Patent ID: 6157332
Filing Date: 2000-12-05
Classification: H03M

Abstract:
A digital-to-analog converter (DAC) for converting an n-bit digital input signal to an analog output signal, the DAC comprising:a control logic circuit which receives the n-bit digital input signal and generates a self-calibration signal therefrom;a converter circuit which receives a copy of the n-bit digital input signal from the control logic circuit and generates an analog output signal therefrom;a first filter capacitor connected between the converter circuit and ground, the first filter capacitor receiving the analog output signal;a first switch connected between the converter circuit and the first filter capacitor, the first switch having an open position and a closed position, wherein in the open position, the first switch prevents transmission of the analog output signal from the converter circuit to the first filter capacitor;an amplitude detector which receives the analog output signal and generates an up signal and a down signal therefrom;a charge pump which receives the up signal and the down signal and generates an output voltage reference signal therefrom, wherein the output voltage reference signal provides a reference voltage to the converter circuit;a second filter capacitor connected between the charge pump and ground, the second filter capacitor receiving the output voltage reference signal; anda second switch connected between the charge pump and the converter circuit, the second switch having an open position and a closed position, wherein in the open position, the second switch prevents transmission of the output reference voltage signal from the charge pump to the converter circuit;wherein the first switch is opened and the second switch is closed in response to the calibration signal being active.