Transimpedance amplifier with PDCM and AGC

A 1.25 Gb/s transimpedance amplifier(TIA) with high precision photodetector current monitor.(PDCM) and auto gain control(AGC) circuit is proposed. The PDCM circuit can get precision and linearity monitor voltage output. The AGC is less dependent on the alteration of devices parameter because of the design technology based on proportional parameter. The design is based on 0.25-mum BICMOS process. HSPICE post simulation shows that in all the worst cases, the PDCM can get a nearly perfect linearity output, and the floating region of initial AGC bias voltage is between -0.384% and 0.307%.