Hybrid Forward and Backward Threshold-Compensated RF-DC Power Converter for RF Energy Harvesting

This paper presents a hybrid forward and backward threshold voltage compensated radio-frequency to direct current (RF-to-DC) power conversion circuit for RF energy harvesting applications. The proposed circuit uses standard p-channel metal-oxide semiconductor transistors in all the stages except for the first few stages to allow individual body biasing eliminating the need for triple-well technology in the previously reported forward compensation schemes. Two different RF-DC power conversion circuits, one optimized to provide high power conversion efficiency (PCE) and the other to produce a large output DC voltage harvested from extremely low input power levels, are designed and fabricated in IBM's 0.13 μm complementary metal-oxide-semiconductor technology. The first circuit exhibits a measured maximum PCE of 22.6% at -16.8 dBm (20.9 μW) and produces 1 V across a 1 MΩ load from a remarkably low input power level of -21.6 dBm (6.9 μW) while the latter circuit produces 2.8 V across a 1 MΩ load from a peak-to-peak input voltage of 170 mV achieving a voltage multiplication ratio of 17. Also, design strategies are developed to enhance the output DC voltage and to optimize the PCE of threshold voltage compensated voltage multiplier.