13.56 MHz Triple Mode Rectifier Circuit With Extended Coupling Range for Wirelessly Powered Implantable Medical Devices

In this work, a wide input/output range triple mode rectifier circuit operating at 13.56 MHz is implemented to power up medical implants. The proposed novel multi-mode rectifier circuit charges the load for an extended coupling range and eliminates the requirement of alignment magnets. The charging process is achieved in three different modes based on the voltage level of the received signal affected by the distance and the alignment of the inductively coupled coils. Current mode (CM) circuit is activated for loosely coupled coils whereas voltage mode (VM) rectification is proposed for high coupling ratios. Extended coupling range is covered with the activation of half wave rectification mode (HWM) in between CM and VM. The rectifier circuit utilizes these three modes in a single circuit operating at 13.56 MHz according to the receiver signal voltage. The circuit is implemented in TSMC 180 nm BCD technology with 0.9 mm
²
active area and tested with printed coils. According to the measurements, the circuit operates in the received power range of 4 to 57.7 mW, which corresponds to 0.10-0.42 coupling range. The maximum power conversion efficiency (PCE) of each operation mode is 51.78%, 82.49%, and 89.34% for CM, HWM, and VM, respectively, while charging a 3.3 V load.