Design of wireless power management SOC for active capsule endoscope

This paper proposes a novel wireless power supply solution, and designs a power management system-on-chip (SOC) for active capsule endoscope. The SOC consists of a high-efficiency rectifier, two excellent performances low-dropout regulator (LDO) and a rapid battery charger management unit. The self-resonant coil inside the human body is used to receive energy, and the energy is rectified and regulated to generate a stable voltage for charging a button battery, which provides stable power for controlling and driving the system by the low dropout (LDO2) regulator fixed in the capsule endoscope. The power management SOC was designed using a 0.18-um CMOS high voltage process. Simulation results indicate that the rectifier has high conversion efficiency of voltage and power under 12mA load. The LDO1 output can keep at 4.4V in spite of the variations of input voltage and loading current. The preliminary system simulation indicates the SOC achieves control of battery charging-recharging.