1.25 Gb/s variable transimpedance amplifier in digital CMOS process

A new CMOS transimpedance amplifier (TIA) with variable gain for optical fiber communication receivers is presented in this paper. The proposed configuration is realized in a low-cost digital 0.35 μm CMOS process and fed from a single 1.8 V voltage supply. A 56−68 dBΩ transimpedance gain variation range is attained with 1 GHz bandwidth. The TIA shows 9 pA/√Hz input-referred spectral noise and only 6.9 mW power consumption.