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A 6.78 MHz single-stage transmitter (TX) using a reconfigurable regulating class-D power amplifier (PA) for wireless power transfer (WPT) applications is presented. Based on a 3-mode modulation scheme, the TX achieves power regulation and transmission with only one power stage. A discontinuous-conduction-mode (DCM) zero-voltage switching (ZVS) scheme is adopted to reduce switching loss. A control loop is set to regulate the output voltage of the WPT receiver (RX) by automatically adjusting the transmitting power. With dual-loop control and a proportional-integral (PI) compensation scheme, the loop achieves tight regulation and fast response. The controller is implemented digitally to benefit from the AirFuel® embedded Bluetooth communication link. The PA was fabricated with a high-voltage 0.35 μm CMOS process, and the digital controller with a standard 0.35 μm CMOS process, respectively. Measurement results show that the output voltage of the RX was correctly regulated to 11.7 V under a load change of 50mA to 500mA, and the WPT system could deliver a maximum power of 7.3 W to the RX over a distance of 4.0 cm, and achieved TX to RX peak efficiency of 57.3%. [ABSTRACT FROM AUTHOR]