A CMOS Readout Circuit for Resistive Tactile Sensor Array Using Crosstalk Suppression and Nonuniformity Compensation Techniques

This article presents a novel readout circuit for the resistive tactile sensor array. Based on the 2-D scanning mechanism, a crosstalk suppression technique is proposed by combining the correlated double sampling (CDS) and zero potential method (ZPM). The output of the same sensor under different bias conditions is captured twice and amplified by a channel-parallel fully differential gain stage, performing analogous subtraction. To achieve nonuniformity compensation, the current injected into the readout channel is adjusted by the channel-parallel digital-to-analog converter (DAC). A successive approximation register (SAR) analog-to-digital converter (ADC) performs quantization, and the chip can be used as a serial peripheral interface (SPI) slave to update register values for gain configuration, power consumption control, and nonuniformity compensation. The 180-nm CMOS prototype chip occupies an area of $4.8~\text {mm}^{2}$ and consumes $285~\mu $ W. In order to validate the design, a tactile sensing system is built, using the readout circuit along with a $10\times 10$ flexible sensor array. With the techniques proposed in this article, the readout error of the sensors in array is less than 0.3‰.