Design and simulation of a new wireless power transfer circuit with a single-stage regulating rectifier for flexible sensor patches

A new wireless power-transfer circuitry with a single-stage regulating rectifier is designed by this study for wearable flexible sensor patches. The patch is orchestrated to measure personal physiological status ubiquitously for long-time care. To ensure high wearability of the patch, the patch usually cannot equipped with a bulky battery for long-time sensing. Instead, wireless power transfer (WPT) is applied to charge a small-sized battery in the patch for ubiquitous and long-term sensing. In this paper, a single-stage regulating rectifier is presented to implement the receiver part of the WPT used in flexible sensor patches, significantly reducing the conduction loss and the complexity of the receiver circuitry, which is usually in a 2-stage topology. It is operating in the Industrial Scientific and Medical (ISM) band, 13.56 MHz. It is integrated with delay lock loop (DLL) feedback to improve high efficiency to solve the problem of long turn-off time. The single-stage regulating rectifier is implemented with 1×/0× mode and pulse frequency modulation control algorithm to regulate the output voltage. The proposed WPT circuit is fabricated by the TSMC 0.35 μm process in a total area of the proposed chip is 2.72 mm². The output voltage can be regulated in 3.3 V to provide power to the sensor patch. The peak efficiency is achieved as 86% with the output power of 200 mW and the setup time is 11 μs from light load to regular load transient response, a favorable integrated performance as compared to prior arts.