Design of analog front-end integrated circuit of tactile sensor for human-machine interface

Abstract

—In this paper, a highly integrated analog front-end chip for sensor data acquisition and readout is designed, which is applied to a pressure-to-capacitance-conversion 16 × 16 tactile sensor array. In this design, a 16-channel capacitance-to-digital converter using a combination of op-amp-based Capacitance-Voltage Converter (CVC) and column-parallel Single-Slope Analog-to-Digital Converter (SS ADC) converters has been implemented, increasing the readout speed of the sensor array and saving the chip area. In addition, a sequence of scanning circuit suitable for the 16 × 16 array is proposed, so that the CVC and column-parallel SS ADCs are in a pipelined working mode, which further improves the speed of data conversion and readout. The integrated circuit (IC) is designed and taped out in a 0.18-μm CMOS process technology. The measurement results show that the chip can reach the capacitance detection range from 1 pF to 9.1 pF, and it achieves a detection accuracy of 9 fF under 10-bit ADC quantization. Under the clock frequency of 64 MHz, the refresh rate of the entire array is 3906 fps, and the overall power consumption of the front-end IC is 7.5 mW.