This work presents a battery-powered hybrid resonant pulse-train generator for ultrasonic wireless power transfer (US-WPT) in implantable medical devices. The ASIC integrates adaptive resonance tracking, burst-mode power regulation, a switched-capacitor-resonant architecture, and residual energy harvesting. Fabricated in 0.18μm BCD, it achieves programmable US power, 68.6% Cp-loss reduction, and 21.7% end-to-end efficiency.

A single transmitter source can power multiple ultrasound piezoelectric transducers to enhance the harvested power; however, the received ultrasonic signals vary in phase and amplitude across each element. This paper introduces a fully integrated, high-frequency SSHC rectifier tailored for miniaturized multi-piezo implants to efficiently harvest power at variable phase offsets with a compact form factor. The design incorporates a novel phase-splicing flipping capacitor-sharing technique between all four ultrasound piezoelectric transducers to improve area efficiency. The proposed 4-stage SSHC rectifier can harvest 5.94x more power than a full bridge rectifier operating at a high ultrasonic excitation frequency of 780 kHz. The proposed system was designed using 180-nm BCD process technology for a 2x2 piezoelectric transducer array, with each element featuring an internal capacitor (C_P) of 63.7pF.