A Readout IC for Capacitive Touch Screen Panels With 33.9 dB Charge-Overflow Reduction Using Amplitude-Modulated Multi-Frequency Excitation

A Readout IC for Capacitive Touch Screen Panels With 33.9 dB Charge-Overflow Reduction Using Amplitude-Modulated Multi-Frequency Excitation

An, J. (TU Delft Electronic Instrumentation)
Ra, Jong Hyun (SK Hynix Inc.)
Kang, E. (Sony Semicondictor Solutions, Oslo)
Pertijs, M.A.P. (TU Delft Electronic Instrumentation)
Han, S.H. (Leading UI Co. Ltd.)

2021

This article presents a readout integrated circuit (ROIC) for capacitive touch-screen panels (TSPs) employing an amplitude-modulated multiple-frequency excitation (AM-MFE) technique. To prevent charge overflow, which occurs periodically at the beat frequency of the excitation frequencies, the ROIC modulates the amplitude of the excitation voltages at a mixing frequency derived from the excitation frequencies. Thus, the ROIC can sense the charge signal without charge overflow and maximize the signal-to-noise ratio (SNR) by increasing the amplitude of the excitation voltages up to the sensing range of the readout circuit. The proposed ROIC was fabricated in a 0.13- $\mu \text{m}$ standard CMOS process and was measured with a 32-in 104 $\times $ 64 touch-screen panel using 1 and 10 mm metal pillars. It reduces charge overflow up to 33.9 dB compared to operation without AM-MFE. In addition, the ROIC achieves a frame rate of 2.93 kHz, and SNRs of 41.7 and 61.6 dB with 1 and 10 mm metal pillars, respectively.

Amplitude-modulated multi-frequency excitation (AM-MFE)
capacitive touch system (CTS)
charge overflow reduction
frame rate
readout IC (ROIC)
signal-to-noise ratio (SNR)
touch screen panel (TSP).

http://resolver.tudelft.nl/uuid:9216eca4-4c7f-48c4-9a0d-d4f677416ced

https://doi.org/10.1109/JSSC.2021.3100470

0018-9200

IEEE Journal of Solid State Circuits, 56 (11), 3486-3498

Accepted Author Manuscript

Institutional Repository

journal article

© 2021 J. An, Jong Hyun Ra, E. Kang, M.A.P. Pertijs, S.H. Han