Adaptive bias circuit and system thereof

An adaptive bias circuit which provides a more sensitive adaptive bias current with respect to power level is used for biasing an electronic circuit. The adaptive bias circuit has a first transistor coupled to a power supply, a voltage bias circuit coupled to the first transistor and the power supply biasing the first transistor, and a first power coupling module coupled to the first transistor and the electronic circuit for coupling a portion of input signal power to the first transistor. A second transistor is coupled to the first transistor and the power supply to increase the current gain of the adaptive bias circuit, and a second current coupling module is coupled to the second transistor and the electronic circuit to provide adaptive bias current to the electronic circuit.