A generic miniature multi-feature programmable wireless powering headstage ASIC for implantable biomedical systems

Wireless powering holds immense promise to enable a variety of implantable biomedical measurement systems with different power supply and current budget requirements. Effective power management demands more functionality in the headstage design like power level detection for range estimation and power save modes for sleep-wake operation. This paper proposes a single chip ASIC solution that addresses these problems by incorporating digitally programmable features and thus has the potential to enable wireless powering for many implantable systems. The ASIC includes an RF rectifier which has a peak efficiency of 17.9% at 900MHz and 11.0% at 2.4GHz, a robust 1V bandgap reference and LDO voltage regulator whose output can be programmed in the range of 1V-1.5V, and can drive upto 4mA of load current. The input RF power level detector has a threshold of 1.6V and the power management block can be programmed to give a 6%, 12.5% or 25% duty cycle power line to the transmitter resulting in upto 60% reduction in average power. The ASIC was fabricated using the TSMC 65nm process, occupies 1mm² die area and the headstage consumes ~300μA at 1.2V regulated supply.