Impact of geometrical scaling on low-frequency noise in SiGe HBTs

The influence of geometrical scaling on low-frequency noise in SiGe HBTs is presented. Small-size transistors show a strong variation in noise across many samples, whereas the noise in larger devices is more statistically reproducible. This size-dependent variation in noise can produce challenges for accurate compact modeling. This effect is investigated using reverse-bias emitter-base stress and calculations based on the superposition of generation/recombination noise.