Wireless Charging and Power Management System for CMOS Biomedical SoCs

Owing to growing rapidly bio-medical electronics and the shrink of the semiconductor fabrication, CMOS biomedical SoCs can have more various circuits such as analog front end, biomedical sensor, analog to digital converter, radio frequency transmitter, radio frequency receiver, digital signal processing and so on…. Then, eachoperation voltage of circuits needs to change with low power operation or high performance operation. In addition, power management integrated circuits (PMICs) play an important role in SoCs. In a wide range of power management ICs, we distinguish roughly among low-dropout regulator (LDO), inductor based switching DC-DC converter and capacitor based switching DC-DC converter whose difference lie in operation mode and energy storage elements. Recently, Inductor based switching DC-DC converter becomes more and more popular due to whose efficiency is the highest of power management ICs. To begin with, a wireless charging and power management interface is reported. In order to apply to implantable or hermetical biomedical devices, the full bridge AC-DC rectifier can receive power and provide a charging voltage for the battery charger with wireless powering. Following, power management supply different sub-circuits of the SoCs. With a temperature sensing and controlling circuit we proposed, the power management unit (PMU) is able to prevent abnormal temperature of the SoCs. In addition, we presented a photovoltaic energy harvesting and power management interface circuit, which extracts a power from PV cell or solar cell to the switching DC-DC boost converter. The li-ion battery charger can charge the battery with a stable dc voltage which generated by the boost converter. By detecting the status of the battery, battery management turns the charging mode on smartly. The former work is fabricated in UMC 0.18μm process, the latter work is fabricated in TSMC 0.35μm process.