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 preamplifier 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.c. performance is examined.