Abstract: A front-end amplifier circuit which can be applied to wide-dynamic-range optical receiver with 2.5Gb/s data rate has been designed based on 0.18 μm CMOS technology.Pre-amplifier utilizes Regulated Cascode (RGC) architecture as Transimpedance Amplifier (TIA),meanwhile,DC-cancellation and Auto Gain Controlling (AGC) circuits are employed to expand its dynamic range.Limiting Amplifier (LA) makes the use of several approaches like scaling-down,shunt peaking and Cherry-Hooper amplifier with active feedback,to enlarge its bandwidth.Simulation result has manifested that the gain at medium frequency of the front-end amplifier (including pre-amp and limiting amp) is 116 dBΩ,-3 dB bandwidth is 2.13 GHz,input dynamic range is 40 dB (0.01~1 mA).