The Study of Large-Signal High-Frequency Effects in Junction Transistors Using Analog Techniques

An analog has been designed and constructed in which the base-emitter junction of a transistor is represented by a transmission line lumped into several elements representing distributed base resistance and base-emitter capacitance. The base-emitter capacitance varies with current and therefore each element of the junction is represented by a special circuit which presents the required impedance at any current. The distributed voltage-dependent collector-base capacitance and the resistance of the collector body are also represented. The analog is used to indicate the magnitude of several effects that arise at large signal levels and high frequencies. The results are generalized to obtain expressions for the variation of base resistance and collector series resistance with transistor parameters and operating conditions.