Investigation of Time-Domain Locus of SiGe HBTs in the Avalanche Region by Using the X-Parameter Measurement Under Large-Signal Drive

In this letter, the high-frequency avalanche effects of silicon germanium (SiGe) heterojunction bipolar transistors (HBTs) on time-domain locus characteristics based on the X-parameter measurement are presented and analyzed by applying the concept of the dead space theory for the first time. The measured X-parameters of the SiGe HBTs are utilized to obtain the time-domain waveform under large-signal drive in the impact ionization region. Input locus of the SiGe HBTs operating in the avalanche regime presents negative slope when compared with the positive slope in the active region. The rotation direction of the transfer locus at breakdown is also investigated.