METROLOGICAL ANALYSIS OF CHARGE TRANSFER CAPACITIVE TRANSDUCER IN THE PRESENCE OF RESISTANCE

One of the major tasks in the design of measuring transducers is improving their accuracy in real conditions. Above all, this problem makes it necessary to evaluate the impact that various non-idealities have on the work of the measuring device. This study points that the presence of active resistance in the input of capacitive transducers, realizing the charge-transfer method, influences the measured result. With a configuration, composed of four analogue switches, the magnitude of the occurring in this case additional error depends on: the value of resistance in the input; the value of the capacity, which is the object of the measurement; the frequency and the phase offset of the clock signals, controlling the switches. The conditions under which error does not exceed 0,1% have been defined and a simple equation, by which its value can be assessed in the general case, has been validated. Presented results are useful in the design and implementation of industrial capacitive transducers

Keywords:

Capacitive transducer, resistance methodological error,

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