Oversampled high signal to noise ratio analog front end for touch screen controllers

    公开(公告)号:US11294504B2

    公开(公告)日:2022-04-05

    申请号:US16704212

    申请日:2019-12-05

    Abstract: A touch screen controller includes an input stage configured to receive and condition a touch output from a touch matrix to produce a touch signal. An accumulation stage is configured to receive the touch signal and accumulate the touch signal to produce an accumulated output. The accumulated output is digitized by an analog to digital converter to produce a touch strength value. A given amount of charge is subtracted from or added to accumulated output during a next accumulation if the touch strength value is greater than an upper threshold or less than a lower threshold. This avoids saturation of components in the touch screen controller and therefore increases the signal to noise ratio.

    Parallel analysis of different sampling rates in a touch screen controller

    公开(公告)号:US11086448B2

    公开(公告)日:2021-08-10

    申请号:US15378188

    申请日:2016-12-14

    Abstract: A touch screen controller disclosed herein includes a circuit configured to generate a digital touch voltage comprises of samples, at a base sampling rate. The touch screen controller also includes a digital processing unit configured to analyze a first subset of samples of the digital touch voltage samples to determine noise content thereof, the first subset of samples corresponding to samples at a first investigated sampling rate that is a first function of the base sampling rate. The digital processing unit is also configured to analyze a second subset of samples of the digital touch voltage to determine noise content thereof, with the second subset of samples corresponding to samples at a second investigated sampling rate that is a second function of the base sampling rate, and determine a preferred sampling rate from among the first and second investigated sampling rates as a function of determined noise content thereof.

    Temperature stable oscillator
    14.
    发明授权

    公开(公告)号:US10742197B2

    公开(公告)日:2020-08-11

    申请号:US16200975

    申请日:2018-11-27

    Abstract: An oscillator circuit includes a first current generator circuit that generates a current complementary to absolute temperature and a second current generator that generates a current proportional to absolute temperature. A temperature slope control circuit adjusts slopes of the current complementary to absolute temperature and the current proportional to absolute temperature in a complementary fashion and adds the current complementary to absolute temperature to the current proportional to absolute temperature after slope control to produce a temperature independent current. A current control circuit adjusts magnitude of the temperature independent current to produce a magnitude adjusted temperature independent current. A current controlled oscillator generates an output signal as a function of the magnitude adjusted temperature independent current.

    Self-sensing touch panel
    15.
    发明授权

    公开(公告)号:US10585528B2

    公开(公告)日:2020-03-10

    申请号:US16014664

    申请日:2018-06-21

    Abstract: A method of differential self-capacitance measurement is used to enhance a signal-to-noise ratio of sense lines in a touch panel display, thereby improving touch sensor accuracy. The differential self-capacitance measurement is implemented for a touch panel using charge sharing between adjacent sense lines of the touch panel matrix. Sequential differential self-capacitance measurements can be compared with one another by computing the difference |CS1−CS2|−|CS2−CS1| to sense a change caused by an intervening event. By scanning the entire touch panel matrix, events can be tracked across the touch panel.

    Sampling frequency and accumulator sweeping in a touch screen controller

    公开(公告)号:US10191589B2

    公开(公告)日:2019-01-29

    申请号:US15235974

    申请日:2016-08-12

    Abstract: A circuit described herein includes a charge to voltage converter circuit having an input coupled to receive a sense signal from a sense node associated with a mutual capacitance to be sensed, and an output. A reset switch is coupled between the output of the charge to voltage converter circuit and the input of the charge to voltage converter. An accumulator circuit is configured to accumulate voltages at the output of the charge to voltage converter circuit and to generate an accumulator output signal. Control circuitry is configured to generate control signals for the reset switch and accumulator circuit so as to reduce noise in the accumulator output signal.

    CONCURRENT SENSING IN TOUCH SCREEN CONTROLLER WITH IMPROVED NOISE REJECTION

    公开(公告)号:US20180173365A1

    公开(公告)日:2018-06-21

    申请号:US15386291

    申请日:2016-12-21

    Abstract: Disclosed herein is an electronic device including a sensing layer including a plurality of sense lines, and a plurality of single ended charge converter circuits each receiving input from a corresponding one of the plurality of sense lines. The electronic device also includes a plurality of current mirror circuits, each respectively mirroring output from one of the plurality of single ended charge converter circuits so as to produce two substantially identical outputs for each of the plurality of single ended charge converter circuits. There may be a plurality of subtractor circuits coupled to the plurality of current mirror circuits, with each of the plurality of subtractor circuits configured to output a voltage that is a function of a difference between outputs from two of the plurality of current mirror circuits associated with adjacent ones of the sense lines.

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