Piezoresistive Acceleration Sensor for Automotive Applications

A small. low-cost piezoresistive acceleration sensor suitable for automotive applications such as advanced breaking control and suspension control systems has been developed.

A piezoresistive semiconductor sensor has such advantages as high output linearity, long-term output repeatability and DC response a piezoelectric sensor doesn't feature. One drawback. however, is that piezoresistive characteristics are quite temperature sensitive: Such that temperature dependence of DC offset and span have to be compensated with a certain electrical circuit. With 1 mV/Vs/G, the low sensitivity of the acceleration sensor [Vs:bridge voltage. G:gravitational acceleration], the temperature shift of DC offset represented in terms of the sensitivity, becomes relatively high.

For this reason, we have used a new temperature compensation circuit including a voltage supply sensitive to temperature and a compensation resistor, achieving about 3% offset temperature error per 1.5G full scale in the operating temperature range from -30 °C to 850°C.