Maxim Integrated Products, Inc.

Qualcomm Incorporated

Qualcomm Technologies, Inc.

Patrick Yin Chan

Ashutosh Ravindra Joharapurkar

Natarajan Viswanathan

Jean CauXuan Le

Rudolph Yeung

Martin T Mason

Arman Hematy

David L Allen

Pierre Haubursin

Yusuf A Haque

David Castaneda

Yuanfang Li

Karthikeya Kodur

Venugopal Reddy

A differential sensing scheme provides a means for detecting one or more touch events on a touch sensitive device in the presence of incident noise. Instead of sensing one touch sensitive channel, such as a row, column, or single touch sensor, multiple touch sensitive channels are sampled at a time. By sampling two nearby channels simultaneously and doing the measurement differentially, noise common to both channels is cancelled. The differential sensing scheme is implemented using simple switch-capacitor AFE circuitry. The originally sensed data on each individual channel is recovered free of common-mode noise. The recovered sensed data is used to determine the presence of one or more touch events and if present the location of each touch event on the touch sensitive device.

Noise cancellation technique for capacitive touchscreen controller using differential sensing

Techniques are described for providing highly integrated and configurable IO ports for integrated circuits that can be individually configured for a variety of general purpose digital or analog functions, such as multiple channel analog-to-digital converters (ADC), multiple channel digital-to-analog converters (DAC), multiplexers, GPIOs, analog switches, switch and multiplexers, digital logic level translators, comparators, temperature sensors and relays, and so forth. The configurations of individual ports can be set by a configuration register that can, for instance, designate the function and voltage range of the port without impacting the other ports. In embodiments, logic mapping of a port order sequence can be defined. A data register can also be included for handling microcontroller commands and storing conversion results from, for instance, a port functioning as an ADC input port. These capabilities can be combined with its multi-range, high voltage and high current capability to increase functionality.

Programmable mixed-signal input/output (IO)

Random sampling techniques include techniques for reducing or eliminating errors in the output of capacitive sensor arrays such as touch panels. The channels of the touch panel are periodically sampled to determine the presence of one or more touch events. Each channel is individually sampled in a round robin fashion, referred to as a sampling cycle. During each sampling cycle, all channels are sampled once. Multiple sampling cycles are performed such that each channel is sampled multiple times. Random sampling techniques are used to sample each of the channels. One random sampling technique randomizes a starting channel in each sampling cycle. Another random sampling technique randomizes the selection of all channels in each sampling cycle. Yet another random sampling technique randomizes the sampling cycle delay period between each sampling cycle. Still another random sampling technique randomizes the channel delay period between sampling each channel.

Use of random sampling technique to reduce finger-coupled noise

A system includes a sub-binary radix digital-to-analog converter (DAC) that converts a digital input signal to an analog output signal based on a sub-radix DAC code. A radix conversion module performs radix conversion on the digital input signal. To perform the radix conversion, the radix conversion module associates bit positions corresponding to the digital input signal with respective analog weights and converts the digital input signal to the sub-radix DAC code based on the respective analog weights.

Precision sub-RADIX2 DAC with analog weight based calibration

A touchscreen system for increasing the dynamic range of the system comprising a touchscreen coupled to an offset cancellation element and a capacitance measuring element. The offset cancellation element is configured to be dynamically changed in capacitance such that it offsets parasitic and sensor capacitances of the touchscreen sensors thereby leaving only touch event capacitance to be measured by the measuring element. The offset cancellation element is able to adjust to the initial unwanted capacitances of each sensor as well as dynamically adjust to changes in the unwanted capacitance due to the environment. In some embodiments, the offset cancellation element is a capacitance digital-to-analog converter that is controlled by a controller for offsetting the unwanted capacitance. As a result, the touchscreen system is able to utilize a small integrating capacitor thereby lowering cost and improving the dynamic range of the system.

Method and apparatus for improving dynamic range of a touchscreen controller

An apparatus to pre-condition an operating integrated circuit (IC) device in a static low power retention state. The apparatus includes a pseudo random number generator that generates a pseudo random number value to pre-condition the static low power retention state of the operating IC device. The apparatus also includes a controller that drives the pseudo random number value into a test scan chain linking logic elements of the operating IC device responsive to the operating IC device entering a sleep mode. Driving the pseudo random number value into the test scan chain by the controller places the operating IC device into the static low power retention state.

Method and circuit to implement a static low power retention state

An integrated circuit is disclosed including one or more communication devices, an operational controller configured by a state device in a normal mode for the communication device, which may consume more power than in a low power mode. The operational controller retains an operational state in a normal mode for the communication device that may be corrupted during low power mode. A save-restore processor operates a configuration bus and an essentially non-volatile memory at the start a low power mode to retain the operational state and end of the low power mode to restore the operational state.

Saving and restoring states through low power mode

A touchscreen controller system determines the actual locations of multiple simultaneous touches by eliminating mutual capacitance between adjacent rows and columns during self-capacitance measurements and selectively enabling mutual capacitance during mutual capacitance measurements. During the self-capacitance measurements, the controller system generates a set of candidate touch locations, which includes the locations of real and ghost touches. During the mutual capacitance measurements, only the locations in the candidate set are measured and, from these measurements, the actual touch locations are determined. By limiting the mutual capacitive measurements to only a small subset of the locations over the entire touch panel, real touch locations are determined on a linear order. Also, by using on-chip integration capacitors, embodiments of the invention are able to perform each measurement in a single cycle.

System for and method of transferring charge to convert capacitance to voltage for touchscreen controllers

An apparatus is disclosed that may include an integrated circuit (IC) with an initialization bus configured to communicate with at least one low power mode latch operating during a initialization mode to set a value into the low power mode latch and configured to respond to the assertion of a low power mode signal by selecting the low power mode latch state to drive at least one logic gate to minimize leakage current during the low power mode. The IC may similarly configure and operate a RAM. A leakage control table may be used during initialization mode and created by other embodiments. The net list of a circuit block including at least part of the configuration block and lower power control latch may be used and/or modified to create a new net list to further minimize leakage current during low power mode. Installation packages and program systems are disclosed.

Reducing leakage current during low power mode

A power level sense circuit which is substantially immune to variations in integrated circuit processing and operating temperature. The sense circuit uses a diode biased to a predetermined average conduction level as the primary element in an envelope detector to detect the envelope of the RF transmit signal. While the DC offset of the diode will vary with temperature and integrated circuit processing, the DC offset is eliminated by an auto zeroing procedure before each power sensing cycle.

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Sunnyvale, CA, United States of America

Patrick Yin Chan