Adaptive bias circuit and power amplifier

The present invention, the bias circuit comprises an envelope detector for detecting an envelope of the input signal for the adaptive bias circuitry and a power amplifier; A source voltage generation unit for generating a source voltage by using the power supply voltage; And envelope amplifier section configured to receive supply of the power source voltage and the source voltage as the drive voltage to produce a first bias voltage and amplifies the envelope signal detected by the envelope detection unit; It may contain.