先分析常用双环自适应前馈电路降低非线性失真及输出功率的特点和不足,通过引入另一个前馈电路,从主功率放大器的输入端耦合部分信号到辅助功率放大器的输入和输出端,经适当调节,进一步改善电路的三阶交调失真(IMD3),并增大输出功率。结果显示,这种改进的自适应前馈电路,IMD3低于信号功率-75dBc,线性度改善效果明显,而且输出功率增大了2~3dB。
In this paper,the merits and disadvantages of the usual biloops adaptive feedforward circuit by decreasing the nonlinearity distortion and exporting enough power are discussed first. Another feedforward circuit by coupling some signal from the input of the main power amplifier to the input and output of the auxiliary power amplifier to reduce more IMD3 and increase the output power are introduced. The results show that the IMD3 reaches below -75 dBc,which is much more acceptable than before,and the output power is increased 2~3 dB.