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) sig-
nals in passive optical networks (PON). A gain-control
input supports AGC operation with optical inputs hav-
ing -6dBm to +2dBm average power. With 62dBΩmax-
imum 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 75ΩCATV output.
This 700mW SiGe RF IC provides a low-cost, low-power
integrated analog CATV receiver solution for FTTH ONTs.
Applications
FTTH Optical Network Termination (ONT)
Features
♦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
♦-40°C to +85°C Operating Temperature Range
♦4mm x 4mm TQFN Package
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
________________________________________________________________ Maxim Integrated Products 1
19-3745; Rev 0; 7/05
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.
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
PKG-CODE
MAX3654ETE+
-40°C to +85°C 16 TQFN - E P *
T1644F-4-A
Pin Configuration appears at end of data sheet.
+ Denotes lead-free package.
*EP = Exposed pad.
DRIVE
OUT+
-6 TO
+2dBm
+5V TO
+12V
0.001µF
10µH
10µH
FERRITE BEAD
FERRITE BEAD
1kΩ
1kΩ100kΩ
0.001µF
0.001µF
0.001µF
OUT-
+
-
IN+
IN-
MUTE
RHYST
75Ω
1:1
HYSTVAGC
OPAMP
MAX3654
FTTH VIDEO TIA
+5V
+5V
TIA
Typical Application Circuit
AC ELECTRICAL CHARACTERISTICS
(VCC = +4.75V to +5.25V, output ZL = 75Ω, typical values at VCC = +5.0V, TA= +25°C, unless otherwise noted.)
PARAMETER
SYM B O L
CONDITIONS
MIN TYP MAX
UNITS
Operating Frequency Range f 47
870
MHz
Frequency Response Flatness 47MHz to 870MHz (Notes 2, 6)
±0.3 ±0.75
dB
VAGC ≤ 0.175V
60.5
62
63.5
VAGC = 0.500V
51.5
53
54.5
47MHz
VAGC = 1.400V 42
43.5
45
dBΩ
Gain Control Stability VAGC = 0 to 1.4V, RHYST = open (Note 3)
±0.75 ±1.6
dB
Gain Tilt Linear, 870MHz compared to 47MHz
(Notes 4, 6) 345.5 dB
Output Second-Order Intercept OIP2 (Note 5)
>47
dBm
Output Third-Order Intercept OIP3 (Notes 4, 5) 18 21
dBm
Equivalent Input Noise Including
Photodiode EIN VAGC ≤ 0.175V (Notes 4, 6) 8
pA/√Hz
RHYST = open
±0.13
Gain Hysteresis, Optical RHYST = GND
±0.65
dB
Differential Output Level, Mute MUTE ≤ 0.8V, 50MHz -58 -45 dBc
RF Output Return Loss -S22 47MHz to 870MHz 13 dB
Note 1: DC parameters are tested at +25°C, and guaranteed by design and characterization at -40°C and +85°C.
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.
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
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= +70°C) (derate 16.9mW/°C above +70°C)....1349.1mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-55°C to +150°C
Lead Temperature (soldering,10s) ..................................+300°C
DC ELECTRICAL CHARACTERISTICS
(VCC = +4.75V to +5.25V, typical values at VCC = +5.0V, TA= +25°C, unless otherwise noted.) (Note 1)
PARAMETER
SYM B O L
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current ICC
136
170 mA
Gain Control Input Current VAGC = 1.4V 50 200 µA
Mute Input High VIH 2.0 V
Mute Input Low VIL 0.8 V
Mute Input Current IIL, IIH 30 µA
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
_______________________________________________________________________________________ 3
** *
SEE PHOTODIODE
MODEL IN FIGURE 2
*FOR 75Ω INPUT IMPEDANCE USE 25Ω RESISTORS
AND ADTL 1-18-75
+5V
IN+
IN-
1kΩ
1kΩ
MINI-CIRCUITS
ADTL
1-18-75
MINI-CIRCUITS
ADTL
1-18-75
VAGC
MAX3654
0.001µF
0.001µF
GAIN, GAIN vs. VAGC, GAIN TILT, S22, IRN TEST CIRCUIT
OIP2, OIP3 TEST CIRCUIT
0.001µF
*MURATA BLM15HD182SN **TDK MLF1608 E100K 10µH
0.001µF
IN+
IN-
75Ω
75Ω
12Ω*
+5V
OUT+
OUT-
GND
OUT+
OUT-
GND
VCC
+5V
VCC
12Ω*
MINI-CIRCUITS
ADTL
1-12*
VAGC
MAX3654
0.001µF
0.001µF
0.001µF
0.001µF
** *
Figure 1. Test Circuits for Characterization
Typical Operating Characteristics
(VCC = +5.0V, TA= +25°C, unless otherwise noted.)
MAXIMUM GAIN vs. FREQUENCY
(VAGC = 0V)
FREQUENCY (MHz)
TRANSIMPEDANCE GAIN (dBΩ)
MAX3654 toc01
0 200 400 600 800 1000
60
61
62
63
64
65
66
67
68
GAIN vs. CONTROL VOLTAGE
VAGC (V)
TRANSIMPEDANCE GAIN (dBΩ)
MAX3654 toc02
0.1 0.2 1.0 1.4
40
45
50
55
60
65
50MHz
870MHz
GAIN TILT vs. CONTROL VOLTAGE
AND TEMPERATURE
VAGC (V)
GAIN TILT (dB)
MAX3654toc03
0 0.4 1 1.6
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
+25°C
-40°C
+85°C
0.2 0.6 0.8 1.2 1.4
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
4_______________________________________________________________________________________
0.6pF
0.6pF
0.6pF
5Ω
5Ω
1nH
1nH
5nH
5nH
0.1pF
0.1pF
Figure 2. Photodiode and Header Model
OUT+/-
IN+/-
MUTE
50dB TO
56dB
44dB TO
50dB
56dB TO
62dB
VAGCHYST
TIA
MAX3654
Figure 3. Functional Diagram
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VCC = +5.0V, TA= +25°C, unless otherwise noted.)
GAIN TILT DEVIATION vs. FREQUENCY
(REFERRED TO A LINE FROM 50MHz
TO 870MHz)
FREQUENCY (MHz)
GAIN TILT DEVIATION (dB)
MAX3654 toc04
0200 400 600 800 1000
-1.0
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
100 300 500 700 900
DIFFERENTIAL S22
(NORMALIZED TO 75Ω)
FREQUENCY (MHz)
S22 (dB)
MAX3654 toc05
0 200 400 600 800 1000
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
INPUT REFERRED NOISE vs. FREQUENCY
(MAXIMUM GAIN, VGA = 0V)
FREQUENCY (MHz)
NOISE (pA/(Hz)1/2)
MAX3654 toc06
0 200 400 600 800 1000
0
2
4
6
8
10
12
14
16
18
20
100 300 500 700 900
+85°C WITH
PHOTODIODE +25°C WITH
PHOTODIODE
+85°C NO
PHOTODIODE
MAX3654toc07
VAGC (V)
OIP3 (dBm)
1.41.20.8 1.00.4 0.60.2
12
14
16
18
20
22
24
26
28
30
10
0 1.6
OIP3 vs. CONTROL VOLTAGE
OIP2 vs. CONTROL VOLTAGE
MAX3654toc08
VAGC (V)
OIP2 (dBm)
1.41.21.00.80.60.40.2
30
40
50
60
70
80
20
0 1.6
Detailed Description
The MAX3654 is a broadband, high-linearity, low-noise
transimpedance amplifier. The transimpedance (gain)
can be adjusted between 43.5dBΩand 62dBΩusing
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.
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.
VAGC and Hysteresis Control
The gain-control pin VAGC sets overall TIA gain imple-
mented 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 62dBΩ(at VAGC = 0.175V) to 43.5dBΩat
(VAGC=1.4V). A set of comparators examines the
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.
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.
Mute
In normal operation, the TTL MUTE pin is held high.
When MUTE is low, the output signal is attenuated by
more than 45dB.
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
6_______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1, 4, 9, 12
VCC +5.0V Power Supply
2IN+ Positive Analog Photodiode Input Connection. Typically connected to photodiode cathode.
3IN- Negative Analog Photodiode Input Connection. Typically connected to photodiode anode.
5VAGC AGC Control Input. Range is 0 to 1.4V. See the Typical Operating Characteristics Gain vs. Control
Voltage graph.
6MUTE Mute Control Input, TTL. MUTE < 0.8V to mute output.
7HYST AGC Hysteresis Control Input. A resistor from HYST to GND controls the hysteresis level.
8, 14, 16 GND Ground
10 OUT- Negative RF Output. The voltage on this pin decreases with increasing optical power when IN+ is
connected to the photodiode cathode.
11 OUT+ Positive RF Output. The voltage on this pin increases with increasing optical power when IN- is
connected to the photodiode anode.
13 TEST1 Reserved for Test. Connect to GND for normal operation.
15 TEST2 Reserved for Test. Connect to GND for normal operation.
EP EP Exposed Pad. The exposed pad must be soldered to the circuit-board ground for proper thermal and
electrical performance.
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
_______________________________________________________________________________________ 7
Applications Information
Photodiode Parasitics
The MAX3654 TIA is designed to operate with a low-
capacitance 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.
RF Output
The differential TIA RF output should be connected
(AC-coupled) to a balun transformer for normal single-
ended 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 photodi-
ode 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 con-
stant and maximum. The nominal gain is given by:
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.
Evaluation Kit and PC Board Layout
The factory-assembled EV kit for the MAX3654 pro-
vides two versions: optical input and electrical input.
The optical input circuit includes photodiode bias cir-
cuitry, an op amp to adjust VAGC according to the DC
photodiode current (for AGC operation), an output
balun, and a 75Ωoutput 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 configu-
rations 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-
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
50Ωinput for use with conventional test and measure-
ment equipment. If desired, the MAX3654 input can
also be terminated with 75Ωas shown in the EV kit data
sheet. The 75ΩEV kit outputs should be connected to
50Ωtest and measurement equipment using a mini-
mum 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
ZT dB dB mV
VAGC mV
V VAGC V
() log ()
(. . ).
ΩΩ=+×
≤≤
62 20 175
0 175 1 4
Chip Information
TRANSISTOR COUNT: 3376
PROCESS: SiGe Bipolar
SUBSTRATE: SOI
15
16
14
13
6
5
7
IN+
VCC
8
VCC
OUT+
VCC
VCC
12
GND
4
12 11 9
TEST2
GND
GND
EP*
HYST
MUTE
VAGC
MAX3654
IN- OUT-
3
10
TEST1
THIN QFN
4mm x 4mm
TOP VIEW
Pin Configuration
*THE EXPOSED PAD MUST BE
CONNECTED TO GROUND.
MAX3654
47MHz to 870MHz Analog CATV
Transimpedance Amplifier
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
©2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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.)
24L QFN THIN.EPS
PACKAGE OUTLINE,
21-0139
2
1
D
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
PACKAGE OUTLINE,
21-0139
2
2
D
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm