A versatile and accurate 300 MHz time generation circuit

A 300-MHz timing generator has been designed and implemented on a digital application-specific integrated circuit (ASIC) platform to act as the fundamental circuit block of a pulse generator. Within this circuit block, all pulse generator timing functions, such as period generation, delay generation, and width generation, have been provided. The circuit implements the various trigger and logic functions which supports all of the operating modes in which a pulse generator must function. A key element of the design is a synchronously gated voltage controlled oscillator (VCO) implemented on an emitter controlled logic (ECL) gate array. Since the platform for the design is a digital ASIC, some compromises are made in the design of the VCO in the areas of linearity and temperature stability. These inaccuracies are compensated for by pulse generator self-calibration and an on-chip thermal sensing diode yielding timing accuracies of under 0.5%