Synaptics Corporation

Lsi Corporation

Integrated Device Technology, Inc.

Semiconductor Components Industries, LLC

Chunbo Liu

Guozhong Shen

Steve Chikin Lo

Zheming Li

Jonathan Ku

Mihai M Bulea

Zhijian Ma

Wenwei Yang

Jeong Yeol Choi

Gang Chen

Gabor Reizik

Selim E Guncer

Rafael Betancourt

Tae-Song Chung

Koji Kishi

Derek Solven

Ranga Seshu Paladugu

Osman Emir Erol

A sensing circuit configured to detect an input object proximate to a sensing region of an input device is provided. The sensing circuit includes an amplifier having an output and is configured to output a resulting signal. The sensing circuit also includes a plurality of mixers configured to receive the resulting signal from the output of the amplifier and to generate a plurality of output signals. At least one output signal is selected based on a comparison of a signal-to-noise ratio of each of the plurality of output signals with a noise threshold. The at least one output signal is selected according to criteria relative to the noise threshold. The input object is detected using the selected at least one output signal.

Multi-frequency simultaneous absolute capacitance touch sensing

A processing system including an amplifier configured to generate, from multiple spatial-common-mode-processed signals, a spatial common mode estimate and multiple feedback signals. The processing system includes multiple charge integrators configured to obtain resulting signals from the capacitive sensor electrodes, each of the resulting signals including a spatial common mode component and a residual noise component. The charge integrators generate multiple spatial-common-mode-processed signals by mitigating the spatial common mode component and the residual noise component in the resulting signals using the feedback signals. The processing system includes a programmable gain amplifier configured to determine the spatial common mode estimate.

Distributed analog display noise suppression circuit

A system and method for mitigating background capacitance and for mitigating the effect of temperature drift in compensation circuitry is provided. The system includes a plurality of sensor electrodes including a first sensor electrode and a second sensor electrode. The first sensor electrode is coupled to a first channel and the second sensor electrode is coupled to a second channel. The system includes a processing system configured to drive the plurality of sensor electrodes with a sensing signal; drive the first channel with a first compensation signal and the second channel with a second compensation signal; determine a first differential capacitance between the first channel and the second channel; drive the first channel with the second compensation signal and the second channel with the first compensation signal; determine a second differential capacitance between the first channel and the second channel; and mitigate temperature drift using the first differential capacitance and the second differential capacitance.

Capacitive sensor with temperature drift mitigation

An input device that includes multiple electrodes disposed in a sensing region of the input device and a sensing circuit coupled to a first electrode and configured to detect an input object proximate the sensing region. The sensing circuit includes an amplifier having an inverting input coupled to the first electrode, a non-inverting input coupled to a drive signal, and an output generating a resulting signal. The sensing circuit includes a feedback capacitor coupled between the output and the inverting input of the amplifier. The drive signal comprises a first sinusoidal signal having a first operating frequency and a second sinusoidal signal having a second operating frequency. The resulting signal is determined by the feedback capacitor and a capacitance of the first electrode caused by the input object. The resulting signal generates a sensing signal on the first electrode.

An input device includes transmitter electrodes disposed in a sensing region of the input device, a receiver electrode in the sensing region, and a processing system. The processing system includes demodulators, and is configured to simultaneously drive at least a subset of the transmitter electrodes using a multitude of transmitter signals with unique frequencies. The processing system is also configured to receive, on the receiver electrode, a resulting signal, and demodulate, using the plurality of demodulators, the resulting signal to generate a multitude, of sensing signals. Each of the of the demodulators operates on a different frequency of the unique frequencies.

Multi-frequency-region touch sensing

An input device comprising a set of electrodes configured to detect a user input of a user and a processing system is provided. The processing system comprises a signal level monitor configured to detect burst noise or impulse noise and one or more processors configured to: perform a scan step of a plurality of scan steps by driving one or more first transmitter electrodes of the plurality of transmitter electrodes with one or more sensing signals; obtain one or more first resulting signals corresponding to the one or more sensing signals used to drive the one or more first transmitter electrodes; detect, based on the one or more first resulting signals, the burst noise or the impulse noise corresponding to the scan step; and in response to detecting the burst noise or the impulse noise, restart the scan step.

System and method for mitigating impulse noise and burst noise in touch sensing

A method and apparatus of global coarse baseline correction (GCBC) for capacitive scanning. An input device may include a number (N) of sensor electrodes, a GCBC circuit, and detection circuitry. Each sensor electrode is associated with a respective channel. The GCBC circuit produces sensing signals in each of the N channels and the detection circuitry may detect changes in the capacitances of one or more sensor electrodes based on the sensing signals. In some implementations, the GCBC circuit may include a current source which outputs a first current, a transimpedance amplifier (TIA) which converts the first current to a sensing voltage, and a number (N) of resistors that can be coupled between the output of the TIA and the N sensor electrodes, respectively. The coupling of each resistor between the TIA and a respective sensor electrode produces a sensing signal in the channel associated with the sensor electrode.

Transimpedance amplifier (TIA)-based global coarse baseline correction (GCBC) for capacitive sensing

A processing system is disclosed. The processing system includes an amplifier including a multitude of input resistors receiving a multitude of reduced noise signals from a multitude of charge integrators and a summing resistor at an output of the amplifier. The amplifier is configured to generate a feedback signal at the output of the amplifier by amplifying each of a multitude of reduced noise signals using a gain value and a cardinality of the multitude of reduced noise signals. The multitude of charge integrators is configured to obtain a multitude of resulting signals from a multitude of capacitive sensor electrodes coupled to a noise source and generate the multitude of reduced noise signals by mitigating noise in the multitude of the resulting signals, at the multitude of charge integrators, using the feedback signal. Resistances of the multitude of input resistors, a resistance of the summing resistor, and the gain values are selected to mitigate the noise.

Noise suppression circuit

A processing system is disclosed. The processing system includes an amplifier configured to generate a feedback signal including a spatial common mode estimate from spatial-common-mode-processed signals. The processing system further includes charge integrators configured to obtain resulting signals from capacitive sensor electrodes, the resulting signals including a spatial common mode, and generate the spatial-common-mode-processed signals by mitigating the spatial common mode in the resulting signals using the feedback signal. The processing system also includes a controller including a programmable gain amplifier capturing the spatial common mode estimate over a summing resistor of the amplifier and a demodulator configured to remove a modulation voltage from the spatial common mode estimate.

Common mode noise suppression with restoration of common mode signal

A processing system and method are provided. The processing system includes a sensor circuit that drives, during a first sensing period, a first plurality of sensor electrodes with first sensing signals, receives first resulting signals from the first plurality of sensor electrodes, and mixes the first resulting signals with a first mixer signal to generate a first mixed signal, wherein the first mixer signal has a first phase and the first mixed signal corresponds to at least a portion of a capacitive image. The processing system also includes a noise measurement circuit that receives second resulting signals from a second plurality of sensor electrodes, and mixes the second resulting signals with a second mixer signal to generate a second mixed signal, wherein the second mixer signal has a second phase and the second mixed signal corresponds to a first noise measurement.

Sensing device with embedded noise measurement

A processing system is disclosed. The processing system includes an amplifier configured to generate a feedback signal, including a spatial common mode estimate generated from spatial-common-mode-processed signals. The processing system further includes charge integrators configured to obtain resulting signals from capacitive sensor electrodes, the resulting signals including a spatial common mode. The charge integrators generate the spatial-common-mode-processed signals by mitigating the spatial common mode in the resulting signals using the feedback signal. The processing system also includes a controller configured to obtain digital touch signals by analog-to-digital converting the spatial-common-mode-processed signals, obtain a digital spatial common mode estimate by analog-to-digital converting the spatial common mode estimate, and obtain at least one digital resulting signal by combining at least one of the digital touch signals with the digital spatial common mode estimate.

A processing system is disclosed. The processing system includes an amplifier configured to generate a feedback signal by amplifying each of multiple reduced noise signals based on a gain value and a cardinality of the reduced noise signals. The processing system also includes multiple charge integrators configured to obtain resulting signals from capacitive sensor electrodes coupled to a noise source and generate the reduced noise signals by mitigating noise in the resulting signals using the feedback signal.

A global coarse baseline correction charge injection circuit comprises: an output capacitor, a slew rate control circuit, a current generator, a first current mirror, and a second current mirror. The output capacitor is configured to store a global coarse baseline correction charge. The slew rate control circuit is configured to receive a modulated voltage, a positive input current, and a negative input current as inputs, and provide a proportional-to-supply-voltage slew-rate controlled voltage as an output voltage to charge the output capacitor. The current generator is configured to receive a supply voltage as an input and provide a proportional-to-supply-voltage (PTSV) current as an output. The first current mirror is configured to mirror the PTSV current to the slew rate control circuit as the positive input current. The second current mirror is configured to mirror the PTSV current to the slew rate control circuit as the negative input current.

Global coarse baseline correction charge injection

Embodiments herein provide input devices that include a display panel on which a discrete capacitive sensor is disposed to form a capacitive sensing region. The capacitive sensor includes a plurality of sensor electrodes that are used to generate capacitive sensing signals indicating user interaction with the input device. Moreover, the input device includes analog interference detection circuitry for mitigating the negative impact of display noise on capacitive sensing. In one embodiment, the input device includes a reference circuit which is capacitively coupled to a display noise source and outputs a reference voltage that biases a charge integrator in a receiver channel used for capacitive sensing. In another embodiment, the input device includes a current conveyor coupled to an idle transmitter electrode of the sensor electrodes which outputs a correction current to a receiver channel to cancel a display noise current injected into the receiver channel.

Growing community of inventors

San Jose, CA, United States of America

Chunbo Liu