Patent ID: 7339406
Filing Date: 2008-03-04
Classification: H03K

Abstract:
1. A sawtooth wave generating apparatus which generates a sawtooth wave, the apparatus comprising: a reference signal generating section which generates a reference signal having a predetermined frequency; a sawtooth wave forming section which forms a sawtooth wave based on the predetermined frequency of the reference signal generated by the reference signal generating section; and a correcting section which automatically corrects a slope of the sawtooth wave defined by ΔV/t which is formed by the sawtooth wave forming section in response to variation of the predetermined frequency of the reference signal; wherein the reference signal is a square-wave having rising edges and trailing edges, and the correcting section comprises: a voltage comparator which compares the voltage of the sawtooth wave formed by the sawtooth wave forming section with a predetermined voltage; a phase comparator which compares the phase of the rising edge of the reference signal generated by the reference signal generating section with the phase of the output signal from the voltage comparator; and a low-pass filter which cuts out a high frequency component of the output signal from the phase comparator, and feeds back the resulting output signal to the sawtooth wave forming section.