Surface micromachined pressure sensors with integrated CMOS read-out electronics

In this paper a single chip pressure and temperature sensor system with on chip electronics is presented. The capacitive pressure sensor is fabricated using a CMOS process with additional surface micromachining steps to form the membranes. The membrane dimensions have been optimized for a pressure range of 2, 4, 10 and 38 bars, respectively. For the signal processing switched capacitor circuits are used. The sensor signals are converted to a pulse width modulated output signal. The silicon chip has an active area of 3.5 mmü. Between 0xC and 80xC a temperature dependence of less than 200 ppm/xC was found.