A new method to improve the unconditional stability of InGaP/GaAs heterojunction bipolar transistor

A new method to improve the unconditional stability of GaAs heterojunction bipolar transistor (HBT) is presented. The key point of this method is to improve the unconditional stability of HBT through optimized design of device physical parameters and avoid using additional stability network in the RF amplifier circuit. The parameter analysis and optimization design were implemented by Synopsys Sentaurus TCAD. The results show that the base doping concentration, the base thickness and the emitter doping concentration have remarkable influence on the GaAs HBT stability. An optimized HBT device with unconditional stability from low frequency (lower than 1GHz) to high frequency was obtained, and the RF gain of this device is almost not sacrificed.