Patent Number: 6,295,315

Title: Jitter measurement system and method

Abstract: A jitter measurement system measures timing variations or "jitter" in aperiodic signal waveform as provided, for example, by a phase-locked loop(PLL). In one implementation, the jitter measurement system includes aperiod gate generator that generates a gate signal with the instantaneousperiod of output signal waveform F.sub.VCO generated by the PLL. The gatesignal includes a leading edge and a trailing edge and is delivered to apair of triggered oscillators that provide respective oscillator outputsignals with substantially matched frequencies. The oscillators aretriggered at the respective leading and trailing edges of the gate signal.The oscillator output signals are delivered to respective oscillationcounters and to a coincidence detector. The oscillation counters count theperiods of the respective oscillator output signals from when they aretriggered until the coincidence detector detects coincidence between thesignals (e.g., coincidence between the trailing edges of the signals). Aperiod measurement of the output signal waveform F.sub.VCO is determinedfrom the counts obtained by the oscillation counters. Multiple such periodmeasurements are obtained to provide information representing jitter inthe output signal waveform F.sub.VCO.

Inventors: Frisch; Arnold M. (Portland, OR), Rinderknecht; Thomas H. (Tualatin, OR)


International Classification:

Expiration Date: 09/25/2013