Modelling the excess noise due to avalanche multiplication in (hetero-junction) bipolar transistors

We study the noise behaviour of bipolar transistors for collector voltages close to and beyond the collector-emitter breakdown voltage. We model the excess noise due to amplification of shot noise and due to the impact ionisation itself, both for weak avalanche and for strong avalanche. Our new model accurately predicts the measurements, without the need for parameter fitting to noise data.