A 92.8% Power Reduction Event-Driven Dual-Mode Touch Analog Front-End IC Featuring 620μW Self-Capacitance Sensing and 500fps Mutual-Capacitance Sensing

This paper presents an energy-efficient dual-mode touch-sensor analog front-end (AFE) IC that supports an event-driven operation. The proposed AFE consists of 1) an ultralow-power self-capacitance sensing (LP-SCS) and 2) a high-performance mutual-capacitance sensing (HP-MCS). Once the LP-SCS detects a touch input during a standby mode, the HP-MCS is triggered to start the mutual capacitance sensing with high SNR and high frame rate. The event-driven dual-mode sensing can reduce the AFE power consumption up to 92.8%. The proposed AFE IC was fabricated in an 80nm CMOS process. The measured power consumptions are 0.62mW and 8.65mW for the LP-SCS and the HP-MCS, respectively. The measured SNRs of the LP-SCS and the HP-MCS are 52.6dB and 40.2dB with frame rate of 60Hz and 500Hz, respectively.