Patent ID: 8269539

Claim:
An output stage configured to control a driving voltage thereof according to an input signal, comprising: a first switching current module, coupled to a node for outputting a first current; a second switching current module, coupled to the node for outputting a second current; a switching capacitor module with a capacitance, coupled to the node; a calibrating control circuit, for calibrating, the first current, the second current and the capacitance; a time constant calibrating circuit, for generating a reference slew rate according to a fixed voltage source and a fixed time source, and controlling the calibrating control circuit to selectively calibrate the first current, the second current and the capacitance, such that a ratio of the first current and the capacitance, and a ratio of the second current and the capacitance conform to the reference slew rate; and a voltage clamper for setting a high/low voltage range and limiting an amplitude of the driving voltage within the high/low voltage range.