Patent ID: 7714756

Claim:
A digital-to-analog converter, comprising: a bias voltage generating unit, for generating a first biasing voltage on a first node and generating a reference current through the first node; a digital-to-analog converting stage, for converting a digital signal into a voltage signal, the digital-to-analog converting stage comprising: a current source, for generating a current, wherein the current flows through a second node; a switching unit, coupled to the current source, for controlling the current to pass the switching unit according to the digital signal; and a load, for outputting the voltage signal when the current flows through the load; and an operating amplifier, coupled to the bias voltage generating unit and the digital-to-analog converting stage, for controlling the current source according to the first biasing voltage; wherein a first input and a second input of the operating amplifier are respectively coupled to the first node and the second node such that the voltage on the first node and the voltage on the second node are substantially equal, and such that the current and the reference current have a predetermined ratio.