A Broadband Transimpedance Amplifier with Optimum Bias Network

A novel transimpedance amplifier (TIA) based on regulated cascode (RGC) configuration was proposed, in which a bias network was added to ensure the main amplifier and the auxiliary amplifier of RGC operate at optimum condition. To achieve high bandwidth, a T-passive matching network was introduced at the input. Since both amplifiers have optimum gain-bandwidth product (GBW), thus low noise and high bandwidth can be obtained in our design scheme. The proposed TIA was designed based on UMC 0.18 mu m CMOS process, and the simulation results demonstrated that our TIA has a transimpedance gain of 51 dB Omega and a -3 dB bandwidth of 14 GHz with a input capacitance of 0.3 pF. The average equivalent input noise current spectral density is about 13 pAi root Hz within-3 dB bandwidth.