A Single-Stage Dual-Output Regulating Rectifier With Sequential Pulse Frequency Modulation Control for Wireless Biomedical Applications

This brief presents a single-stage dual-output voltage-doubling (VD) regulating rectifier with sequential pulse frequency modulation (SPFM) for biomedical wireless power transfer (WPT). Improved by the traditional VD power stage, the dual-output DC voltages are achieved by adding a power transistor. Thanks to the proposed power stage topology, the dual-output DC voltages realize full-wave rectification charging and a voltage conversion ratio (VCR) greater than 1 can be realized, which benefits the robustness of the WPT system under the loosely coupled link. The SPFM control is proposed to regulate the dual-output voltages sequentially. Under the SPFM control, each operating phase occupies an independent rectification cycle to avoid channel conduction problems. Moreover, to gain better power conversion efficiency (PCE), the offset current delay compensation technique is used. The proposed regulating rectifier is fabricated in 180nm CMOS process, occupying an area of 0.45mm. The measurement results show that the proposed dual-output regulating rectifier outputs DC voltages at 3.3V and 2.5V respectively with ripples of 65.4mV and 52.7mV and achieves fast load transient responses. The maximum PCE and VCR are achieved at 90% and 1.67, respectively. The rectifier can output a maximum power of 60.7 mW, satisfying sub-100mW biomedical implants.