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This paper is going to discuss typical requirements for micromachined sensors. The most common examples today are pressure and acceleration sensors. We will discuss the function and applications of pressure and acceleration sensors. There are two differences between accelerometers and pressure sensors: sensor technology and signal conditioning. Pressure sensors employ bulk micromachining techniques where accelerometers use surface micromachining. Pressure sensors are typically signal conditioned with bipolar circuitry. Acceleration sensors use CMOS signal conditioning. We will also explain the electrical characteristics of both pressure and acceleration sensors along with mechanical package styles. We will be focusing our effort on automotive based applications. Some typical applications for pressure sensors in the automotive environment are MAP, BAP, lumbar seat, air bag and tire pressure. The requirements of the MAP/BAP application will also be discussed in detail.

A monolithic sensing solution for manifold absolute pressure (MAP) is presented. This work includes examination of design, fabrication, temperature compensation, packaging and electromagnetic compatibility (EMC) testing of the fully integrated monolithic sensor. The circuit uses integrated bipolar electronics and conventional IC processing. The amplification circuit consists of three op-amps, seven laser trimmable resistors, and other active and passive components. Also discussed is a summary of an automotive application MAP sensor general specification, test methods, assembly, packaging, reliability and media testing for a single chip solution.