Transmission Line Analog of Junction Transistors

ABSTRACT

The flow of minority carriers in a semiconductor has its circuit analogy in the flow of current down an RC transmission line. This fact forms the basis of simulation of a semiconductor device by a transmission line analog. The design and construction of an analog to represent the alloy type junction transistor OC70 is described. The hole density distributions in the base region have been measured on the analog for various biasing conditions of the collector. The small signal h-parameters and other performance characteristics of the analog have been measured and the experimental results indicate a close correlation between the parameters of the actual device and its analog.

The transmission line analog also enables the measurement of switching times due to the intrinsic device alone and thus facilitates the separation of the transient response of the device into circuit and transistor dependent parts. Knowing the intrinsic properties, the performance of the device under given external circuit conditions can be predicted with greater ease. The utility of the analog in separating out the intrinsic transient response times from the switching times of the actual transistor has also been established.

It is shown that the transmission line analog serves as a simple laboratory tool for predicting the changes in the performance characteristics due to changes in the design parameters of the device.