In this work, we introduce a multimode and wideband quadrature balanced CMOS RF front end (RFFE) supporting full-duplex (FD), half-duplex (HD), and frequency-division duplex (FDD) operation at the 5–6 GHz band. The proposed RFFE is enhanced by nonlinear digital algorithms that maintain optimal performance at high transmit (Tx) power levels. A theoretical model of the transmit–receive (TR) cross-modulation (CM) distortion mechanism stemming from instantaneous variations in the power amplifiers (PAs) output impedance is laid out and verified in simulation and measurement. A 2-D digital postdistortion (2-D DPoD) algorithm that utilizes the known baseband Tx signal and the downconverted distorted Rx signal is proposed to linearize the CM-distorted Rx signal, in conjunction with wideband digital RF and baseband cancellation of the Tx self-interference at the receiver input and 1-D digital predistortion to linearize the Tx signal. The system was characterized in simultaneous TR operation using 802.11ac VHT Wi-Fi signals at 10 dBm average Tx power. In the FD mode using 20 MHz signals, TR isolation of 66 dB was achieved, and the 2-D DPoD corrected Rx error vector magnitude (EVM) by 11 dB to a value of −33 dB. In the FDD mode with 800 MHz frequency separation, 14 dB improvement was demonstrated in Rx EVM with 2-D DPoD to the levels of −35 and −31 dB for 20 and 160 MHz signals, respectively. Similar EVM values were measured in the HD Rx mode at −40 dBm average Rx power, along with Rx insertion loss lower than 1 dB without using a TR switch.

中文翻译：

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具有发送-接收交叉调制失真校正功能的多模 5-6 GHz FD/HD/FDD 正交平衡 CMOS 前端

在这项工作中，我们介绍了一种支持全双工 (FD)、半双工 (HD) 和频分双工 (FDD) 在 5–6 GHz 频段操作的多模和宽带正交平衡 CMOS 射频前端 (RFFE) . 建议的 RFFE 由非线性数字算法增强，该算法在高发射 (Tx) 功率水平下保持最佳性能。由功率放大器 (PA) 输出阻抗的瞬时变化引起的发射 - 接收 (TR) 交叉调制 (CM) 失真机制的理论模型被设计出来，并在仿真和测量中得到验证。提出了一种利用已知基带 Tx 信号和下变频失真 Rx 信号的二维数字后失真 (2-D DPoD) 算法来线性化 CM 失真 Rx 信号，结合宽带数字 RF 和基带消除接收器输入端的 Tx 自干扰和一维数字预失真以线性化 Tx 信号。该系统的特点是使用 802.11ac VHT Wi-Fi 信号以 10 dBm 平均 Tx 功率进行同步 TR 操作。在使用 20 MHz 信号的 FD 模式中，实现了 66 dB 的 TR 隔离，并且 2-D DPoD 将 Rx 误差矢量幅度 (EVM) 校正了 11 dB 至 -33 dB 的值。在具有 800 MHz 频率间隔的 FDD 模式下，在具有 2-D DPoD 的 Rx EVM 中，20 和 160 MHz 信号的电平分别提高了 14 dB 至 -35 和 -31 dB。在 HD Rx 模式下以 -40 dBm 平均 Rx 功率测量到类似的 EVM 值，同时 Rx 插入损耗低于 1 dB，且不使用 TR 开关。