An efficient DFT-based algoritiim for the charger noise problem in capacitive touch applications

Huang, Shih-Lun; Hung, Sheng-Yi; Chen, Chung-Ping

doi:10.1109/iscas.2017.8050812

Cited by 2 publications

(1 citation statement)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The other types of applications, such as self-capacitive touch applications, optical touch applications, biometric capacitive fingerprint applications, and biometric optical fingerprint applications, could be considered based on our algorithm and theorems in future studies. presented at the 2017 IEEE International Symposium on Circuits and Systems [1].…”

Section: Discussionmentioning

confidence: 99%

Frequency Hopping and Parallel Driving With Random Delay Especially Suitable for the Charger Noise Problem in Mutual-Capacitive Touch Applications

2019

Self Cite

View full text Add to dashboard Cite

Charger noise can cause inaccurate touch points and fake touch points to appear; this can cause a device to behave incorrectly. The intensity of charger noise could be much larger than the intensities of the original touch signals. Furthermore, the frequency of charger noise varies for each different charger. Therefore, industry experts have identified charger noise as the most difficult problem in capacitive touch applications. The demand for a solution to this problem has become crucial for the mobile market. In this paper, we prove that a particular combination of frequency hopping and repeated integration is an effective method to handle this problem. In addition, we propose an efficient discrete Fourier transform-based algorithm to select an effective sensing frequency. We propose parallel driving with random delay to enhance the signal-to-noise ratio (SNR). We show an efficient hardware-software co-design that facilitates the application of our methods in touch ICs. The experimental results show that our methods can increase SNR by over 45 dB and can find an effective sensing frequency fast and dynamically.INDEX TERMS Charger noise, parallel driving, frequency hopping, repeated integration, mutual-capacitive touch.

show abstract

Section: Discussionmentioning

confidence: 99%