Junction Capacitance

Author: Leonard Krugman

Before the actual transistor circuit is considered, some additional and important characteristics must be defined. In Chapter 2, the collector junction capacitance was mentioned in connection with transistor high-frequency characteristics. In the equivalent network, this parameter acts in parallel with the collector resistance. The value of collector junction capacitance C_c varies in units of the same type, but for a typical junction transistor is approximately 10 pF. The value of capacitance is primarily a function of the junction area, although it also depends on the width of the junction layer and the resistivity of the base layer.