A 2.5Gb/s low noise CMOS transimpedance amplifier

A novel low noise CMOS common-gate transimpedance amplifier, which can be used in the receiver in 2.5 Gbit/s optical communication system, is presented. In order to reduce the input-referred noise current, active feedback is used instead of resistor feedback, and source follower instead of common-source as the second stage. Simulation results using TSMC´s 0.18 mu m CMOS process give a transimpedance of 61.89 dB with the bandwidth of 2 GHz, a low average input-referred noise current spectral density(7.3 pA/ radicHz), and 2.6 mW power consumption of the core circuit.