An Improved-Accuracy Approach for Readout of Large-Array Resistive Sensors

Large-array resistive sensors have found a variety of applications from industrial instrumentation to medical wearable applications. In such large-array sensors, several non-idealities limit the accuracy of the readout circuit. In this paper, after analyzing the crosstalk error caused by the input offset voltage and input bias current of the operational amplifier, a novel double-sampling technique is proposed to considerably reduce the error. Spice simulation results of a 20 × 20 array confirm that for a 1-MQ resistance, the proposed technique can decrease the maximum measureable relative error from 20% to 0.089%. Furthermore, the measurement results of a 20 × 20 array confirm that for a resistance value of 19 MQ being measured, the proposed technique can reduce the error from 84% to 0.69%.