MAX3558 Datasheet by Maxim Integrated

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General Description
The MAX3558 broadband quad-output low-noise ampli-
fier (LNA) is designed for digital set tops and digital ter-
restrial applications. The LNA covers a 50MHz to
878MHz input frequency range, while integrating a sep-
arate automatic gain-control (AGC) function with over
30dB of control range for each of four balanced out-
puts. 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
Features
♦Quad Outputs with Independent AGCs and
Shutdown
♦50MHz to 878MHz Broadband Operation
♦Integrated Power Detector
♦High Linearity: 15.6dBm IIP3
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
________________________________________________________________ Maxim Integrated Products 1
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22232425262728
21
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8 9 10 11 12 13 14
POWER
DETECTOR
BIAS
LB
RFIN+
RFIN-
VCC
V
CC
PDAGC
PDOUT
PDREF
V
CC
SHDN4
AGC4
OUT4-
OUT4+
SHDN3
AGC3
OUT3+
OUT3-
AGC2
OUT2-
OUT2+
SHDN2
AGC1
OUT1-
OUT1+
V
CC
EXPOSED PADDLE IS CONNECTED TO GND
TOP VIEW
SHDN1
GND
MAX3558
Pin Configuration/Functional Diagram
Ordering Information
19-3025; Rev 1; 6/06
EVALUATION KIT
AVAILABLE
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.
*EP = Exposed paddle.
+Denotes lead-free package.
PART TEMP RANGE PIN-
PACKAGE
PKG
CODE
MAX3558CGI 0°C to +70°C28 QFN-EP*
(5mm x 5mm) g2855-2
MAX3558CTI+ 0°C to +70°C28 QFN-EP*
(5mm x 5mm) t2855-3
[VI/J XI [VI
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC = 4.75V to 5.25V, no RF signal applied, RBIAS = 1.1kΩ, RPDREF = 10kΩ, LLB = 82nH, TA= 0°C to +70°C, unless otherwise
noted. Typical values are at VCC = 5V, TA= +25°C, unless otherwise noted.)
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.
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= +70°C)
28-Pin QFN.......................................................................2.1W
Operating Temperature Range...............................0°C to +70°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering ,10s) .................................+300°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply Voltage 4.75 5.25 V
Four outputs active, VAGC_ = 3V 241 287
Three outputs active, VAGC_ = 3V 206 245
Four outputs active, 10dB gain reduction 306 366
Four outputs active, VAGC_ = 0.5V 329 396
Supply Current
Four outputs shut down 103 121
mA
PDOUT = VCC - 0.5V 1
Power-Detector Output Current PDOUT = 0.5V -0.8 mA
Analog Input Current AGC_, PDAGC = 0 to 5V -100 +100 µA
Logic-Low Input Voltage 0.8 V
Logic-High Input Voltage 2.0 V
Logic Input Current -100 +10 µA
CAUTION! ESD SENSITIVE DEVICE
[VI/IX I [VI
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
_______________________________________________________________________________________ 3
AC ELECTRICAL CHARACTERISTICS
(VCC = 4.75V to 5.25V, fRFIN = 50MHz to 878MHz, 75Ωsystem impedance, VAGC_ = 3V, VSHDN_ = VCC, RBIAS = 1.1kΩ, RPDREF = 10kΩ,
LLB = 82nH, TA= 0°C to +70°C, unless otherwise noted. Typical values are at VCC = 5V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Frequency Range Gain specification is met across the frequency band 50 878 MHz
Differential output load, maximum gain (Note 2) 4.0 6.8 9.3
Voltage Gain Differential output load, VAGC_ = 0.5V, minimum gain -27.6 -15.7 dB
Gain Flatness 50MHz to 878MHz ±0.4 dB
Noise Figure Worst case across band, 75Ω source, at maximum gain 8.4 9.9 dB
Maximum gain -1.1
Input P1dB Compression Point 10dB gain reduction +1.3
dBm
Maximum gain, PIN = -9dBm 14.4
Input 3rd-Order Intercept Point
(IIP3) (Note 3) 10dB gain reduction, PIN = -9dBm (Note 2) 15.6 dBm
Maximum gain, PIN = -9dBm +45.9
Input 2nd-Order Intercept Point
(IIP2) (Note 3) 10dB gain reduction, PIN = -9dBm (Note 2) +29.5
dBm
Input Return Loss Any gain setting 9 dB
Output Return Loss 75Ω differential output load 8 dB
OUT_ to RFIN Isolation 65 dB
RFIN to OUT_ Shutdown Isolation VGA in shutdown, fRFIN = 54MHz to 72MHz 40 dB
Output-to-Output Isolation Between any two outputs 45 dB
Power-Detector Operating Range
(per Channel) fRFIN = 50MHz to 878MHz (Note 4) -3 +17 dBmV
AGC Attack Range (per Channel) RPDREF = 800Ω to 12kΩ, flat input of 130 channel
loading (Notes 4, 5) -3 +6 dBmV
AGC Attack Accuracy
(per Channel) 130 channel loading (Notes 2, 4) -2.2 +2.2 dBmV
Attack Point Variation Any one output in shutdown mode (Note 4) -0.5 +0.5 dBm
AGC Attack Slope Change of POUT_ over 12dB change in PRFIN after
reaching AGC attack point (Notes 2, 4) -2 +2 dB
Note 1: Guaranteed by design and characterization.
Note 2: Guaranteed by production test.
Note 3: Measured with two input tones (f1= 800MHz, f2= 845MHz).
Note 4: PDOUT connected to PDAGC and AGC_.
Note 5: PIN is single-tone equivalent to 130 channel loading.
[VIIJXIIM
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX3558 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.35.14.7 4.9
210
220
230
240
250
260
270
280
200
4.5 5.5
TA = +70°C
TA = +25°C
TA = 0°C
VAGC_ = 3V
GAIN vs. FREQUENCY
MAX3558 toc02
FREQUENCY (MHz)
GAIN (dB)
750 850550 650250 350 450150
1
2
3
4
5
6
7
8
9
10
0
50
VCC_ = 5V
VAGC_ = 3V
TA = 0°C
TA = +25°C
TA = +70°C
GAIN vs. FREQUENCY
MAX3558 toc03
FREQUENCY (MHz)
GAIN (dB)
750 850550 650250 350 450150
1
2
3
4
5
6
7
8
9
10
0
50
VAGC_ = 3V
TA = +25°C
VCC = 4.75V, 5V, 5.25V
GAIN vs. FREQUENCY
MAX3558 toc04
FREQUENCY (MHz)
GAIN (dB)
850750550 650250 350 450150
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
-12
50
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 = +25°C
NOISE FIGURE vs. FREQUENCY
MAX3558 toc05
FREQUENCY (MHz)
NOISE FIGURE (dB)
850750650550450350250150
2
4
6
8
10
12
0
50
TA = +25°C
TA = 0°C
VAGC_ = 3V
TA = +70°C
NOISE FIGURE vs. GAIN
MAX3558 toc06
GAIN (dB)
NOISE FIGURE (dB)
50-20 -15 -10 -5
5
10
15
20
25
30
35
40
0
-25 10
TA = +25°C
857MHz
390MHz
50MHz
IIP3 vs. FREQUENCY
MAX3558 toc07
FREQUENCY (MHz)
IIP3 (dBm)
850750550 650250 350 450150
2
4
6
8
10
12
14
16
18
20
22
0
50 950
TA = +70°C
TA = +25°C
TA = 0°CVAGC_ = 3V
IIP3 vs. FREQUENCY
MAX3558 toc08
FREQUENCY (MHz)
IIP3 (dBm)
850750550 650250 350 450150
2
4
6
8
10
12
14
16
18
20
22
0
50 950
TA = +70°C
TA = +25°C
TA = 0°C
10dB GAIN
REDUCTION
IIP2 vs. FREQUENCY
MAX3558 toc09
FREQUENCY fA (MHz)
IIP2 (dBm)
850750650550450350250150
10
20
30
40
50
60
0
50
TA = +25°CTA = 0°C
VAGC_ = 3V
fA + fB = 860MHz
TA = +70°C
Typical Operating Characteristics
(MAX3558 EV kit, VCC = 5V, fRFIN = 50MHz to 878MHz, VAGC_ = 3V, VSHDN_ = VCC, RBIAS = 1.1kΩ, RPDREF = 10kΩ, LLB = 82nH, TA=
+25°C, unless otherwise noted.)
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
4 _______________________________________________________________________________________
[MAXI/Ill
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
_______________________________________________________________________________________ 5
AGC ATTACK POINT vs. RPDREF
MAX3558 toc13
RPDREF (kΩ)
AGC ATTACK POIN T (dBmV)
1110892345671
-8
-6
-4
-2
0
2
4
6
8
10
-10
012
VCC_ = 5V
TA = +25°C
SINGLE-TONE INPUT
EQUIVALENT TO 130
CHANNEL LOADING
PORT-TO-PORT ISOLATION
vs. FREQUENCY
MAX3558 toc14
FREQUENCY (MHz)
ISOLATION (dB)
850750550 650250 350 450150
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
50
VAGC_ = 3V
TA = +25°C
OUTPUT TO RFIN ISOLATION
vs. FREQUENCY
MAX3558 toc15
FREQUENCY (MHz)
ISOLATION (dB)
850750550 650250 350 450150
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
50
VAGC_ = 3V
TA = +25°C
RFIN TO OUTPUT ISOLATION
vs. FREQUENCY
MAX3558 toc16
FREQUENCY (MHz)
ISOLATION (dB)
850750550 650250 350 450150
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
50
VAGC_ = 3V
TA = +25°C
VGA IN SHUTDOWN
INPUT RETURN LOSS vs. FREQUENCY
MAX3558 toc17
FREQUENCY (MHz)
INPUT RETURN LOSS (dB)
800600400200
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
-20
0 1000
75Ω SYSTEM
MAX GAIN AND MIN GAIN
OUTPUT RETURN LOSS vs. FREQUENCY
MAX3558 toc18
FREQUENCY (MHz)
OUTPUT RETURN LOSS (dB)
800600400200
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
-20
0 1000
75Ω SYSTEM
MAX GAIN AND MIN GAIN
IIP2 vs. FREQUENCY
MAX3558 toc10
FREQUENCY fA (MHz)
IIP2 (dBm)
850750650550450350250150
10
20
30
40
50
60
0
50
10dB GAIN REDUCTION
fA + fB = 860MHz
TA = 0°C
TA = +70°C
TA = +25°C
IIP2 vs. FREQUENCY
MAX3558 toc11
FREQUENCY fA (MHz)
IIP2 (dBm)
850750650550450350250150
10
20
30
40
50
60
0
50 950
VAGC_ = 3V
fA - fB = 50MHz
TA = +25°C
TA = 0°C
TA = +70°C
IIP2 vs. FREQUENCY
MAX3558 toc12
FREQUENCY (MHz)
IIP2 (dBm)
850750650550450350250150
10
20
30
40
50
60
0
50 950
VAGC_ = 1.5V
fA - fB = 50MHz
10dB GAIN REDUCTION
TA = +70°C
TA = +25°C
TA = 0°C
Typical Operating Characteristics (continued)
(MAX3558 EV kit, VCC = 5V, fRFIN = 50MHz to 878MHz, VAGC_ = 3V, VSHDN_ = VCC, RBIAS = 1.1kΩ, RPDREF = 10kΩ, LLB = 82nH, TA=
+25°C, unless otherwise noted.)
[VI/JXIIVI
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
6 _______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1 BIAS External Bias. Connect an external 1.1kΩ ±1% resistor to set the bias current.
2 LB Inductor Bias. Connect an 82nH inductor to ground for proper operation.
3, 4 RFIN+,
RFIN-
Differential LNA RF Input. Requires external DC-blocking capacitors. For single-ended input, AC-
couple RFIN- to GND.
5, 13, 23, 28 VCC VCC Power Supply. Bypass each VCC with a 0.01µF capacitor to ground as close to the device as
possible.
6 PDAGC Power-Detector AGC Input. Connect PDAGC to PDOUT for closed-loop AGC control.
7 PDOUT Power-Detector Output. PDOUT can be connected to AGC_ for closed-loop operation. PDOUT
bandwidth is set by an external capacitor.
8 PDREF Power-Detector Reference Input. Connect an external resistor to ground to lower the attack point.
9SHDN4 Shutdown Input 4. Drive logic low to disable OUT4_ and AGC4. Drive logic high for normal operation.
10 AGC4 Automatic Gain-Control Input 4. AGC4 sets the gain of the LNA output OUT4_.
11, 12 OUT4-,
OUT4+ Differential LNA Output 4. Requires external DC-blocking capacitors.
14 SHDN3 Shutdown Input 3. Drive logic low to disable OUT3_ and AGC3. Drive logic high for normal operation.
15, 16 OUT3+,
OUT3- Differential LNA Output 3. Requires external DC-blocking capacitors.
17 AGC3 Automatic Gain-Control Input 3. AGC3 sets the gain of the LNA output OUT3_.
18 GND Ground
19 AGC2 Automatic Gain-Control Input 2. AGC2 sets the gain of the LNA output OUT2_.
20, 21 OUT2-,
OUT2+ Differential LNA Output 2. Requires external DC-blocking capacitors.
22 SHDN2 Shutdown Input 2. Drive logic low to disable OUT2_ and AGC2. Drive logic high for normal operation.
24, 25 OUT1+,
OUT1- Differential LNA Output 1. Requires external DC-blocking capacitors.
26 AGC1 Automatic Gain-Control Input 1. AGC1 sets the gain of the LNA output OUT1_.
27 SHDN1 Shutdown Input 1. Drive logic low to disable OUT1_ and AGC1. Drive logic high for normal operation.
—EP
Exposed Paddle Ground. The exposed paddle must be soldered to GND for DC and RF return and
better thermal dissipation.
[VI/JXI [VI
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
_______________________________________________________________________________________ 7
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 detec-
tor that can be used to control the AGC function. The
MAX3558 is available in a space-saving 28-pin QFN
package.
Broadband LNA
The broadband LNA input is differential and internally
matched to 75Ω. The LNAs require only DC-blocking
capacitors while maintaining 6dB input return loss. The
input stage drives four variable-gain amplifiers (VGAs).
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 corre-
sponds to AGC_ voltage of 3V. AGC inputs can be dri-
ven from a demodulator’s AGC output, which normally
controls a tuner’s RF AGC, or from the MAX3558’s on-
chip 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 75Ω.
Each output has its own shutdown pin. The shutdown
function disables the selected VGA to reduce power
consumption while also providing significant input-to-
output isolation.
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 broad-
band 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
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 require-
ments while ensuring good SNR and distortion perfor-
mance. The on-chip power detector allows the device
to be used with multiple tuners without complicated RF
AGC circuitry.
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 800Ωand 12kΩ. 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 0.1µF capacitor from
PDOUT to ground for filtering. The PDOUT can be con-
nected to any one of the AGC input pins to prevent
overload conditions.
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 spec-
ified distortion and noise-figure performance, set RBIAS
to 1.1kΩ±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 high-
frequency traces. For proper operation, solder the
exposed paddle evenly to the ground plane. Use abun-
dant 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.
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MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
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
© 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
Chip Information
TRANSISTOR COUNT: 4930
PROCESS: Bipolar REFERENCE: 28-pin QFN 5mm ✕5mm
PACKAGE CODE: G2855-2
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POWER
DETECTOR
RFIN
RBIAS
1.1kΩ
RPDREF
10kΩ
5.1nH
82nH
VCC
V
CC
V
CC
AGC4
OUT4-
OUT4+
AGC3
OUT3+
OUT3-
AGC2
OUT2-
OUT2+
0.01µF
0.01µF
0.01µF0.01µF
0.01µF0.01µF
0.01µF
0.01µF
0.01µF
0.01µF
0.01µF
AGC1
OUT1-
OUT1+
V
CC
EXPOSED PADDLE IS CONNECTED TO GND
SHDN1
GND
SHDN2
SHDN3
SHDN4
MAX3558
0.01µF
0.01µF
0.01µF
0.01µF
0.01µF
0.01µF
0.01µF
Package Information
For the latest package outline information, go to
www.maxim-ic.com/packages.
Typical Application Circuit

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