MAX3864ESA-T [MAXIM]
Support Circuit, 1-Func, Bipolar, PDSO8, 0.150 INCH, MS-012AA, SOIC-8;
| 型号： | MAX3864ESA-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Support Circuit, 1-Func, Bipolar, PDSO8, 0.150 INCH, MS-012AA, SOIC-8 放大器 |
| 文件： | 总12页 (文件大小：869K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1790; Rev 0; 8/00
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
General Description
Features
The MAX3864 is a transimpedance preamplifier for
applications in SDH/SONET systems operating up to
2.5Gbps. It features 490nA (typ) input-referred noise,
2.0GHz bandwidth, and 2mA input overload.
ꢀ 490nA (typ) Input-Referred Noise
ꢀ 2000MHz Bandwidth
ꢀ 2mA Input Overload
The MAX3864 operates from a single +3.0V to +5.5V
supply. It includes an integrated low-frequency com-
pensation capacitor, as well as a filter connection that
ꢀ 100Ω Differential Output Impedance
ꢀ 112mW Power Dissipation at +3.3V
ꢀ Integrated Filter Resistor
ꢀ CML Outputs
provides positive bias through a 750Ω resistor to V
.
CC
These features save external components, simplifying
design and assembly into a TO-46 header with a photo-
diode.
ꢀ Single +3.0V to +5.5V Supply Voltage
The MAX3864 has a typical optical dynamic range of
-24dBm to 0dBm using a PIN photodetector.
Ordering Information
PART
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 SO
Applications
MAX3864ESA
MAX3864E/D
SDH/SONET Transmission Systems
PIN Preamplifier Receivers
APD Preamplifier Receivers
2.5Gbps ATM Receivers
Dice*
* Dice are designed to operate with junction temperatures of -40°C
to +140°C but are tested and guaranteed only at T = +25°C.
A
Pin Configuration
Regenerators for SDH/SONET
TOP VIEW
V
1
2
3
4
8
7
6
5
GND
OUT+
OUT-
GND
CC
N.C.
IN
MAX3864
FILTER
SO
Typical Application Circuit
V
CC
0.01µF
750Ω
V
CC
FILTER
0.1µF
100Ω
C
400pF
FILTER
OUT+
OUT-
PHOTODIODE
IN
LIMITING
AMPLIFIER
0.1µF
MAX3864
GND
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
- GND).................................-0.5V to +6.0V
Storage Temperature Range.............................-55°C to +150°C
Operating Junction Temperature ......................-55°C to +150°C
Processing Temperature (die) .........................................+400°C
Lead Temperature (soldering, 10s) .................................+300°C
CC
IN Current..............................................................-4mA to +4mA
FILTER Current......................................................-8mA to +8mA
Voltages at OUT+, OUT-.................(V
- 1.5V) to (V
+ 0.5V)
CC
CC
Continuous Power Dissipation (T = +85°C)
A
8-Pin SO package (derate 6.7mW/°C above +85°C) ..436mW
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.
ELECTRICAL CHARACTERISTICS
(V
= +3.0V to +5.5V, 100Ω load between OUT+ and OUT-, 0.1µF coupling capacitors on OUT+ and OUT-, T = -40°C to +85°C,
A
CC
unless otherwise noted. Typical values are at +3.3V, source capacitance = 0.85pF, and T = +25°C.) (Note 1)
A
PARAMETER
Input Bias Voltage
CONDITIONS
MIN
TYP
0.83
34
MAX
0.99
63
UNITS
0.66
V
mA
Ω
Supply Current
Transimpedance
Output Impedance
Differential, measured with 40µAp-p input
2100
48
2750
50
3400
52
Single ended (per side)
Ω
Input = 2mAp-p with 100Ω differential output
termination
Maximum Differential Output Voltage
220
380
750
575
930
mVp-p
Filter Resistor
600
2
Ω
mAp-p
mA
AC Input Overload
DC Input Overload
1
Input-Referred RMS Noise
Input-Referred Noise Density
Small-Signal Bandwidth
Low-Frequency Cutoff
490
11
668
nA
Bandwidth = 2.0GHz (Note 2)
pA/√(Hz)
MHz
1525
40
2000
30
-3dB, input ≤ 20µADC
kHz
Gain at 40µAp-p is within 5% of the small-
signal gain
Transimpedance Linear Range
µAp-p
3.13V < V
< 5.5V (Note 3)
24
24
67
77
CC
Deterministic Jitter
ps
3.0V ≤ V
≤ 3.13V (Note 3)
CC
Output referred, f < 2MHz,
PSRR = -20log(∆V /∆Vcc)
Power-Supply Rejection Ratio (PSRR)
50
dB
OUT
Note 1: Source capacitance represents the total capacitance at the IN pin during characterization of noise and bandwidth parame-
ters. Noise and bandwidth will be affected by the source capacitance. See the Typical Operating Characteristics for more
information.
Note 2: Input-referred noise is calculated as (RMS output noise) / (Gain at f = 10MHz). Noise density is (Input-Referred Noise) /
1/2
(Bandwidth) . No external filters are used for the noise measurements.
Note 3: Deterministic jitter is defined as the arithmetic sum of pulse-width distortion and pattern dependent jitter measured with a
repeating 20-bit pattern of 00111110101100000101 (K28.5). See Typical Operating Characteristics.
2
_______________________________________________________________________________________
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
Typical Operating Characteristics
(V = 3.3V, T = +25°C and MAX3864 EV kit source capacitance = 0.85pF, unless otherwise noted).
CC
A
INPUT-REFERRED RMS NOISE
vs. TEMPERATURE
DETERMINISTIC JITTER
vs. INPUT AMPLITUDE
FREQUENCY RESPONSE
100
90
80
70
60
50
40
30
20
10
0
600
75
70
65
60
55
50
C
C
= 1.5pF
IN
IN
550
500
450
400
350
300
250
200
= 1.0pF
C
IN
= 0.5pF
C
IS SOURCE CAPACITANCE
IN
PRESENTED TO DIE, INCLUDES
PACKAGE PARASITIC, PIN DIODE,
AND PARASITIC INTERCONNECT
CAPACITANCE.
1
10
100
1k
10k
-40 -20
0
20
40
60
80 100
10
100
1000
10,000
FREQUENCY (MHz)
JUNCTION TEMPERATURE (°C)
INPUT CURRENT AMPLITUDE (µAp-p)
INPUT-REFERRED RMS NOISE CURRENT
vs. DC INPUT CURRENT
SMALL-SIGNAL TRANSIMPEDANCE
vs. TEMPERATURE
BANDWIDTH vs. TEMPERATURE
1000
900
800
700
600
500
400
300
200
100
0
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
1.5
1.4
70
69
68
67
66
65
64
63
62
61
60
C
IN
= 1.0pF
C
IN
= 0.5pF
C
IN
= 1.5pF
C
IN
IS SOURCE CAPACITANCE
PRESENTED TO DIE, INCLUDES
PACKAGE PARASITIC, PIN DIODE,
AND PARASITIC INTERCONNECT
CAPACITANCE.
1
10
100
1000
-40 -20
0
20
40
60
80 100
-40 -20
0
20
40
60
80 100
DC INPUT CURRENT (µA)
AMBIENT TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
DIFFERENTIAL OUTPUT AMPLITUDE
vs. TEMPERATURE
EYE DIAGRAM (INPUT = 2mAp-p)
EYE DIAGRAM (INPUT = 2mAp-p)
500
480
460
440
420
400
380
360
340
320
300
13
INPUT = 2 -1 PRBS WITH 72 CID
13
INPUT = 2 -1 PRBS WITH 72 CID
INPUT = 2mA
V
= 3.0V AT T = -40°C
CC
A
V
= 3.13V AT T = -40°C
CC
A
50mV/div
50mV/div
-40 -20
0
20
40
60
80 100
80ps/div
80ps/div
AMBIENT TEMPERATURE (°C)
_______________________________________________________________________________________
3
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
Typical Operating Characteristics (continued)
V
CC
= 3.3V, T = +25°C and MAX3864 EV kit source capacitance = 0.85pF, unless otherwise noted).
A
DC TRANSFER FUNCTION
EYE DIAGRAM (INPUT = 2mAp-p)
EYE DIAGRAM (INPUT = 20µAp-p)
200
100
0
INPUT = 223 -1 PRBS
INPUT = 223 -1 PRBS
-100
-200
-100
-50
0
50
100
80ps/div
80ps/div
INPUT CURRENT (µA)
Pin Description
PIN
NAME
FUNCTION
1
2
3
V
Supply Voltage
No Connection
Amplifier Input
CC
N.C.
IN
Provides bias voltage for the photodiode through a 750Ω resistor to V . When grounded, this pin
disables the DC cancellation amplifier to allow a DC path from IN to OUT+ and OUT- for testing.
CC
4
FILTER
5
6
7
8
GND
OUT-
OUT+
GND
Ground
Inverting Output. Current flowing into IN causes V
to decrease.
OUT-
Noninverting Output. Current flowing into IN causes V
Ground
to increase.
OUT+
Voltage Amplifier
Detailed Description
The voltage amplifier converts single-ended signals to
differential signals and introduces a voltage gain.
The MAX3864 transimpedance amplifier is designed for
2.5Gbps fiber optic applications. As shown in Figure 1,
the MAX3864 comprises a transimpedance amplifier, a
voltage amplifier, an output buffer, an output filter, and
a DC cancellation circuit.
Output Buffer
The output buffer provides a back-terminated voltage
output. The buffer is designed to drive a 100Ω differen-
tial load between OUT+ and OUT-. The output voltage
is divided between internal 50Ω load resistors and the
external load resistor. In the typical operating circuit,
this creates a voltage-divider with a ratio of 1/2. The
MAX3864 can also be terminated with higher output
impedances, which increases gain and output voltage
swings.
Transimpedance Amplifier
The signal current at the input flows into the summing
node of a high-gain amplifier. Shunt feedback through
converts this current to a voltage. Schottky diodes
clamp the output voltage for large input currents
(Figure 2).
R
F
4
_______________________________________________________________________________________
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
MAX3864
R = 1k
F
VOLTAGE
AMPLIFIER
OUTPUT
BUFFER
OUTPUT
FILTER
TRANSIMPEDANCE
AMPLIFIER
50Ω
50Ω
OUT+
OUT-
IN
LOWPASS FILTER
V
CC
V
CC
GND
DISABLE
DC CANCELLATION
CIRCUIT
750Ω
FILTER
Figure 1. Functional Diagram
AMPLITUDE
AMPLITUDE
INPUT FROM PHOTODIODE
TIME
TIME
OUTPUT (SMALL SIGNALS)
OUTPUT (LARGE SIGNALS)
INPUT (AFTER DC CANCELLATION)
Figure 2. Limited Output
Figure 3. DC Cancellation Effect on Input
For optimum supply-noise rejection, the MAX3864
should be terminated with a differential load. If a single-
ended output is required, the unused output should be
transimpedance amplifier’s linear range, thereby reduc-
ing pulse-width distortion (PWD) on large input signals.
The DC cancellation circuit is internally compensated
and therefore does not require external capacitors. This
circuit minimizes PWD for data sequences that exhibit a
50% duty cycle and mark density. A duty cycle or mark
density significantly different from 50% causes the
MAX3864 to generate PWD.
terminated with 50Ω to V . The MAX3864 will not drive
CC
a DC-coupled, 50Ω grounded load.
Output Filter
The MAX3864 includes a one-pole lowpass filter that
limits the circuit bandwidth and improves noise perfor-
mance.
DC cancellation current is drawn from the input and
creates noise. For low-level signals with little or no DC
component, this is not a problem. Amplifier noise will
increase for signals with significant DC component (see
Typical Operating Characteristics).
DC Cancellation Circuit
The DC cancellation circuit uses low-frequency feed-
back to remove the DC component of the input signal
(Figure 3). This feature centers the input signal within the
_______________________________________________________________________________________
5
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
where ρ is the photodiode responsivity, including fiber-
POWER
PI
to-photodiode coupling efficiency in A/W and I in µA.
N
For example, if SNR = 12.7, I = 0.490µA, r = 10, and
N
e
ρ = 1, then sensitivity is -24dBm.
Input Optical Overload
The overload is the largest input that the MAX3864
accepts while meeting deterministic jitter specifications.
The optical overload can be estimated in terms of aver-
age power with the following equation (assumes
P
IN
P
AVG
r = ∞):
e
PO
2mAp-p × 1000
2ρ
Overload = 10log
dBm
TIME
Figure 4. Optical Power Relations
Optical Linear Range
The MAX3864 has high gain, which limits the outputs
when the input signal exceeds 40µAp-p. The MAX3864
operates in a linear range for inputs not exceeding:
Table 1. Optical Power Relations
PARAMETER
SYMBOL
RELATION
Average Power
P
P
AVE
= (P + P ) / 2
AVE
0
1
40µAp-p r +1 × 1000
(
)
e
Linear Range = 10log
dBm
Extinction Ratio
r
r = P / P
e 1 0
e
2ρ r −1
(
)
e
Optical Power of a 1
Optical Power of a 0
P
P
P = 2P
1
r / (r + 1)
AVE e e
1
0
P = 2P
0
/ (r + 1)
e
AVE
Layout Considerations
P
= P - P = 2P
1 0 AVE
IN
Signal Amplitude
P
IN
Use good high-frequency design and layout techniques.
The use of a multilayer circuit board with separate ground
and power planes is recommended. Connect the GND
pins to the ground plane with the shortest possible traces.
(r - 1) / (r + 1)
e
e
Note: Assuming a 50% average input duty cycle and mark
density.
Noise performance and bandwidth will be adversely
affected by capacitance at the IN pin. Minimize capaci-
tance on this pin, and select a low-capacitance photodi-
ode. Assembling the MAX3864 in die form using chip and
wire technology provides the best possible performance.
Figure 5 shows the recommended layout for a TO
header.
Applications Information
Optical Power Relations
Many of the MAX3864 specifications relate to the input
signal amplitude. When working with fiber optic receivers,
the input is usually expressed in terms of average optical
power and extinction ratio. Figure 4 shows relations that
are helpful for converting optical power to input signal
when designing with the MAX3864.
The SO package version of the MAX3864 is offered as an
easy way to characterize the circuit and to become famil-
iar with the circuit’s operation, but it does not offer opti-
mum performance. When using the SO version of the
MAX3864, the package capacitance adds approximately
0.3pF at the input. The PC board between the MAX3864
input and the photodiode also adds parasitic capaci-
tance. Keep the input line short, and remove power and
ground planes beneath it.
Optical power relations are shown in Table 1; the defini-
tions are true if the average duty cycle and mark densi-
ty of the input data are 50%.
Optical Sensitivity Calculations
The MAX3864 input-referred RMS noise current (I )
N
generally determines the receiver sensitivity. To obtain
a system bit-error rate (BER) of 1E-10, the minimum sig-
nal-to-noise ratio (SNR) is 12.7. The input sensitivity,
expressed in average power, can be estimated as:
GND
Connect GND as close to the AC ground of the photode-
tector diode as possible. The photodetector AC ground is
usually the ground of the filter capacitor from the photode-
tector cathode. The total loop (from GND, through the
bypass capacitor and the diode, and back to IN) should
be no more than approximately 1/5th of a wavelength.
SNR × I r +1
(
)
N e
Sensitivity=10log
dBm
2ρ r −1 × 1000
(
)
e
6
_______________________________________________________________________________________
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
TOP VIEW OF TO-46 HEADER
V
CC
V
CC
V
CC
C
FILTER
200Ω
PHOTODIODE
OUT-
OUT+
IN
MAX3864
CASE IS GROUND
GND
Figure 5. Suggested Layout for TO-46 Header
Figure 6. Equivalent Input Circuit
Photodiode Filter
Wire Bonding
Supply voltage noise at the photodiode cathode pro-
For high current density and reliable operation, the
MAX3864 uses gold metalization. Connections to the
die should be made with gold wire only, using ball-
bonding. Wedge bonding is not recommended. Die
thickness is typically 15mils (0.375mm).
duces a current I = C
receiver sensitivity (C
∆V / ∆t, which reduces the
is the photodiode capaci-
PD
PD
tance). The filter resistor of the MAX3864, combined
with an external capacitor, can be used to reduce this
noise (see the Typical Application Circuit). Current gen-
erated by supply noise voltage is divided between
C
FILTER
and C . The input noise current due to sup-
PD
ply noise is (assuming the filter capacitor is much larg-
er than the photodiode capacitance):
V
C
(
NOISE)( PD
)
I
=
NOISE
R
C
(
FILTER)( FILTER
)
If the amount of tolerable noise is known, the filter
capacitor can be easily selected:
V
C
(
NOISE)( PD
)
C
=
FILTER
R
I
(
FILTER)(NOISE
)
For example, with a maximum noise voltage equal to
100mVp-p, C
= 0.85pF, R
= 750Ω, and I
PD
FILTER NOISE
selected to be 250nA (half of the MAX3864’s input noise):
100mV 0.85pF
(
)(
)
C
=
= 453pF
FILTER
750Ω 250nA
(
)(
)
_______________________________________________________________________________________
7
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
V
CC
50Ω
50Ω
OUT+
OUT-
GND
Figure 7. Equivalent Output Circuit
8
_______________________________________________________________________________________
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
Chip Topography
Chip Information
TRANSISTOR COUNT: 320
PROCESS: BIPOLAR (SILICON GERMANIUM)
OUT+
OUT-
50mils
1.27mm
GND
GND
V
CC
INPUT
FILTER
30mils
(0.762mm)
_______________________________________________________________________________________
9
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
Package Information
10 ______________________________________________________________________________________
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
NOTES
______________________________________________________________________________________ 11
2.5Gbps, +3V to +5.5V, Wide Dynamic Range
Transimpedance Preamplifier
NOTES
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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