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.