Patent ID: 8120558

Claim:
A driving apparatus, comprising: a digital to analog converter, for receiving a digital data and converting the digital data into an analog signal; and a signal amplifier, coupled to the digital to analog circuit, for receiving the analog signal and generating a driving signal and dynamically changing a driving capability of the driving signal according to at least one bit of the digital data, wherein the signal amplifier comprises an operational amplifier, the operational amplifier comprises a first controlled current source, and the first controlled current source comprises: a first current source having a first terminal serving as the first terminal of the first controlled current source, and a second terminal of the first current source serving as the second terminal of the first controlled current source; a second current source, having a first terminal directly connected to the first terminal of the first current source; and a first switch having a first terminal coupled to a second terminal of the second current source, a second terminal of the first switch coupled to the second terminal of the first current source such that the on-off state of the first switch is determined by the signal from the control terminal of the operational amplifier.