CMOS Rectifier with on-chip Transformer-Coupled Tunable Matching Network for Biomedical Implants

In this work, we present a 0.13-um CMOS rectifier that is designed for wirelessly powered implantable devices in general, and for a wirelessly powered medical stent interface, in particular. A double-tuned transformer-based tunable matching network is co-designed with the differential cross-coupled rectifier at 910 to 970 MHz. The circuit model of the medical stent is also characterized for co-simulation with the circuit blocks. Post-layout simulation results show that for a −2.2 dBm available power received by the stent (which dually acts as an antenna in the context of smart stent applications), a rectifier power conversion efficiency (PCE) of 44% can be achieved for a 2 kΩ load. In this condition and with a 60 mV available voltage induced at the stent terminal from 910 to 970 MHz, a DC output voltage that is greater than 500 mV can be generated at the output of the rectifier.