Constant fraction discriminator with automatic adjustment of optimal triggering level and automatic suppression of AC and DC input interference signals
A constant fraction discriminator equipped with automatic controlled triggering point based on a feedback loop controller principle is described. The circuit can accept at the input dc (±150mB) and low frequency interferences (±100 mV, ⩾ 400 Hz) as well as high counting rates of change (0-10 MHz of 10 ns fwhm, -2 V pulses) without degradation of timing performance. The trigger was designed for signal rates up to 100 MHz and provides walk equal to ±100 ps over a dynamic range of 400. The timing performance of the discriminator compared to some commercially available ones is shown.