High-Accuracy Readout Circuits for High-Resolution Active Matrix Resistive Sensor Arrays

The active matrix resistive sensor arrays are widely used in a variety of fields because they can eliminate the crosstalk current problem found in passive matrix resistive sensor arrays. However, the ON-resistance of the pixel transistor used in the active matrix resistive sensor array causes voltage drop and reduces the sensing accuracy. Increasing the width of the pixel transistor can reduce the ON-resistance and improve accuracy, but it increases the required circuit area, resulting in a decrease in the integration density and spatial resolution of the array. To solve the problem of inaccuracy and large circuit area found in conventional active matrix resistive sensor arrays, we propose two types of readout circuits based on an additional feedback path. With the additional feedback path between the sensor and the column amplifier, the effect of the voltage drop on the pixel transistor can be eliminated. The measurement results show that the proposed Type I and Type II readout circuits achieve less than 0.1% of the maximum error, remarkably reduced from 997.4% of the conventional counterpart.