A Fast Zero-Crossing and Constant Fraction Timing Discriminator with Emitter Coupled Integrated Circuits

A fast timing circuit suitable for zero-crossing and constant fraction pulse-height trigger constructed with matched pairs of emitter coupled integrated circuits and a tunnel diode is described, the former for the negative leading pulse recognition and the latter for the true zero-crossing detection. Current pedestal is generated internally to assure true zero-crossing detection without external bias signals. Zero-level bias compensation was found to be necessary for slow zero-cross detection and a method suitable for the purpose is given together with a brief discussion.