Tiny implantable medical devices in millimeter size demand advanced wireless power solutions that operate at hundreds of megahertz and mainly use passive rectifiers for ac–dc power conversion. A conventional cross-connected (CC) rectifier can operate with high frequency and low input voltage but only achieves good efficiencies in a very narrow input power range, due to the shoot-through and reverse currents. This work presents a CMOS passive rectifier with active bias tuning (ABT), allowing a widely extended input range with high power conversion efficiency (PCE). In addition, we compensate for the process, voltage, and temperature variations with the ABT scheme that leads to a robust design for very-high-frequency (VHF) operation. Meanwhile, we propose a peak $V_{\mathrm {OUT}}$ searching scheme to indicate the charging/discharging directions for the ABT. We obtain a bias-voltage balancing among stacked rectifier stages with a switched-capacitor network. The proposed rectifier is fabricated in a 65-nm CMOS process. Measurement results of three chips show that the proposed rectifier improves the PCE over a wide input range, with an average maximum PCE of 64.4%.

中文翻译：

---

具有有源偏置调谐的 VHF 宽输入范围 CMOS 无源整流器

毫米尺寸的微型植入式医疗设备需要先进的无线电源解决方案，其工作频率为数百兆赫兹，主要使用无源整流器进行交流-直流电源转换。传统的交叉连接 (CC) 整流器可以在高频和低输入电压下工作，但由于直通和反向电流，只能在非常窄的输入功率范围内实现良好的效率。这项工作提出了一种具有有源偏置调谐 (ABT) 的 CMOS 无源整流器，允许广泛扩展的输入范围和高功率转换效率 (PCE)。此外，我们使用 ABT 方案补偿工艺、电压和温度变化，从而为甚高频 (VHF) 操作带来稳健的设计。同时，我们提出了一个峰值 $V_{\mathrm {OUT}}$ 搜索方案来指示 ABT 的充电/放电方向。我们使用开关电容器网络在堆叠整流器级之间获得偏置电压平衡。建议的整流器采用 65 纳米 CMOS 工艺制造。三个芯片的测量结果表明，所提出的整流器在较宽的输入范围内提高了 PCE，平均最大 PCE 为 64.4%。