A 15nW Per Button Noise-Immune Readout IC for Capacitive Touch Sensor

Hussaini, Said; Jiang, Hui; Walsh, P.S.; MacSweeney, D.; Makinwa, Kofi A. A.

doi:10.1109/esscirc.2018.8494283

Cited by 3 publications

(5 citation statements)

References 4 publications

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“…Tc and Tcp are high-voltage cycles with and without touch, respectively. This time is represented by the count of timer inside the MCU [16], and its relationship is shown in (13). Using the Count corresponding to th C of each electrode as the threshold, while maintaining consistency in other circuit parameters, connect the 6 electrodes to the recognition circuit in sequence.…”

Section: Evaluation Methods Validation Experimentsmentioning

confidence: 99%

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A Simulation and Evaluation Method to Estimate the Capacitive Effect on Electrode of Touch Sensors

Wen,

Chen,

Wan

2024

IEEE Access

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Touch sensors are ubiquitous in daily life. As a type of touch sensor, touch buttons now face the diverse design requirements for electrode patterns. There is no method for evaluating the rationality of electrode shape during the electrode design phase. At this stage, developers typically design electrode shapes based on experience. And in the subsequent stages, multiple electrodes of different shapes will be made for testing and evaluation, and the electrode with the best effect will be selected. Due to the diversity and uncertainty of electrode shape design, this process will consume a lot of time, manpower, and material resources. There are numerous studies on simulation method of touch panels and touch screens, but due to differences in electrode structures, it is difficult to apply their results to evaluate surface sensing touch buttons. Therefore, it is meaningful to study the influence of electrode shape on sensing ability of touch buttons and find a simulation and evaluation method to guide electrode design. This research proposes a new statistical calculation method for touch mutual capacitance based on the finite element method (FEM). Subsequently, calculate the new mutual capacitance matrix within the recognition region based on the boundary conditions. Next, evaluation indicators and calculation methods are proposed based on the difference between the ideal recognition area and the simulation results. Finally, a series of experiments are designed and an experimental platform is developed to verify the simulation results.

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Section: Evaluation Methods Validation Experimentsmentioning

confidence: 99%

“…The result shows that in the control group with reduced size, except for electrode No.7, all other electrodes don't experience mistaken triggering, and the evaluation values E are consistent with the touch counts. On the other hand, the control group with increased size shows varying degrees of mistaken touch phenomenon except for electrodes No 16. and No.18.…”

mentioning

confidence: 94%

A Simulation and Evaluation Method to Estimate the Capacitive Effect on Electrode of Touch Sensors

Wen,

Chen,

Wan

2024

IEEE Access

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“…The energy requirements of the solutions suggested by various manufacturers vary. Hussaini et al, (2017) [49] report values between 3.961 µW and 0.6910 µW per button for various MCUs scanning at 8 Hz.…”

Section: Touch Detectionmentioning

confidence: 99%

“…Hussaini et al [49] proposed a very low-power architecture for capacitive sensing that requires only 0.015 µW per button. Among others, that architecture uses a relaxation oscillator to reduce the requirements of scanning, with the assumption that a very accurate clock is not needed.…”

Section: Touch Detectionmentioning

confidence: 99%

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

Meli

Favre

Maij

et al. 2023

JLPEA

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Harvesting energy for IoT nodes in places that are permanently poorly lit is important, as many such places exist in buildings and other locations. The need for energy-autonomous devices working in such environments has so far received little attention. This work reports the design and test results of an energy-autonomous sensor node powered solely by solar cells. The system can cold-start and run in low light conditions (in this case 20 lux and below, using white LEDs as light sources). Four solar cells of 1 cm2 each are used, yielding a total active surface of 4 cm2. The system includes a capacitive sensor that acts as a touch detector, a crystal-accurate real-time clock (RTC), and a Cortex-M3-compatible microcontroller integrating a Bluetooth Low Energy radio (BLE) and the necessary stack for communication. A capacitor of 100 μF is used as energy storage. A low-power comparator monitors the level of the energy storage and powers up the system. The combination of the RTC and touch sensor enables the MCU load to be powered up periodically or using an asynchronous user touch activity. First tests have shown that the system can perform the basic work of cold-starting, sensing, and transmitting frames at +0 dBm, at illuminances as low as 5 lux. Harvesting starts earlier, meaning that the potential for full function below 5 lux is present. The system has also been tested with other light sources. The comparator is a test chip developed for energy harvesting. Other elements are off-the-shelf components. The use of commercially available devices, the reduced number of parts, and the absence of complex storage elements enable a small node to be built in the future, for use in constantly or intermittently poorly lit places.

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“…However, compared to the conventional SAR algorithm, the required logic is significantly more complex. This paper presents a stand-alone readout IC [21] that consists of an asynchronous tracking CDC, whose power consumption depends on touch activity, and which is periodically triggered by a nano-power timer. The CDC employs a differential architecture, which confers considerable robustness to common mode interference and human finger noise, i.e.…”

Section: Introductionmentioning

confidence: 99%

A 15-nW per Sensor Interference-Immune Readout IC for Capacitive Touch Sensors

Hussaini

Jiang

Walsh³

et al. 2019

IEEE J. Solid-State Circuits

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This paper presents a readout IC that uses an asynchronous capacitance-to-digital-converter (CDC) to digitize the capacitance of a touch sensor. A power-efficient tracking algorithm ensures that the CDC consumes negligible power consumption in the absence of touch events. To facilitate its use in wake-on-touch applications, the CDC can be periodically triggered by a co-integrated ultra-low power relaxation oscillator. At a 38 Hz scan-rate, the readout IC consumes 15 nW per touch sensor, which is the lowest reported to date.

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A 15nW Per Button Noise-Immune Readout IC for Capacitive Touch Sensor

Cited by 3 publications

References 4 publications

A Simulation and Evaluation Method to Estimate the Capacitive Effect on Electrode of Touch Sensors

A Simulation and Evaluation Method to Estimate the Capacitive Effect on Electrode of Touch Sensors

Energy Autonomous Wireless Sensing Node Working at 5 Lux from a 4 cm2 Solar Cell

A 15-nW per Sensor Interference-Immune Readout IC for Capacitive Touch Sensors

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