High-precision readout circuit for LIGA acceleration sensors

Abstract For the past few years capacitive LIGA acceleration sensors have been fabricated at the Karlsruhe Nuclear Research Center. The advantages of LIGA acceleration sensors are their high zero-acceleration capacitance of 5 pF, temperature-compensated design with low offset temperature coefficient (TCO = 1.5 × 10−4 FSO K−1) and high linearity. In addition, a high-precision readout circuit has been developed. The electronic circuit's distinguishing feature is its extremely low noise, so that capacitance changes of 5 aF Hz −1 2 can be detected. Combined with a 1g LIGA acceleration sensor, a resolution of 1μg Hz −1 2 has been achieved. A feedback system has been developed for a further improvement of linearity. The electronic circuit has been realized as a multichip module (MCM) in multilayer thick-film technique on a 10 mm × 20 mm Al2O3 substrate. The final result is a sensor system with excellent properties as regards temperature behaviour, dynamic range and resolution.