A Reconfigurable 40-to-67 dB SNR, 50-to-6400 Hz Frame-Rate, Column-Parallel Readout IC for Capacitive Touch-Screen Panels

Park, Jun-Eun; Lim, Dong-Hyuk; Jeong, Deog‐Kyoon

doi:10.1109/jssc.2014.2336800

Cited by 57 publications

(33 citation statements)

References 23 publications

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“…However, this kind of pseudo-differential architecture may not recognize some special touch events when only two adjacent cells are touched because these adjacent cell signals have the same level and they are not sensed differentially. Therefore, some recent works [3,4,6] inserted additional differential amplifiers between adjacent touch-cell pairs to cover the whole touch events as shown in Fig. 1(b).…”

Section: Architecturementioning

confidence: 99%

“…According to the touch-sensor location in the display panel, the TSPs are classified as add-on, on-cell, and in-cell [2]. As in-cell TSPs that embed touch sensors in the display glass become dominant [2], their thin form factor requirement severely increases display noise interference coupled from the display panel [3]. In addition, there exist various environmental noises such as battery-charger noise [4], fluorescent lamp noise and HUM noise [5].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, in order to improve the immunity to these display and environmental noises and also achieve better sensitivity, recent researches have tried to make the touch-sensing topology differential as much as possible and also adopt noise-avoiding techniques such as chopping method [2][3][4][5][6][7]. But most sensing structures are still pseudo-differential, which is mainly caused by the usage of single-ended charge amplifier and results in limited rejection of common-mode noises.…”

Section: Introductionmentioning

confidence: 99%

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

Kwon¹,

Kim²,

Bien³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

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Abstract-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.

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Section: Architecturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Kwon¹,

Kim²,

Bien³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

View full text Add to dashboard Cite

show abstract

“…This increased RC time constant limits the sampling rate, resulting in a decreased number of samples for a given time period. Moreover, in a larger-sized TSP, the total number of sensing channels increases, resulting in a reduced scan time allotted to each channel [6]. Consequently, the reduced scan time per channel limits the ability to perform multiple sampling, resulting in a deteriorated signal-to-noise ratio (SNR).…”

Section: Introductionmentioning

confidence: 99%

72 dB SNR, 240 Hz Frame Rate Readout IC With Differential Continuous-Mode Parallel Architecture for Larger Touch-Screen Panel Applications

Heo

Song

et al. 2016

IEEE Trans. Circuits Syst. I

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This paper presents a mutual capacitive touch screen panel (TSP) readout IC (ROIC) with a differential continuousmode parallel operation architecture (DCPA). The proposed architecture achieves a high product of signal-to-noise ratio (SNR) and frame rate, which is a requirement of ROIC for large-sized TSP. DCPA is accomplished by using the proposed differential sensing method with a parallel architecture in a continuousmode. This architecture is implemented using a continuous-type transmitter for parallel signaling and a differential-architecture receiver. A continuous-type differential charge amplifier removes the common-mode noise component, and reduces the self-noise by the band-pass filtering effect of the continuous-mode charge amplifier. In addition, the differential parallel architecture cancels the timing skew problem caused by the continuous-mode parallel operation and effectively enhances the power spectrum density of the signal. The proposed ROIC was fabricated using a 0.18-μm CMOS process and occupied an active area of 1.25 mm 2 . The proposed system achieved a 72 dB SNR and 240 Hz frame rate with a 32 channel TX by 10 channel RX mutual capacitive TSP. Moreover, the proposed differential-parallel architecture demonstrated higher immunity to lamp noise and display noise. The proposed system consumed 42.5 mW with a 3.3-V supply.Index Terms-Capacitor sensor, common-mode feedback, differential sensing, parallel operation, touch screen panel. 1549-8328

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“…Recently, the self-capacitive touch sensor has been applied to a gesture sensor [5], and a tradeoff between signal-to-noise ratio (SNR) and frame rate has been demonstrated with a mutual-capacitive touch sensor [6]. Mutual-capacitive touch sensors have also been developed for large displays [7].…”

Section: Introductionmentioning

confidence: 99%

An LCD-VCOM-Noise Resilient Mutual-Capacitive Touch-Sensor IC Chip With a Low-Voltage Driving Signal

et al. 2015

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A mutual-capacitive touch-sensor read-out integrated circuit (ROIC) with a differential sensing scheme is proposed to reduce the driving pulse amplitude of touch sensor panel (TSP) down to 0.4 V. This reduction is achieved by mitigating the effect of the liquid crystal display (LCD) commonvoltage (VCOM) noise, which is time periodic. To accomplish this mitigation, the TSP driving pulse (VSTM) is synchronized to the gate-driver-pulse generating signal (GCLK) of LCD, and its frequency is set to (2n + 1) times the frequency of GCLK, where n is a non-negative integer. The repetition period T N of the VCOM noise is one half of the GCLK period. A receiver channel consists of a charge amplifier, a chopper, and an integrator; all are in differential circuits. The chopper is driven by the VSTM. The integration period of the integrator is set to 2T N to suppress the periodic LCD noise. A referenceless clock and data recovery circuit are used to generate VSTM from GCLK continuously with time in spite of the discontinuity of GCLK during the vertical blanking period. The proposed ROIC fabricated in a 0.35-µm CMOS was applied to a 6.9 in 12 × 16 TSP located on a rather noisy 23 in in-plane switching LCD monitor. The measured signal-to-noise ratio changes from 27 to 9 dB as the VSTM amplitude changes from 3.3 to 0.4 V, where the GCLK frequency is 16.8 kHz and the VSTM frequency is 352.8 kHz. The reporting rate of the ROIC is 175 Hz.Index Terms-Capacitive touch sensor, referenceless CDR, time periodic noise, VCOM display noise.

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A Reconfigurable 40-to-67 dB SNR, 50-to-6400 Hz Frame-Rate, Column-Parallel Readout IC for Capacitive Touch-Screen Panels

Cited by 57 publications

References 23 publications

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

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

72 dB SNR, 240 Hz Frame Rate Readout IC With Differential Continuous-Mode Parallel Architecture for Larger Touch-Screen Panel Applications

An LCD-VCOM-Noise Resilient Mutual-Capacitive Touch-Sensor IC Chip With a Low-Voltage Driving Signal

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