A 200-MHz Wide Input Range CMOS Passive Rectifier with Active Bias Tunning

A high efficiency wireless power transfer system that operates in the very high frequency (VHF) band is desirable for miniaturized implantable medical devices (IMD), but also challenging. This work presents an integrated VHF passive rectifier with closed-loop active bias tuning (ABT). Power PMOS and NMOS transistors are separately cross-connected, such that the DC bias voltages of the NMOS gates can be dynamically adjusted. We employed a search scheme for V _OUT -peak to obtain the optimum bias voltage over a wide input range. A prototype fabricated in 65nm std-CMOS process measured a power convention efficiency of 64% at 200MHz with 3kΩ loading.