Title :
A low-noise differential front-end and its controller for capacitive touch screen panels
Author :
Lim, Dong-Hyuk ; Park, Jun-Eun ; Jeong, Deog-Kyoon
Author_Institution :
Dept. Electr. Eng. & Comput. Sci., Seoul Nat. Univ., Seoul, South Korea
Abstract :
A low-noise front-end and its controller are proposed for capacitive touch screen panels. The proposed front-end circuit based on a ΔΣ ADC uses differential sensing and integration scheme to maximize the input dynamic range. In addition, supply and internal reference voltage noise are effectively removed in the sensed touch signal. Furthermore, the demodulation process in front of the ΔΣ ADC provides the maximized oversampling ratio (OSR) so that the scan rate can be increased at the targeted resolution. The proposed IC is implemented in a mixed-mode 0.18-μm CMOS process. The measurement is performed on a bar-patterned 4.3-inch touch screen panel with 12 driving lines and 8 sensing channels. The report rate is 100 Hz, and SNR and spatial jitter are 54 dB and 0.11 mm, respectively. The chip area is 3 × 3 mm2 and total power consumption is 2.9 mW with 1.8-V and 3.3-V supply.
Keywords :
analogue-digital conversion; capacitive sensors; integration; low-power electronics; remote consoles; tactile sensors; touch sensitive screens; ΔΣ ADC; IC; OSR; SNR; capacitive touch screen panel; differential sensing; frequency 100 Hz; gain 54 dB; integration scheme; internal reference voltage noise; low-noise differential front-end circuit; maximized oversampling ratio; mixed-mode CMOS process; power 2.9 mW; sensed touch signal; size 0.11 mm; size 0.18 mum; size 4 in; spatial jitter; total power consumption; voltage 1.8 V; voltage 3.3 V; Capacitance; Indium tin oxide; Integrated circuits; Sensors; Signal generators; Signal to noise ratio;
Conference_Titel :
ESSCIRC (ESSCIRC), 2012 Proceedings of the
Conference_Location :
Bordeaux
Print_ISBN :
978-1-4673-2212-6
Electronic_ISBN :
1930-8833
DOI :
10.1109/ESSCIRC.2012.6341302
