Quiescent current control for low distortion linear power amplifier

This paper proposes and analyzes a quiescent current control scheme on linear power amplifier, which allows the amplifier to achieve low distortion amplification that is free from zero-crossing distortion as a Class A amplifier, while achieving energy efficiency comparable to a Class B amplifier. The proposed circuit offers great design flexibility by allowing individual adjustment in the quiescent currents flowing in the push/pull output transistors individually. Moreover, the push/pull transistors in the proposed circuit can be implemented in identical NMOS transistors, thus releases the stringent transconductance matching requirement at the output stage. The circuit performance is analytically analyzed and validated by SPICE simulation.