Kentaro Mizuno

Analog CMOS integrated circuits for high-temperature operation with leakage current compensation

To facilitate high-temperature operation of CMOS analog integrated circuits, we proposed new compensation circuits which compensated for PN-junction leakage current more precisely than conventional compensation circuits. As the result of applying these circuits to a voltage reference circuit, the operating temperature region was extended 20-40/spl deg/C.

Digital interface circuits using sigma-delta modulation for integrated micro-fluxgate magnetic sensors

This paper presents a high-resolution micro fluxgate magnetic sensor interface circuit based on 2nd-order sigma-delta modulation. The fluxgate sensing element is placed in the modulation loop. This technique allows us to realize pulse negative feedback in the magnetic flux domain, and the instability due to the use of a ferromagnetic core can be reduced. As one of the integrators, a continuous-time integrator is used, and that is also used for the multi-aliasing filter for phase sensitive detector output. The oversampling A/D conversion using 2nd-order sigma-delta modulation results in the high-precision detection of extremely weak magnetic field in the order of sub-nanotesla. The interface circuit chip is designed and evaluated by circuit simulation and behavior-level simulation.

Silicon Angular Rate Sensor for Automotive Control with Open Beam Structure

An angular rate sensor of SOI (silicon on insulator) has been developed for automotive control. The sensor detects yaw rate of automobiles. The concept of the sensor design is the open beam structure (OBS). In the OBS, excitation and detection electrodes are open toward exterior bonding pads in a plane. The OBS has high independency between excitation and detection modes. The FEM analysis was carried out and the results showed the OBS was highly independent compared to other structures. This good feature contributed to the stability of vibration mode for the sensor. The OBS also made it possible to wire from the electrodes besides the mass to the exterior bonding electrodes with mono-layer silicon of the SOI. By means of the easy wirings the process and the packaging became simple. The sensor was fabricated by surface micro machining process to miniaturize the size. The measured characteristics show the OBS is suitable for angular rate sensor to be small, highly precise, and low cost