Masaki Tagome

Normally-Off 1400V/30A 4H-SiC DACFET and its Application to DC-DC Converter

Large (3.6 x 3.6 mm2) chips of the SiC DACFET were fabricated and mounted in TO220 packages. The drain-source avalanche breakdown voltage without any gate bias (Vgs=0V) is measured to be >1400V. The SiC DACFET keeps the normally-off characteristics even at 150°C. Ron and specific Ron of the SiC DACFET is measured to be 62mΩ and 6.7 mΩcm2 at RT while those at 150°C change to 107 mΩ and 11.6 mΩcm2. The 400V / 3 kW DC-DC switched-mode power-conversion circuit with 100kHz switching was fabricated using the SiC DACFET and the SiC SBD. The turn-off switching loss reduces dramatically using the SiC-DACFET down to 77μJ/pulse which is less than 1/10 of that using the Si-IGBT.

New camera module with thin structure, high resolution and distance-detection capability

Our new type of camera module has a four-lens-array and an imaging sensor. The imaging sensor is divided to four regions, and these four regions are aligned in one-to-one correspondence with the four lenses. Four color filters are placed over the four imaging regions. First region has a blue filter, second has a red, and the other two have green filters, and two regions with green filters are aligned diagonally. Diffraction gratings are formed on aspheric surfaces of the four lenses, and MTF characteristics of these lenses are improved. The four images taken through the different lenses have parallax, but these parallaxes can be calculated by comparison of the two green images. Pixel shifts of blue, red and green images are realized by rotating the four-lens-array slightly with respect to the imaging sensor. After correcting the parallaxes, the green image, the parallax-corrected blue image and the parallax-corrected red image are composed to generate the resultant color image with high resolution. Distances between objects and the four-lens-array are detected by use of the above parallaxes, and measurement error is less than 2.5% for near objects. With above configuration and functions, our camera module has realized smaller height, higher image resolution and distance-detection capability, and will be applied for cellular phones and automobile vehicles.