View MAX3558CTI_1273059.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-3025; Rev 1; 6/06
KIT ATION EVALU BLE AVAILA
Quad-Output LNA with AGC for Cable TV Applications
General Description Features
Quad Outputs with Independent AGCs and Shutdown 50MHz to 878MHz Broadband Operation Integrated Power Detector High Linearity: 15.6dBm IIP3
MAX3558
The MAX3558 broadband quad-output low-noise amplifier (LNA) is designed for digital set tops and digital terrestrial applications. The LNA covers a 50MHz to 878MHz input frequency range, while integrating a separate automatic gain-control (AGC) function with over 30dB of control range for each of four balanced outputs. Each output has its own shutdown control to reduce power consumption when not used. The MAX3558 also includes a power detector that can be used to close the loop on any of the AGCs to prevent overload conditions. The LNA's attack point is adjustable with an external resistor. The MAX3558 is available in a very small 28-pin QFN package with exposed paddle (EP).
Applications
Digital Set-Top Boxes Digital Terrestrial Receivers Tuner Preamps
MAX3558CGI MAX3558CTI+ PART
Ordering Information
TEMP RANGE 0C to +70C 0C to +70C PINPACKAGE 28 QFN-EP* (5mm x 5mm) 28 QFN-EP* (5mm x 5mm) PKG CODE g2855-2 t2855-3
*EP = Exposed paddle. +Denotes lead-free package.
Pin Configuration/Functional Diagram
TOP VIEW
SHDN1
AGC1
OUT1-
28
27
26
25
24
23
22
SHDN2
VCC
OUT1+
VCC
BIAS LB RFIN+ RFINVCC PDAGC PDOUT
1
21 OUT2+
MAX3558
2 3 4 5 6 7 POWER DETECTOR 20 OUT219 AGC2 18 GND 17 AGC3 16 OUT315 OUT3+
8
9
10
11
12
13
14
OUT4+
SHDN4
EXPOSED PADDLE IS CONNECTED TO GND
________________________________________________________________ Maxim Integrated Products
SHDN3
PDREF
OUT4-
AGC4
VCC
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.
Quad-Output LNA with AGC for Cable TV Applications MAX3558
ABSOLUTE MAXIMUM RATINGS
VCC, OUT_ _ to GND ............................................-0.3V to + 6.3V BIAS, LB, RFIN_, PDAGC, PDOUT, PDREF, SHDN_, AGC_ to GND ...........................-0.3V to (VCC + 0.3V) OUT_ _ Short-Circuit Duration....................................Continuous Continuous Power Dissipation (TA = +70C) 28-Pin QFN.......................................................................2.1W
CAUTION! ESD SENSITIVE DEVICE 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.
Operating Temperature Range...............................0C to +70C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering ,10s) .................................+300C
DC ELECTRICAL CHARACTERISTICS
(VCC = 4.75V to 5.25V, no RF signal applied, RBIAS = 1.1k, RPDREF = 10k, LLB = 82nH, TA = 0C to +70C, unless otherwise noted. Typical values are at VCC = 5V, TA = +25C, unless otherwise noted.)
PARAMETER Supply Voltage CONDITIONS Four outputs active, VAGC_ = 3V Three outputs active, VAGC_ = 3V Supply Current Four outputs active, 10dB gain reduction Four outputs active, VAGC_ = 0.5V Four outputs shut down Power-Detector Output Current Analog Input Current Logic-Low Input Voltage Logic-High Input Voltage Logic Input Current 2.0 -100 +10 PDOUT = VCC - 0.5V PDOUT = 0.5V AGC_, PDAGC = 0 to 5V 1 -0.8 -100 +100 0.8 MIN 4.75 TYP 241 206 306 329 103 MAX 5.25 287 245 366 396 121 mA A V V A mA UNITS V
2
_______________________________________________________________________________________
Quad-Output LNA with AGC for Cable TV Applications
AC ELECTRICAL CHARACTERISTICS
(VCC = 4.75V to 5.25V, fRFIN = 50MHz to 878MHz, 75 system impedance, VAGC_ = 3V, V SHDN_ = VCC, RBIAS = 1.1k, RPDREF = 10k, LLB = 82nH, TA = 0C to +70C, unless otherwise noted. Typical values are at VCC = 5V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Frequency Range Voltage Gain Gain Flatness Noise Figure Input P1dB Compression Point Input 3rd-Order Intercept Point (IIP3) (Note 3) Input 2nd-Order Intercept Point (IIP2) (Note 3) Input Return Loss Output Return Loss OUT_ to RFIN Isolation RFIN to OUT_ Shutdown Isolation Output-to-Output Isolation Power-Detector Operating Range (per Channel) AGC Attack Range (per Channel) AGC Attack Accuracy (per Channel) Attack Point Variation AGC Attack Slope VGA in shutdown, fRFIN = 54MHz to 72MHz Between any two outputs fRFIN = 50MHz to 878MHz (Note 4) RPDREF = 800 to 12k, flat input of 130 channel loading (Notes 4, 5) 130 channel loading (Notes 2, 4) Any one output in shutdown mode (Note 4) Change of POUT_ over 12dB change in PRFIN after reaching AGC attack point (Notes 2, 4) CONDITIONS Gain specification is met across the frequency band Differential output load, maximum gain (Note 2) Differential output load, VAGC_ = 0.5V, minimum gain 50MHz to 878MHz Worst case across band, 75 source, at maximum gain Maximum gain 10dB gain reduction Maximum gain, PIN = -9dBm 10dB gain reduction, PIN = -9dBm (Note 2) Maximum gain, PIN = -9dBm 10dB gain reduction, PIN = -9dBm (Note 2) Any gain setting 75 differential output load 8 65 40 45 -3 -3 -2.2 -0.5 -2 +17 +6 +2.2 +0.5 +2 +29.5 9 -1.1 +1.3 14.4 15.6 +45.9 MIN 50 4.0 6.8 -27.6 0.4 8.4 9.9 TYP MAX 878 9.3 -15.7 UNITS MHz dB dB dB dBm dBm dBm dB dB dB dB dB dBmV dBmV dBmV dBm dB
MAX3558
Note 1: Note 2: Note 3: Note 4: Note 5:
Guaranteed by design and characterization. Guaranteed by production test. Measured with two input tones (f1 = 800MHz, f2 = 845MHz). PDOUT connected to PDAGC and AGC_. PIN is single-tone equivalent to 130 channel loading.
_______________________________________________________________________________________
3
Quad-Output LNA with AGC for Cable TV Applications MAX3558
Typical Operating Characteristics
(MAX3558 EV kit, VCC = 5V, fRFIN = 50MHz to 878MHz, VAGC_ = 3V, VSHDN_ = VCC, RBIAS = 1.1k, RPDREF = 10k, LLB = 82nH, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX3558 toc01
GAIN vs. FREQUENCY
9 8 7 GAIN (dB) GAIN (dB) 6 5 4 3 2 1 0 TA = 0C TA = +25C TA = +70C VCC_ = 5V VAGC_ = 3V
MAX3558 toc02
GAIN vs. FREQUENCY
9 8 7 6 5 4 3 2 1 0 VCC = 4.75V, 5V, 5.25V VAGC_ = 3V TA = +25C
MAX3558 toc03
280 VAGC_ = 3V 270 SUPPLY CURRENT (mA) 260 250 240 230 220 210 200 4.5 4.7 4.9 5.1 5.3 TA = +70C TA = +25C TA = 0C
10
10
5.5
50 150 250 350 450 550 650 750 850 FREQUENCY (MHz)
50 150 250 350 450 550 650 750 850 FREQUENCY (MHz)
SUPPLY VOLTAGE (V)
GAIN vs. FREQUENCY
12 10 8 6 4 2 0 -2 -4 -6 -8 GAIN (dB)
MAX3558 toc04
NOISE FIGURE vs. FREQUENCY
MAX3558 toc05
NOISE FIGURE vs. GAIN
35 30 NOISE FIGURE (dB) TA = +25C 50MHz
MAX3558 toc06
VAGC_ = 3V VAGC_ = 1.97V VAGC_ = 1.81V VAGC_ = 1.69V VAGC_ = 1.59V VAGC_ = 1.50V VAGC_ = 1.42V VAGC_ = 1.35V VAGC_ = 1.28V
VCC_ = 5V TA = +25C
12 VAGC_ = 3V 10 NOISE FIGURE (dB) 8 6 4 2 0 TA = +25C TA = 0C TA = +70C
40
25 20 15 10 5 0 390MHz 857MHz
-10 -12 50 150 250 350 450 550 650 750 850 FREQUENCY (MHz)
50 150 250 350 450 550 650 750 850 FREQUENCY (MHz)
-25
-20
-15
-10
-5
0
5
10
GAIN (dB)
IIP3 vs. FREQUENCY
MAX3558 toc07
IIP3 vs. FREQUENCY
MAX3558 toc08
IIP2 vs. FREQUENCY
VAGC_ = 3V
MAX3558 toc09
22 20 18 16 IIP3 (dBm) 14 12 10 8 6 4 2 0 TA = +25C TA = +70C TA = 0C VAGC_ = 3V
22 20 18 16 IIP3 (dBm) 12 10 8 6 4 2 0 TA = 0C 14 TA = +70C 10dB GAIN REDUCTION
60 50 40 IIP2 (dBm) 30 20 10 fA + fB = 860MHz 0 TA = +25C TA = 0C TA = +70C
TA = +25C
50 150 250 350 450 550 650 750 850 950 FREQUENCY (MHz)
50 150 250 350 450 550 650 750 850 950 FREQUENCY (MHz)
50
150
250 350 450 550 650 750 850 FREQUENCY fA (MHz)
4
_______________________________________________________________________________________
Quad-Output LNA with AGC for Cable TV Applications
Typical Operating Characteristics (continued)
(MAX3558 EV kit, VCC = 5V, fRFIN = 50MHz to 878MHz, VAGC_ = 3V, VSHDN_ = VCC, RBIAS = 1.1k, RPDREF = 10k, LLB = 82nH, TA = +25C, unless otherwise noted.)
IIP2 vs. FREQUENCY
MAX3558 toc10
MAX3558
IIP2 vs. FREQUENCY
MAX3558 toc11
IIP2 vs. FREQUENCY
TA = +70C 50 40 VAGC_ = 1.5V
MAX3558 toc12
60 50 40 IIP2 (dBm) TA = +25C TA = +70C
60 TA = +70C 50 40 IIP2 (dBm) TA = +25C 30 20 TA = 0C VAGC_ = 3V
60
IIP2 (dBm)
30 20 10 0 50 150
TA = 0C
30 20
TA = +25C TA = 0C fA - fB = 50MHz 10dB GAIN REDUCTION
10dB GAIN REDUCTION fA + fB = 860MHz 250 350 450 550 650 750 850 FREQUENCY fA (MHz)
10 0
fA - fB = 50MHz
10 0
50 150 250 350 450 550 650 750 850 950 FREQUENCY fA (MHz)
50 150 250 350 450 550 650 750 850 950 FREQUENCY (MHz)
AGC ATTACK POINT vs. RPDREF
8 AGC ATTACK POIN T (dBmV) 6 4 2 0 -2 -4 -6 -8 -10 0 1 2 3 4 5 6 7 8 9 10 11 12 RPDREF (k) SINGLE-TONE INPUT EQUIVALENT TO 130 CHANNEL LOADING VCC_ = 5V TA = +25C
MAX3558 toc13
PORT-TO-PORT ISOLATION vs. FREQUENCY
MAX3558 toc14
OUTPUT TO RFIN ISOLATION vs. FREQUENCY
-10 -20 ISOLATION (dB) -30 -40 -50 -60 -70 -80 -90 -100 VAGC_ = 3V TA = +25C
MAX3558 toc15
10
0 -10 -20 ISOLATION (dB) -30 -40 -50 -60 -70 -80 -90 -100 50 150 250 350 450 550 650 750 850 FREQUENCY (MHz) VAGC_ = 3V TA = +25C
0
50 150 250 350 450 550 650 750 850 FREQUENCY (MHz)
RFIN TO OUTPUT ISOLATION vs. FREQUENCY
MAX3558 toc16
INPUT RETURN LOSS vs. FREQUENCY
MAX3558 toc17
OUTPUT RETURN LOSS vs. FREQUENCY
-2 OUTPUT RETURN LOSS (dB) -4 -6 -8 -10 -12 -14 -16 -18 -20 MAX GAIN AND MIN GAIN 75 SYSTEM
MAX3558 toc18
0 -10 -20 ISOLATION (dB) -30 -40 -50 -60 -70 -80 -90 -100 50 150 250 350 450 550 650 750 850 FREQUENCY (MHz) VAGC_ = 3V TA = +25C VGA IN SHUTDOWN
0 -2 INPUT RETURN LOSS (dB) -4 -6 -8 -10 -12 -14 -16 -18 -20 0 200 400 600 800 MAX GAIN AND MIN GAIN 75 SYSTEM
0
1000
0
200
400
600
800
1000
FREQUENCY (MHz)
FREQUENCY (MHz)
_______________________________________________________________________________________
5
Quad-Output LNA with AGC for Cable TV Applications MAX3558
Pin Description
PIN 1 2 3, 4 5, 13, 23, 28 6 7 8 9 10 11, 12 14 15, 16 17 18 19 20, 21 22 24, 25 26 27 -- NAME BIAS LB RFIN+, RFINVCC PDAGC PDOUT PDREF SHDN4 AGC4 OUT4-, OUT4+ SHDN3 OUT3+, OUT3AGC3 GND AGC2 OUT2-, OUT2+ SHDN2 OUT1+, OUT1AGC1 SHDN1 EP FUNCTION External Bias. Connect an external 1.1k 1% resistor to set the bias current. Inductor Bias. Connect an 82nH inductor to ground for proper operation. Differential LNA RF Input. Requires external DC-blocking capacitors. For single-ended input, ACcouple RFIN- to GND. VCC Power Supply. Bypass each VCC with a 0.01F capacitor to ground as close to the device as possible. Power-Detector AGC Input. Connect PDAGC to PDOUT for closed-loop AGC control. Power-Detector Output. PDOUT can be connected to AGC_ for closed-loop operation. PDOUT bandwidth is set by an external capacitor. Power-Detector Reference Input. Connect an external resistor to ground to lower the attack point. Shutdown Input 4. Drive logic low to disable OUT4_ and AGC4. Drive logic high for normal operation. Automatic Gain-Control Input 4. AGC4 sets the gain of the LNA output OUT4_. Differential LNA Output 4. Requires external DC-blocking capacitors. Shutdown Input 3. Drive logic low to disable OUT3_ and AGC3. Drive logic high for normal operation. Differential LNA Output 3. Requires external DC-blocking capacitors. Automatic Gain-Control Input 3. AGC3 sets the gain of the LNA output OUT3_. Ground Automatic Gain-Control Input 2. AGC2 sets the gain of the LNA output OUT2_. Differential LNA Output 2. Requires external DC-blocking capacitors. Shutdown Input 2. Drive logic low to disable OUT2_ and AGC2. Drive logic high for normal operation. Differential LNA Output 1. Requires external DC-blocking capacitors. Automatic Gain-Control Input 1. AGC1 sets the gain of the LNA output OUT1_. Shutdown Input 1. Drive logic low to disable OUT1_ and AGC1. Drive logic high for normal operation. Exposed Paddle Ground. The exposed paddle must be soldered to GND for DC and RF return and better thermal dissipation.
6
_______________________________________________________________________________________
Quad-Output LNA with AGC for Cable TV Applications
Detailed Description
The MAX3558 broadband LNA consists of a single input and four independent outputs. Each output has its own AGC and shutdown function. The LNA covers the 50MHz to 878MHz cable and terrestrial TV frequency range. In addition, the device includes a power detector that can be used to control the AGC function. The MAX3558 is available in a space-saving 28-pin QFN package. an external resistor connected to PDREF. Because the power detector has a broadband frequency response, the MAX3558 allows the RF AGC attack point to be set according to the total input power, as opposed to the tuned channel. This minimizes the linearity requirements while ensuring good SNR and distortion performance. The on-chip power detector allows the device to be used with multiple tuners without complicated RF AGC circuitry.
MAX3558
Broadband LNA
The broadband LNA input is differential and internally matched to 75. The LNAs require only DC-blocking capacitors while maintaining 6dB input return loss. The input stage drives four variable-gain amplifiers (VGAs).
Applications Information
Using a Power Detector to Set the Attack Point
The on-chip power detector can be used closed loop as an automatic gain-control circuit for any one (or all) of the LNA outputs. The power detector is designed for the attack point to be set in the -3dBmV to +6dBmV range with the resistor RPDREF. The resistor value is chosen between 800 and 12k. A larger resistor value sets a higher output attack point. See Attack Point vs. RPDREF in the Typical Operating Characteristics. For on-chip closed-loop operation, PDAGC must be connected to PDOUT. Connect a 0.1F capacitor from PDOUT to ground for filtering. The PDOUT can be connected to any one of the AGC input pins to prevent overload conditions.
RF VGAs
The RF VGAs feature an independent gain-control range of more than 30dB. The voltage applied at the AGC pin controls the gain. Minimum gain corresponds to AGC_ voltage of 0.5V and maximum gain corresponds to AGC_ voltage of 3V. AGC inputs can be driven from a demodulator's AGC output, which normally controls a tuner's RF AGC, or from the MAX3558's onchip power detector. Should an overload condition occur, the closed-loop AGC circuitry continues to reduce the gain to ensure good distortion performance. For optimum distortion and signal-to-noise ratio (SNR) performance, set the AGC attack point between +3dBmV to +5dBmV with an external resistor connected to PDREF. The VGA outputs are differentially balanced to achieve good IIP2 performance while providing at least 8dB return loss. The outputs are internally matched to 75. Each output has its own shutdown pin. The shutdown function disables the selected VGA to reduce power consumption while also providing significant input-tooutput isolation.
Bias Current
The MAX3558 uses an external resistor for adjusting the biasing current. A resistor, RBIAS, connected from BIAS to ground sets the supply current. To achieve the specified distortion and noise-figure performance, set RBIAS to 1.1k 1%.
Layout Considerations
The EV kit serves as a guide for PC board layout. Keep RF signal lines as short as possible to minimize losses and radiation. Use controlled impedance on all highfrequency traces. For proper operation, solder the exposed paddle evenly to the ground plane. Use abundant vias beneath the exposed paddle for maximum heat dissipation. Use abundant ground vias between RF traces to minimize undesired coupling. Each VCC pin must have its own bypass capacitor placed close to the pin.
Power Detector
The MAX3558 includes on-chip power-detector circuitry that can be used to control the gain of any of the four RF VGAs to prevent overload conditions. The broadband power detector allows the circuit to automatically limit the gain when the total input power reaches a set level. This level, or attack point, is user adjustable with
_______________________________________________________________________________________
7
Quad-Output LNA with AGC for Cable TV Applications MAX3558
Typical Application Circuit
AGC1 OUT10.01F
OUT1+
0.01F 0.01F
SHDN1
0.01F
0.01F
VCC
28 RBIAS 1.1k 1 82nH 2 5.1nH RFIN 0.01F 4 VCC 0.01F 6 7 5 0.01F 3
VCC SHDN2
26 25 24 23 22 0.01F 0.01F
27
21
OUT2+ OUT2AGC2 0.01F 0.01F
MAX3558
20 19 18 17 16
GND
AGC3 0.01F 0.01F OUT3OUT3+
POWER DETECTOR
15
8 RPDREF 10k
9
10
11
12
13
14
SHDN4
VCC 0.01F
0.01F
SHDN3
AGC4
0.01F EXPOSED PADDLE IS CONNECTED TO GND
OUT4+
0.01F
OUT4-
Chip Information
TRANSISTOR COUNT: 4930 PROCESS: Bipolar
Package Information
For the latest package outline information, go to www.maxim-ic.com/packages.
REFERENCE: 28-pin QFN 5mm 5mm PACKAGE CODE: G2855-2
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

▲Up To Search▲

Price & Availability of MAX3558CTI

	To Download MAX3558CTI Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .