Gain Stabilization Using Nonlinear Circuit Elements

Some conventional methods of stabilizing transistor currents using temperature sensitive elements have been studied with a view to stabilize the voltage gain of the transistor amplifier. It is found that when the transistor currents of an amplifier are perfectly constant the a.c. gain of the circuit is not properly stabilized. A remarkable improvement in the stabilization of the transistor gain against temperature variations is possible through the use of a temperature sensitive element placed between the collector lead of the transistor and the load resistor RL. Relations have been derived to determine the value of the resistance of this element at various temperatures. When this element is heated along with the transistor, the gain temperature response of the amplifier is found to extend to temperatures upto 300°C.