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19-3745; Rev 0; 7/05
47MHz to 870MHz Analog CATV Transimpedance Amplifier
General Description
The MAX3654 analog transimpedance amplifier (TIA) is designed for CATV applications in fiber-to-the-home (FTTH) networks. This high-linearity amplifier is intended for 47MHz to 870MHz subcarrier multiplexed (SCM) signals in passive optical networks (PON). A gain-control input supports AGC operation with optical inputs having -6dBm to +2dBm average power. With 62dB maximum gain at 47MHz and 18dB gain control range, the minimum RF output level is 14dBmV/channel at -6dBm optical input. A compact 4mm x 4mm package includes all of the active RF circuitry required to convert analog PIN photocurrent to a 75 CATV output. This 700mW SiGe RF IC provides a low-cost, low-power integrated analog CATV receiver solution for FTTH ONTs. 47MHz to 870MHz Operation -6dBm to +2dBm Optical Input Range 21dBm OIP3, 47dBm OIP2 5.5pA/Hz EIN (Amplifier Alone) 62dB Gain at 47MHz 18dB Transimpedance (Gain) Control Integrated +4dB Gain Tilt (with Typical Photodiode) +5V Single-Supply Operation 700mW Power Dissipation -40C to +85C Operating Temperature Range 4mm x 4mm TQFN Package
Features
MAX3654
Applications
FTTH Optical Network Termination (ONT)
PART MAX3654ETE+
Ordering Information
TEMP RANGE PINPACKAGE PKG-CODE T1644F-4-A
-40C to +85C 16 TQFN-EP*
Pin Configuration appears at end of data sheet.
+ Denotes lead-free package. *EP = Exposed pad.
Typical Application Circuit
+5V TO +12V 10H FERRITE BEAD +5V 1k 0.001F IN+ 0.001F TIA INVAGC 1k 100k + OPAMP RHYST HYST DRIVE OUTMUTE 0.001F +5V 75
MAX3654 FTTH VIDEO TIA
0.001F OUT+ 1:1
-6 TO +2dBm
FERRITE BEAD
10H
________________________________________________________________ Maxim Integrated Products
1
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC.............................................-0.3V to +6.0V IN+, IN-, VAGC, OUT+, OUT-, MUTE, HYST.........-0.3V to +5.5V TEST1, TEST2........................................................-0.3V to +5.5V Output Current (OUT+, OUT-) ............................................56mA Continuous Power Dissipation, 16-Lead TQFN-EP Package (TA = +70C) (derate 16.9mW/C above +70C)....1349.1mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-55C 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 = +4.75V to +5.25V, typical values at VCC = +5.0V, TA= +25C, unless otherwise noted.) (Note 1)
PARAMETER Supply Current Gain Control Input Current Mute Input High Mute Input Low Mute Input Current VIH VIL IIL, IIH SYMBOL ICC VAGC = 1.4V 2.0 0.8 30 CONDITIONS MIN TYP 136 50 MAX 170 200 UNITS mA A V V A
AC ELECTRICAL CHARACTERISTICS
(VCC = +4.75V to +5.25V, output ZL = 75, typical values at VCC = +5.0V, TA = +25C, unless otherwise noted.)
PARAMETER Operating Frequency Range Frequency Response Flatness Transimpedance, Differential (ZT) Gain Control Stability Gain Tilt Output Second-Order Intercept Output Third-Order Intercept Equivalent Input Noise Including Photodiode Gain Hysteresis, Optical Differential Output Level, Mute RF Output Return Loss -S22 OIP2 OIP3 EIN SYMBOL f 47MHz to 870MHz (Notes 2, 6) VAGC 0.175V 47MHz VAGC = 0.500V VAGC = 1.400V VAGC = 0 to 1.4V, RHYST = open (Note 3) Linear, 870MHz compared to 47MHz (Notes 4, 6) (Note 5) (Notes 4, 5) VAGC 0.175V (Notes 4, 6) RHYST = open RHYST = GND MUTE 0.8V, 50MHz 47MHz to 870MHz 0.13 0.65 -58 13 -45 18 3 60.5 51.5 42 CONDITIONS MIN 47 0.3 62 53 43.5 0.75 4 >47 21 8 TYP MAX 870 0.75 63.5 54.5 45 1.6 5.5 dB dB dBm dBm pA/Hz dB dBc dB dB UNITS MHz dB
Note 1: DC parameters are tested at +25C, and guaranteed by design and characterization at -40C and +85C. Note 2: Maximum difference between frequency response at any point and a straight line connecting frequency response at end points. Note 3: Gain control stability is the maximum variation in transimpedance (over process, voltage, and temperature) for any VAGC control voltage. Note 4: AC parameters guaranteed by design and characterization. Note 5: OIP2 and OIP3 measured using two tones at f1 = 800MHz and f2 = 850MHz, POUT = -16dBm, VAGC = 1.4V. Note 6: Includes the effects of a packaged photodiode having the characteristics shown in Figure 2.
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
+5V MINI-CIRCUITS ADTL 1-12* 0.001F 12* IN+ OUT+ 0.001F 12* INVAGC *FOR 75 INPUT IMPEDANCE USE 25 RESISTORS AND ADTL 1-18-75 GND
MAX3654
VCC
MINI-CIRCUITS ADTL 0.001F 1-18-75 75
OUT0.001F
OIP2, OIP3 TEST CIRCUIT
+5V
**
*
+5V 1k 0.001F IN+ OUT+ 0.001F INVAGC 1k GND MAX3654 VCC MINI-CIRCUITS ADTL 1-18-75 75 0.001F
SEE PHOTODIODE MODEL IN FIGURE 2
OUT0.001F
**
*
GAIN, GAIN vs. VAGC, GAIN TILT, S22, IRN TEST CIRCUIT
*MURATA BLM15HD182SN **TDK MLF1608 E100K 10H
Figure 1. Test Circuits for Characterization
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
5
1nH 0.6pF 0.6pF
5nH
44dB TO 50dB
0.1pF
50dB TO 56dB
5
1nH 0.6pF
5nH 0.1pF
IN+/-
TIA
56dB TO 62dB
OUT+/-
MAX3654
MUTE
HYST
VAGC
Figure 2. Photodiode and Header Model
Figure 3. Functional Diagram
Typical Operating Characteristics
(VCC = +5.0V, TA = +25C, unless otherwise noted.)
MAXIMUM GAIN vs. FREQUENCY (VAGC = 0V)
MAX3654 toc01
GAIN vs. CONTROL VOLTAGE
870MHz TRANSIMPEDANCE GAIN (dB) 60 50MHz
MAX3654 toc02
GAIN TILT vs. CONTROL VOLTAGE AND TEMPERATURE
5.5 5.0 GAIN TILT (dB)
MAX3654toc03
68 67 TRANSIMPEDANCE GAIN (dB) 66 65 64 63 62 61 60 0 200 400 600 FREQUENCY (MHz) 800
65
6.0
55
4.5 4.0
-40C +25C
50
3.5 +85C 3.0
45 2.5
1000
40 0.1 0.2 VAGC (V) 1.0 1.4
2.0 0 0.2 0.4 0.6 0.8 VAGC (V) 1 1.2 1.4 1.6
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
Typical Operating Characteristics (continued)
(VCC = +5.0V, TA = +25C, unless otherwise noted.)
MAX3654 toc05
MAX3654 toc04
0.8 0.6 GAIN TILT DEVIATION (dB) 0.4
-2 -4 -6 S22 (dB) -8 -10 -12 -14 -16 -18 -20
18 16 NOISE (pA/(Hz)1/2) 14 12 10 8 6 4 2 0 +85C NO PHOTODIODE +85C WITH PHOTODIODE +25C WITH PHOTODIODE
0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 100 200 300 400 500 600 700 800 900 1000 FREQUENCY (MHz)
0
200
400 600 FREQUENCY (MHz)
800
1000
0 100 200 300 400 500 600 700 800 900 1000 FREQUENCY (MHz)
OIP3 vs. CONTROL VOLTAGE
MAX3654toc07
OIP2 vs. CONTROL VOLTAGE
MAX3654toc08
30 28 26 24 OIP3 (dBm) 22 20 18 16 14 12 10 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
80 70 60 OIP2 (dBm) 50 40 30 20
1.6
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
VAGC (V)
VAGC (V)
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MAX3654 toc06
1.0
GAIN TILT DEVIATION vs. FREQUENCY (REFERRED TO A LINE FROM 50MHz TO 870MHz)
DIFFERENTIAL S22 (NORMALIZED TO 75)
0 20
INPUT REFERRED NOISE vs. FREQUENCY (MAXIMUM GAIN, VGA = 0V)
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
Pin Description
PIN 1, 4, 9, 12 2 3 5 6 7 8, 14, 16 10 11 13 15 EP NAME VCC IN+ INVAGC MUTE HYST GND OUTOUT+ TEST1 TEST2 EP +5.0V Power Supply Positive Analog Photodiode Input Connection. Typically connected to photodiode cathode. Negative Analog Photodiode Input Connection. Typically connected to photodiode anode. AGC Control Input. Range is 0 to 1.4V. See the Typical Operating Characteristics Gain vs. Control Voltage graph. Mute Control Input, TTL. MUTE < 0.8V to mute output. AGC Hysteresis Control Input. A resistor from HYST to GND controls the hysteresis level. Ground Negative RF Output. The voltage on this pin decreases with increasing optical power when IN+ is connected to the photodiode cathode. Positive RF Output. The voltage on this pin increases with increasing optical power when IN- is connected to the photodiode anode. Reserved for Test. Connect to GND for normal operation. Reserved for Test. Connect to GND for normal operation. Exposed Pad. The exposed pad must be soldered to the circuit-board ground for proper thermal and electrical performance. FUNCTION
Detailed Description
The MAX3654 is a broadband, high-linearity, low-noise transimpedance amplifier. The transimpedance (gain) can be adjusted between 43.5dB and 62dB using the voltage at an external control input (VAGC). When connected as shown in the Typical Application Circuit, optical input levels from -6dBm to +2dBm will produce a minimum output of 14dBmV/channel, and 4dB tilt compensation. Gain deviation over frequency from 47MHz to 870MHz is less than 0.75dB.
VAGC input to select a gain stage. As the voltage at VAGC crosses the two locations in the gain vs. VAGC curve, where the gain stage changes (350mV and 700mV), there will be small deviations in the output which may lead to a brief interruption of CATV signals. See the Typical Operating Characteristics for Gain vs. Control Voltage. A hysteresis control input is provided to limit dithering when the optical level is close to a gain-switching point. The hysteresis level is controlled by the value of RHYST. Hysteresis is minimum (0.13dB) when this pin is open.
Low-Noise Variable Gain Amplifier
The input stage is a low-noise analog transimpedance amplifier (TIA) connected differentially to the analog photodiode. Desired performance can be achieved with a photodiode having capacitance (CPD) up to 1pF.
RF Output and Cable Tilt Compensation
With a typical photodiode, the gain at 870MHz is 4dB higher than at 47MHz. The overall frequency response of the TIA is within 0.75dB of a straight line connecting the values at 47MHz and 870MHz.
VAGC and Hysteresis Control
The gain-control pin VAGC sets overall TIA gain implemented as three switchable gain stages, each with a continuously variable gain control, as shown in Figure 3. This produces a continuously variable gain ranging from 62dB (at VAGC = 0.175V) to 43.5dB at (VAGC=1.4V). A set of comparators examines the
Mute
In normal operation, the TTL MUTE pin is held high. When MUTE is low, the output signal is attenuated by more than 45dB.
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47MHz to 870MHz Analog CATV Transimpedance Amplifier
Applications Information
Photodiode Parasitics
The MAX3654 TIA is designed to operate with a lowcapacitance analog photodiode. Proper system design includes considerations of lead configuration, pad, and through-hole geometry, and PC board layer selection for connections to the IC. The TIA is designed to operate correctly when the total capacitance of the photodiode, package, leads and PC board is between 1.0pF and 2.5pF. ed with 5mm (nominal) leads into through-hole vias as in the EV kit configuration, a 4dB uptilt will normally be achieved. It is important to configure the layout with capacitance and inductance in the anode and cathode connection as symmetric as possible. The electrical input circuit is normally configured with a 50 input for use with conventional test and measurement equipment. If desired, the MAX3654 input can also be terminated with 75 as shown in the EV kit data sheet. The 75 EV kit outputs should be connected to 50 test and measurement equipment using a minimum loss pad. For more information, see the Maxim website: MAX3654 EV Kit data sheet-- http://www.maxim-ic.com/Fiber.cfm Minimum Loss Pad-- http://www.maxim-ic.com/appnotes.cfm/appnote_number/972
MAX3654
RF Output
The differential TIA RF output should be connected (AC-coupled) to a balun transformer for normal singleended output.
AGC Operation
For AGC operation, the optical average power can be measured from the voltage drop across the lower bias resistor, using high impedance to isolate the photodiode as shown in the EV kit schematic. TIA gain is inversely proportional to the voltage present at VAGC from 0.175V to 1.4V. From 0 to 0.175V, the gain is constant and maximum. The nominal gain is given by: 175mV ZT(dB) = 62dB + 20 x log VAGC(mV) (0.175V VAGC 1.4V). When connected as shown in the Typical Applications Circuit, the MAX3654 will maintain the electrical output constant (15dBmV/ch) for optical signals in the -6dBm to +2dBm range.
Pin Configuration
OUT+ VCC OUT10 VCC 9
TOP VIEW
12
11
TEST1 13 GND 14 TEST2 15 GND 16
8 7
GND HYST MUTE VAGC
MAX3654
EP*
6 5
Evaluation Kit and PC Board Layout
IN+ VCC INVCC
The factory-assembled EV kit for the MAX3654 provides two versions: optical input and electrical input. The optical input circuit includes photodiode bias circuitry, an op amp to adjust VAGC according to the DC photodiode current (for AGC operation), an output balun, and a 75 output connector. Through-hole pads are provided to attach the triplexer analog photodiode leads. Since photodiode capacitance and package lead inductance affect the amount of uptilt, in configurations where lead inductance is significantly lower than the value shown in Figure 2, the uptilt may be increased by providing discrete inductance on the PC board. When a CPD = 0.5pF (typ) photodiode is mount*THE EXPOSED PAD MUST BE CONNECTED TO GROUND.
1
2
3
4
THIN QFN 4mm x 4mm
Chip Information
TRANSISTOR COUNT: 3376 PROCESS: SiGe Bipolar SUBSTRATE: SOI
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47MHz to 870MHz Analog CATV Transimpedance Amplifier MAX3654
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) For the latest package outline information, go to www.maxim-ic.com/packages.) (TQFN 4mm x 4mm x 0.8mm, Package Code: T1644.)
PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
D
1
2
PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
D
2
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) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
24L QFN THIN.EPS

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