Performance Comparisons of Interface Circuits for Measuring Capacitances

This paper reviews some of the recent signal conditioning and Interface circuits for the capacitive type sensors. This paper gives the brief idea of advantages and limitations of interface circuits for the various capacitive sensors. The sensor output may be either current or voltage but it has to be converted to the desired output range only by the signal conditioning circuit. Signal conditioning circuits provides the analog output in the desired range; this can be converted to digital through Analog to Digital converter. The signal conditioning circuit should able to produce not only the convenient of output voltage or current levels but it has to provide the isolation, impedance matching, linearization with the input, proper gain adjustment with the amplification, filtering of unwanted signals, etc. Here we reviewed the four different methodologies of the proposed signal conditioning and interfacing circuits with its advantageous and limitations.