• Integrated Photodetector/Transimpedance Amplifier Family Optimized for High Speed Optical
Communications Applications
• Integrated AGC
• Fibre Channel and Gigabit Ethernet
Part Number
VSC77101.251300.2275
Data Rate
(Gb/s)
Bandwidth
(MHz)
• High Bandwidth
• Low Input Noise Equivalent Power
• Single 5V Supply
Input Noise
µW rms)
(
Optically Active Area
µm diameter)
(
General Description
The VSC7710 integrated PIN Photodetector/Transimpedance Amplifiers provides a highly integrated solution for converting 1300 nm light from a fiber optic communications channel into a differential output voltage.
The benefits of Vitesse Semiconductor’s Gallium Arsenide H-GaAs-III process are fully utilized to provide a
very high bandwidth and low noise amplifier. The PIN detector is 75
plied internally eliminating the need for a separate bias connection. The sensi t ivit y, duty cycle distortion and jitter meet or exceed all Fibre Channel and Gigabit Ethernet application requirements. Parts are available in flatwindowed or lensed packages.
The use of a photodetector and transimpedance amplifier hybrid, reduces the input capacitance, resulting in
higher sensitivity and bandwidth and improved speed of response. These parts can easily be used in developing
Fibre Channel and Gigabit Ethernet electro-optic Receivers for the 900- 1600 nm spectra l range w hich exhibit
very high performance and ease of use.
In order to relate the junction temperature to an equivalent 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 Size0.168cm x 0.104cmThermal Path
Chip Area A0.015 cm
Die height (T
Epoxy thickness (T
Header thickness (Theader)
(ave. for TO-46 and TO- 56)
K GaAs0.55W / cm °C
K epoxy0.0186W / cm °C
K kovar0.17W / cm °C
)0.066 cm
die
)0.0076 cm
epoxy
Thermal Conductivities
0.115 cm
2
T
J
θ
GaAs
θ
EXPOXY
θ
T
C
KOVAR
T
GaAsA
K
T
epoxyA
K
T
kovarA
K
die
epoxy
kovar
θ
GaAs
θ
epoxy
θ
kovar
θ
JC
= Thermal Resistance from Junction to Case = (8 + 27.24 + 47) = 82.24 °C/W
Example:
For VSC7710 at nominal supply current of 25mA and V
Temperature rise from junction to case = 0.025A x 5V x 82.24 °C/W = 10.28 °C