High-Frequency Clock Jitter Analyzer/Synthesizer
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
An instrument is needed to accurately measure the amount of jitter on a high-frequency (20 MHz) system clock and reproduce another clock signal with the same amount of jitter for evaluating the sensitivity of other circuitry to that jitter. This is achieved using a programmable logic delay line and high-speed flip-flop as a pulse period detector, along with a conventional universal frequency counter for time-interval measurement. Together they form a programmable Jitter Analyzer/Synthesizer with 20 pico-second resolution. Referring to the drawing, the reference clock is first selected and its period measured by the frequency counter. The reference clock is a stable, low-jitter crystal-controlled clock, corresponding in frequency to the input clock.