An ultra-low-power monitoring system for inductively coupled biomedical implants

In this paper, an ultra-low-power system for wireless monitoring of inductively coupled biomedical implants is presented. The system is fully integrated and composed of custom rectifier, alignment and monitoring circuits with enhanced performance. The proposed system is described in the context of a smart-stent system that monitors the re-narrowing of blood vessels at the smart-stent site. The building blocks of the system are designed and simulated in a 0.13-μm CMOS technology. Simulation results for the monitoring system show that the proposed rectifier provides 53% power conversion efficiency (PCE) for -10.36 dBm input power (in the alignment mode) and 62% PCE for -4.06 dBm input power (in the monitoring mode). The alignment unit is capable of operating by drawing a 12 μA from a supply voltage as low as 0.6 V and the monitoring circuit consumes as low as 176 μW.