Wideband High Gain Active Feedback Transimpedance Amplifier

A new wideband high gain CMOS transimpedance amplifier is presented without using any inductor. In the proposed TIA, gain enhancing path is introduced in the active voltage-current feedback TIA topology to increase both the gain and bandwidth. This path increases the transconductance of the proposed TIA which reduces the input resistance and leads to bandwidth extension. Additionally, for utilizing the benefit of this topology, cascading of common source stage is also done to increase the gain further without deteriorating the bandwidth. Mathematical analysis is also performed to evaluate both the gain and bandwidth enhancement. These analyses are supported by simulations that are done using TSMC 0.18 µm CMOS technology with the input photodiode capacitance of 0.3 pF. The proposed TIA occupies 0.019 mm2 area and consumes 3.2 mW from 1.8 V supply voltage. The transimpedance gain of the proposed TIA is found to be 57.15 dBΩ over the bandwidth of 6.5 GHz. The input noise is 17.16 pA/√Hz.