Synaptics Corporation

Standard Microsystems Corporation

Marshall J Bell, Jr

Eric Scott Bohannon

Jeffrey Alan Small

Jeffrey S Lillie

Yihong Yang

Stephen L Morein

Kirk Hargreaves

Thomas A Mackin

Murat Ozbas

John Childs

A method and related processing system and input device are disclosed, the method comprising driving a first capacitive sensing signal with first sensing frequency onto a first group of a plurality of sensor electrodes, and acquiring first capacitive measurements of resulting signals received by a second group of the plurality of sensor electrodes. Acquiring first capacitive measurements comprises applying a first demodulation signal with a predefined first mixing period defined within a sensing period associated with the first sensing frequency. The method further comprises driving a second capacitive sensing signal having a second sensing frequency different than the first sensing frequency onto a third group of the plurality of sensor electrodes, and acquiring second capacitive measurements of resulting signals received by a fourth group of the plurality of sensor electrodes. Acquiring second capacitive measurements comprises applying a second demodulation signal having a different predefined second mixing period.

Reduced capacitive baseline shift via mixing period adjustments

A processing system, and associated input device and method are disclosed suitable for reducing a receiver size within the input device. The processing system comprises a delta-sigma modulator comprising one or more input nodes configured to receive a signal based on a sensor signal received from at least a first sensor electrode of the plurality of sensor electrodes. The delta-sigma modulator further comprises an integrator coupled with the one or more input nodes and configured to produce an integration signal, a quantizer coupled with an output of the integrator and configured to quantize the integration signal, and a feedback digital-to-analog converter (DAC) controlled based by the quantizer. The processing system further comprises a digital filter coupled with an output of the delta-sigma modulator and configured to mitigate a quantization noise of the quantizer.

Input device receiver with delta-sigma modulator

Embodiments herein describe a user device that includes a dual purpose coil (or inductor) used when performing inductive sensing and when transferring electrical power to the user device. When performing inductive sensing, the user device couples the coil to a sensing circuit which measures a resistivity of a lossy material inductively coupled to the coil. In one embodiment, the user device may be worn on the wrist of the user so that the sensing circuit measures the resistivity corresponding to the flow of blood in an artery or vein. By monitoring changes in the resistivity of the blood or artery, the user device can identify the heartbeat of the user. When transferring electrical power, the user device couples the coil to a charging circuit which receives the power provided by an external charging device that is inductively coupled to the coil.

Inductive non-contact resistance measurement

Embodiments of the present invention generally provide a processing system for a display device having an integrated sensing device. The processing system includes a driver module that includes driver circuitry, the driver module coupled to source lines and sensor electrodes. Each sensor electrode including one or more common electrodes configured for display updating and input sensing. The driver module is configured to select a first display line for display updating during a first display update period, drive the sources lines with first display update signals during the first display update period to update the first display line, drive a first sensor electrode of the plurality of sensor electrodes for capacitive sensing during a non-display update period, and operate the source lines in a restore mode during a restart period, wherein the restart period is after the non-display update period and before a second display update period.

Reducing display artifacts after non-display update periods

The embodiments herein are generally directed to using a current-mode CBC circuit to maintain a voltage bias setting at a receiver when performing capacitive sensing. To do so, the CBC circuit may compensate for the change in voltage at a receiver by providing a current at the input of the receiver. Instead of using a passive CBC capacitor for each receiver, the input device may use a single CBC capacitor and a plurality of current mirrors to source and sink the current required to correct the input voltage at a plurality of receivers. As a result, the current-mode CBC circuit includes only one passive capacitor (or bank of capacitors) and a plurality of current mirrors which may provide space and cost benefits relative to a CBC circuit that uses a passive capacitor (or bank of capacitors) for each receiver channel.

Current-mode coarse-baseline-correction

A processing system for an input device includes a receiver module and a charge distributor. The receiver module includes a first charge integrator coupled to a first sensor electrode and configured to integrate a charge on the first sensor electrode. The charge distributor includes a current conveyor and a plurality of output stages coupled to the current conveyor, wherein a first output stage of the plurality of output stages comprises a plurality of current mirrors and is configured to output a first scaled mirrored charge to offset the charge integrated by the first charge integrator, wherein the first scaled mirrored charge is based on a charge signal provided via the current conveyor.

Charge distribution

Various embodiments enable driving one or more sub-pixels with a source voltage while concurrently modulating the voltage of one or more common electrodes coupled to the sub-pixels to perform input sensing with the common electrodes. The voltage driven onto the sub-pixel may be shifted while the common electrode is modulated by a value about equal to about the amplitude of the modulation applied to the common electrode. Thus, the potential difference between the source line and common electrode remains substantially unchanged so that display asperities are not introduced while input sensing while concurrently updating a sub-pixel with display information. Thus, the common electrode(s) may be modulated for input sensing without interfering with display updating of the one or more sub-pixels, greatly increasing the amount of time available for performing input sensing and/or display updating.

Source driver touch transmitter in parallel with display drive

Embodiments of the invention are generally directed to improving the slew rate of an amplifier as the amplifier charges or discharges a capacitive load. In one embodiment, the amplifier is coupled to a slew-enhancing circuit which uses a control signal from the amplifier to aid the amplifier when charging or discharging the load. For example, the control signal may be an internal voltage used by the amplifier to control circuit elements within the amplifier. By routing the control signal to the slew-enhancing circuit, the control signal biases the circuit elements within the slew-enhancing circuit to source a boost current when charging the capacitive load or sink the boost current when discharging the capacitive load.

Slew-enhanced operational transconductance amplifier

A charge distributor comprises a charge generator configured to output a charge, a current conveyor, and a plurality of output stages. The current conveyor is configured to receive the charge from the charge generator as an input and to couple this charge to a plurality of output stages. A first output stage, of the plurality of output stages, comprises a plurality of current mirrors. The plurality of current mirrors is configured to mirror and scale the charge received from the current conveyor into a scaled mirrored charge. The first output stage is configured to provide the scaled mirrored charge as an output.

A system and method for a fast stabilizing output buffer. A differential driver circuit is provided with an amplifier stage for receiving a differential input signal and generating a differential output based upon the input signal. The differential output has a corresponding common-mode (CM) voltage level typically based upon a value half of the power supply. A common-mode feedback buffer (CMFB) stage detects a change in the CM voltage level and recovers the CM voltage level to its desired value within a very fast settling time based upon a very high bus frequency. The CMFB stage utilizes a topology comprising only a single device. In one embodiment, this single device is a nmos transistor utilized as a transimpedance stage. Stability is provided by a circuit biasing stage and a shunting capacitor within the CMFB stage.

Growing community of inventors

Dripping Springs, TX, United States of America

Marshall J Bell, Jr