Posted on Feb 12, 2013 9361
This two-chip receiver with minimum external component count has been designed for low-cost fiber optic applications to 100-M baud (50 MHz). The receiver is divided into pre-and postamplifier !Cs for increased stability. The preamplifier IC features low noise with a differential transresistance design. The postamplifier IC incorporates an auto-zeroed first stage with noise shaping, high-gain symmetrical-limiting amplifier, and a matched rise/fall time TTL output buffer. -A wide-band full-wave rectifier functions as a link-status indicator.
To ensure stability, a surface mount, small outline (SO), package is used. The received signal in the -35 dBm optical (average) to -9 dBm range is converted into a small unipolar current by the pin diode. The pin diode then feeds its signal current to a preamplifier, such as the NE5212. The preamplifier output is fed to a high-gain limiting amplifier, simply known as the post amp. The NE5214/NE5217 postamplifiers are low-cost !Cs that provide up to 60 dB of gain at 50 MHz to bring mV level signals up to TTL levels. The postamplifier IC incorporates an auto-zeroed first stage with noise shaping, a high-gain symmetrical-limiting amplifier, and a matched rise/fall time TTL output buffer. A secondary amplifier chain functions as a link-status indicator.