It should be noted that the reverse branch of I-V characteristics of diodes does not have sharp breakdown region
. That is why current of around 100 mA is believed to be the beginning of breakdown process.
Electronic circuits, employing bipolar junction transistors biased into the avalanche breakdown region
are known for many years , .
The phase relationships between harmonics are critical in nonlinear circuits where devices may, or may not, be operating past their breakdown regions
, depending on the instantaneous amplitude of the waveform.