A 10.1” 183- \mu \text /electrode, 0.73-mm2/sensor High-SNR 3-D Hover Sensor Based on Enhanced Signal Refining and Fine Error Calibrating Techniques

• Published in: IEEE journal of solid-state circuits Vol. 53; no. 4; pp. 1079 - 1088
• Main Authors: Huh, Yeunhee, Hong, Sung-Wan, Park, Sang-Hui, Shin, Changsik, Bang, Jun-Suk, Park, Changbyung, Park, Sungsoo, Cho, Gyu-Hyeong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 3-D hover sensor; analog front end (AFE); Capacitance; CMOS readout integrated circuit (ROIC); Detection; Electrodes; Error detection; high-voltage driving; Inductors; Offsets; Optimization; panel offset; self-capacitive sensing (SCS); Sensors; Signal to noise ratio; Tactile sensors; touch screen panel (TSP); touch sensor
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2017.2772803

A high-signal-to-noise ratio (SNR) inductor-free 3-D hover sensor is presented. This paper solved the low-signal component issue, which is the biggest problem in 3-D hover sensing. For this purpose, we propose a power- and cost-effective high-voltage driving technique in the self-capacitance sensing scheme (SCSS) and lateral resolution optimization of a touch panel. In addition, the huge panel offsets in the SCSS from both vertical panel capacitance (C SV ) and horizontal panel capacitance (C SH ) can effectively be eliminated by exploiting the panel's natural characteristics, without using other costly resources. Therefore, in the proposed design, the total calibration block is minimized only for parasitic capacitance mismatches. Last, by adopting new driving scheme, two-phase simultaneous sensing is enabled to increase the SNR further. The proposed hover sensing system achieved a 39-dB SNR at a 1-cm hover point under a 240-Hz scan rate condition in noise experiments, while consuming 183 <inline-formula> <tex-math notation="LaTeX">\mu \text{W} </tex-math></inline-formula>/electrode and 0.73 mm 2 /sensor, which are the lowest power per electrode performance and the smallest die-area per sensor performance, respectively, in comparison to the state-of-the-art 3-D hover systems.