A single envelope modulator-based envelope tracking (ET) power amplifier (PA) structure with a related digital predistortion (DPD) technique for multiple-input and multiple-output (MIMO) wireless transmitters is presented in this paper. By generating a common tracking envelope, only one envelope modulator is employed for controlling supply voltage of the RF PAs in all branches in the system, which dramatically reduces the system implementation cost. Due to the structurechange, additional distortion is introduced, and it is difficult to directly compensate by using the conventional DPD because the tracking envelope is no longer the same as the RF envelope and thus the MIMO ET PA becomes a two-input and one-output system. To resolve this problem, in this paper we propose a novel DPD technique in which the PA input and output data are reconstructed into multiple data subsets according to variations of the tracking envelope. It converts the 2-to-1 mapping into multiple 1-to-1 ones, where the conventional DPD can be employed again. Experimental results demonstrated that the distortion, including static nonlinearities, memory effects and additional distortion caused by the structure change, can be effectively compensated by using the proposed DPD technique. Compared to the conventional ET, the overall efficiency of the system is only slightly decreased, but the system cost is much lower because only one envelope modulator is required in the whole system.
展开▼
机译:本文提出了一种基于单包络调制器的包络跟踪(ET)功率放大器(PA)结构,该结构具有相关的数字预失真(DPD)技术,用于多输入多输出(MIMO)无线发射机。通过产生公共的跟踪包络,仅采用一个包络调制器来控制系统中所有分支中RF PA的电源电压,从而大大降低了系统实现成本。由于结构的变化,引入了额外的失真,并且由于跟踪包络不再与RF包络相同,因此MIMO ET PA变成了两输入单输出,因此很难通过使用传统的DPD直接补偿。系统。为了解决这个问题,本文提出了一种新颖的DPD技术,其中,根据跟踪包络的变化,将PA输入和输出数据重构为多个数据子集。它将2对1映射转换为多个1对1映射,可以再次使用常规DPD。实验结果表明,使用所提出的DPD技术可以有效地补偿包括静态非线性,记忆效应和结构变化引起的其他失真在内的失真。与传统的ET相比,系统的整体效率仅略有降低,但是由于整个系统仅需要一个包络调制器,因此系统成本要低得多。
展开▼