Wireless energy-harvesting circuit and system with error-correction ASK demodulator for body sensor network with ultra-high-frequency RFID healthcare system

Abstract

This study presents a low-power energy-harvesting circuit with error-correction demodulation for body sensor networks with radio-frequency identification (RFID) systems. The proposed circuit adopts a new structure that facilitates the demodulation of amplitude-shift-keying (ASK) signals, and it includes a power unit consisting of a wake-up circuit and a poweron-reset control circuit. The wireless bio-signal acquisition system and the digital processor are implemented on a fieldprogrammable gate array to demonstrate the proposed RFID tag. The proposed energy-harvesting circuit can substantially decrease the capacitance used by the demodulator circuit and the wake-up circuit to as low as 14 pF. Moreover, a detection circuit and a correcting circuit are utilised to reduce the bit error rate of decoding. The wireless bio-signal acquisition scenario is also set up and the communication signal between reader and tag is measured to demonstrate the system that can be employed in body sensor network with the healthcare system. The chip was implemented in complementary metal-oxide-semiconductor 0.18 μm technology. The sensitivity of this work is -13 dBm. The pulse width error can be reduced to <1% by the error-correction demodulator to fit the EPC Gen-2 standard.