HBT dynamic charging modeling using EH_VBIC and waveform verification

Dynamic charging effects have large impact on power, PAE of power amplifiers. When simulating a Power amplifier with InGaP-GaAs HBTs, modeling often fails to predict well a higher PAE at high power density region, unless some parameter sets to unreasonable value. This has been a controversial issue and could not correctly modeled by existing commercial available HBT models. We present a novel time- domain characterization method, to reveal dynamic charge effects of HBTs. It is shown that charge-storage and extraction of the base-collector at a high-power drive is the root cause of better PAE and that is crucial only when the base-emitter junction is at forward conduction. A modified EH-VBIC model can excellently account for those effects without reasonable modification of BC diode charge model.