A Fully-Differential Correlated Doubling Sampling Readout Circuit for Mutual-capacitance Touch Screens

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JSTS:Journal of Semiconductor Technology and Science, ISSN: 1598-1657, Vol: 15, Issue: 3, Page: 349-355

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Citations 6
Citation Indexes 6
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Kwon, Kihyun, Kim, Sung Woo, Bien, Franklin, Kim, Jae Joon
The Institute of Electronics Engineers of Korea, IEEK PUBLICATION CENTER
Engineering, Materials Science, Sensor interface, readout circuit, Touch screen, differential, mutual capacitance
article description
A fully-differential touch-screen sensing architecture is presented to improve noise immunity and also support most multi-touch events minimizing the number of amplifiers and their silicon area. A correlated double sampling function is incorporated to reduce DC offset and low-frequency noises, and a stabilizer circuit is also embedded to minimize inherent transient fluctuations. A prototype of the proposed readout circuit was fabricated in a 0.18 mm CMOS process and its differential operation in response to various touch events was experimentally verified. With a 3.3 V supply, the current dissipation was 3.4 mA at normal operation and 140 mA in standby mode.