A Single-to-Differential Transimpedance Amplifier for Low-Noise and High-Speed Optical Receivers

This paper presents a transimpedance amplifier (TIA) topology to realize single-ended to differential conversion with no need for a dummy amplifier. The proposed structure includes a Common-Gate Common-Source (CG-CS) topology incorporating an input impedance modification path which allows a large photodiode capacitance. Accordingly, the TIA is designed in 0.35-µm CMOS technology and post-layout simulations show that the circuit can be used in wideband optical communication systems. Consuming 10mW from a 3.3 V supply, the circuit has 2.25 GHz bandwidth and 56.1 dB gain rendering possible a 400 fF capacitance at the input node of the TIA. The input-referred noise of the circuit is lower than 15.5 pA/√Hz and the integrated input noise current is less than 0.6 µA. The TIA demonstrates a gain and phase imbalance of less than 1.5 dB and 5 degrees respectively in the entire bandwidth of interest.