Parallel Tunnel Diode Coincidence Circuit

A fast coincidence circuit which operates reliably over a wide range of input-pulse amplitudes is described. The ratio of the current which is applied to the main tunnel diode when the circuit receives a noncoincident input-pulse to that when both inputs of the circuit receive coincident input-pulses, is always one to four, independent of input-pulse amplitudes. The value of the current to be applied to the main tunnel diode by input pulses is decided by the bias current of the circuit. The resolving time of the circuit is measured as 2 ns in the typical operation of the circuit and as 400 ps by adjusting input-pulse amplitudes and the bias current.