A 50.7dB-DR Finger-Resistance Extractable Multi-Touch Sensor IC Achieving Finger-Classification Accuracy of 97.7% on 6.7-inch Capacitive Touch Screen Panel

Abstract

This paper presents a 2D touch readout IC embedding finger resistance extraction (FRE) on a capacitive touch screen panel (TSP). The resonance-driven FRE technique and the clamped zoom-in integrator are exploited to achieve a wide dynamic range (DR). To readout the FRE and touch sensing (TS) signals, the switched-capacitor current-controlled oscillator (SC-CCO) based 14-bit ADC was also designed, which benefits low noise and compact size. The prototype chip offers the measured 37.5dB-SNR and 50.7dB-DR in TS and FRE modes, respectively, in a 6.7-inch TSP. By applying a support vector machine (SVM) learning to the FRE data, five different user-fingers were successfully classified with 97.7% accuracy after 500 learning-cycles, thereby bringing the reliable user-differentiation to multi-user collaborative touch interfaces.