Patent ID: 8125366

Claim:
An integrating digital-to-analog converter (DAC) circuit, comprising: an analog comparator; at least two parallel circuit branches connected to an output of the analog comparator, wherein each circuit branch includes: a current source; a capacitor; a first switch operable for connecting the current source to the capacitor for establishing a reference voltage during a calibration stage and for setting a target analog voltage during a conversion stage, the first switch also operable for disconnecting the current source from the capacitor during the calibration phase; a second switch operable for connecting an analog comparator to the capacitor for establishing the reference voltage during the calibration stage, the comparator operable for comparing the capacitor voltage with the reference voltage and for triggering when the reference voltage and the capacitor voltage are about equal or differ by a threshold amount; a digital counter operable for counting a number of cycles until the analog comparator triggers, wherein the number of cycles establishes a relationship between capacitor voltage and a digital value; and a third switch operable for bypassing the capacitor to remove the capacitor charge during the calibration stage and the conversion stage.