An analytical expression for avalanche multiplication of a novel vertical SiGe partially depleted heterojunction bipolar transistor(HBT)on a thin silicon-on-insulator(SOI)layer is obtained,considering vertical and horizontal impact ionization effects.The avalanche multiplication is found to be dependent on the collector width and doping concentration,and shows kinks with the increase of reverse base-collector bias,which is quite different from that of a conventional bulk HBT.The model is consistent with the experimental and simulation data and is found to be significant for the design and simulation of 0.13µm millimeter wave SiGe SOI BiCMOS technology.
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