Characterization of Transistor Matching in Silicon-Germanium Heterojunction Bipolar Transistors

Abstract

Transistor mismatch is a crucial design issue in high precision analog circuits, and is investigated here for the first time in SiGe HBTs. The goal of this work is to study the effects of mismatch under extreme conditions including radiation, high temperature, and low temperature.

One portion of this work reports collector current mismatch data as a function of emitter geometry both before and after 63 MeV proton exposure for first-generation SiGe HBTs with a peak cut-off frequency of 60 GHz. However, minimal changes in device-to-device mismatch after radiation exposure were experienced.

Another part of the study involved measuring similar devices at different temperatures ranging from 298K to 377K. As a general trend, it was observed that device-to-device mismatch improved with increasing temperature.