A temperature-stable linear gate for nanosecond signals and an optional stretcher circuit

A temperature-stable linear gate with an optional stretcher circuit has been developed for gating nanosecond signals from photomulitpliers. Stabilization of the gate circuit results in a baseline drift at a 50 Ω output of less than a millivolt for a 500C change in temperature from 0 to 500C. In addition to good temperature stability and linearity, this direct-coupled circuit switches in less than 5 ns with small transients; moreover, it is unaffected by the gating or duty cycle. Gate intervals from 30 ns to any larger interval are possible. The response is linear to within 2% over 30:1 range of input pulse heights. A linear dynamic range of 300:1 has been achieved with a combination of two circuits. The optional stretcher circuit integrates the gated pulse from the photomuliplier anode and generates a streched analog signal which is proportional to the total charge of the gated signal. (Auth.)