Four-Terminal P-N-P-N Transistors

The equivalent circuit of a p-n-p-n transistor is obtained. It is demonstrated that a p-n-p transistor and an n-p-n transistor can be connected so that the combination has the same equivalent circuit as the p-n-p-n structure. A simplified circuit is obtained which can be used when the p-n-p-n transistor is connected as a hook-collector transistor. A method of adjusting the current gain of p-n-p-n transistors by external means is given as well as experimental results.