Patent ID: 6483287
Filing Date: 2002-11-19
Classification: G01R

Abstract:
A waveform measuring apparatus comprising:a sampling section which samples a signal under test having an input predetermined repetition cycle by means of a sampling signal having a cycle longer than the repetition cycle of the signal under test; a data processing section which obtains an enveloped waveform of the signal under test sampled by means of the sampling section, and which produces a signal waveform of the signal under test from the enveloped waveform; a frequency synthesized signal generator which has a reference signal input terminal, and which outputs a frequency synthesized signal having a frequency equal to a repetition frequency of the signal under test; a phase comparator which detects a phase difference between a phase of the frequency synthesized signal output from the frequency synthesized signal generator and a phase of the signal under test, and which then outputs a phase difference signal; a voltage control oscillator which generates a reference signal that is phase synchronized with the signal under test based on the phase difference signal output from the phase comparator, and which then feeds the reference signal back to the reference signal input terminal of the frequency synthesized signal generator; and a sampling signal generator circuit which generates the sampling signal by employing the reference signal output from the voltage control oscillator.