Transimpedance amplifier for a 2.5 Gbit/s direct transmission optical system using GaAs MESFETS

摘要

This paper shows a new closed form expressions intended to analyze the cascode structure with resistive feedback used as Transimpedance Amplifier, derived from the equivalent circuit parameters of the FETS. The predicted transimpedance magnitude, -3 dB bandwidth and ripple are in good agreement with simulations. We used this technique to implement a DC to 2.5 GHz amplifier on GaAs MMIC. with 67 dB? of transimpedance and a good noise performance. Using a commercially available photodiode and the described amplifier it has been constructed an optical receiver with a flat responsivity of 32 dB-A/W and 6 pA/V(Hz) of equivalent input noise current averaged in band.