Patent ID: 7009549

Claim:
A multiplying digital-to-analog converter (DAC), comprising: an operational amplifier, having first and second inputs, and having an output driving a signal over an output range between first and second output level voltages responsive to signals received at the first and second inputs; a first sampling capacitor circuit, comprising a first sample capacitor, for receiving an input voltage and storing the input voltage at the first sample capacitor in a first clock phase, the first sampling capacitor circuit having an output coupled to a first input of the operational amplifier; a first feedback switch, connected between the output of the operational amplifier and the first sample capacitor, for connecting the first sample capacitor in a feedback loop in a second clock phase; and a first reference capacitor circuit, comprising: a first reference capacitor, coupled to the first input of the operational amplifier; a first parallel capacitor, coupled to the first input of the operational amplifier; clocked switches, for coupling the input voltage to the first reference capacitor and the first parallel capacitor in the first clock phase; and switch circuitry, for receiving a reference voltage that exceeds the first output level voltage by a factor, and for charging the first reference capacitor with the reference voltage in the second clock phase, the first reference capacitor having a capacitance less than a capacitance of the first sample capacitor by the factor.