Linearization of Class AB Amplifier Using Envelope Detection Bias Control

In spite of the advantage of simple circuit, small size, and low price, predistortered power amplifier does not satisfy the IMD specification at low power range because of an IMD hump characteristic. To reduce the performance degradation by IMD hump, the method which is to control the operating point of amplifier according to its output power is presented. This method using envelope detection bias control is applied to the implemented class AB predistortered 16 W power amplifier. The measured result shows 10 dB improvement of IMD performance in wide dynamic range of output power.