An Integrated Wireless Power Management and Data Telemetry IC for High-Compliance-Voltage Electrical Stimulation Applications

Abstract

This paper describes a 13.56-MHz wireless power recovery system with bidirectional data link for high-compliance-voltage neural/muscle stimulator. The power recovery circuit includes a 2-stage rectifier, 2 LDOs and a high voltage charge pump to provide 3 DC outputs: 1.8 V, 3.3 V and 20 V for the stimulator. A 2-stage time division based rectifier is proposed to provide 3 DC outputs simultaneously. It improves the power efficiency without introducing any impact on the forward data recovery. The 20 V output is generated by a modified low ripple charge pump that reduces the ripple voltage by 40%. The power management system shows 49% peak power efficiency. The data link includes a clock and data recovery (CDR) circuit and a load shift keying (LSK) modulator for bidirectional data telemetry. The forward and backward data rates of the data telemetry are 61.5 kbps and 33.3 kbps, respectively. In addition, a power monitor circuit for closed-loop power control is implemented. The whole system has been fabricated in a 24 V HV LDMOS option 1.8 mu m CMOS process, occupying a core area of around 3.5 mm(2).