A dual-path step-down converter (DPDC) is presented for achieving high power efficiency in the mobile power management ICs (PMICs). Adopting a hybrid structure using one inductor and one flying capacitor, the proposed DPDC supplies a load current via two parallel paths, relieved an intrinsic problem of the conventional buck converter (CBC) topology, which is a significant power loss from a large DCR of the inductor (RDCR). Therefore, DPDC achieves a high power efficiency and thus also reduces the heating problem, which is another critical issue in the mobile set. Moreover, DPDC can shrink the volume of the PMIC set with a low manufacturing cost by alleviating an RDCR specification of the inductor. In this paper, although a 250 mΩ of large RDCR inductor is used for our measurements, a 96.2% of peak efficiency was achieved and the power loss of total parasitic resistances can be reduced to up to 30% of that of CBC. Moreover, according to our measurement plots, it is verified that DPDC achieves the efficiency notably higher not only in a wide load current (ILOAD) range but also in a wide conversion ratio (VOUT/VIN) range, compared to CBC.

This paper proposes a new boost converter topology called dual-path step-up DC-DC converter (DPUC). Unlike the conventional boost converter (CBC), the DPUC has a hybrid structure using one inductor and one flying capacitor to make dual current delivery paths. This allows continuous current delivering to the output, reducing both the DC level of the inductor current and the output voltage ripple. Therefore, the DPUC has higher efficiency and smaller output voltage ripple than those of CBC. In addition, the feedforward characteristic of the flying capacitor can alleviate the effect of RHP-zero that degrades the transient response. Even with the inductor DCR of 200mΩ, the DPUC achieves a high efficiency of 95.2% and a small ripple of up to 15mV.

A non-inverting buck-boost converter with state- based current control is proposed for Li-ion battery management. Unlike conventional multi-mode control in buck-boost converters, our control scheme utilizes a state controller with a single-level error current and a state checking clock to define the operation mode at every cycle. The state-based buck-boost (S3B) converter enables seamless mode transition and stable output regulation with fixed interleaving patterns even when input and output voltages are similar, ensuring robust mode change with inherent hysteresis. The prototype IC was fabricated in 0.18-μm BCD process and achieved 90.9% efficiency with 1.1-A maximum load current capability at 1-MHz switching frequency.

A high-efficiency power conversion system to drive high-density plasma is proposed for plasma CO2 reforming (PCR). For high durability, the system is designed for inductively coupled plasma (ICP) without performance degradation. The proposed system consists of a novel control method and a 10 kW 4 MHz switching inverter to obtain a high-induced electromotive force that is necessary to generate and maintain ICP. The proposed control method quickly tracks the resonance frequency of plasma impedance with high frequency resolution, which guarantees zero-voltage switching (ZVS) operation and power supply under highly variable plasma impedance. Moreover, the inverter is designed to be suitable for high-power high-frequency switching operation, consisting of SiC-MOSFETs and gate driver circuits with a negative turn-off voltage. Owing to the proposed system, plasma with much higher density than that of conventional plasma generators can be safely driven. A prototype system is presented to demonstrate the proposed operation, and the technical feasibility of PCR is verified. The proposed control can also be widely utilized for various high-frequency switching inverters that operate in variable load impedance.