The design of p-i-n-bipolar transimpedance pre-amplifiers for optical receivers

The factors limiting speed, sensitivity and dynamic range in p-i-n-b.j.t. transimpedance pre-amplifiers for optical receivers are examined. It is shown that a common-collector front end design is the best input configuration if a wideband response with good sensitivity is required. Two low-cost discrete pre-amplifier designs suitable for 140 Mbit/s and 650 Mbit/s are presented, together with three monolithic integrated circuits. The i.c.s were used in 320 Mbit/s receivers and had typical sensitivities of ¿34.6 dBm and optical dynamic ranges of at least 18.4 dB. The effect of circuit parasitics and of reducing transistor geometry on the i.e. performance is examined.