12.5 2D Coded-aperture-based ultra-compact capacitive touch-screen controller with 40 reconfigurable channels

Jang, Hanhwi; Shin, Hyungcheol; Ko, Sangjin; Yun, Ilhyun; Lee, Kwyro

doi:10.1109/isscc.2014.6757407

Cited by 25 publications

(7 citation statements)

References 4 publications

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“…Orthogonal frequency division multiplexing (OFDM) can be applied because the frequencies used for driving may interfere with each other [ 33 ]. For code-division multiple sensing similar to CDMA, orthogonal signals are applied to each TX line, and the output value for each sensor is separated through post-processing calculations [ 34 , 35 ]. Figure 19 b shows an example using the 4 × 4 matrix Walsh–Hadamard matrix.…”

Section: Technical Issues Of the Capacitive Sensor Readout Systemmentioning

confidence: 99%

Readout Circuits for Capacitive Sensors

Yoo

Choi

2021

Micromachines

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The development of microelectromechanical system (MEMS) processes enables the integration of capacitive sensors into silicon integrated circuits. These sensors have been gaining considerable attention as a solution for mobile and internet of things (IoT) devices because of their low power consumption. In this study, we introduce the operating principle of representative capacitive sensors and discuss the major technical challenges, solutions, and future tasks for a capacitive readout system. The signal-to-noise ratio (SNR) is the most important performance parameter for a sensor system that measures changes in physical quantities; in addition, power consumption is another important factor because of the characteristics of mobile and IoT devices. Signal power degradation and noise, which degrade the SNR in the sensor readout system, are analyzed; circuit design approaches for degradation prevention are discussed. Further, we discuss the previous efforts and existing studies that focus on low power consumption. We present detailed circuit techniques and illustrate their effectiveness in suppressing signal power degradation and achieving lower noise levels via application to a design example of an actual MEMS microphone readout system.

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Section: Technical Issues Of the Capacitive Sensor Readout Systemmentioning

confidence: 99%

Readout Circuits for Capacitive Sensors

Yoo

Choi

2021

Micromachines

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“…Hence in the modified , the first column is omitted and the remaining well balanced columns are only used in an actual driving pattern; the RX incoming charge through static components (offset) of s are autonomously canceled out by the balanced characteristic of the modified . Because only the dynamic components of s are sensed, an additional offset charge canceling scheme [12] is not required to enhance dynamic range of the sensor.…”

Section: A Multi-tx Schemementioning

confidence: 99%

A Pen-Pressure-Sensitive Capacitive Touch System Using Electrically Coupled Resonance Pen

Park

Kim

Park

et al. 2016

IEEE J. Solid-State Circuits

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A touch system sensing pen-pressure of the proposed electrically coupled resonance (ECR) pen is implemented, which can replace costly digitizer system containing electro magnetic resonance (EMR) and capacitive touch system. The proposed system detects the location of the ECR pen and finger using proposed position sensor, and senses pen-pressure of ECR pen using proposed pen-pressure sensor. For the position sensor, to detect even small variation of the mutual capacitance on touch screen panel (TSP) of the pen, a simultaneous driving scheme is proposed with modified Hadamard matrix, resulting in highly increased dynamic range and SNR. In the proposed pen-pressure sensor, the resonant frequency of the ECR pen is measured by a frequency to voltage converter based sensor. The measured SNR for the pen position is 49 dB with 1 mm metal pillar, and 6.5-bit resolution is achieved for pen-pressure sensor in criteria.

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“…However, this separation also reduces the signal component of the ROIC output. In [11] and [12], the ROIC applies digital signals encoded with a code division multiple access (CDMA) to multiple lines of the TSP to reduce noise; this approach requires large digital circuitry for CDMA decoding.…”

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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12.5 2D Coded-aperture-based ultra-compact capacitive touch-screen controller with 40 reconfigurable channels

Cited by 25 publications

References 4 publications

Readout Circuits for Capacitive Sensors

Readout Circuits for Capacitive Sensors

A Pen-Pressure-Sensitive Capacitive Touch System Using Electrically Coupled Resonance Pen

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

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