Figure 19 shows a circuit designed as a receiver for high-frequency fiber-optic communication systems.
The circuit uses a back-biased silicon photodiode. It provides an output
with transistor-transistor logic (TTL). In this system,
the light emerging from the optical fiber is incident on the detector.
The resulting signal is amplified. If this circuit is employed in a relay station in
a telecommunications link, the output may be used to drive a laser diode source
that retransmits the information into the next segment of the fiber-optic cable.