JITTER MEASUREMENT SYSTEM AND METHOD

摘要

A jitter measurement system (10) measures timing variations or "jitter" in a periodic signal waveform as provided, for example, by a phase-locked loop (PLL) (12). In one implementation, the jitter measurement system (10) includes a period gate generator (13) that generate a gate signal with the instantaneous period of output signal waveform FVCO generated by the PLL. The gate signal includes a leading edge and a trailing edge and is delivered to a pair of triggered oscillators (20, 22) that provide respective oscillator output signal with substantially matched frequencies. The oscillator output signals are delivered to respective oscillation counters (30, 32) and to a coincidence detector (34). The oscillation counters (30, 32) count the periods of the respective oscillator output signals from when they are triggered until the coincidence detector detects coincidence between the signals. A period measurement of the output signal waveform FVCO is determined from the counts obtained by the oscillation counters.