Unseen emitter-base breakdown in RF power amplifiers- a possible hazard

RF power amplifier circuits other than Class A have a previously unreported operating characteristic which can cause emitter-base reverse breakdown once each RF cycle. The breakdown is not necessarily observable at the external terminals of the transistor; it can be deduced from the observed emitter-base terminal voltage and base current and the transistor internal lead inductances and junction capacitances. Certain symptoms of RF power transistor deterioration and failure reported by other workers appear to be consistent with the possible effects of such repetitive breakdowns. Common-base amplifiers should be more likely to suffer from this problem than common-emitter amplifiers. Transistor specialists disagree in their predictions of whether such operation would damage the RF power transistor. Controlled experiments could provide definitive information as to the effects on the transistor of such operation.