A 23 GHz Baseband HBT Distributed Amplifier for Optical Communication Systems

This paper reports on a practical HBT distributed amplifier MMIC suitable for optical receiver applications. The circuit topology is based upon application of a novel technique which allows baseband operation in conjunction with dc bias stabiliastion and does not consume a large amount of chip area. 2×2 ¿m2 single emitter finger InGaP/GaAs HBTs with fT = 60 GHz and ßdc ¿ 100 have been employed. Simulation results show a bandwidth extending from near- dc to 23 GHz and an S21 gain of 11±1 dB at midband. The amplifier has a transimpedance gain of 45±1 dB¿ and a group delay variation of ±30 ps across the passband. Eye diagram simulations indicate its potential for handling data rates of up to 30 Gbit/s when employed as an optical receiver preamplifier.