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19-1606; Rev 0; 1/00
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
General Description
The MAX2720/MAX2721 are low-cost, high-performance, direct I/Q modulators designed for use in widebandCDMA and wireless local-loop (WLL) systems. Their direct-upconversion architecture reduces system cost, component count, and board space compared to devices with dual-conversion architectures. The MAX2720/MAX2721 include an I/Q modulator, a variable gain amplifier (VGA), and a power amplifier (PA) driver. The quadrature modulator accepts differential baseband I/Q signals and directly modulates an RF carrier in the 1.7GHz to 2.1GHz range (MAX2720) or the 2.1GHz to 2.5GHz range (MAX2721). The VGA provides 35dB of output power control. The modulator's amplitude and phase balance yield 35dBc of sideband suppression and 30dBc of carrier suppression. These devices feature an LO frequency doubler that allows the external LO source to operate at half-frequency or full-frequency when disabled. The MAX2720/MAX2721 operate from a single +2.7V to +3.3V supply and require only 77mA (MAX2720) or 86mA (MAX2721) of supply current. An additional 20mA of supply current is saved by disabling the stand-alone PA driver. A low-power shutdown mode further reduces supply current to less than 0.1A. The device is packaged in the small 20-pin TSSOP-EP with exposed paddle to improve RF performance. o RF Frequency Range 1.7GHz to 2.1GHz (MAX2720) 2.1GHz to 2.5GHz (MAX2721) o Integrated I/Q Modulator, LO Doubler, VGA, and PA Driver o 35dB VGA Gain Control Range o 35dBc Sideband Suppression o 30dBc Carrier Suppression o Low Supply Current 77mA (MAX2720), 86mA (MAX2721) 20mA Reduction with PA Driver Disabled o 0.1A Supply Current in Shutdown Mode o +2.7V to +3.3V Single-Supply Operation
Features
MAX2720/MAX2721
Ordering Information
PART MAX2720EUP MAX2721EUP *Exposed paddle. TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 20 TSSOP-EP* 20 TSSOP-EP*
Applications
Wireless Local Loop (WLL) Wideband CDMA Systems LMDS/MMDS 2.4GHz Broadband ISM Radios DCS/PCS Base Stations
GND 1 DROUT 2
Functional Diagram
MAX2720/MAX2721
PA DRIVER VGA SHDN 3 VCC 4 GND 5 90 VCC 6 I- 7 I+ 8 LO PHASE SHIFTER 0 15 VCC 14 Q13 Q+ 12 VCC x2 LO DOUBLER 11 LO 18 PC 17 MODOUT 16 ENX2 20 DRIN 19 GND
Pin Configuration appears at end of data sheet.
VCC 9 GND 10
BIAS
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V ENX2, SHDN, PC, I+, I-, Q+, Q-, LO, DRIN to GND ........................................-0.3V to (VCC + 0.3V) ENX2, SHDN Continuous Current.....................................10mA PC Continuous Current.....................................................10mA I+ to I-, Q+ to Q- ....................................................................2V MODOUT, DROUT to GND Short-Circuit Duration .................10s Continuous Power Dissipation (TA = +70C) 20-Pin TSSOP-EP (derate 21.7mW/C above +70C) ......1.74W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range ............................ -65C to +150C 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
(VCC = +2.7V to +3.3V; SHDN = VCC; ENX2 = GND; VPC = 0.5V; no input AC signals applied to I+, I-, Q+, Q-, LO, DRIN. MODOUT and DROUT = VCC, TA = -40C to +85C. Typical values are at VCC. = +3V, TA = +25C, unless otherwise noted.) PARAMETER Supply Voltage Supply Current Supply Current with PA Driver Disabled Shutdown Supply Current Logic Input High Voltage Logic Input Low Voltage Logic Input Bias Current PC Input Bias Current 0.5V < VPC < 2.5V 0.5V < VPC < 2.5V, SHDN = GND -1 -5 2.5 MAX2720 MAX2721 MAX2720, DRIN = GND MAX2721, DRIN = GND SHDN = GND 2.0 0.5 1 5 CONDITIONS MIN 2.7 77 86 59 67 0.1 TYP MAX 3.3 119 129 86 96 10 UNITS V mA mA A V V A A
AC ELECTRICAL CHARACTERISTICS
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER I/Q BASEBAND INPUTS I/Q Input -1dB Bandwidth (Note 2) I/Q Input -3dB Bandwidth (Note 2) I/Q Differential Input Level I/Q Gain Imbalance I/Q Phase Imbalance I/Q Input Resistance I/Q Input Resistance Mismatch I/Q Input Capacitance Group Delay Ripple Group Delay Mismatch fI = fQ < BW-3dB, 0.5V < VPC < 2.5V fI = fQ < BW-3dB, 0.5V < VPC < 2.5V fI = fQ < BW-1dB fI = fQ < BW-1dB fI = fQ < BW-1dB 100kHz < fI+ = fQ+ < 2MHz 100kHz < fI = fQ < 2MHz 1.6 14 20 40 200 0.2 1.0 2.0 18 5 1 1 630 MHz MHz mVp-p dB degrees k pF ns ns CONDITIONS MIN TYP MAX UNITS
2
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER MODULATOR OUTPUT Frequency Range (Note 3) MAX2720 MAX2721 MAX2720, VPC = 2.5V, ENX2 = VCC or GND, TA = +25C (Note 3) MAX2721, VPC = 2.5V, ENX2 = VCC or GND, TA = +25C (Note 3) VPC = 2.5V, TA = -40C to +85C VPC = 0.5V, ENX2 = VCC or GND MAX2720 MAX2721 MAX2720 MAX2721 MAX2720 MAX2721 MAX2720 MAX2721 29 28 +1 +3 +8 +9 1700 2100 -12.5 -10.5 -8.5 -5.0 1.0 0.8 35 32 19 +5 +6 +14 +14 2:1 -141 26 24 20 30 28 33 31 25 40 35 50 VCC = +3.0V + 100mVp-p at 10kHz/300kHz 41 45 dBc dB dBc dBc -137 dBm/Hz 23 2100 2500 -6.0 dBm -2.5 1.8 1.5 dB dB dB/V dBm dBm MHz CONDITIONS MIN TYP MAX UNITS
MAX2720/MAX2721
Output Power, High
Output Power Variation Over Temperature Power Control Range PC Slope Output 1dB Compression Point Output Third-Order Intercept Point (Note 4) Output VSWR Out-of-Band Noise Density Carrier Suppression
Slope between VPC = 1V and VPC = 2V VPC = 2.5V VPC = 2.5V 0.5V < VPC < 2.5V VPC = 2.5V, I/Q terminated in 50 MAX2720, 0.5V < VPC < 2.5V MAX2721 0.5V < VPC < 2.5V VPC = 2.5V VPC = 0.5V MAX2720 MAX2721
Sideband Suppression MODOUT to LO Input Isolation Power-Supply Ripple Rejection (Note 5)
LO BUFFER, LO FREQUENCY DOUBLER, QUADRATURE GENERATOR MAX2720 LO Frequency Range (Note 3) MAX2721 MAX2720 LO Input VSWR MAX2721 LO Input Power (Note 3) ENX2 = GND ENX2 = VCC ENX2 = GND ENX2 = VCC ENX2 = GND ENX2 = VCC ENX2 = GND ENX2 = VCC -16 850 1700 1050 2100 1.9:1 1.8:1 1.8:1 1.6:1 -10 dBm 1050 2100 1250 2500 MHz
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1) PARAMETER PA DRIVER Frequency Range (Note 6) Gain (Note 6) Gain Variation Over Temperature Noise Figure Output 1dB Compression Point Output Third-Order Intercept Point Reverse Isolation DROUT to LO Input Isolation Input VSWR Output VSWR MAX2720 MAX2721 MAX2720 MAX2721 TA = -40C to +85C MAX2720 MAX2721 MAX2720 MAX2721 MAX2720 (Note 7) MAX2721 (Note 8) +9.5 +8 +22 +20 MAX2720 MAX2721 1700 2100 11 8.5 13.5 11.5 0.4 0.3 2.4 2.6 +12.5 +11 +24 +24 19 65 1.5:1 1.5:1 2100 2500 15.5 15.5 0.8 0.8 MHz dB dB dB dBm dBm dB dB CONDITIONS MIN TYP MAX UNITS
Note 1: Min/max limits are guaranteed by design and characterization and are not production tested. Note 2: I/Q input bandwith is determined by the baseband source impedance and the I/Q input capacitance. The bandwith can be increased by lowering the baseband source impedance. Note 3: MODOUT output power specifications are met over this frequency range for VPC = 2.5V and TA = +25C. Note 4 IP3 measured with two tones, f1 = 500kHz and f2 = 600kHz, at 100mVp-p each. Note 5: Measured relative to desired upconverted signal level. Note 6 DROUT gain specifications are met over this frequency range at TA = +25C. Note 7: IP3 measured with two tones, f1 = 1900MHz and f2 = 1901MHz, at -18dBm each. Note 8: IP3 measured with two tones, f1 = 2315MHz and f2 = 2316MHz, at -18dBm each.
4
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720
SUPPLY CURRENT vs. SUPPLY VOLTAGE WITH PA DRIVER ENABLED
MAX2720/21toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE WITH PA DRIVER DISABLED
MAX2720/21toc02
MODULATOR OUTPUT POWER vs. RF FREQUENCY
VPC = 2.5V -10 OUTPUT POWER (dBm) -20 -30 -40 -50 VPC = 0.5V TA = +85C TA = -40C 1700 1800 1900 2000 2100 RF FREQUENCY (MHz) VPC = 1.5V TA = +25C
MAX2720/21toc04
100 90 80 SUPPLY CURRENT (mA) 70 60 50 40 30 20 10 0 2.7 ENX2 = GND ENX2 = VCC 2.8 2.9 3.0 3.1 3.2 TA = -40C TA = +85C TA = +25C
100 90 80 SUPPLY CURRENT (mA) 70 60 50 40 30 20 10 0 ENX2 = GND ENX2 = VCC 2.7 2.8 2.9 3.0 3.1 3.2 TA = -40C TA = +25C DRIN = GND TA = +85C
0
-60 3.3
3.3
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
MODULATOR PERFORMANCE vs. LO POWER (ENX2 = GND)
MAX2720/21toc05
MODULATOR PERFORMANCE vs. LO POWER (ENX2 = VCC)
OUTPUT POWER OUTPUT POWER (dBm) AND CARRIER AND SIDEBAND SUPPRESSION (dBc) -10 -20 -30 -40 -50 -60 -70 SIDEBAND SUPPRESSION -19 -17 -15 -13 -11 -9 -7 -5 CARRIER SUPPRESSION
MAX2720/21toc06
0 OUTPUT POWER (dBm) AND CARRIER AND SIDEBAND SUPPRESSION (dBc) OUTPUT POWER -10 -20 -30 -40 SIDEBAND SUPPRESSION -50 -60 -19 -17 -15 -13 -11 -9 -7 CARRIER SUPPRESSION
0
-5
LO POWER (dBm)
LO POWER (dBm)
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5
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc07
MODULATOR CARRIER SUPPRESSION vs. PC VOLTAGE (ENX2 = GND)
-5 CARRIER SUPPRESSION (dBc) -10 -15 -20 2.1GHz -25 -30 -35 -40 1.7GHz -60 0 0.5 1.0 1.5 2.0 2.5 3.0 1.9GHz
MAX2720/21toc08
MODULATION SIDEBAND SUPPRESSION vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc09
0 -5 -10 OUTPUT POWER (dBm) -15 -20 -25 -30 -35 -40 -45 -50 0 0.5 1.0 1.5 2.0 2.5 1.9GHz 1.7GHz 2.1GHz
0
0 SIDEBAND SUPPRESSION (dBc) -10 -20 -30 -40 -50 1.7GHz
1.9GHz 2.1GHz
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = VCC)
MAX2720/21toc10
MODULATOR CARRIER SUPPRESSION vs. PC VOLTAGE (ENX2 = VCC)
MAX2720/21toc11
MODULATOR SIDEBAND SUPPRESSION vs. PC VOLTAGE (ENX2 = VCC)
-5 SIDEBAND SUPPRESSION (dBc) -10 -15 -20 -25 -30 -35 -40 -45 -50 2.1GHz 0 0.5 1.0 1.5 2.0 2.5 3.0 1.9GHz 1.7GHz
MAX2720/21toc12
0 -5 -10 OUTPUT POWER (dBm) -15 -20 -25 -30 -35 -40 -45 -50 0 0.5 1.0 1.5 2.0 2.5 2.1GHz 1.9GHz 1.7GHz
0 -10 CARRIER SUPPRESSION (dBc) -20 2.1GHz -30 -40 -50 -60 -70 1.7GHz 1.9GHz
0
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc13
MODULATOR CARRIER SUPPRESSION vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc14
MODULATOR SIDEBAND SUPPRESSION vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc15
0 -5 -10 OUTPUT POWER (dBm) -15 -20 -25 -30 -35 -40 -45 -50 0 0.5 1.0 1.5 2.0 2.5 TA = +85C TA = +25C TA = -40C
0 -5 CARRIER SUPPRESSION (dBc) -10 -15 -20 -25 -30 -35 TA = +85C -40 TA = -40C TA = +25C
0 -10 -20 -30 -40 -55 TA = +25C -60 TA = -40C TA = +85C
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
SIDEBAND SUPPRESSION (dBc)
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = VCC)
MAX2720/21toc16
MODULATOR CARRIER SUPPRESSION vs. PC VOLTAGE (ENX2 = VCC)
MAX2720/21toc17
MODULATOR SIDEBAND SUPPRESSION vs. PC VOLTAGE (ENX2 = VCC)
MAX2720/21toc18
0 -5 -10 OUTPUT POWER (dBm) -15 -20 -25 -30 -35 -40 -45 -50 0 0.5 1.0 1.5 2.0 2.5 TA = +25C TA = +85C TA = -40C
0 -10 CARRIER SUPRESSION (dBc) -20 TA = +85C -30 -40 -50 -60 -70 0 0.5 1.0 1.5 2.0 2.5 TA = +25C TA = -40C
0 -10 SIDEBAND SUPRESSION (dBc) -20 TA = +85C -30 -40 -50 -60 TA = -40C TA = +25C
3.0
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = -40C)
MAX2720 toc19
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = +25C)
MAX2720 toc20
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = +85C)
0 OUTPUT POWER (dBm) -10 -20 -30 -40 -50 -60 VPC = 2.5V VPC = 2.0V VPC = 1.5V VPC = 1.0V VPC = 0.5V
MAX2720 toc21
10 0 OUTPUT POWER (dBm) -10 VPC = 1.0V -20 -30 -40 -50 -60 10 100 1000 VPC = 2.5V VPC = 2.0V VPC = 1.5V VPC = 0.5V
10 0 OUTPUT POWER (dBm) -10 VPC = 1.0V -20 -30 -40 -50 -60 VPC = 2.5V VPC = 0.5V VPC = 2.0V VPC = 1.5V
10
10,000
10
100
1000
10,000
10
100
1000
10,000
INPUT LEVEL (mVp-p)
INPUT LEVEL (mVp-p)
INPUT LEVEL (mVp-p)
MODULATOR OUTPUT IP3 vs. PC VOLTAGE
MAX2720/21toc22
LO PORT VSWR vs. LO FREQUENCY (ENX2 = GND)
MAX2720-24
LO PORT VSWR vs. LO FREQUENCY (ENX2 = VCC)
MAX2720-25
25 20 15 10 OUTPUT IP3 (dBm) 5 0 -5 -10 -15 -20 -25 -30 0 0.5 1.0 1.5 2.0 2.5 TA = -40C TA = +85C TA = +25C
2.8
2.8
2.4
2.4
VSWR
VSWR
2.0
2.0
1.6
1.8
1.2
1.4
1.0 3.0 850 890 930 970 1010 1050 PC VOLTAGE (V) FREQUENCY (MHz)
1.0 1700 1780 1860 1940 2020 2100 FREQUENCY (MHz)
8
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720/MAX2721
MAX2720
PA DRIVER GAIN vs. SUPPLY VOLTAGE
MAX2720/21toc27
PA DRIVER OUTPUT IP3 vs. SUPPLY VOLTAGE
MAX2720/21toc28
PA DRIVER OUTPUT P1dB vs. SUPPLY VOLTAGE
19 18 OUTPUT P1dB (dBm) 17 16 15 14 13 12 11 10 TA = +25C TA = -40C 2.7 2.8 2.9 3.0 3.1 3.2 3.3 TA = +85C
MAX2720/21toc29
15 TA = -40C 14
30 29 28 OUTPUT IP3 (dBm) 27 26 25 24 23 22 21 TA = -40C TA = +85C TA = +25C
20
GAIN (dB)
13 TA = +85C 12
TA = +25C
11
10 2.7 2.8 2.9 3.0 3.1 3.2 3.3 SUPPLY VOLTAGE (V)
20 2.7 2.8 2.9 3.0 3.1 3.2
Page 1
3.3
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
PA DRIVER GAIN vs. RF FREQUENCY
MAX2720/21toc30
PA DRIVER OUTPUT IP3 vs. FREQUENCY
MAX2720/21toc31
18 16 14 GAIN (dB) 12 10 8 6 4 2 0 1700 1800 1900 2000 TA = +25C TA = +85C TA = -40C
29 28 OUTPUT IP3 (dBm) 27 26 25 24 23 22 21 20 1700 1800 1900 FREQUENCY (MHz) 2000 TA = -40C TA = +85C TA = +25C
19 18 OUTPUT P1dB (dBm) 17 16 15 14 13 12 11 TA = +85C 1700 1800 1900 FREQUENCY (MHz) 2000 TA = +25C TA = -40C
2100
2100
10 2100
RF FREQUENCY (MHz)
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MAX2720/21toc32
20
30
PA DRIVER OUTPUT P1dB COMPRESSION POINT vs. FREQUENCY
20
9
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2720
PA DRIVER NOISE FIGURE vs. FREQUENCY
MAX2720/21toc33
PA DRIVER OUTPUT POWER vs. INPUT POWER
TA = +25C 15 TA = +85C OUTPUT POWER (dBm) 10 5 0 -5 -10 TA = -40C
MAX2720/21toc34
5.0 4.5 4.0 NOISE FIGURE (dB) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 1700 1800 1900 FREQUENCY (MHz) TA = -40C 2000 TA = +25C TA = +85C
20
-15 2100 -25 -20 -15 -10 -5 0 5 10 15 20 INPUT POWER (dBm)
10
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1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
SUPPLY CURRENT vs. SUPPLY VOLTAGE WITH PA DRIVER ENABLED
MAX2720/21toc35
SUPPLY CURRENT vs. SUPPLY VOLTAGE WITH PA DRIVER DISABLED
MAX2720/21toc36
110 100 SUPPLY CURRENT (mA) 90 80 70 60 50 40 30 20 2.7 2.8 2.9
TA = +85C
110 100 SUPPLY CURRENT (mA) 90 80 70 60 50 40
DRIN = GND
-5 -10 OUTPUT POWER (dBm) -15 -20 -25 -30 -35 -40 -45 -50
VPC = 2.5V VPC = 1.5V
TA= -40C
TA = +85C
TA = +25C
TA= +25C
TA= +85C
TA = +25C TA = -40C
TA = -40C ENX2 = GND ENX2 = VCC 3.0 3.1 3.2 3.3
VPC = 0.5V
30 20 2.7
ENX2 = GND ENX2 = VCC 2.8 2.9 3.0 3.1
3.2
3.3
2100
2200
2300
2400
2500
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
RF FREQUENCY (MHz)
MODULATOR PERFORMANCE vs. LO POWER (ENX2 = GND)
MAX2720/21toc39
OUTPUT POWER (dBm) AND CARRIER AND SIDEBAND SUPPRESSION (dBc)
OUTPUT POWER (dBm) AND CARRIER AND SIDEBAND SUPPRESSION (dBc)
-5 -10 -15 -20 -25 -30 -35 -40
OUTPUT POWER
-5 -10 -15 -20 -25 -30 -35 -40
OUTPUT POWER
SIDEBAND SUPPRESSION
SIDEBAND SUPPRESSION
CARRIER SUPPRESSION -19 -17 -15 -13 -11 -9 RF FREQUENCY (MHz) -7 -5
CARRIER SUPPRESSION
-19
-17
-15
-13
-11
-9
-7
-5
LO POWER (dBm)
______________________________________________________________________________________
MAX2720/21toc40
0
MODULATOR PERFORMANCE vs. LO POWER (ENX2 = VCC)
0
11
MAX2720 toc38
120
120
0
MODULATOR OUTPUT POWER vs. RF FREQUENCY
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = GND)
MAX2720/21toc41
MAX2720/21toc42
2.1GHz -5 OUTPUT POWER (dBm) -10 -15 -20 -25 -30 -35 -40 0 0.5 1.0 1.5 2.0 2.5 2.3GHz 2.5GHz
-5 CARRIER SUPPRESSION (dBm) -10 -15 -20 2.5GHz -25 -30 -35 2.3GHz 2.1GHz
-5 SIDEBAND SUPRESSION (dBc) -10 -15 -20 -25 -30 -35 -40 2.1GHz 0 0.5 1.0 2.5GHz
2.3GHz 1.5 2.0 2.5 3.0
3.0
-40 0 0.5 1.0 1.5 2.0 2.5 3.0 PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = VCC)
MAX2721 TOC44
MODULATOR CARRIER SUPRESSION vs. PC VOLTAGE (ENX2 = VCC)
-5 CARRIER SUPRESSION (dBc) -10 -15 2.3GHz -20 -25 -30 -35 2.1GHz -40 -45 2.5GHz
MAX2721 TOC45
MODULATOR SIDEBAND SUPRESSION vs. PC VOLTAGE (ENX2 = VCC)
-5 SIDEBAND SUPRESSION (dBc) -10 -15 -20 -25 2.3GHz -30 -35 2.1GHz -40 0 0.5 1.0 1.5 2.0 2.5 3.0 2.5GHz
MAX2721 TOC46
0 -5 OUTPUT POWER (dBm) -10 -15 -20 -25 -30 -35 -40 -45 0 0.5 1.0 1.5 2.0
2.1GHz 2.3GHz 2.5GHz
0
0
2.5
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
12
______________________________________________________________________________________
MAX2721 TOC43
0
CARRIER SUPPRESSION vs. PC VOLTAGE (ENX2 = GND)
0 0
SIDEBAND SUPRESSION vs. PC VOLTAGE (ENX2 = GND)
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = GND)
MAX2721 TOC47
MODULATOR CARRIER SUPRESSION vs. PC VOLTAGE (ENX2 = GND)
MAX2721 TOC48
MODULATOR SIDEBAND SUPRESSION vs. PC VOLTAGE (ENX2 = GND)
-5 SIDEBAND SUPRESSION (dBc) -10 -15 -20 -25 -30 -35 TA = +85C -40 0 0.5 1.0 1.5 2.0 2.5 3.0 TA = -40C TA = +25C
MAX2721 TOC49
0 -5 OUTPUT POWER (dBm) -10 -15 -20 -25 -30 -35 -40 0 0.5 1.0 1.5 2.0 2.5 TA = +25C TA = -40C
0 -5 CARRIER SUPRESSION (dBc) -10 -15 -20 TA = -40C -25 -30 TA = +25C -35 TA = +85C
0
TA = +85C
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
PC VOLTAGE (V)
MODULATOR OUTPUT POWER vs. PC VOLTAGE (ENX2 = VCC)
-5 OUTPUT POWER (dBm) -10 -15 -20 -25 -30 -35 -40 0 0.5 1.0 1.5 2.0 2.5 3.0 PC VOLTAGE (V) TA = +25C TA = +85C TA = -40C
MAX2721 TOC450
MODULATOR CARRIER SUPRESSION vs. PC VOLTAGE (ENX2) = VCC
MAX2721 TOC51
-5 CARRIER SUPPRESSION (dBc) -10 -15 -20 -25 -30 -35 -40 0 0.5 1.0 1.5 2.0 2.5 TA = +85C TA = +25C TA = -40C
-5 SIDEBAND SUPPRESSION (dBc) -10 -15 -20 -25 -30 -35 -40 TA = +85C 0 0.5 1.0 1.5 2.0 2.5 TA = -40C TA = +25C
3.0
3.0
PC VOLTAGE (V)
PC VOLTAGE (V)
______________________________________________________________________________________
13
MAX2721 TOC52
0
0
0
MODULATOR SIDEBAND SUPPRESSION vs. PC VOLTAGE (ENX2 = VCC)
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = -40C)
MAX2721 TOC53
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = +25C)
MAX2721 TOC54
MODULATOR OUTPUT POWER vs. INPUT LEVEL (TA = +85C)
10 OUTPUT POWER (dBm) 0 -10 -20 -30 -40 -50 -60 VPC = 2.5V VPC = 2.0V VPC = 1.5V VPC = 1.0V VPC = 0.5V 10 100 1000 10,000
MAX2721 TOC55
20 10 OUTPUT POWER (dBm) 0 -10 -20 -30 -40 -50 -60 10 100 1000 VPC = 2.5V VPC = 2.0V VPC = 1.5V VPC = 1.0V VPC = 0.5V
20 10 OUTPUT POWER (dBm) 0 -10 -20 -30 -40 -50 -60 10 VPC = 2.5V VPC = 2.0V VPC = 1.5V VPC = 1.0V VPC = 0.5V 100 1000
20
10,000
10,000
INPUT LEVEL (mVp-p)
INPUT LEVEL (mVp-p)
INPUT LEVEL (mVp-p)
MODULATOR OUTPUT IP3 vs. PC VOLTAGE
20 15 OUTPUT IP3 (dBm) 10 5 0 -5 -10 -15 -20 -25 -30 0 0.5 1.0 1.5 2.0 2.5 3.0 INPUT LEVEL (mVp-p) TA = -40C TA = +25C
MAX2721 TOC56
MODULATOR OUTPUT P1dB COMPRESSION POINT vs. PC VOLTAGE
MAX2720/21toc57
LO PORT VSWR vs. LO FREQUENCY (ENX2 = VCC)
MAX2721toc58
25 TA = +85C
25 20 15 OUTPUT P1dB (dBm) 10 5 0 -5 -10 -15 -20 -25 0.5 1.0 1.5 PC VOLTAGE (V) 2.0 TA = +85C TA = +25C TA = -40C
2.6
2.4
2.0 VSWR 2.5
1.8
1.4
1.0 2100 2180 2260 2340 2420 2500 FREQUENCY (MHz)
14
______________________________________________________________________________________
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
LO PORT VSWR vs. FREQUENCY (ENX2 = GND)
MAX2721toc59
PA DRIVER GAIN vs. SUPPLY VOLTAGE
MAX2721 TOC61
PA DRIVER OUTPUT IP3 vs. SUPPLY VOLTAGE
29 28 OUTPUT IP3 (dBm) 27 26 25 24 23 22 TA = -40C TA = +85C TA = +25C
MAX2720/21toc62
2.0
15
30
1.8 GAIN (dB)
14
VSWR
13 TA = -40C TA = +25C
1.6
12
1.4 11 TA = +85C 1.0 1050 1090 1130 1170 1210 1250 FREQUENCY (MHz) 10 2.7 2.8 2.9 3.0 3.1 3.2 3.3 SUPPLY VOLTAGE (V)
21 20 2.7 2.8 2.9 3.0 3.1 3.2 3.3 SUPPLY VOLTAGE (V)
PA DRIVER OUTPUT P1dB vs. SUPPLY VOLTAGE
MAX2720/21toc63
PA DRIVER GAIN vs. RF FREQUENCY
MAX2720/21toc64
PA DRIVER OUTPUT IP3 vs. FREQUENCY
28 27 OUTPUT IP3 (dBm) 26 25 24 23 22 21 20 TA = -40C TA = +25C TA = +85C
MAX2720/21toc65
18 17 16 OUTPUT P1dB (dBm) 15 TA = +85C
18 16 14 12 GAIN (dB) 10 8 6 4 2 TA = +25C TA = +85C TA = -40C
29
14 13 12 11 10 9 8 2.7 2.8 2.9 3.0 3.1 3.2 3.3 SUPPLY VOLTAGE (V) TA = -40C TA = +25C
0 -2 2100 2200 2300 2400 2500 RF FREQUENCY (MHz)
2100
2200
2300 FREQUENCY (MHz)
2400
2500
______________________________________________________________________________________
15
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Typical Operating Characteristics (continued)
(MAX2720/MAX2721 EV Kit, VCC = +3.0V, SHDN = VCC, ENX2 = GND, VPC = 2.5V, input I/Q signals driven in quadrature, from a 1k source impedance, single-ended, fI+ = fQ+ = 500kHz, VI+ = VQ+ = 200mVp-p, PLO = -13dBm, fLO = 950MHz (MAX2720), fLO = 1157.5MHz (MAX2721), PDRIN = -12dBm, fDRIN = 1900MHz (MAX2720), fDRIN = 2315MHz (MAX2721), MODOUT and DROUT ports are matched to a 50 load, TA = +25C, unless otherwise noted.) (Note 1)
MAX2721
PA DRIVER OUTPUT P1dB vs. FREQUENCY
MAX2720/21toc66
PA DRIVER NOISE FIGURE vs. FREQUENCY
9 8 NOISE FIGURE (dB) 7 6 5 4 3 2 1 0 TA = +25C 2100 2200 2300 FREQUENCY (MHz) 2400 2500 TA = +85C TA = -40C
MAX2720/21toc67
20 18 16 OUTPUT P1dB (dBm) 14 12 10 8 6 4 2 0 2100 2200 2300 FREQUENCY (MHz) 2400 TA = -40C TA = +25C TA = +85C
10
2500
PA DRIVER OUTPUT POWER vs. INPUT POWER
TA = +25C 15 OUTPUT POWER (dBm) TA = -40C 10 TA = +85C
MAX2720/21toc68
2.0
5
-10
-15 -25 -20 -15 -10 -5 0 -5 10 15 20 INPUT POWER (dBm)
16
______________________________________________________________________________________
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
Pin Description
PIN 1, 5, 10, 19, EP NAME GND FUNCTION Ground. Connect to ground plane with lowest inductance path. Solder exposed paddle evenly to the board ground plane. PA Driver Open-Collector Output Port. Requires an external matching network and a pullup inductor to VCC for proper biasing. See Typical Application Circuit for recommended component values. Shutdown Control Input. Drive with a logic-level high to enable the device. Drive with a logiclevel low to disable the device. Bypass with a 1000pF capacitor to ground, as close to the pin as possible to minimize the amount of external noise coupled onto the control line. Supply Voltage Input. Bypass to ground with the specified capacitor as close to the pin as possible. (See Typical Application Circuit.) In-Phase Differential Input Ports. Requires DC-blocking capacitors. See Typical Application Circuit for recommended component values. Local Oscillator input. Internally matched to 50 over the operating frequency band. Requires a DC-blocking capacitor. See Typical Application Circuit for recommended component values. Quadrature Differential Input Ports. Requires DC-blocking capacitors. See Typical Application Circuit for recommended component values. Logic-Level Enable Input for LO Doubler. Drive with a logic-level low to enable the doubler, allowing the external LO to run at half-frequency, fLO = fOUT / 2. Drive with a logic-level high to disable the doubler, and allow the external LO to run at full-frequency, fLO = fOUT. Bypass with a 1000pF capacitor to ground as close to the pin as possible to minimize noise coupled into the control line. Modulator Open-Collector Output Port. Requires an external matching network and a pullup inductor to VCC for proper biasing. See Typical Application Circuit for recommended component values. Modulator Power Control Input. Apply a voltage between 0.5V to 2.5V to vary the output power of the I/Q modulator over a 30dB range. Bypass with a 1000pF capacitor to ground as close to the pin as possible to minimize noise on the control line. PA Driver Amplifier Input Port. Requires an external matching network and a DC-blocking capacitor that can be part of the matching network. See Typical Application Circuit for recommended component values. Connect to ground to disable the PA Driver and reduce supply current.
MAX2720/MAX2721
2
DROUT
3
SHDN
4, 6, 9, 12, 15 7, 8
VCC I-, I+
11
LO
13, 14
Q+, Q-
16
ENX2
17
MODOUT
18
PC
20
DRIN
Detailed Description
The MAX2720/MAX2721 upconvert in-phase (I) and quadrature (Q) baseband signals directly to RF frequencies of 1700MHz to 2100MHz (MAX2720) or 2100MHz to 2500MHz (MAX2721). They are designed for wideband-CDMA and WLL systems where direct I/Q modulation of the RF carrier reduces system cost, component count, and board space compared to dual-conversion architectures.
Internally, the MAX2720/MAX2721 include an I/Q modulator, a variable gain amplifier (VGA), and a PA driver. Separate modulator output and PA driver input ports allow insertion of a bandpass filter between the modulator and PA driver for increased noise rejection. Disable the stand-alone PA driver to reduce current consumption. A low-power shutdown mode further reduces current consumption to less than 0.1A. Additionally, a logiclevel control disables or enables an internal frequency doubler that allows the external LO to run at full or half frequency.
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17
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
I/Q Modulator
The MAX2720/MAX2721 modulator is composed of a pair of matched double-balanced mixers, an active LO quadrature generator, and a summing amplifier. The pair of mixers accept differential I/Q baseband signals that directly modulate the internal 0 and 90 LO signals applied to the I/Q mixers. An external LO source drives an internal LO quadrature generator that shifts the phase of the LO signal applied to the Q mixer by 90 relative to the LO signal applied to the I channel mixer. The modulated output of the I/Q mixers is summed together, and the undesired sideband is suppressed. The I+, I-, Q+, and Q- input ports feature high-linearity buffer amplifiers with a -1dB bandwidth of 20MHz and a -3dB bandwidth of 38MHz (1k I/Q source impedance), and accept differential input voltages up to 630mVp-p. Input bandwith can be extended to beyond 100MHz by lowering the I/Q source impedance. The ports are internally biased and therefore require DCblocking capacitors. For single-ended operation, bypass the I- and Q- ports with a capacitor to ground equal in value to the DC-blocking capacitors used on the I+ and Q+ ports. See the Typical Application Circuit for recommended component values. MAX2721 Typical Application Circuit for recommended component values. See Table 1 for matching to other frequencies.
LO Buffer and LO Frequency Doubler
The MAX2720/MAX2721 feature an internal LO frequency doubler that allows the external LO source to run at full or half frequency (Table 2). Operating the LO at half frequency reduces injection-pulling of the voltage-controlled oscillator (VCO) from the PA, and reduces the complexity of designing a high-frequency VCO. An internal two-pole bandpass filter is integrated before the LO phase-shift network to help reduce LO harmonic content and spurious mixing. To enable the LO frequency doubler, drive ENX2 to a logic-level low and operate the external LO source at half the RF carrier frequency. To disable the LO frequency doubler, drive ENX2 to a logic-level high and run the external LO source at the RF carrier frequency. See Table 2 for LO input frequency ranges. The LO port is a single-ended input that achieves a VSWR of better than 2:1 over the specified LO input frequency range. Since the port is internally terminated with 50, it requires a DC-blocking capacitor. See the Typical Applications Circuits for recommended component values. For optimum performance, drive the LO port with an input power of -16dBm to -10dBm. Driving the LO port with lower input power levels may affect quadrature performance, while higher input powers may increase LO leakage.
Variable Gain Amplifier (VGA)
A VGA follows the summing amplifier of the I/Q modulator. Apply a voltage between 0.5V and 2.5V to PC to vary the output power of the modulator over a 32dB span. The open-collector MODOUT output requires a pull-up inductor to VCC for proper biasing, an external matching network for optimum power transfer, and a DC-blocking capacitor. Since the MAX2720/MAX2721 are optimized for different frequency ranges, they require different output matching networks. See the MAX2720 and
PA Driver Amplifier
The PA driver provides a gain of 13.5dB for the MAX2720 and 11.5dB for the MAX2721. The DRIN input port requires an external matching network and a
Table 1. VGA MODOUT S22 Parameters (VCC = 3.0V, VPC = 2.5V, TA = +25C)
MAX2720 FREQUENCY (MHz) 1700 1750 1800 1850 1900 1950 2000 2050 2100 18 S22 MAG 0.914 0.909 0.896 0.884 0.871 0.868 0.878 0.892 0.897 S22 PHASE (degrees) -66.6 -68.9 -71.0 -73.0 -74.6 75.4 -77.1 -79.6 82.5 FREQUENCY (MHz) 2100 2150 2200 2250 2300 2350 2400 2450 2500 MAX2721 S22 MAG 0.861 0.861 0.832 0.811 0.807 0.834 0.866 0.891 0.905 S22 PHASE (degrees) -86.5 -91.3 -93.8 -94.4 -94.7 -94.8 -97.1 -100.5 -104.5
______________________________________________________________________________________
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
Table 2. LO Input Frequency Range
ENX2 LOGIC LEVEL Low High LO INPUT FREQUENCY RANGE (MHz) MAX2720 850 to 1050 1700 to 2100 MAX2721 1050 to 1250 2100 to 2500
tance. In direct I/Q modulator applications, radiated power from the PA can couple into the VCO tank. To reduce PA injection-pulling, the external VCO should be housed in a separate shielded compartment if possible.
MAX2720/MAX2721
Power-Supply, Logic, and PC Input Bypassing
Proper voltage supply bypassing is essential for high-frequency circuit stability. With the exception of pin 6, bypass all VCC pins with a 470pF capacitor as close to the VCC pins as possible. The decoupling capacitor for pin 6 also serves as part of an on-chip matching network, so it should be chosen to resonate out series inductance on the board. Some empirical adjustment may yield increased output power. See the MAX2720/MAX2721 Typical Application Circuit for suggested values. Bypass the ENX2, SHDN, and PC inputs with a 1000pF capacitor to ground to minimize noise injected into the device. Use a series resistor (10k typ) to further reduce coupling of high-frequency signals into the device. Voltage supply layout is also critical to achieve optimum performance. The IC has several RF processing stages that use the various V CC pins, and while they have on-chip decoupling, off-chip interaction between them may degrade gain, linearity, carrier suppression, and output power control range. The supplies associated with pins 2, 6, 15 (MAX2721 only), and 17 lie directly in the RF signal path. Pins 4, 12, and 15 carry LO signal currents, so it is important to keep them from interacting with the RF signal path to prevent poor carrier suppression. The VGA generates discarded signal currents on pin 4, which also need to be kept away from the signal path supplies. Because there is a great deal of gain following from the first RF stage, it is also important to prevent coupling from pins 2, 4, 15, and 17 to pin 6; excessive coupling may degrade stability.
DC-blocking capacitor that can be part of the matching network. The DROUT open-collector output port requires an external matching network and a pull-up inductor to VCC for proper biasing. The pull-up inductor is incorporated as part of the matching network. See the MAX2720 and MAX2721 Typical Application Circuit for recommended component values. Refer to Table 3 for matching to other frequencies. If the additional gain of the PA driver is not required, disable the PA driver to reduce current consumption. To disable the PA driver, short pin 20 (DRIN) to ground and leave pin 2 unconnected.
Shutdown
Apply a logic-level high to the SHDN pin to enable the MAX2720/MAX2721. Apply a logic-level low voltage to disable the device and reduce supply current to less than 0.1A.
Applications Information
Layout Considerations
A properly designed PC board is an essential part of any RF circuit. A ground plane is essential. Keep RF signal lines as short as possible to reduce losses, radiation, and inductance. Use separate, low-inductance vias to the ground plane for each pin. For best performance, solder the exposed pad on the bottom of the device package evenly to the board ground plane. Remove the ground plane under the external VCO and lowpass filters to reduce the effects of parasitic capaci-
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19
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Table 3. PA Driver S-Parameters (VCC = 3.0V, TA = +25C)
FREQUENCY (MHz) 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 S11 MAG 0.321 0.347 0.383 0.418 0.449 0.421 0.425 0.440 0.452 0.470 0.475 0.473 0.456 0.462 0.447 0.437 0.425 S11 PHASE 151.6 152.7 152.0 149.4 145.3 140.1 142.8 142.8 142.9 141.3 139.0 136.9 135.8 135.3 132.9 132.2 130.3 S21 MAG 4.708 4.588 4.389 4.370 4.160 3.946 3.801 3.690 3.567 3.492 3.360 3.268 3.176 3.087 3.013 2.929 2.848 S21 PHASE 178.1 171.5 161.7 153.5 144.3 135.2 128.4 120.4 112.3 104.2 96.2 87.4 80.4 71.7 63.5 55.4 47.0 S12 MAG 0.092 0.094 0.097 0.093 0.093 0.091 0.096 0.100 0.105 0.102 0.106 0.106 0.110 0.117 0.118 0.123 0.125 S21 PHASE 164.7 154.2 147.2 138.2 129.7 128.7 121.2 112.8 104.9 97.2 88.0 84.2 75.9 67.9 59.7 51.6 40.9 S22 MAG 0.162 0.158 0.142 0.123 0.095 0.082 0.091 0.083 0.082 0.066 0.055 0.046 0.051 0.042 0.031 0.026 0.015 S22 PHASE -82.4 -90.3 -99.5 -109.2 -118.4 -100.8 -111.0 -120.3 -128.8 -138.0 -142.7 -138.9 -133.9 -153.1 -141.0 -144.9 -97.8
20
______________________________________________________________________________________
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
Typical Application Circuit
VCC
MAX2720/MAX2721
470pF 3.9nH 2.0pF PA DRIVER OUTPUT 100k 3 1000pF VCC 470pF 4 VCC MODOUT 17 SHDN PC 18 2 DROUT GND 19 1 GND DRIN 20
3pF PA DRIVER INPUT VCC
SHUTDOWN CONTROL
10k 1000pF
VGA POWER CONTROL
470pF 1.5nH (1.2nH*) 1.0pF (27pF*) 0nH (3.3nH*) MODOUT OUTPUT
100k 5 VCC 8pF (5pF*) 6 0.1F 7 0.1F I MODULATION VCC 9 470pF 10 GND LO 11 47pF *COMPONENT VALUE FOR MAX2721 0NLY. VCC VCC 12 470pF LO INPUT 8 I+ Q+ 13 VCC IQ- 14 0.1F Q MODULATION VCC GND ENX2 16 1000pF VCC 470pF VCC 15 0.1F
LO DOUBLER ENABLE
MAX2720 MAX2721
______________________________________________________________________________________
21
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
Pin Configuration
TOP VIEW
GND 1 DROUT 2 SHDN 3 VCC 4 GND 5 VCC 6 I- 7 I+ 8 VCC 9 GND 10 20 DRIN 19 GND 18 PC 17 MODOUT
Chip Information
TRANSISTOR COUNT: 1041
MAX2720 MAX2721
16 ENX2 15 VCC 14 Q13 Q+ 12 VCC 11 LO
TSSOP-EP
22
______________________________________________________________________________________
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver
Package Information
TSSOP.EPS
MAX2720/MAX2721
______________________________________________________________________________________
23
1.7GHz to 2.5GHz, Direct I/Q Modulator with VGA and PA Driver MAX2720/MAX2721
NOTES
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.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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