VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7810
Photodetector/Transimpedance Amplifier
Family for Optical Communication
G52145-0, Rev 4.1
Page 1
04/05/01
VITESSE
SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Features
General Description
The VSC7810 integrated Photodetector/Transimpedance Amplifier provides a highly integrated solution
for converting light from a fiber optic communications channel into a differential output voltage. The benefits
of Vitesse Semiconductor's Gallium Arsenide H-GaAs process are fully utilized to provide very high bandwidth
and low noise in a product with a large optically active area for easy alignment. The sensitivity, duty cycle dis-
tortion and jitter meet or exceed all Fibre Channel and Gigabit Ethernet application requirements. Parts are
available in either die form, flat-windowed packages or in ball-lens packages.
By using a metal-semiconductor-metal (MSM) photodetector with a monolithic integrated transimpedance
amplifier, the input capacitance is lowered which allows for a larger optically active area than in discrete photo-
detectors. Integration also allows superior tracking over process, temperature and voltage between the photode-
tector and the amplifier, resulting in higher performance. This part can easily be used in developing Fibre
Channel Electro-Optic Receivers which exhibit very high performance and ease of use.
VSC7810 Block Diagram
Part Number
Data Rate
Bandwidth
(MHz)
Input Noise
(
W rms)
Optically Active Area
(
m diameter)
VSC7810
Full Speed: 1.25Gb/s
1200
0.45
100
Integrated Photodetector/Transimpedance
Amplifier Optimized for High-Speed Optical
Communications Applications
Integrated AGC
Fibre Channel/Gigabit Ethernet Compatible
High Bandwidth
Low Input Noise Equivalent Power
Large Optically Active Area
Single 5V Power Supply
Both DOUTP and DOUTN are back-terminated to 25
.
Photodetector/Transimpedance Amplifier
DOUTP
DOUTN
+3.3V
GND
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7810
Photodetector/Transimpedance Amplifier
Family for Optical Communication
Page 2
G52145-0, Rev 4.1
04/05/01
VITESSE
SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Table 1: Electro-Optical Specifications
(1)
Notes: (1) Specified over 0C (ambient) to 70C (case). (2) Typical conditions 25C and 3.3V power supply. (3) See Note 1 in
Application Note 48. (4) P = Incident Optical Power (5) See Note 2 in Application Note 48.
Symbol
Parameter
Min
Typ
(2)
Max
Units
Conditions
V
SS
Supply Voltage
4.5
5.0
5.5
V
I
DD
Supply Current
13
26
40
mA
PSRR
Power Supply Rejection Ratio
35
-
-
dB
Frequencies up to 40MHz
(includes external filter).
Wavelength
700
840
850
nm
f
C
Low Frequency Cutoff
-
-
1.8
MHz
-3dB, P
= -15dBm @ 50MHz
(4)
BW
Optical Modulation Bandwidth
800
1200
1300
MHz
-3dB, P = -15dBm @ 50MHz
(4)
S
Sensitivity
-22
-25
-27
dBm
1.063Gb/s, BER10
-12(3)
R
O
Single-Ended Output Impedance
25
-
60
V
D
Differential Output Voltage
0.35
0.52
0.65
V
P = -4.5dBm,
R
LOAD
= 100
differential
R
D
Differential Responsivity
0.8
2.2
-
mV/
W
R
LOAD
= 100
P = -15dBm @ 50MHz
V
DC
Output Bias Voltage
1.2
1.5
2.5
V
V
DC
Bias Offset Voltage
-
40
150
mV
NEP
O
Input Noise Equivalent Power
0.35
0.45
0.93
W rms
P = 0mW
(5)
V
NO
Output Noise Voltage
0.55
0.66
0.75
mV rms
P = 0mW
(5)
DCD
Duty Cycle Distortion
-
1.5
4.5
%
P = -4.5dBm
I
OUT
Output Drive Current
2.5
-
8
mA
PDJ
Pattern Dependent Jitter
20
40
60
ps
P = -4.5dBm
+/-10% Voltage Window
Optically Active Area
-
100
-
m Diameter
PPJ
PP Jitter
120
160
200
ps
P = -5dBm
t
R
Rise Time
310
355
400
ps
20%-80% P = -4.5dBm
t
F
Fall Time
280
325
370
ps
20%-80% P = -4.5dBm
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7810
Photodetector/Transimpedance Amplifier
Family for Optical Communication
G52145-0, Rev 4.1
Page 3
04/05/01
VITESSE
SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Figure 1: Amplifude vs. Frequency
Table 2: Absolute Maximum Ratings
Table 3: Recommended Operating Conditions
NOTE: (1) See Note 1 in "Notes on Measurement Conditions & Applications" section of this data sheet for extended temperature range
operation.
Symbol
Parameter
Limits
V
SS
Power Supply
6V
T
STG
Storage Temperature
-55C to 125C (case temperature under bias)
H
STG
Storage Humidity
5 to 95% R.H. (including condensation)
H
OP
Operating Humidity
8 to 80% R.H. (excluding condensation)
P
INC
Incident Optical Power
+3dBm
IS Impact
Shock
500 G. Half Sine Wave
Pulse Duration 1 +/-0.5 ms
3 blows in each direction
V
IB
Vibration
20 > 2000 > 20 Hz, 10 Minutes
10 G. Peak Acceleration
4 Complete Cycles, 3 Perpendicular Axes
V
ESD
ESD Voltage on DOUTP, DOUTN, VSS,
GND
1500V
Symbol
Parameter
Limits
V
SS
Power Supply
4.5V to 5.5V (5V nominal)
T
OP
Operating Temperature
0C (ambient) to 70 C (case) normal range and 90C (case) extended range
(1)
1 096.795 514 MHz
1 000.150
1 999.700
21
3
Amplitude
Frequency (MHz)
Frequency response of VSC7810WB upper 3db frequency is measured with respect to response at 50 MHz
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7810
Photodetector/Transimpedance Amplifier
Family for Optical Communication
Page 4
G52145-0, Rev 4.1
04/05/01
VITESSE
SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Table 4: Pin Table Specifications for Ball Lens Packages, Flat Window Packages and Bare Die
Note: Pin Diagram is identical for both TO-46 and TO-56 package styles.
Figure 2: Pin Diagram
Figure 3: Schematic View of Bare Die Pad Assignments
Symbol
Description
DOUTP
Data output normal (with reference to incident light)
DOUTN
Data output complement (inverting, with reference to incident light)
VSS
Power supply
GND
Ground (package case)
DOUTP
DOUTN
GND
VSS
Bottom View
DOUTN
GND
GND
GND
VSS
DOUTP
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC7810
Photodetector/Transimpedance Amplifier
Family for Optical Communication
G52145-0, Rev 4.1
Page 5
04/05/01
VITESSE
SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Temperature Dependence of Operating Parameters
This section describes the dependence of important operating parameters shown in Table 1 as a function of
die (or equivalently junction) tempeature and power supply. In order to relate the die temperature to an equiva-
lent case temperature, the following thermal characteristics of the package are provided (note that the thermal
conductivity is identical for TO-46 and TO-56 package styles.
Table 5: Thermal Resistance Calculation for TO-56 and TO-46 Packages
Chip Size
0.168cm x 0.104cm
Thermal Path
Chip Area A
0.015cm
2
Die Height (T
DIE
)
0.066cm
Epoxy Thickness (T
EPOXY
)
0.0076cm
Header Thickness (T
HEADER
)
(Average for TO-46 and TO-56 package)
0.115cm
Thermal Conductivities
K GaAs
0.55W/cm C
K epoxy
0.0186W/cm C
K kovar
0.17W/cm C
GaAs
K
GaAs
A
T
die
0.066
0.55 x 0.015
= 8
C/W
=
=
epoxy
K
epoxy
A
T
epoxy
0.0076
0.0186 x 0.015
= 27.24
C/W
=
=
kovar
K
kovar
A
T
kovar
0.12
0.17 x 0.015
= 47
C/W
=
=
JC
= Thermal Resistance from Junction to Case = (8 + 27.24 + 47) = 82.24
C/W
Example:
For VSC7810 at nominal supply current of 25mA and Vss = 5V
Temperature rise from junction to case = 0.025A x 5V x 82.24
C/W = 10.28
C
T
J
GaAs
EXPOXY
KOVAR
T
C
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