Performances and potentialities of a very simple self-compensated pressuresensor demonstrator

A pressure sensor demonstrator has been designed and mounted using a simple analog-digital BiCMOS converter and a capacitive Silicon-Pyrex sensing cel l. The measurements as a function of pressure and temperature have enabled to evaluate the efficiency of a ratiometric scheme to self-compensate therm al drifts and nonlinearities, The best demonstrator is characterized by a t hermal coefficient of the offset smaller than 20 ppm/K and a nonlinearity l ower than or equal to +/-1.2% FS, The essential features of the sensor have been modeled by a simple analytical expression. The model specifies the po tential gains in pressure sensitivity and nonlinearity, The best design is based on a quasisymmetrical architecture in which stray capacitors are mini mized. This study demonstrates the feasibility of self-compensated capaciti ve sensors characterized by an overall accuracy in the order of a few perce nts of the measurement scale over a temperature range of 100 K at very low cost.