Amplifier apparatus and soft-start method thereof

An amplifier apparatus, comprising:

• a differential input pair, comprising:
• a first transistor comprising a first terminal, a second terminal, and a control terminal, wherein the control terminal of the first transistor receives a reference voltage;
• a second transistor comprising a first terminal, a second terminal, and a control terminal, wherein the first terminal of the second transistor is coupled to the first terminal of the first transistor, and the control terminal of the second transistor receives an input voltage;
• and
• an auxiliary transistor comprising a first terminal, a second terminal, a control terminal, and a bulk/body terminal, wherein the first terminal of the auxiliary transistor is coupled to the first terminal of the first transistor, the second terminal of the auxiliary transistor is coupled to the second terminal of the first transistor, the control terminal of the auxiliary transistor receives a control voltage, and the base terminal of the auxiliary transistor receives a power supply voltage;
• a current source coupled to the first terminal of the first transistor and the first terminal of the second transistor;
• and
• a load coupled to the second terminal of the first transistor and the second terminal of the second transistor, wherein a voltage value of the control voltage changes according to a change of a voltage value of the power supply voltage.