主动谐波消除多电平射频脉宽调制策略及其性能分析

为降低全数字发信机(All-Digital Transmitters, ADTx)的输出谐波要求,提高系统宽频带工作性能,提出并实现适用于全数字发信机的多电平射频脉宽调制(Radio Frequency Pulse Width Modulation, RF-PWM)策略。该方法通过控制各子脉冲的脉冲宽度,在基波分量加权之和正比于输入信号包络的前提下,实现对RF-PWM脉冲序列特定谐波分量的有效抑制。以3次谐波消除为例,对该5电平RF-PWM策略实现方案进行推导,同时分析验证了该方案下脉冲基波分量与信号幅度之间的最佳增益系数。在此基础上,利用软件仿真验证了理论分析结果以及主动谐波抑制RF-PWM策略的有效性。

Selective harmonic elimination multi-level RF-PWM strategy and performance analysis

In order to relax the filtering requirements and improve the wideband performance of the all-digital transmitters, a novel multi-level RF-PWM(radio frequency pulse width modulation) method for all-digital transmitters was introduced. This method limits the selective harmonics of RF-PWM signals by controls the pulsewidth of the corresponding subpulses to make the selected harmonics cancel each other out and keep the weighted superposition of fundamental frequency components proportional to input envelope. For the third harmonic elimination, the corresponding 5-level RF-PWM scheme was presented. And the optimal gain index for 5-level RF-PWM scheme was also analyzed and proved. On this basis, the proposed scheme was verified by extensive simulations.