A systematic approach for sensor bridge linearisation and readout

A general concept for the linearisation of impedance bridges with circuit components changing in only one polarity is presented. The method can be applied for DC or AC bridges and the linearisation can conveniently be integrated with the readout circuit, resulting in a highly linear sensor readout. A feedback-loop using a trans-admittance amplifier, properly designed and matched to the nominal value of the bridge components, reduces non-linearity from 9% to 0.4% over ±20% of bridge imbalance. In addition to the linearization of the bridge transfer function itself, the method can be applied for the linearization of a range of transducers with a hyperbolic transfer function.