Electrical and Electronic Engineering
Semiconductor System Laboratory
Research Fields
Analog Integrated Circuits, RF Circuits, A/D D/A Converter, Actuator Driver Circuits, Digitally Direct Driven System, Digital Speaker, Digital Motor
High Precision, Low Power, High Efficiency, High Power, Delta-Sigma, Digital Speaker, Digital Motor
 Our laboratory focuses on high-performance analog signal converters including A/D, D/A converter, RF system, and actuator driving system. High accuracy and efficient converter are important to realize high-performance equipment such as smartphones and industrial systems. Our aim is to improve the analog performance with digital processing.

 The converter accuracy depends on elements value accuracy such as resistance. Improving conversion accuracy beyond elements values accuracy we develop a novel mismatch shaper that reduces the noise caused by the mismatch.

 Applying this system to an A/D, D/A converter the conversion accuracy is greatly improved to over 100dB SNR with 1% element value mismatches. Expanding this method to make up the actuator system a digitally direct driven motor system is realized, which shows low torque ripple and high power efficiency. A digital speaker system using the proposed method can reproduce high-quality audio sound, which is a superior system to realize high-resolution audio equipment. The digital speaker system is released in a market by several companies. We are developing high-performance analog and digital mixed-mode systems in order to make future life wealthy.