Kouhei Yamada

A Frequency Compensation Technique for Variable Output Low Dropout Regulators

A novel approach to implement low dropout (LDO) regulator for low equivalent series resistance (ESR) capacitive load is presented. The design utilizes internal Miller compensation circuit, which acts only for heavy load. The compensation circuit improves frequency response of the LDO without using zero generated by the ESR of the load capacitor or feedback network. The proposed circuit was fabricated and tested in 0.6mum CMOS process technology

Low power consumption and high power density integrated DC-DC converter for portable equipments

We developed an integrated buck type DC-DC converter for portable electronic equipments. A newly developed pulse frequency modulation (PFM) control integrate circuits (1 Cs), which includes output power MOSFETs, achieved a low quiescent current below 14 muA and small chip size of 1.4 times 1.1 mm2 in 0.35 mum CMOS process. The integrated converter consisted of the PFM control 1Cs on a planar inductor and had a maximum efficiency of 90 % and a power density above 100 W/cm3.

High Efficiency PWM Controlled Micro DC-DC Converter for Portable Electronic Equipments

In this paper, the characteristics of a micro DC-DC converter for portable electronic equipments are described. In the converter, an inductor, switching devices and control integrated circuits (ICs) were integrated. The external size of the converter module was 3.0 mm x 3.0mm × 1.0 mm. And the converter had a high efficiency of 83% at the input voltage of 7.2 V and the output voltage of 1.5 V. The miniaturization of the converter was achieved by developing a small inductor of the size of 3.0mm x 3.0 mm x 0.525 mm. High efficiency was achieved by adopting 0.6 μm CMOS process for ICs and switching devices, using N channel MOSFET for a high side power switch, and controlling a dead time adaptively. The efficiency characteristics of the converter were analyzed experimentally and theoretically. And the losses of the converter were theoretically analyzed.