Patent ID: 7436341
Filing Date: 2008-10-14
Classification: H03M

Abstract:
1. A digital/analog converter for converting an input digital signal to an analog signal comprising: an operational amplifier, having an output terminal, an inverse-phase input terminal and a non-inverse-phase input terminal, wherein the non-inverse-phase input terminal is coupled to a reference voltage; a first filter, having a first end coupled to the output terminal and a second end coupled to the inverse-phase input terminal; a first switch; a second filter, having a first end coupled to the output terminal via the first switch and a second end coupled to the inverse-phase input terminal , wherein in a first duration the first switch is turned on and the second switch is turned off; and in a second duration the first switch is turned off and the second switch is turned on; a plurality of conversion units, each comprising: a second switch, coupled between the inverse-phase input terminal and the conversion units, wherein the conversion units are connected in parallel between the second switch and the output terminal; wherein in the first duration each of the capacitors of the conversion units is charged to a corresponding voltage according to corresponding control signals based on a first digital signal, a first inverse digital signal having an inverse phase to the first digital signal, and a corresponding second digital signal, wherein the first digital signal and the second digital signal respectively correspond to polarity and a corresponding bit value of the input digital signal; wherein in the second duration, each of the second ends of the capacitors of the conversion units is coupled to the inverse-phase input terminal of the operational amplifier via the second switch, and each of the first ends of the capacitors of the conversion units is coupled to the output terminal of the operational amplifier to generate the analog signal.