A 25Gbps Differential Low Noise TIA with 10.9 pA/√Hz in 45RFSOI

Abstract

A 25Gbps single-ended to differential (S2D) low noise transimpedance amplifier (TIA) in 45RFSOI is presented. A ac-coupling capacitor and a capacitor cross-coupled pair are used to achieve S2D differential output. To optimize both noise and bandwidth, a high-gain low-bandwidth input stage followed by a continuous-time linear equalizer (CTLE) is adopted, where the CTLE uses inductive peaking and negative capacitance to achieve a bandwidth extension ratio (BWER) of 3.9 with less than 0.5dB peaking. Post simulation results show that the designed TIA achieves 63.3 dB transimpedance gain, and 22.6-GHz overall bandwidth while the photodiode capacitance is accounted for 70fF. The input average noise current spectral density is 10.9 pA/ √Hz, and the power consumption is 38mW with 1.3V supply.