Takashi Kasai

Novel concept for a MEMS microphone with dual channels for an ultrawide dynamic range

We develop a novel MEMS microphone with a wide dynamic range. The microphone has two channels and consists of two condensers, a single diaphragm and a backplate. Each channel has a different role. The Normal channel has higher sensitivity and an intermediate dynamic range, whereas the High channel has lower sensitivity and a higher dynamic range. By switching the two channels to correspond to sound pressure levels, the device can act as a single-channel microphone in digital signal processors.

Small Silicon Condenser Microphone Improved with a Backchamber with Concave Lateral Sides

We have developed a very small, high-sensitivity silicon condenser microphone, in which a back chamber with concave lateral sides and a specific diaphragm were used as improvements. The concave sides increase the volume of the back chamber and thus solve the trade-off between chip downsizing and sensitivity. The novel back chamber was fabricated using a combination of isotropic and anisotropic etching. The diaphragm is supported only at the four corners to yield good deformation. The chip is 1.2 mmtimes1.3 mmtimes0.4 mm. The sensitivity is -41 dBV (8.8 mV/Pa) at 1 kHz and the frequency response is flat between 100 Hz and 10 kHz.