A Random Tail Pulse Generator

A random pulse generator has been designed that utilizes a charge control concept to provide controlled voltage transitions at average rates from 10 Hz to 1 MHz. These voltage transitions may be coupled to a charge sensitive amplifier system via the standard calibration capacitor to induce impulses of charge, thereby closely approximating the signal from a detector. Between pulses, the voltage decays in an exponential fashion not unlike any tail pulse generator. However, the voltage transition (or step) is independent of the decay, thus recurring steps will ride up the tail of the decay, eliminating the step amplitude dependance upon decay time (¿d) found in other tail pulse generators. This last fact permits repetition rates far in excess of the 1/8 ¿d limitation commonly incurred. To complement this pulse shaping ability, the clock circuit provides both periodic triggers and random triggers. The random time distribution has been measured at several rates and verified to be Poisson. Pulse shaping controls and a polarity switch provide versatility and an output buffer amplifier allows cable termination without affecting the pulse shape. The amplitude has been measured over the frequency range of 10 Hz to 100 kHz and was found to vary less than ±0.05%. The random pulse generator is packaged in a double width NIM and utilizes± 12 volts and ± 24 volts for the power source.