Analysis and simulation of the performances of Si/SiGe HBTs and monolithic integrated preamplifiers of photoreceivers

摘要

Abstract: In this paper, we analyzed the characteristics of the noise, current gain, frequency performance and dynamic range of Si/SiGe heterojunction bipolar transistors (Si/SiGe HBTs) for photoreceivers. They are influenced by the following factors: (1) the doping density, the thickness of the high doped and low doped layers of the emitter, (2) recombination currents in the interface of the emitter-base heterojunction, (3) the germanium (Ge) and Boron (B) content and profile in base region, (4) the collector-base heterojunction barrier effect. Then we gave the device analysis model, noise analysis model and their equivalent circuits of the Si/SiGe HBTs, for simulating and optimizing the performance of Si/SiGe HBTs used in photoreceivers. A novel Si/SiGe HBTs of preamplifiers for photoreceivers has been designed and fabricated. Its current gain $beta$-max$/ equals 300, the cut off frequency f$-T$/ equals 10 GHz and the maximum oscillation frequency f$-MAX$/ equals 5 GHz. Based on this, we analyzed, simulated and optimized the performances of the preamplifiers of photoreceivers, include the sensitivity, the dynamic range, the transimpedance characteristics, frequency response, and bit rate of the transimpedance preamplifiers of photoreceivers composed of SiGe HBTs, and optimized the design of SiGe HBTs- based monolithic integrated preamplifiers of photoreceivers. !5