A Discrete Controlled Fully Integrated Class E Coil Driver With Power Efficient ASK Modulation for Powering Biomedical Implants

An integrated feedback controlled class E coil driver for wirelessly powering biomedical implants was implemented in a high voltage 0.18 μm CMOS process. The coil driver was compensated using a discrete switched-capacitor controller for reducing the compensation capacitor area. A linearized discrete-time model was also developed for analyzing the stability of the proposed coil driver. Different methods to reduce the on-resistance of the coil driver switch had also been investigated. When compared to the previous design, the figure of merit for measuring the effectiveness of generating coil current was improved over 2.5 times. ASK modulation on the coil current was achieved by switching on or off an additional off-chip capacitor. Power increase during ASK modulation was reduced by 49.4% when compared to the previous design.