Precision bypass clock for high speed testing of a data processor

摘要

A system clock circuit that provides a high-speed reference clock signal for operating an integrated circuit. The system clock circuit comprises a frequency combiner circuit that receives a first external clock signal having a frequency F1 and a second external clock signal having frequency F2, where F2 is an integer multiple of F1. The second external clock signal is phase-shifted by P degrees with respect to the first external clock signal. The frequency combiner circuit generates from the first and second external clock signals a first output clock signal having an operating frequency that is the sum of F1 and F2. The system clock circuit also comprises a clock selection circuit that selectively applies the first output clock signal to the integrated circuit.