Design of wireless power supply microsystem for capsule endoscope

A novel wireless powering solution for active capsule endoscope has been presented in this paper. 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 (LDO) regulator fixed in the capsule endoscope. The charging microsystem is designed using a 0.18 μm CMOS high voltage process. Simulation results indicate that the rectifier conversion efficiency of voltage and power is about 82.14% and 83.50%, respectively. The regulator and LDO provide relatively constant output voltage in spite of the variations of input voltage and loading current. The design of power management integrated circuits meets the requirement for controlling the charging-recharging of the battery and providing stable voltage for the control and drive system of the capsule endoscope.