Sampling signal generating circuit for sampling apparatus and digital oscilloscope

摘要

A signal from an original oscillation circuit is inputted into a phase-locked loop circuit capable of continuously varying a frequency of this signal derived from the original oscillation circuit. The phase-locked loop circuit changes the frequency of the signal derived from the original oscillation circuit into another frequency corresponding to sweep rate variable information derived from a sampling control unit, and then outputs the signal having the changed frequency. This signal outputted from the phase-locked loop circuit is supplied to a variable frequency dividing circuit. This variable frequency dividing circuit frequency-divides the frequency of the signal outputted from the phase-locked loop circuit at an arbitrary frequency dividing ratio corresponding to the sweep rate range information given from the sampling control unit, and thereafter outputs the signal with the frequency-divided frequency as a sampling signal.