Predictions based on the maximum oscillator frequency of a transistor
Paul R. Drouilhet · IRE Transactions on Circuit Theory · 1955
A CONVENIENT starting point for any consideration of the transistor as a circuit element is the adoption of an equivalent circuit. Much has been written on this subject, and many different equivalent circuits proposed. Since an equivalent circuit which specified the transistor over the whole possible operating range would be impractically complex, it is necessary to make approximations, thereby restricting the region of usefulness of the equivalent circuit.