Patent ID: 8294494

Claim:
A triangular-wave generating circuit comprising: a capacitor having a fixed electric potential at one end; a charge-discharge circuit that charges or discharges said capacitor; a first comparator that compares an output voltage of the other end of said capacitor with a first threshold voltage and outputs a first comparison signal in accordance with a comparison result; an edge detecting circuit that detects an edge of a synchronization signal input from the outside and having a frequency of about ½ of a triangular-wave signal generated by the triangular-wave generating circuit, and outputs an edge detection signal that will be at a predetermined level for each of the detected edges; and a charge-discharge controller that receives said first comparison signal output from said first comparator and said edge detection signal output from said edge detecting circuit, and switches between a charge state and a discharge state of said charge-discharge circuit in accordance with a level transition of these signals, wherein a voltage of said capacitor is output as a triangular-wave signal.