Patent ID: 8890586

Claim:
A sawtooth wave generating circuit comprising: a capacitor coupled between a first node and a ground; a calibration circuit configured to receive a sawtooth wave signal that is fed back from the first node, configured to generate a plurality of voltage signals based on the sawtooth wave signal and configured to select one of the voltage signals to generate a calibration output signal; a charging circuit configured to charge the capacitor in response to the calibration output signal; and a discharging circuit configured to discharge the capacitor in response to a short pulse signal, wherein the calibration circuit comprises: a feedback circuit configured to compare the sawtooth wave signal with a first reference voltage to generate a counter enable signal; a counter configured to generate a digital code having N bits in response to the counter enable signal; a decoder configured to decode the digital code having the N bits to generate the voltage signals; and a multiplexer configured to select one of the voltage signals to generate the calibration output signal.