On the scaling of emitter stripes of SiGe power HBTs

Abstract

The lateral scaling issues of the emitter stripe width of large-area power SiGe heterojunction bipolar transistors (HBTs) are analytically studied and experimentally verified. It is found that, due to increased parasitics along with the increase of device area, the maximum oscillation frequency (fmax) of a power SiGe HBT cannot be improved monotonically with the shrinking of the emitter stripe width, which is different from the downscaling of the low-power (few emitter stripes) counterparts. It is concluded that the emitter stripe width of large-area devices ought to be properly upscaled, relative to that of low-power devices, in order to optimize the RF performance of large-area SiGe power HBTs.