A high efficiency inductive power link and backward telemetry for biomedical applications

High-performance wireless power transmission working as a continuous power source of implantable devices can prevent biohazard from leakage of buttery fluid or skin infection from transcutaneous cable. This work reports a high efficiency inductive powering and backward telemetry for implantable medical devices. A new differential class-E type power oscillator with high efficiency excites the external unit, the resonant link coils transfer the power to the internal unit, a modified rectifier circuit rectifies and boosts the recovered signal, and a Zener diode based voltage regulator regulates the output DC voltage. The recovered power is then used to run a ring oscillator-based sensor readout circuit to generate data signal based on sensor current variation and finally a load-shift-keying (LSK) is used to back transit the data to the external unit. The system has been designed using 0.5-μm standard CMOS process with off-chip zener diode, opamp and inductors. The over all power-efficiency of the system is found to be 74.0%.