A high-efficiency charge pump for ultra-low voltage boost systems

To meet the demands for fast voltage boosting and high efficiency in ultra-low-voltage boost converters, this paper proposes a charge pump structure specifically tailored for such applications. The proposed charge pump employs a pair of NMOS and PMOS transistors as the charge transfer switch (CTS), with their gates connected to internal nodes to enhance the overdrive voltage, while dynamic gate biasing is incorporated to suppress reverse leakage current. Furthermore, a dual-branch architecture is introduced to ensure that both the NMOS and PMOS on both sides of the CTS are turned off during clock transitions, thereby eliminating undesired charge transfer. Simulation results based on a 0.18 μm BCD process demonstrate that, compared with alternative charge pump topologies, the proposed design improves the boosting speed by 10.1%–55.0% and achieves an 8.8%–20.4% enhancement in peak power efficiency. Moreover, the boost converter system incorporating the proposed charge pump achieves rapid start-up under a 0.5 V input voltage.