38.1: A Low-Power Fast Readout Circuit using a Dual-Mode Sensing Algorithm for Medium-Size Capacitive Touch Screen Panels

A new readout circuit architecture for capacitive touch screen panels (TSPs) is introduced to enhance the reporting rate and to improve the signal to noise ratio (SNR) with low power consumption. The proposed Dual‐Mode Sensing (DMS) method finds the actual touch spots without feedback from the TSP to the MCU. In addition, the effect of noise coupled to the touch signal is reduced owing to the averaging effect of the proposed continuous‐time integration (CTI) technique. The circuit was designed for a 0.35 μm CMOS technology. The proposed sensing scheme shows a 257 Hz reporting rate under a simultaneous 10 touch condition on a 10.1 inch TSP, providing a 33 dB SNR with power consumption of 679 μW from a 3.3V supply.