Patent ID: 6876254

Claim:
A dual-amplifier circuit, comprising: an input terminal to which an input signal is supplied; an output terminal from which an output signal is supplied; a first amplifier coupled between the input terminal and the output terminal; a second amplifier coupled in parallel to the first amplifier between the input terminal and the output terminal; a selecting circuit which supplies a selection signal to couple one of the first and second amplifiers alternately between the input terminal and the output terminal, wherein each of the first and second amplifiers comprises: 1) a first supply terminal to which a first level of supply voltage is provided; 2) a second supply terminal to which a second level of supply voltage is provided; and 3) a control transistor unit, which is coupled between the first and second supply terminals and a gate of which is applied with a bias voltage, wherein a resistance value of the control transistor unit is increased when the corresponding amplifier is not selected for use.