Power amplifier and circuit protection method

A circuit protection method, comprising:

• providing a power amplifier, wherein the power amplifier comprises a first amplification circuit, a second amplification circuit, and a bias circuit, wherein the first amplification circuit and the second amplification circuit are connected in series to amplify a radio frequency signal received from an input end, and the bias circuit outputs a bias current to the second amplification circuit;
• generating a digital control signal according to the bias current by a current detection circuit;
• and
• selectively reducing the radio frequency signal input to a first signal input end in the power amplifier according to the digital control signal by the first protection circuit, wherein the first protection circuit is coupled between the input end of the power amplifier and the first signal input end of the first amplification circuit.

A power amplifier, comprising:

• an input end, used to input a radio frequency signal;
• an output end, used to output the amplified radio frequency signal;
• an amplification circuit, comprising a first signal input end coupled to the input end and a first signal output end and used to amplify the radio frequency signal received from the input end;
• a bias circuit, used to output a bias current to the amplification circuit;
• a current detection circuit, coupled to the signal input end and used to generate a digital control signal according to the bias current;
• and
• a first protection circuit, coupled between the input end of the power amplifier and the signal input end of the amplification circuit and used to selectively reduce the radio frequency signal input to the signal input end according to the digital control signal.