This study presents a merged backside series/parallel hybrid piezoelectric resonator-based (BSPPR) DC-DC converter that improves the performance of conventional piezo-resonator-based (baseline PR) converters at large step-down ratios. The proposed topology incorporates a 2:1 series-parallel switched capacitor (SC) network with the output of the baseline PR converter, enabling efficient step-down conversion over a wider range. By placing the piezoelectric resonator (PR) on the high voltage side, the resonant current is reduced, extending the operable load range, and minimizing PR vibration losses (I2R losses). Moreover, by leveraging the merged hybrid converter concept, the operational principle remains unchanged, preserving all the benefits of the baseline PR converter, including zero-voltage-switching (ZVS). A prototype of the BSPPR converter is constructed using disk-shaped lead zirconate titanate (PZT) PRs, which achieves a peak efficiency of 95.78% under 48/10V, 1.5W conditions, surpassing the efficiency of the baseline PR converter across all test points.
