1.25-Gb/s CMOS front-end amplifier for optical receiver

This paper presents a front-end amplifier for 1.25 Gbit/s optical receiver applications, realized in 0.18 mu m CMOS technology. The circuit consists of a transimpedance amplifier followed by a limiting amplifier based on improved Cherry-Hooper structure. It is designed for a relatively large integrated-photodiode capacitance, approximately 1500 fF and fed from a single 1.8 V power supply. The power consumption of the circuit is 68 mW. The equivalent input noise current spectral density is 12 pA/root Hz at 1 GHz: while the whole transimpedance gain achieve's 114 dB Omega. A clear output eye-diagram is obtained with an input voltage 1 mV at 1.25 Gbit/s.