A Multi-Path Inductor-First Inductor-on-Ground Switched-Capacitor Hybrid DC-DC Converter

Energy-efficient compact smart devices operate at a supply voltage as low as 0.5 V, powered by either a battery (3–4.2 V) or a universal serial bus (USB) port (5 V), demanding a voltage conversion ratio (VCR) as large as 10:1. This work proposes a multi-path inductor-first inductor-on-ground switched-capacitor (L²SC) hybrid buck dc-dc converter for large VCR and high-power density. The inductors on the input and the ground nodes combine and reuse the parasitic inductors from PCB routing and bonding wire, enable a continuous input current, and relieve the electromagnetic interference (EMI) issue. In addition, the two inductors in this converter operate in an interleaved fashion, obtaining reduced output current ripple. The SC network reduces the average inductor current and enlarges the output capability. This work, fabricated in a 180-nm BCD process, uses only 2-V NMOS power transistors, withstanding 3–5-V input and delivering 0.5–1.2-V output. This work achieves a peak efficiency of 96.1% with a high chip-area current density of 1.02 A/mm².