RF power transistor storage time: theory and measurements

Measurements on two types of UHF power transistors are given. The measured charge storage time constants (τ/SUB s/) were 89 ns and 173 ns, effectively `infinite´ for most applications. Then t/SUB s/ is essentially independent of τ/SUB s/, and depends mainly on circuit properties: base drive and collector current waveforms. The measured dependence of t/SUB s/ on circuit and transistor parameters is in accordance with analytical predictions. Therefore storage time can be accounted for explicitly in a priori circuit design of RF power amplifiers.