Output stage circuit

An output stage circuit comprising:

• a bias voltage generator, coupled to an output terminal of the output stage circuit to generate a bias voltage according to an output voltage of the output terminal;
• a first amplifier circuit, coupled to the output terminal of the output stage circuit, a first power supply terminal and the bias voltage generator, the first amplifier circuit receives a first pre-driving signal, a first predetermined voltage and the bias voltage, according to the first pre-driving signal, the first predetermined voltage and the bias voltage, the first amplifier circuit determines whether to turn on the first amplifier circuit to transmit a first voltage from the first power supply terminal to the output terminal to serve as the output voltage;
• and
• a second amplifier circuit, coupled to the output terminal of the output stage circuit, a second power supply terminal and the bias voltage generator, the second amplifier circuit receives a second pre-driving signal, a second predetermined voltage and the bias voltage, according to the second pre-driving signal, the second predetermined voltage and the bias voltage, the second amplifier circuit determines whether to turn on the second amplifier circuit to transmit a second voltage from the second power supply terminal to the output terminal to serve as the output voltage, wherein the bias voltage generator comprises:
• a first comparison voltage generating circuit, dividing the output voltage into a first comparison voltage according to a predetermined ratio;
• a second comparison voltage generating circuit, generating a second comparison voltage according to the output voltage;
• and
• a comparator, comprising a first terminal receiving the first comparison voltage and comprising a second terminal receiving the second comparison voltage, wherein the comparator provides a larger one of the first comparison voltage and the second comparison voltage to an output terminal of the comparator to serve as the bias voltage.