A Novel Biasing Technique for Low Adjacent Channel Power in Microwave Power Amplifiers

The proposed biasing technique is to change the DC quiescent point of the microwave power amplifiers self- adaptively with the input power. It not only manipulates the position of the third-order intermodulation distortion (IMD3) minimum dynamically, but also manages the DC bias power of the power amplifier adaptively. Therefore, the adjacent channel power can be reduced under the specified level, while the power consumption of the amplifier can be minimized. For the operation power ranging from 0.1 W to 0.5 W, a constant IMD3 of -25 dBm with above 25% of DC-to-RF conversion efficiency are achieved in a 1.95 GHz Class A power amplifier.