HIGH-PRECISION READOUT CIRCUIT FOR LIGA ACCELERATION SENSORS

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 capacitanc e of 5 pF, temperature-compensated design with low offset temperature coefficient (TCO=1.5x10(-4) FSO K-1) and high linearity. In addition, a high-precision readout circuit has been developed. The electronic ci rcuit's distinguishing feature is its extremely low noise, so that cap acitance changes of 5 aF Hz-(1/2) can be detected. Combined with a 1g LIGA acceleration sensor, a resolution of 1 mu g Hz-(1/2) has been ach ieved. 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 x 20 mm Al2 O3 substrate. The final result is a sensor system with excellent prope rties as regards temperature behaviour, dynamic range and resolution.