A Reconfigurable Passive Voltage Multiplier for Wireless Mobile IoT Applications

Battery-less wireless systems generate their supply voltage from the incoming RF signal, and need to deal with the problem of generating sufficient voltage level required by their various blocks from weak input signals, while maintaining high efficiency. The presented voltage multiplier (VM) seeks to maximize the power conversion efficiency (PCE) by changing the RF-to-DC converter topology in the VM based on the incoming signal. Besides topology, the number of stages in the VM can change for the desired output dc voltage from the varying RF input signal. A prototype is fabricated in 0.35-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> standard CMOS process, operating at 13.56 MHz with a 2 <inline-formula> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> load. The core element in the VM yields a peak PCE of 76% with the cross-coupled topology at low input power, while the hybrid topology provides 70% PCE at higher input power. This reconfigurable VM can be used in RFID or Internet-of-Things (IoT) mobile applications to regulate power against changes in the distance between the power source and the target.