Low noise capacitive sensor for multi-touch mobile handset's applications

Ko, Sangjin; Shin, Hyungcheol; Lee, Jaemin; Jang, Hanhwi; So, Byeong-Cheol; Yun, Ilhyun; Lee, Kwyro

doi:10.1109/asscc.2010.5716570

Cited by 21 publications

(3 citation statements)

References 4 publications

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“…Table 1 compares the SNR of the proposed TSP SCS system before and after the proposed calibration is performed, in the presence of a 12% self-capacitance mismatch with a 120 Hz frame rate. SNR,

, and

were calculated from the frame data in Figure 9 , as follows: [ 13 , 14 ]

where

, and

are the n -th frame data when touched, the average of 100 frame data when touched, and the average of 100 frame data when not touched, respectively.

is defined as the difference between

and

, and it represents the strength of touch signal variation caused by changes in

due to touch.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Table 1 compares the SNR of the proposed TSP SCS system before and after the proposed calibration is performed, in the presence of a 12% self-capacitance mismatch with a 120 Hz frame rate. SNR, TouchStrength Sensed , and Noise RMS were calculated from the frame data in Figure 9, as follows: [13,14] SNR(dB) = 20 log 10 (|TouchStrength Sensed /Noise RMS |)…”

Section: Figurementioning

confidence: 99%

See 1 more Smart Citation

Self Capacitance Mismatch Calibration Technique for Fully-Differential Touch Screen Panel Self Capacitance Sensing System

Seong

Lee

Bae

et al. 2023

Sensors

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This paper presents a fully-differential touch screen panel (TSP) self-capacitance sensing (SCS) system with a self-capacitance mismatch calibration technique. Due to the self-capacitance mismatch of TSP, the analog front-end (AFE) of the receiver (RX) circuit suffers from dynamic range degradation and gain limitations, which lead to the signal-to-noise ratio (SNR) loss for the TSP SCS system. The proposed calibration introduces the difference in input resistance and the driving amplifier’s strength between the fully-differential input. Thus, the mismatch effect is efficiently relieved in terms of area and power consumption. The proposed calibration restores the SNR by 19.54 dB even under the worst self-capacitance mismatch case.

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“…Table 1 compares the SNR of the proposed TSP SCS system before and after the proposed calibration is performed, in the presence of a 12% self-capacitance mismatch with a 120 Hz frame rate. SNR,

, and

were calculated from the frame data in Figure 9 , as follows: [ 13 , 14 ]

where

, and

are the n -th frame data when touched, the average of 100 frame data when touched, and the average of 100 frame data when not touched, respectively.

is defined as the difference between

and

, and it represents the strength of touch signal variation caused by changes in

due to touch.…”

Section: Simulation Resultsmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Self Capacitance Mismatch Calibration Technique for Fully-Differential Touch Screen Panel Self Capacitance Sensing System

Seong

Lee

Bae

et al. 2023

Sensors

View full text Add to dashboard Cite

show abstract

“…The capacitive type touch panels require sensor readout circuits that can effectively detect the touch panel capacitance variation. Conventional capacitive type touch sensor readout circuits are based on capacitive charge transfer [2,3,4] or capacitance-to-time (C-to-T) conversion [5]. Charge transfer schemes require huge off-chip capacitors that limit the on-chip implementation and require longer detection time.…”

Section: Introductionmentioning

confidence: 99%

Touch sensor readout circuit with comparator threshold self-adjustment

Asgari

Lee

2018

IEICE Electron. Express

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This work describes a capacitive type touch sensor readout circuit using a current based capacitance-to-time converter with comparator threshold level self-adjustment. The proposed circuit generates an output pulse with duty-cycle corresponding to the panel capacitance variation using a simple switch control block, a current generator, and a comparator. This does not require additional amplifiers and passive capacitors/resistors. As a result, the proposed scheme can lead to small size and low power on-chip solution with fast detection time compared to conventional touch sensor readout circuits. Furthermore, due to the comparator threshold level selfadjustment, the readout circuit is less sensitive to component mismatch and process variations. The readout circuit is implemented using CMOS 0.35 µm technology with core area of 100 µm × 27 µm and power consumption of 52 µW, which can detect the touch panel capacitance ranging from 5 pF to 50 pF.

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A Multiplier-Free Noise Trapped Touch Algorithm for Low Cost 4x4 Matrix Panel Design

Wang

Sun

2013

Advances in Intelligent Systems and Applications - Volume 2

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Low noise capacitive sensor for multi-touch mobile handset's applications

Cited by 21 publications

References 4 publications

Self Capacitance Mismatch Calibration Technique for Fully-Differential Touch Screen Panel Self Capacitance Sensing System

Self Capacitance Mismatch Calibration Technique for Fully-Differential Touch Screen Panel Self Capacitance Sensing System

Touch sensor readout circuit with comparator threshold self-adjustment

A Multiplier-Free Noise Trapped Touch Algorithm for Low Cost 4x4 Matrix Panel Design

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