Evaluation of piezoresistive ceramic pressure sensors using noise measurements

The development of low-temperature co-fired ceramic (LTCC) technology is increasing the interest in ceramic pressure sensors (CPS). This technology and materials in combination with conventional thick-film technology offers a feasible solution to increase the sensitivity of pressure sensors and the flexibility in design, both with the aim to replace silicon-based pressure sensors in some applications. The sensor characteristics, i.e., offset stability and sensitivity, are always influenced by the level of electronic noise. We are concentrating our efforts on the use of low-frequency noise as a diagnostic tool for a reliability improvement and sensitivity increase. 1/f noise is dominant in the low-frequency region. It is given by two components; one is connected to the material structure and the second one is influenced by the defects and imperfection in the structure. The measurements of the electronic noise level could be used for an evaluation of different technologies in order to tune the pressure sensor technology and for the evaluation of sensor quality within one technology. We show the correlation between the noise of the sensing resistor technology and the noise of the output voltage on the measured pressure sensor.