DESCRIPTION
This “system on a chip” features an auto-zeroed first stage with noise shaping, a symmetrical limiting second stage, and a matched rise/fall time TTL output buffer. The system is user-configurable to provide noise filtering, adjustable input thresholds and hysteresis. The threshold capability allows the user to maximize signal-to-noise ratio, insuring a low Bit Error Rate (BER). An Auto-Zero loop can be used to minimize the number of external coupling capacitors to one. A signal absent flag indicates when signals are below threshold. Additionally, the low signal condition forces the overall TTL output to a logical Low level. User interaction with this “jamming” system is available. The SA5214 is packaged in a standard 20-pin surface-mount package and typically consumes 42mA from a standard 5V supply. The SA5214 is designed as a companion to the SA5211/5212 transimpedance amplifiers. These differential preamplifiers may be directly coupled to the post-amplifier inputs. The SA5212/5214 or SA5211/5214 combinations convert nanoamps of photodetector current into standard digital TTL levels.
Philips
