Daisuke Uchida

Highly Stable GaN Photocatalyst for Producing H2 Gas from Water

Efficient production of H2 from water without the use of an extra bias or any sacrificial reagents is possible using a GaN photocatalyst with a NiO cocatalyst. The average energy conversion efficiency from light energy to H2 energy was approximately 1% for 500 h. The total amount of hydrogen was 184 mL/cm2 of the GaN surface. H2 production rate was as high as 0.37 mL/(cm2h).

Image sensor/digital logic 3D stacked module featuring inductive coupling channels for high speed/low-noise image transfer

This paper proposes 3D stacked module consisting of image sensor and digital logic dies connected through inductive coupling channels. Evaluation of a prototype module revealed radiation noise from the inductive coils to the image sensor is less than 0.4-LSB range along with ADC code, i.e., negligible. Aiming at high frame rate image sensor/processing module exploiting this attractive off-die interface, we also worked on resolving another throughput-limiter, namely power consuming TDC used in column parallel ADCs. Novel intermittent TDC operation scheme presented in this paper can reduce its power dissipation 57% from conventional ones.

Copper Plating Method on Flat Surface for High Frequency Signal Transfer

A copper plating process for printed wiring boards operating in the GHz frequency range has been developed that improves the adhesion strength between the copper interconnects and the resin substrate by using an imidazole compound to form coordinate bonds. The coordinate bonds are prepared by impregnating the resin substrate with an aqueous solution of amino-group-containing imidazole (AI). The adhesion strength is measured by a tensile test with various concentrations of AI solution and different treatment times of impregnation. As a result, the highest adhesion strength of 4.2–5.1 Ncm-1 can be obtained on the entire surface of a 340×340 mm2 substrate, where the flatness is down to 58.7 nm. This result is due to the optimization of the impregnating condition for AI and of the removal condition for weak boundary layers. The signal transmission characteristics of the interconnects on the substrates fabricated by this processes are compared with the conventional process by S21 parameter extraction in the GHz frequency range. The transmission characteristics of this process are markedly improved compared with those of conventional processes.

An image sensor/processor 3D stacked module featuring ThruChip interfaces

1,000 fps motion vector (MV) estimation and classification engine for highspeed computational imaging in a 3D stacked imager/processor module is proposed, prototyped, assembled, and also tested. The module features 1) ThruChip interfaces for high fps image transfer, 2) orders of magnitude more area/power efficient MV estimation architecture compared to conventional ones, and 3) a cognitive classification scheme employed on MV patterns, enabling the classification of moving objects not possible in conventional proposals.

CMOS common-mode rejection filter with floating active transformer operation

We propose an inductorless common-mode rejection filter with a gyrator-C network for common-mode-noise reduction. By adopting a gyrator-C network and ladder structure, high-order and small filter circuits with active transformer operation were fabricated. The filter was designed and fabricated in a Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 µm CMOS process. This filter exhibited a CMRR of 80 dB, output noise voltage of 103 nV/Hz1/2, third-order input intercept point of 8.8 dBm at 1 MHz operation, and cutoff frequency of under 6 MHz. The total power consumption was 14.8 mW with a 2.5 V supply, and the chip area was 0.7 × 0.4 mm2.

CMOS Common-Mode Filter with Gyrator-C Network

We propose an inductor less common mode filter with a gyrator-C network. The filter was designed and fabricated in a TSMC 0.18-m CMOS process. This filter exhibited a CMRR of 80 dB, output noise voltage of 103 nV/Hz 1/2 , cutoff frequency of under 6 MHz. The total power consumption was 14.8 mW with a 2.5-V supply, and the chip area was 0.7 x 0.4 mm 2 .