A 56-Gb/s Transimpedance Amplifier in 0.13-µm SiGe BiCMOS for an Optical Receiver with -18.8-dBm Input Sensitivity

This paper describes a 56-Gb/s transimpedance amplifier with a level-shift circuit and double-feedback-loop (DFB) compensation architecture to achieve high input sensitivity. The level-shift circuit placed between a main transimpedance amplifier and a post amplifier mitigates the trade-off between the bandwidth and noise of the receiver, which reduces the input referred noise by 70%. The DFB compensates for process variation without increasing the noise. The transimpedance amplifier was fabricated in 0.13-um SiGe BiCMOS technology and packaged with an avalanche photodiode. The 3-dB bandwidth of 38.4 GHz and the input referred noise current density of 14.8 pA/rtHz are achieved. These are the best performance among published 50-Gb/s-class transimpedance amplifiers for optical communication.