Intermodulation in heterojunction bipolar transistors

The authors examine the modeling of small-signal intermodulation distortion (IM) in heterojunction bipolar transistors (HBTs). It is shown that IM current generated in the exponential junction is partially canceled by IM current generated in the junction capacitance, and that this phenomena is largely responsible for the unusually good IM performance of these devices. The authors propose a nonlinear HBT model suitable for IM calculations and show how to measure its parameters. Its accuracy has been verified experimentally.<>