MAXIM MAX3558CTI+

19-3025; Rev 1; 6/06
KIT
ATION
EVALU
E
L
B
AVAILA
Quad-Output LNA with AGC for
Cable TV Applications
Features
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).
♦ Quad Outputs with Independent AGCs and
Shutdown
♦ 50MHz to 878MHz Broadband Operation
♦ Integrated Power Detector
♦ High Linearity: 15.6dBm IIP3
Applications
Ordering Information
Digital Set-Top Boxes
TEMP RANGE
PINPACKAGE
MAX3558CGI
0°C to +70°C
28 QFN-EP*
(5mm x 5mm)
MAX3558CTI+
0°C to +70°C
PART
Digital Terrestrial Receivers
Tuner Preamps
28 QFN-EP*
(5mm x 5mm)
PKG
CODE
g2855-2
t2855-3
*EP = Exposed paddle.
+Denotes lead-free package.
Pin Configuration/Functional Diagram
BIAS
VCC
SHDN1
AGC1
OUT1-
OUT1+
VCC
SHDN2
TOP VIEW
28
27
26
25
24
23
22
21 OUT2+
1
MAX3558
LB
2
20 OUT2-
RFIN+
3
19 AGC2
RFIN-
4
18 GND
VCC
5
17 AGC3
PDAGC
6
8
9
10
11
12
13
14
AGC4
OUT4-
OUT4+
VCC
SHDN3
15 OUT3+
SHDN4
7
PDREF
PDOUT
16 OUT3POWER
DETECTOR
EXPOSED PADDLE IS CONNECTED TO GND
________________________________________________________________ Maxim Integrated Products
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.
1
MAX3558
General Description
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
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 = +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
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.
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.)
PARAMETER
Supply Voltage
CONDITIONS
MIN
4.75
Four outputs active, VAGC_ = 3V
Supply Current
Analog Input Current
MAX
5.25
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
103
121
Four outputs shut down
Power-Detector Output Current
TYP
PDOUT = VCC - 0.5V
1
PDOUT = 0.5V
-0.8
AGC_, PDAGC = 0 to 5V
-100
Logic-Low Input Voltage
Logic-High Input Voltage
Logic Input Current
2
_______________________________________________________________________________________
mA
mA
+100
µA
0.8
V
+10
µA
2.0
-100
UNITS
V
V
Quad-Output LNA with AGC for
Cable TV Applications
(VCC = 4.75V to 5.25V, fRFIN = 50MHz to 878MHz, 75Ω system impedance, VAGC_ = 3V, V SHDN_ = 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
Frequency Range
CONDITIONS
MIN
Gain specification is met across the frequency band
50
Differential output load, maximum gain (Note 2)
4.0
TYP
MAX
UNITS
878
MHz
6.8
9.3
Differential output load, VAGC_ = 0.5V, minimum gain
-27.6
-15.7
Gain Flatness
50MHz to 878MHz
±0.4
Noise Figure
Worst case across band, 75Ω source, at maximum gain
Voltage Gain
Input P1dB Compression Point
8.4
Maximum gain
-1.1
10dB gain reduction
+1.3
Maximum gain, PIN = -9dBm
14.4
10dB gain reduction, PIN = -9dBm (Note 2)
15.6
Input 2nd-Order Intercept Point
(IIP2) (Note 3)
Maximum gain, PIN = -9dBm
Input Return Loss
Any gain setting
Output Return Loss
75Ω differential output load
OUT_ to RFIN Isolation
dB
9.9
dB
dBm
Input 3rd-Order Intercept Point
(IIP3) (Note 3)
10dB gain reduction, PIN = -9dBm (Note 2)
dB
dBm
+45.9
dBm
+29.5
9
dB
8
dB
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:
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
MAX3558
AC ELECTRICAL CHARACTERISTICS
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.)
TA = 0°C
230
220
210
200
5
4
TA = 0°C
TA = +25°C
TA = +70°C
5.1
5.3
2
1
1
5.5
MAX3558 toc04
TA = +70°C
VAGC_ = 1.81V
VAGC_ = 1.69V
VAGC_ = 1.59V
VAGC_ = 1.50V
VAGC_ = 1.42V
VAGC_ = 1.35V
8
6
TA = +25°C
TA = 0°C
4
2
25
20
390MHz
857MHz
15
0
-20
-15
20
16
14
14
10
IIP3 (dBm)
16
TA = +25°C
12
TA = 0°C
10dB GAIN
REDUCTION
8
6
6
4
4
2
2
0
5
10
IIP2 vs. FREQUENCY
TA = +25°C
10
8
0
TA = +70°C
18
-5
60
VAGC_ = 3V
TA = +70°C
50
40
IIP2 (dBm)
MAX3558 toc07
VAGC_ = 3V
IIP3 vs. FREQUENCY
22
-10
GAIN (dB)
MAX3558 toc08
IIP3 vs. FREQUENCY
TA = 0°C
-25
50 150 250 350 450 550 650 750 850
FREQUENCY (MHz)
22
TA = +70°C
50MHz
5
0
20
TA = +25°C
35
10
VAGC_ = 1.28V
FREQUENCY (MHz)
4
NOISE FIGURE vs. GAIN
40
30
VAGC_ = 1.97V
NOISE FIGURE (dB)
GAIN (dB)
VAGC_ = 3V
10
50 150 250 350 450 550 650 750 850
12
FREQUENCY (MHz)
NOISE FIGURE vs. FREQUENCY
12
-10
-12
18
50 150 250 350 450 550 650 750 850
FREQUENCY (MHz)
VCC_ = 5V
TA = +25°C
MAX3558 toc03
0
50 150 250 350 450 550 650 750 850
GAIN vs. FREQUENCY
VAGC_ = 3V
4
3
NOISE FIGURE (dB)
4.9
VCC = 4.75V, 5V, 5.25V
5
2
MAX3558 toc05
4.7
6
3
SUPPLY VOLTAGE (V)
4
2
0
-2
-4
-6
-8
MAX3558 toc02
7
6
0
4.5
12
10
8
6
8
7
240
VAGC_ = 3V
TA = +25°C
9
MAX3558 toc09
250
8
10
GAIN (dB)
TA = +25°C
VCC_ = 5V
VAGC_ = 3V
9
GAIN (dB)
SUPPLY CURRENT (mA)
TA = +70°C
260
MAX3558 toc01
VAGC_ = 3V
270
GAIN vs. FREQUENCY
GAIN vs. FREQUENCY
10
MAX3558 toc06
SUPPLY CURRENT vs. SUPPLY VOLTAGE
280
IIP3 (dBm)
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
TA = +25°C
30
TA = 0°C
20
10
fA + fB = 860MHz
0
0
50 150 250 350 450 550 650 750 850 950
50 150 250 350 450 550 650 750 850 950
FREQUENCY (MHz)
FREQUENCY (MHz)
50
150
250 350 450 550 650 750 850
FREQUENCY fA (MHz)
_______________________________________________________________________________________
Quad-Output LNA with AGC for
Cable TV Applications
TA = +70°C
TA = 0°C
20
TA = +25°C
30
TA = 0°C
20
10dB GAIN REDUCTION
fA + fB = 860MHz
10
fA - fB = 50MHz
0
50 150 250 350 450 550 650 750 850 950
FREQUENCY fA (MHz)
FREQUENCY fA (MHz)
FREQUENCY (MHz)
AGC ATTACK POINT vs. RPDREF
PORT-TO-PORT ISOLATION
vs. FREQUENCY
OUTPUT TO RFIN ISOLATION
vs. FREQUENCY
ISOLATION (dB)
4
2
0
-2
-30
-40
-50
-60
-30
-40
-50
-60
-70
-70
-6
-80
-80
SINGLE-TONE INPUT
EQUIVALENT TO 130
CHANNEL LOADING
-10
3
4
5
6
7
8
-90
-100
-100
50 150 250 350 450 550 650 750 850
9 10 11 12
RFIN TO OUTPUT ISOLATION
vs. FREQUENCY
-20
VAGC_ = 3V
TA = +25°C
VGA IN SHUTDOWN
-30
-40
-50
-60
-70
INPUT RETURN LOSS vs. FREQUENCY
75Ω SYSTEM
-2
INPUT RETURN LOSS (dB)
-10
FREQUENCY (MHz)
0
MAX3558 toc16
0
50 150 250 350 450 550 650 750 850
FREQUENCY (MHz)
RPDREF (kΩ)
OUTPUT RETURN LOSS vs. FREQUENCY
-4
-6
MAX GAIN AND MIN GAIN
-8
-10
-12
-14
0
-2
OUTPUT RETURN LOSS (dB)
2
-90
MAX3558 toc17
1
-6
MAX GAIN AND MIN GAIN
-8
-10
-12
-14
-16
-90
-18
-18
-100
-20
-20
FREQUENCY (MHz)
75Ω SYSTEM
-4
-80
50 150 250 350 450 550 650 750 850
VAGC_ = 3V
TA = +25°C
-20
-4
-8
MAX3558 toc15
VAGC_ = 3V
TA = +25°C
-20
-10
ISOLATION (dB)
6
0
MAX3558 toc14
MAX3558 toc13
0
-10
MAX3558 toc18
250 350 450 550 650 750 850
VCC_ = 5V
TA = +25°C
0
fA - fB = 50MHz
10dB GAIN REDUCTION
50 150 250 350 450 550 650 750 850 950
150
10
8
TA = 0°C
10
0
50
TA = +25°C
30
20
10
0
VAGC_ = 1.5V
40
IIP2 (dBm)
IIP2 (dBm)
IIP2 (dBm)
TA = +70°C
50
40
30
AGC ATTACK POIN T (dBmV)
VAGC_ = 3V
50
40
ISOLATION (dB)
IIP2 vs. FREQUENCY
60
MAX3558 toc11
MAX3558 toc10
TA = +70°C
TA = +25°C
50
IIP2 vs. FREQUENCY
60
MAX3558 toc12
IIP2 vs. FREQUENCY
60
-16
0
200
400
600
FREQUENCY (MHz)
800
1000
0
200
400
600
800
1000
FREQUENCY (MHz)
_______________________________________________________________________________________
5
MAX3558
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.)
MAX3558
Quad-Output LNA with AGC for
Cable TV Applications
Pin Description
PIN
NAME
1
BIAS
FUNCTION
External Bias. Connect an external 1.1kΩ ±1% resistor to set the bias current.
2
LB
3, 4
RFIN+,
RFIN-
Differential LNA RF Input. Requires external DC-blocking capacitors. For single-ended input, ACcouple 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.
Shutdown Input 4. Drive logic low to disable OUT4_ and AGC4. Drive logic high for normal operation.
6
Inductor Bias. Connect an 82nH inductor to ground for proper operation.
9
SHDN4
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
27
SHDN1
—
EP
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.
_______________________________________________________________________________________
Quad-Output LNA with AGC for
Cable TV Applications
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.
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 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 75Ω.
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.
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
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.
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 800Ω and 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 connected 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 specified 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 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.
_______________________________________________________________________________________
7
MAX3558
Detailed Description
Quad-Output LNA with AGC for
Cable TV Applications
AGC1
MAX3558
Typical Application Circuit
OUT10.01µF
OUT1+
0.01µF
SHDN1
0.01µF
0.01µF
VCC
0.01µF
VCC
SHDN2
28
27
26
25
24
23
22
RBIAS
1.1kΩ
21
1
82nH
MAX3558
2
20
0.01µF
0.01µF
OUT2+
OUT2-
0.01µF
5.1nH
RFIN
3
19
4
18
5
17
0.01µF
GND
AGC2
0.01µF
0.01µF
VCC
0.01µF
6
16
POWER
DETECTOR
7
8
10
11
12
13
0.01µF
OUT3OUT3+
14
SHDN3
VCC
0.01µF
SHDN4
RPDREF
10kΩ
9
15
AGC3
0.01µF
EXPOSED PADDLE IS CONNECTED TO GND
AGC4
0.01µF
0.01µF
Chip Information
OUT4+
0.01µF
OUT4-
Package Information
For the latest package outline information, go to
www.maxim-ic.com/packages.
TRANSISTOR COUNT: 4930
PROCESS: Bipolar
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
© 2006 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.