO bias circuitry--it is used to filter out noise within the loop bandwidth of the PLL (about 50kHz). The value for this capacitor is critical--be sure to use the 2000pF capacitor specified in the Typical Application Circuit. Keep this cap as close to the IC as possible, since noise pickup on this trace couples directly into the VCO bias and degrade phase noise.
MAX2822
PC Board Layout
Careful PC board layout is mandatory for any radio to meet its specifications. General rules for RF layout apply: keep differential pairs close together, keep all RF traces as short as possible, keep RF bypassing as close to the IC as possible, provide a separate filtered supply line from a large central filter capacitor for each VCC pin (star supply bypassing topology), and have each ground pin use its own via to the ground plane-- do not connect ground pins directly to the ground slug on the IC. In addition, below is a list of more specific layout issues to keep in mind for the MAX2822: * RF I/O: Keep RF differential pair from the IC to the balun/filter electrically and environmentally symmetrical. That is, shape the top layer ground equally on either side of the traces, and place the RF decoupling caps for the nearby RF supplies in a symmetrical fashion. This minimizes second-order distortion of the signal on the differential pair. * RBIAS: This external resistor sets the bias for the RF section of the transceiver, and this pin is connected directly to the bias section. The network connected to this port must look high impedance to RF, so do not place any RF filtering here--use only a 1% or 2% 12k resistor, as specified in the Typical Application Circuit. Place this resistor as close to the IC as possible on the top layer of the PC board. * GND_DIG: Use a via to connect this digital ground to the main PC board ground plane. The small inductance of the trace and the via helps to filter out the noise from the digital interface, and helps keep the main system ground clean. It is very important not to connect this directly to the IC ground slug, or directly to any other ground pins, which allows noise from the digital section to couple into sensitive sections of the radio. * PLL section (CP_OUT, GND_CP, GND_VCO, TUNE): The capacitors directly at the output of the PLL's charge pump need to have their ground return connected as close to the charge pump's ground as possible, and as isolated from the VCO's ground as possible. Create separate vias to the ground plane for each of the two grounds (GND_CP and GND_VCO). Referring to the Typical
Supply and Regulation
The typical application circuit for the MAX2822 employs two low-dropout linear regulators (LDOs)--one supplies the internal VCO, and the other supplies everything else (see the Pin Description table for details on supply pin names, numbers, and functions). Supplying the VCO from a dedicated LDO minimizes noise pickup by the VCO that can degrade phase noise and produce spurs. The VCO only draws 10mA, so power dissipation is not an issue. Choose a small, low-noise, high-PSRR LDO like the MAX8510. This LDO comes in a tiny 5-pin SC70 package and is available in many preset output voltages in the 2.7V to 3.0V range. Having the VCO and the rest of the IC supplied from different voltages is acceptable. Therefore, if the MAX2822 main supply is 2.7V, but the application already has a low-noise, 3.0V supply available, simply run the VCO from this 3.0V supply--there is no need for another dedicated 2.7V supply for the VCO. Switching power supplies should not be used to directly power any RF transceiver; the spurious content of their outputs often falls in the middle of the system's baseband spectrum (50kHz to 11MHz). This can couple into the Tx path and degrade the output spectrum, and can couple into the Rx path and degrade sensitivity and BER. When laying out the supply lines for the IC, always use a star bypassing topology. Have a large (10F) lowESR capacitor at the main supply connection point, and run dedicated traces to each of the supply pins (there are about ten in total). Each supply pin should have a pair of smaller decoupling caps (10nF and 100pF work well). It is especially important to isolate the supplies for the LNA bias (VCC_LNA) and the Rx baseband filter bias (VCC_BUF). Also be sure to use local RF decoupling on the logic lines. Proper decoupling minimizes noise pickup and coupling.
23
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Typical Application Circuit
DIGITAL MODE-CONTROL SIGNALS FROM/TO BASEBAND IC Rx ANALOG OUTPUT SIGNAL DIGITAL MODE-CONTROL SIGNALS TO/FROM BASEBAND IC TO BASEBAND IC
DAC OUTPUT FROM BASEBAND IC
VCC_RMX
VCC_BUF
RX_BBQN
RX_BBQP
RX_BBIN
RX_BBIP
RX_AGC
RX_ON
TX_ON
RX_1K
38
48 VCC_LNA VREF RF_GAIN VCC_REF GND RFP 1 2 3 4 5 6 7 8 9 10 PWR DET PWR_DET INPUT MATCH
47
46
45
44
43
42
41
40
39
DOUT
37 36 35 34 33 32 SHDNB VCC_RXF VCC_LO VCC_VCO BYP TUNE GND_VCO GND_CP CP_OUT LOOP FILTER VCC_CP CSB SCLK
PROGRAMMING AND MODE CONTROL
TO BBIC
Rx GAIN-CONTROL SIGNALS TO/FROM BASEBAND IC
N.C.
MAX2822
T/R SWITCH OUTPUT MATCH 90 0
31 30
RF I/O TO RF BPF AND ANT
RFN GND VCC_PA VCC_DRVR BIAS TX_GC
90
0
INTEGER-N SYNTHESIZER
29 28 27
11 12 13 14 15 16 17
VOS COMP
SERIAL INTERFACE
26 25
DAC OUTPUT FROM BASEBAND IC
SERIAL INTERFACE TO BASEBAND IC
18
19
20
21
22
23
24
PWR_DET
ROSCP
VCC_TMX
GND_DIG
TX_BBQP
VCC_DIG
TX_BBIN
TX_BBIP
ROSCN
TX_BBQN
VCC_TXF
REFERENCE OSCILLATOR INPUT Tx ANALOG INPUT SIGNAL FROM BASEBAND IC PA POWER-DETECTOR OUTPUT
DIN
Chip Information
TRANSISTOR COUNT: 16,097
24
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX2822
PACKAGE OUTLINE 32,44,48L QFN, 7x7x0.90 MM
21-0092
H
1 2
______________________________________________________________________________________
32, 44, 48L QFN.EPS
25
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
U
PACKAGE OUTLINE, 32,44,48L QFN, 7x7x0.90 MM
21-0092
H
2 2
26
______________________________________________________________________________________
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX2822
D2 D D/2 k
C L
b D2/2
E/2 E2/2 (NE-1) X e
C L
E
E2
k L DETAIL A e (ND-1) X e
C L
C L
L
L
e
e
A1
A2
A
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE 32, 44, 48L QFN THIN, 7x7x0.8 mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0144
1 2
B
______________________________________________________________________________________
32, 44, 48L QFN .EPS
27
2.4GHz 802.11b Zero-IF Transceiver with Integrated PA and Tx/Rx Switch MAX2822
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
COMMON DIMENSIONS
EXPOSED PAD VARIATIONS
** NOTE: T4877-1 IS A CUSTOM 48L PKG. WITH 4 LEADS DEPOPULATED. TOTAL NUMBER OF LEADS ARE 44.
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE 32, 44, 48L QFN THIN, 7x7x0.8 mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0144
2 2
B
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
28 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX2822ETM

	To Download MAX2822ETM Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .