Mathematical Analysis of Switching HBT Devices

Developing highly efficient power amplifiers using HBT devices at mm-wave frequencies is in active research due to their high f
T
/f
max
. This paper focuses on formulating a general mathematical analysis of HBT devices for switching-mode power amplifiers (SMPAs) at mm-wave frequencies. This analysis helps identify and quantify the switching device's loss mechanisms and collector efficiency. The analysis results of the transferred-substrate InP DHBT device are presented, which are comparable to other HBT technologies. The conduction loss is the primary reason for lower collector efficiency at the W-band rather than the switching loss. The Push-Push configuration and the effects of knee voltage and f
T
of the switching device are studied to improve the SMPA collector efficiency.