Pseudoinverse-based noise equalization

Abstract

The method includes obtaining a first single-ended measurement signal and a second single-ended measurement signal, and generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal and the second single-ended measurement signal.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit under 35 U.S.C. §119(e) of the priority date of U.S. Provisional Patent Application No. 63 / 381,718, entitled "EQUALIZED RECONSTRUCTION," filed October 31, 2022, the contents and disclosure of which are incorporated herein by reference in their entirety.

[0002] FIELD OF THE INVENTION One or more embodiments relate to differential signaling systems and differential measurement systems. One or more embodiments relate to noise equalization and noise equalization in differential and mutual capacitance measurement systems. [Background technology]

[0003] Differential signaling is utilized in a variety of operating situations. To easily identify the discussion of any particular element or function, the most significant digit(s) of a reference number refers to the figure number in which that element is first introduced. [Brief explanation of the drawings]

[0004] [Figure 1] 1 is a block diagram depicting an apparatus for equalizing a measurement signal generated by a differential measurement system using pseudoinverse matrix-based equalization, in accordance with one or more embodiments. [Figure 2] 1 is a block diagram of an apparatus for equalization of a measurement signal generated by a differential measurement system, according to one or more embodiments. [Figure 3] 1 is a block diagram of an apparatus for equalization of a measurement signal generated by a differential measurement system, according to one or more embodiments. [Figure 4] FIG. 1 is a block diagram depicting a system representing a portion of a differential measurement system that provides first and second single-ended measurement signals for pseudoinverse-based noise equalization, in accordance with one or more embodiments. [Figure 5]1 illustrates an exemplary process for equalizing a measurement signal generated by a differential measurement system using pseudoinverse matrix-based equalization, in accordance with one or more embodiments. [Figure 6] 1 illustrates an example process for generating a predetermined pseudo-inverse channel matrix, according to one or more embodiments. [Figure 7] 1 illustrates an example process for generating an equalized measurement signal based at least in part on a first single-ended measurement signal and a second single-ended measurement signal, according to one or more embodiments. [Figure 8] 1 illustrates an example process for generating an equalized measurement signal based at least in part on a first single-ended measurement signal and a second single-ended measurement signal, according to one or more embodiments. [Figure 9] 1 illustrates an exemplary process for equalizing a single-ended measurement signal using pseudo-inverse matrix-based noise equalization, according to one or more embodiments. [Figure 10] FIG. 1 is a schematic block diagram depicting a system including pseudo-inverse matrix-based mode conversion for generating a differential measurement signal, according to one or more embodiments. [Figure 11] FIG. 1 is a block diagram of a lens bending filter according to one or more embodiments. [Figure 12] FIG. 1 is a schematic block diagram depicting portions of a touch display system utilizing pseudoinverse-based noise equalization, according to one or more embodiments. [Figure 13] 10A-10C are graphs depicting the delta (Δ) signal, the reconstructed signal, the scaled reconstructed signal, and the boosted touch signal in several different touch scenarios in a mutual capacitance measurement system in accordance with one or more embodiments. [Figure 14] 10A-10C are graphs depicting the delta (Δ) signal, the reconstructed signal, the scaled reconstructed signal, and the boosted touch signal in several different touch scenarios in a mutual capacitance measurement system in accordance with one or more embodiments. [Figure 15]10A-10C are graphs depicting the delta (Δ) signal, the reconstructed signal, the scaled reconstructed signal, and the boosted touch signal in several different touch scenarios in a mutual capacitance measurement system in accordance with one or more embodiments. [Figure 16] 10A-10C are graphs depicting the delta (Δ) signal, the reconstructed signal, the scaled reconstructed signal, and the boosted touch signal in several different touch scenarios in a mutual capacitance measurement system in accordance with one or more embodiments. [Figure 17] In some examples, block diagrams of circuitry that may be used to implement various functions, operations, acts, processes, or methods disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0005] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific examples in which the present disclosure may be practiced. These examples are described in sufficient detail to enable those skilled in the art to practice the present disclosure. However, other examples may be utilized, and changes in structure, materials, and processes may be made without departing from the scope of the present disclosure.

[0006] The illustrative diagrams presented herein are not meant to be actual illustrations of any particular method, system, device, or structure, but are merely idealized representations used to explain embodiments of the present disclosure. The drawings presented herein are not necessarily drawn to scale. Similar structures or components in various drawings may retain the same or similar numbering for the convenience of the reader. However, similarity in numbering does not necessarily mean that the structures or components are identical in size, composition, configuration, or any other characteristic.

[0007] The following description may include examples to aid in enabling those skilled in the art to practice the disclosed embodiments. The use of the terms "exemplary," "example," and "for example" means that the associated description is illustrative, and the scope of the disclosure is intended to encompass examples and legal equivalents. The use of such terms is not intended to limit the examples or the scope of the disclosure to the specified components, steps, features, functions, etc.

[0008] It will be readily understood that the components of the examples, as generally described herein and illustrated in the figures, could be arranged and designed in a wide variety of different configurations. Thus, the following description of various examples is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While various aspects of the examples may be presented in figures, the figures are not necessarily drawn to scale unless specifically indicated.

[0009] Furthermore, the specific implementations shown and described are merely examples and should not be construed as the only way to implement the present disclosure, unless otherwise specified herein. Elements, circuits, and functions may be shown in block diagram form so as not to obscure the present disclosure in unnecessary detail. Conversely, the specific implementations shown and described are merely exemplary and should not be construed as the only way to implement the present disclosure, unless otherwise specified herein. In addition, the block definitions and partitioning of logic between various blocks are illustrative of specific implementations. It will be readily apparent to one skilled in the art that the present disclosure can be implemented with numerous other partitioning solutions. For the most part, details regarding timing considerations and the like have been omitted; such details are not necessary to obtain a complete understanding of the present disclosure and are within the capabilities of those skilled in the art.

[0010] Those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. Some figures may show a signal as a single signal for clarity of presentation and explanation. Those skilled in the art will understand that a signal may represent a bus of signals, which may have various bit widths, and that the present disclosure may be implemented with any number of data signals, including a single data signal.

[0011] The various illustrative logic blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed using a general-purpose processor, a special-purpose processor, a digital signal processor (DSP), an integrated circuit (IC), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor (also referred to herein as a host processor or simply a host) may be a microprocessor, although the processor may alternatively be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. A general-purpose computer including a processor is considered a special-purpose computer, and the general-purpose computer executes computing instructions (e.g., software code) associated with the embodiments of the present disclosure.

[0012] The embodiments may be described in terms of a process that is depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. While a flowchart may describe operational acts as a sequential process, many of these acts may occur in another sequence, in parallel, or substantially simultaneously. Additionally, the order of acts may be rearranged. A process may correspond to, but is not limited to, a method, a thread, a function, a procedure, a subroutine, or a subprogram. Further, methods disclosed herein may be implemented in hardware, software, or both. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another.

[0013] Any reference to elements herein using designations such as "first," "second," etc. does not limit the quantity or order of those elements unless such limitation is expressly stated. Rather, these designations may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, reference to a first element and a second element does not imply that only two elements may be used or that the first element must precede the second element in any manner. Additionally, unless otherwise specified, a set of elements may include one or more elements.

[0014] As used herein, the term "substantially" when referring to a given parameter, characteristic, or condition means and includes the extent to which one of ordinary skill in the art would understand that the given parameter, characteristic, or condition is met with slight variations, such as, for example, within acceptable manufacturing tolerances. As an example, depending on the particular parameter, characteristic, or condition that is substantially met, the parameter, characteristic, or condition may be at least 90% met, at least 95% met, or even at least 99% met.

[0015] As used herein, any relative terms such as, but not limited to, "over," "under," "on," "underlying," "upper," "lower," etc., are used for clarity and convenience in understanding this disclosure and the accompanying drawings, and do not imply or rely on any particular preference, orientation, or order unless the context clearly dictates otherwise.

[0016] In this description, the term "coupled" and its derivatives may be used to indicate that two elements cooperate or interact with each other. When an element is described as "coupled" to another element, the elements may be in direct physical or electrical contact, or there may be intervening elements or layers present. In contrast, when an element is described as "directly coupled" to another element, there are no intervening elements or layers present. The term "connected" may be used interchangeably with the term "coupled" herein and have the same meaning unless expressly stated otherwise or the context indicates otherwise to one of ordinary skill in the art.

[0017] As used herein, the terms "assert," "de-assert," and their derivatives, when used in reference to a pin, mean to respectively assert or de-assert a signal associated with the pin (e.g., without limitation, a signal specifically assigned to the pin or a signal to which the pin is specifically assigned).

[0018] <Background of Differential Signals> A differential signal represents information by utilizing the difference between a pair of signals carried on different physical conductors (for example, but not limited to, electrical conductors). Such signals used to represent a differential signal are called a "differential pair."

[0019] Differential signals and signaling are contrasted with single-ended signals and signaling, in which a single signal, typically referenced to ground (a "single-ended signal"), uses the amplitude of the signal (relative to ground) to represent information, at least in part. A single conductor may carry a single-ended signal.

[0020] Differential signals are sometimes referred to as "balanced" signals because the design of the differential signaling system requires that any noise affecting one of the signals in the differential pair should be substantially (e.g., without limitation, mostly) reflected to the other signal in the differential pair. Single-ended signals are sometimes referred to as "unbalanced" signals because noise affecting the signal is not necessarily reflected to ground.

[0021] Differential signaling systems can offer various advantages, including noise rejection: noise induced equally on both of the lines carrying the differential pair (also called "common-mode noise") can be rejected (e.g., without limitation, canceled) because the information is represented by the difference between the two signals of the differential pair, and not by the absolute value of either signal itself.

[0022] Differential mode noise is noise that affects the lines carrying a differential pair unevenly. Differential mode noise can have the same or different sources as common mode noise. Differential mode noise can affect the difference between two signals and therefore disrupt how information is represented by the differential pair, and can generally affect the information carried by a differential signaling system.

[0023] Mode conversion is the process of generating a differential signal based at least in part on a single-ended signal. Mode conversion may include converting differential-mode noise to common-mode noise, or suppressing differential-mode noise while enhancing or preserving common-mode noise. A differential pair generated through mode conversion may appear to be substantially (e.g., without limitation, nearly) balanced.

[0024] A non-limiting example source of differential-mode noise in a differential pair is channel effects. Channel effects are any disturbances, distortions, or alterations experienced by a signal as it traverses a communication channel. The channel can be a physical medium such as a wire, cable, twisted pair, electrical circuit, wireless medium, or a combination thereof. Non-limiting examples of channel effects include attenuation, dispersion, reflections (due to impedance mismatch), or crosstalk. If the two lines of a differential pair have different physical properties or lengths, they may attenuate noise differently, resulting in imbalance and differential-mode noise. Differential-mode noise can be caused when one line of a differential pair picks up interference from a neighboring channel and the other line of the differential pair does not or picks it up in a different way. Impedance mismatches within the channel can cause reflections. If such reflections affect the lines of the differential pair unevenly, they can cause differential-mode noise.

[0025] Additionally or alternatively, channel effects may be caused by physical asymmetries between the physical media (e.g., but not limited to, conductors) carrying the differential pair. Any physical asymmetry, such as different line lengths, widths, or distances to noise sources, can result in channel effects, including, but not limited to, differential mode noise, as a non-limiting example, when one line picks up more (or different) noise than the other line.

[0026] Equalization is the process of reducing channel effects, including differential-mode noise, if present, in a signal received over a channel. In a differential signaling system, equalization may be performed on one or both signals of a differential pair to reduce the channel effects. One example of an approach for equalization is to model the channel (more specifically, the channel effects of the channel) as a matrix of values, functions, or both (the "channel matrix") and use the inverse of the channel matrix (the "inverse channel matrix") to determine a noise equalizer for reducing the channel effects present in the signal. When a signal is represented as a matrix, matrix multiplication of the signal matrix by the inverse channel matrix cancels (e.g., without limitation, reduces) the channel effects described in and represented in the channel matrix.

[0027] Inverting the channel matrix exactly may not be practical or even possible. Alternatively, a "best fit" inverse channel matrix, called a "pseudo-inverse channel matrix" or simply a "pseudo-inverse matrix," may be used. The pseudo-inverse channel matrix (sometimes denoted with a superscript "+") may be used, as a non-limiting example, to determine a noise equalizer that reduces the mean square error between the equalized signal (the output of the noise equalizer) and the target differential signal.

[0028] <Background of the differential measurement system> In a differential measurement system, measurement information (target signal) is represented by the difference between pairs of signals, i.e., "differential measurement pairs." At least a portion of a differential measurement system may be intended to be a differential signaling system. As a non-limiting example, in a mutual capacitance measurement system, the determined capacitance is the capacitance between one or more pairs of adjacent electrodes. Each line (e.g., without limitation, a conductor) of the adjacent electrodes carries a signal generated in response to a predetermined mutual capacitance measurement process. Such carried signals on the lines of the adjacent electrodes are a differential pair. The lines of the adjacent electrodes, individually or together, may be considered as channels for carrying differential signals.

[0029] The channels carrying each signal of the differential measurement pair may be subject to channel effects. As a non-limiting example, the conductors carrying each signal of the differential measurement pair may have physical asymmetries. Such physical asymmetries may be for convenience (e.g., without limitation, to physically accommodate specific operating conditions) or may be unintentional. In one non-limiting example of such physical asymmetries, the number of nodes per line may vary across the touch sensor. Measurement information in the measurement signal, or a target signal included in the measurement signal, may be reduced by such channel effects.

[0030] One or more embodiments generally relate to equalizing a measurement signal using a pseudo-inverse matrix-based noise equalizer.

[0031] In one or more embodiments, the measurement signal may be a differential measurement signal. In one or more embodiments, the measurement signal may be a differentially derived single-ended signal, i.e., a single-ended measurement signal including differential measurement information derived from (e.g., without limitation, based at least in part on) or representable by a differential measurement signal. If the noise is unbalanced (unequal), or, for example, if differential-mode noise is present in one or both of the signals utilized to form the differential measurement signal, common noise rejection / cancellation may not be achieved. It should be understood that in one or more embodiments, the differential measurement information may be actual or implicit, i.e., the single-ended measurement signal may include actual or implicit differential measurement information.

[0032] In one or more embodiments, the measurement signal may be generated in response to a measurement process (such as, but not limited to, a mutual capacitance measurement process) that is at least partially controlled by the measurement circuitry.

[0033] In one or more embodiments, the single-ended measurement input signal can be generated by adding a first single-ended measurement signal and an inverted version of a second single-ended measurement signal. In one or more embodiments, the single-ended measurement input signal can be generated by subtracting the second measurement signal from the first measurement signal.

[0034] One or more embodiments generally relate to generating a pseudo-inverse channel matrix for one or more channels of a differential measurement system. In one or more embodiments, to generate the pseudo-inverse channel matrix, noise on each line of a differential measurement pair may be monitored and characterized in a channel matrix.

[0035] In one or more embodiments, the pseudoinverse may be performed, by way of non-limiting example, symbolically, using numerical processing, or a combination thereof, to obtain the pseudoinverse channel matrix. As a non-limiting example of the pseudoinverse, the pseudoinverse may be calculated using Singular Value Decomposition (SVD) of the channel matrix. The SVD-based calculation may be computer-assisted by utilizing predetermined system characteristics (e.g., without limitation, predetermined touch sensor characteristics). While the pseudoinverse is "doing its job" in the background, the actual operation of the device is not calculating the pseudoinverse from one moment to another.

[0036] In one or more embodiments, noise monitoring and characterization may be performed for a single noise source or multiple noise sources, individually or as a group. In one or more embodiments, the channel for which a channel matrix is ​​generated may include one line of a differential measurement pair or both lines of a differential measurement pair. In the case of multiple noise sources, without limitation, a channel matrix may be generated for each noise source per channel, a noise profile may be generated for a combination or subcombination of noise sources per channel, or a channel matrix may be generated for each channel based on the entire set of modeled noise sources.

[0037] In one or more embodiments, one or more pseudo-inverse channel matrices may be generated based at least in part on one or more channel matrices generated as discussed above. Each pseudo-inverse channel matrix may be stored in, without limitation, a memory, a look-up-table (LUT), or both.

[0038] One or more embodiments generally relate to generating a noise equalizer or mode converter, such as, but not limited to, a pseudoinverse-based noise equalizer or a pseudoinverse-based mode converter, based at least in part on one or more pseudoinverse channel matrices generated as discussed above. One or more embodiments generally relate to a differential measurement system, or a portion thereof, that includes a pseudoinverse-based noise equalizer or a pseudoinverse-based mode converter for generating a differential measurement signal, and optionally utilizes the differential measurement signal to determine a target signal, a target condition, or both.

[0039] FIG. 1 is a block diagram depicting an apparatus 100 for equalizing a measurement signal generated by a differential measurement system using pseudoinverse-based equalization, according to one or more embodiments.

[0040] The apparatus 100 includes a differential measurement system portion 102 and an equalization system 104. The equalization system 104 includes a predetermined pseudo-inverse channel matrix 106.

[0041] The apparatus 100 may perform pseudo-inverse matrix-based equalization, as discussed herein, on the first single-ended measurement signal 108, the second single-ended measurement signal 110, or a signal based thereon, to generate an equalized measurement signal 112. The first single-ended measurement signal 108 and the second single-ended measurement signal 110 are generated by the differential measurement system portion 102.

[0042] The differential measurement system portion 102 is at least a portion of a differential measurement system that represents measurement information via the difference between a pair of signals, a differential measurement pair, here a first single-ended measurement signal 108 and a second single-ended measurement signal 110.

[0043] First single-ended measurement signal 108 and second single-ended measurement signal 110 are carried by respective conductors (conductors not shown) in differential measurement system portion 102 and are intended to be a differential pair, but need not necessarily, although more likely, be unbalanced.

[0044] In one or more embodiments, a differential measurement system including differential measurement system portion 102 may include, in addition to differential measurement system portion 102, one or more differential measurement system portions that generate respective pairs of single-ended measurement signals, where the measurement information is represented by the respective differences between the single-ended measurement signals.

[0045] The equalization system 104 receives the first single-ended measurement signal 108 and the second single-ended measurement signal 110 and, at least in part, responds thereto to generate an equalized measurement signal 112. The equalization system 104 determines the equalized measurement signal 112 based at least in part on the first single-ended measurement signal 108, the second single-ended measurement signal 110, and a predetermined pseudo-inverse channel matrix 106.

[0046] The predetermined pseudo-inverse channel matrix 106 may be, may be based at least in part on, or may include one or more pseudo-inverse channel matrices for reducing channel effects present in the first single-ended measurement signal 108, the second single-ended measurement signal 110, or a single-ended measurement signal based on the difference between the first single-ended measurement signal 108 and the second single-ended measurement signal 110, as discussed below. In one or more embodiments, the predetermined pseudo-inverse channel matrix 106 may represent a pseudo-inverse matrix that can be factorized into a sum or product of different matrix elements.

[0047] Such channel effects may be present in the differential measurement system portion 102 or in each line of the differential measurement system portion 102 carrying the first single-ended measurement signal 108 and the second single-ended measurement signal 110. In one or more embodiments, reducing channel effects may include reducing differential mode noise.

[0048] In one or more embodiments, the predetermined pseudo-inverse channel matrix 106 may include one or more coefficients. The coefficients may represent a determined degree of noise coupling into one or more channels of the differential measurement system portion 102. In one or more embodiments, the degree of noise coupling may be determined based at least in part on a determined amount of non-uniform spatial distribution of noise intensity or noise characteristics.

[0049] In one or more embodiments, the equalization system 104 may generate the equalized measurement signal 112, which may be or include a single equalized single-ended measurement signal, multiple equalized single-ended measurement signals, or a differential measurement signal, as discussed below. The channel effects present in the equalized measurement signal 112 may be reduced or lower relative to the first single-ended measurement signal 108 or the second single-ended measurement signal 110. The differential-mode noise present in the equalized measurement signal 112 may be reduced or lower relative to the first single-ended measurement signal 108 or the second single-ended measurement signal 110.

[0050] 2 is a block diagram of an apparatus 200 for equalizing a measurement signal generated by a differential measurement system, according to one or more embodiments. Apparatus 200 is a non-limiting example of equalization system 104 and may also be referred to herein as "equalization system 200."

[0051] In the non-limiting example depicted in FIG. 2 , equalization system 200 generates a single-ended measurement signal based on each single-ended measurement signal generated by the differential measurement system and mode converts the single-ended measurement signals into a differential measurement signal that contains differential information present in the difference between the single-ended measurement signals generated by the differential measurement systems.

[0052] The equalization system 200 includes a subtractor 206 , a differential signal reconstructor 210 , a noise equalizer 214 , an optional filter 218 , and an optional target signal amplifier 222 .

[0053] Subtractor 206 receives first single-ended measurement signal 202 and second single-ended measurement signal 204 (for example, but not limited to, from a differential measurement system or portion thereof) and combines first single-ended measurement signal 202 and second single-ended measurement signal 204 to generate single-ended measurement input signal 208, as discussed below. Subtractor 206 receives first single-ended measurement signal 202 at a non-inverting input (+) and second single-ended measurement signal 204 at an inverting input (−), and sums first single-ended measurement signal 202 and the inverted second single-ended measurement signal 204 to generate single-ended measurement input signal 208. In this manner, the single-ended measurement input signal 208 is based at least in part on the difference between the first single-ended measurement signal 202 and the second single-ended measurement signal 204, and at least implicitly contains measurement information present in the difference between the first single-ended measurement signal 202 and the second single-ended measurement signal 204.

[0054] Because the first single-ended measurement signal 202 and the second single-ended measurement signal 204 are single-ended, in addition to measurement information, they may contain one or more of common-mode noise and differential-mode noise, the latter optionally due to channel effects. Thus, the single-ended measurement input signal 208 may contain differential measurement information and some combination of the respective differential-mode noise present in the first single-ended measurement signal 202 or the second single-ended measurement signal 204. Any common-mode noise present in the first single-ended measurement signal 202 or the second single-ended measurement signal 204 should be canceled when the signals are combined by the subtractor 206.

[0055] The differential signal reconstructor 210 receives the single-ended measurement input signal 208 and generates a preliminary differential measurement signal 212 at least partially in response to the single-ended measurement input signal 208. In one or more embodiments, the differential signal reconstructor 210 may be operable to perform a reconstruction process such as a zero-mean technique, which assumes that the differential signal should have a zero mean over time and attempts to find a solution based on a pseudo-inverse matrix that has substantially zero mean (or a mean below a predetermined threshold).

[0056] In one or more embodiments, the differential signal reconstructor 210 utilizes any suitable technique, including estimation, to determine the preliminary differential measurement signal 212 based at least in part on the single-ended measurement input signal 208. As a non-limiting example, the differential signal reconstructor 210 may include an analog-to-digital converter (ADC) that receives an analog version of the single-ended measurement input signal 208 and converts it to a digital version. The differential signal reconstructor 210 may further include logic circuitry that infers the content of the output of the ADC, which processes the differential analog signal to generate a differential digital signal.

[0057] In one or more embodiments, generating the preliminary differential measurement signal 212 is an intermediate operation in generating a differential measurement pair; although the signals of the preliminary differential measurement signal 212 are intended for differential purposes, they are not yet balanced and therefore do not form a differential measurement pair.

[0058] Noise equalizer 214 receives preliminary differential measurement signal 212 and, at least in part in response thereto, generates differential measurement signal 216. Specifically, noise equalizer 214 determines differential measurement signal 216 based at least in part on preliminary differential measurement signal 212 and predetermined pseudo-inverse channel matrix 226. Predetermined pseudo-inverse channel matrix 226 is a non-limiting example of predetermined pseudo-inverse channel matrix 106 of FIG.

[0059] In one or more embodiments, the preliminary differential measurement signal 212 may be represented by a matrix, and the predetermined pseudo-inverse channel matrix 226 may include a predetermined noise coupling coefficient. The noise equalizer 214 may matrix-multiply the matrix of the preliminary differential measurement signal 212 with the predetermined pseudo-inverse channel matrix 226 to generate a matrix representing the differential measurement signal 216. The value of the predetermined noise coupling coefficient of the predetermined pseudo-inverse channel matrix 226 may be preset based at least in part on a predetermined amount. Such a predetermined amount may represent the amount by which the values ​​of the matrix of the preliminary differential measurement signal 212 should be increased or decreased to reduce channel effects, including differential-mode noise.

[0060] Some channel effects may be caused by permanent or temporary physical asymmetries. As a non-limiting example, reliably predictable mechanical deformations may occur during operation of the measurement system. Such channel effects are referred to herein as "artifacts." In one or more embodiments, one or more gradients may be predetermined to represent the channel effects, the physical asymmetries, or both. In one or more embodiments, each gradient may be applied to the differential measurement signal to reduce any artifacts that may be present.

[0061] Equalization system 200 may include an optional filter 218 to reduce or remove artifacts. Filter 218 receives differential measurement signal 216 and processes differential measurement signal 216 (e.g., without limitation, by applying one or more of the gradients discussed above) to remove artifacts and generate filtered differential measurement signal 220. Filter 218 is optional, and the inclusion of filter 218 in equalization system 200 may depend on particular operating conditions, by way of non-limiting example. In addition to or as an alternative to filter 218, equalization system 200 may include a common-mode noise filter at the output of noise equalizer 214 to reduce common-mode noise that may be present in differential measurement signal 216.

[0062] Artifact filtering or common-mode filtering may reduce or suppress the target signal in the differential measurement signal (e.g., without limitation, based at least in part on the filtering technique employed). Accordingly, in one or more embodiments, equalization system 200 may include an optional target signal amplifier 222 for amplifying the target signal in filtered differential measurement signal 220 to an operational level. Target signal amplifier 222 may receive filtered differential measurement signal 220, amplify measurement information in filtered differential measurement signal 220, and generate amplified differential measurement signal 224 including the amplified measurement information. In one or more embodiments, the amount by which target signal amplifier 222 amplifies the target signal may be based at least in part on coefficients of a predetermined pseudo-inverse channel matrix 226. More specifically, the amount of filtering by filter 218 may be proportional to the difference in the degree of noise coupling between the channels. When the coefficients of the predetermined pseudo-inverse channel matrix 226 are set based at least in part on the difference in the degree of noise coupling, these coefficients may be proportional to the amount of filtering applied by the filter 218, and therefore the amount by which the target signal is reduced may be determined based at least in part on the coefficients of the predetermined pseudo-inverse channel matrix 226 and utilized to calculate the amount of amplification.

[0063] Notably, in one or more embodiments, the differential signal reconstructor 210 and the noise equalizer 214 may form part of or all of a mode converter that generates a differential signal from a single-ended signal.

[0064] The amplified differential measurement signal 224 may be used as the equalized measurement signal 112 of FIG.

[0065] In one or more embodiments, a respective pseudo-inverse channel may be generated for each line of a differential measurement system that generated the single-ended measurement signal, with the difference between the respective lines comprising the target measurement information, as opposed to the case where a pseudo-inverse channel matrix is ​​generated for a single-ended measurement signal (e.g., single-ended measurement input signal 208 of FIG. 2) comprising differential measurement information.

[0066] 3 is a block diagram of an apparatus 300 for equalizing a measurement signal generated by a differential measurement system, according to one or more embodiments. Apparatus 300 is a non-limiting example of equalization system 104 and may also be referred to herein as "equalization system 300."

[0067] The equalization system 300 includes a first noise equalizer 314 , a second noise equalizer 334 , and a differential driver 310 .

[0068] The equalization system 300 applies respective equalizations to the single-ended measurement signals generated by the differential measurement system and generates differential measurement signals based at least in part on the equalized measurement signals, with the respective equalizations applied to the single-ended measurement signals being based at least in part on respective predetermined pseudo-inverse channel matrices.

[0069] The first noise equalizer 314 receives the first single-ended measurement signal 330 and, at least in part, in response thereto, generates an equalized first single-ended measurement signal 336. The first noise equalizer 314 determines the equalized first single-ended measurement signal 336 based at least in part on the first single-ended measurement signal 330 and a first predetermined pseudo-inverse channel matrix 326. The second noise equalizer 334 receives the second single-ended measurement signal 332 and, at least in part, in response thereto, generates an equalized second single-ended measurement signal 338. The second noise equalizer 334 determines the equalized second single-ended measurement signal 338 based at least in part on the second single-ended measurement signal 332 and a second predetermined pseudo-inverse channel matrix 340.

[0070] In one or more embodiments, the respective values ​​of the first predetermined pseudo-inverse channel matrix 326 and the second predetermined pseudo-inverse channel matrix 340 are determined as discussed above to reduce channel effects, including differential mode noise, that may be present in the first single-ended measurement signal 330 or the second single-ended measurement signal 332.

[0071] The differential driver 310 generates a differential signal (differential measurement signal 318) based on a pair of input signals (here, an equalized first single-ended measurement signal 336 and an equalized second single-ended measurement signal 338).

[0072] FIG. 4 is a block diagram illustrating a system 400 representing a portion of a differential measurement system that provides first and second single-ended measurement signals for pseudoinverse-based noise equalization, according to one or more embodiments.

[0073] System 400 includes summer 416, subtractor 414, summer 418, and equalization system 424. Summer 416, subtractor 414, and summer 418 may form at least a portion of a differential measurement system, such as differential measurement system portion 102 of FIG. 1. Alternatively, subtractor 414 may be part of equalization system 424.

[0074] The first differential mode noise 410 is combined with the first target signal component 408 in summer 416 and the second differential mode noise 420 is combined with the target signal component 422 in summer 418 .

[0075] In one or more embodiments, summer 416 and summer 418 may combine first differential mode noise 410 and second differential mode noise 420 with first target signal component 408 and target signal component 422 to different degrees (or may represent portions of such signals combined) due to respective channel effects that cause non-uniform capacitive coupling. In other words, first differential mode noise 410 and second differential mode noise 420 may represent noise that is substantially equal but impacts first target signal component 408 and target signal component 422 differently due to channel effects.

[0076] In one or more embodiments, the first differential mode noise 410 and the second differential mode noise 420 may represent different noises due to, by way of non-limiting example, spatial variations. In this case, summer 416 and summer 418 may combine the first differential mode noise 410 and the second differential mode noise 420 with the first target signal component 408 and the target signal component 422, respectively, in response to similar degrees of capacitive coupling, yet the first single-ended measurement signal 402 and the second single-ended measurement signal 406 still include different amounts of differential mode noise.

[0077] In either case, when the first single-ended measurement signal 402 and the second single-ended measurement signal 406 are combined by the subtractor 414 to generate the single-ended measurement input signal 404, the differential mode noise in the single-ended measurement input signal 404 obscures the first target signal component 408 and the target signal component 422, the difference between which represents the target signal. The equalization system 424 may process the single-ended measurement input signal 404 using pseudo-inverse matrix-based noise equalization to generate the differential target signal.

[0078] 5 illustrates an exemplary process 500 for equalizing a measurement signal generated by a differential measurement system using pseudoinverse-based equalization, according to one or more embodiments. Some or all of the operations of process 500 may be performed by apparatus 100, equalization system 200, equalization system 300, system 400, system 1000, and touch display system portion 1200, discussed below, as non-limiting examples.

[0079] Although the example process 500 depicts a particular sequence of operations, the sequence may be changed without departing from the scope of the present disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence without significantly affecting the functionality of the process 500. In other examples, various components of the example device or system implementing the process 500 may perform functions substantially simultaneously or in a particular sequence.

[0080] In one or more embodiments, the process 500 may include, at operation 502, obtaining a first single-ended measurement signal and a second single-ended measurement signal.

[0081] In one or more embodiments, process 500 may include, at operation 504, generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal and the second single-ended measurement signal.

[0082] 6 shows an example process 600 for generating a predetermined pseudo-inverse channel matrix according to one or more embodiments. Some or all of the operations of process 600 may be performed by device 100, equalization system 200, equalization system 300, system 400, system 1000, or touch display system portion 1200, as non-limiting examples.

[0083] The exemplary process 600 depicts certain operations that may be a sequence of operations, and the sequence may be changed without departing from the scope of the present disclosure. For example, some operations may be performed in parallel or in a different sequence without significantly affecting the functionality of the process 600. In other examples, various components of the exemplary device or system implementing the process 600 may perform functions substantially simultaneously or in a particular sequence.

[0084] In one or more embodiments, the process 600 may include, at operation 602, setting coefficients of a predetermined pseudo-inverse channel matrix to reduce channel effects.

[0085] 7 illustrates an example process 700 for generating an equalized measurement signal based at least in part on a first single-ended measurement signal and a second single-ended measurement signal, according to one or more embodiments. Some or all of the operations of process 700 may be performed by apparatus 100, equalization system 200, equalization system 300, system 400, system 1000, or touch display system portion 1200, as non-limiting examples.

[0086] Although the example process 700 depicts a particular sequence of operations, the sequence may be changed without departing from the scope of the present disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence without significantly affecting the functionality of the process 700. In other examples, various components of the example device or system implementing the process 700 may perform functions substantially simultaneously or in a particular sequence.

[0087] In one or more embodiments, the process 700 may include, at operation 702, generating a single-ended measurement input signal based at least in part on a relationship between the first single-ended measurement signal and the second single-ended measurement signal.

[0088] In one or more embodiments, the process 700 may include, at operation 704, generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and a single-ended measurement input signal.

[0089] 8 shows an example process 800 for generating an equalized measurement signal based at least in part on a first single-ended measurement signal and a second single-ended measurement signal, according to one or more embodiments. Some or all of the operations of process 800 may be performed by apparatus 100, equalization system 200, equalization system 300, system 400, system 1000, or touch display system portion 1200, as non-limiting examples.

[0090] Although the example process 800 depicts a particular sequence of operations, the sequence may be changed without departing from the scope of the present disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence without significantly affecting the functionality of the process 800. In other examples, various components of the example device or system implementing the process 800 may perform functions substantially simultaneously or in a particular sequence.

[0091] In one or more embodiments, the process 800 may include, at operation 802, generating a first single-ended equalized measurement signal based at least in part on the first single-ended measurement signal and a first predetermined pseudo-inverse channel matrix.

[0092] In one or more embodiments, process 800 may include, at operation 804, generating a second single-ended equalized measurement signal based at least in part on the second single-ended measurement signal and a second predetermined pseudo-inverse channel matrix.

[0093] In one or more embodiments, process 800 may include, at operation 806, generating a differential measurement signal based at least in part on the first single-ended equalized measurement signal and the second single-ended equalized measurement signal.

[0094] 9 shows an example process 900 for generating a differential measurement signal (or equalizing a single-ended measurement signal) using pseudoinverse-based noise equalization, according to one or more embodiments. Some or all of the operations of process 900 may be performed by, as non-limiting examples, apparatus 100, equalization system 200, equalization system 300, system 400, system 1000, or touch display system portion 1200. In one or more embodiments, process 900 may be a non-limiting example of a process for generating a differential measurement signal of operation 806 of process 800.

[0095] Although the example process 900 depicts a particular sequence of operations, the sequence may be changed without departing from the scope of the present disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence without significantly affecting the functionality of the process 900. In other examples, various components of the example device or system implementing the process 900 may perform functions substantially simultaneously or in a particular sequence.

[0096] In one or more embodiments, process 900 may include, at operation 902, generating a first single-ended equalized measurement signal includes multiplying the first single-ended measurement signal with a first predetermined pseudo-inverse channel matrix.

[0097] In one or more embodiments, process 900 may include, at operation 904, generating a second single-ended equalized measurement signal includes multiplying the second single-ended measurement signal with a second predetermined pseudo-inverse channel matrix.

[0098] FIG. 10 is a schematic block diagram illustrating a system 1000 including pseudo-inverse matrix based mode conversion for generating a differential measurement signal, according to one or more embodiments.

[0099] The system 1000 includes an electrode connection block 1002 , a differential amplification block 1004 , an analog-to-digital converter (A / D) block 1006 , a reconstruction block 1008 , a correction block 1010 , a filter block 1012 , and a signal amplification block 1014 .

[0100] The electrode connection block 1002 includes electrode connections for receiving current (electrical current) signals Y0, Y1, Y2, and Y3 generated at least in part in response to the mutual capacitance measurement process.

[0101] The differential amplifier block 1004 includes a differential amplifier for receiving current signals (e.g., without limitation, signals Y0, Y1, Y2, and Y3) from at least two adjacent ones of the electrode connections of the electrode connection block 1002, and amplifying the difference between the respective received current signals to generate analog single-ended difference signals P0, P1, P2, and P3. As used herein, the term "adjacent" when referring to electrode connections encompasses physically adjacent electrode connections (e.g., without limitation, in a layout where the respective electrode connections are located immediately next to each other) and electrically adjacent electrode connections (e.g., without limitation, when a target signal is based at least in part on respective electrode connections that may or may not be physically adjacent).

[0102] In a specific non-limiting example illustrated by FIG. 10, the first differential amplifier I0 of the differential amplification block 1004 is coupled to receive currents Y0 and Y1 and amplify the difference therebetween, the second differential amplifier I1 of the differential amplification block 1004 is coupled to receive currents Y1 and Y2 and amplify the difference therebetween, the third differential amplifier I2 of the differential amplification block 1004 is coupled to receive currents Y2 and Y3 and amplify the difference therebetween, and the fourth differential amplifier I3 of the differential amplification block 1004 is coupled to receive currents Y3 and Y0 and amplify the difference therebetween.

[0103] The A / D block 1006 receives the analog single-ended difference signals P0, P1, P2, and P3 and generates, via analog-to-digital signal conversion, digital single-ended signals d0, d1, d2, and d3 based at least in part on the respective signals of the received single-ended signals.

[0104] The reconstruction block 1008 receives the digital single-ended difference signals d0, d1, d2, and d3 and generates, at least in part, uncorrected reconstructed differential signals r0, r1, r2, and r3 based thereon. In a specific, non-limiting example illustrated by FIG. 10 , the determination of the uncorrected reconstructed differential signals r0, r1, r2, and r3 by the reconstruction block 1008 includes determining respective dot products of a matrix 1020 containing the respective digital single-ended difference signals d0, d1, d2, and d3 with a further matrix 1016 representing a mathematical model of the reconstruction. Given a vector of differential measurements d, a reconstructed value (r) can be calculated by multiplying the measurements (d) with a matrix (h).

[0105] The correction block 1010 receives the respective digital single-ended difference signals d0, d1, d2, and d3 and generates, at least in part, correction signals n0, n1, n2, and n3 in response thereto. In a specific, non-limiting example illustrated by FIG. 10 , the correction block 1010 determines the correction signals n0, n1, n2, and n3 by determining a dot product of a matrix 1020 including the respective digital single-ended difference signals d0, d1, d2, and d3 with a further matrix 1018 including a pseudo-inverse channel matrix (e.g., but not limited to, predetermined pseudo-inverse channel matrix 106, predetermined pseudo-inverse channel matrix 226). The value of each coefficient “k” of the pseudo-inverse channel matrix 1018 may be set to reduce channel effects and may be proportional to a determined degree of noise coupling for one or more channels.

[0106] The correction signals n0, n1, n2, and n3 are applied to the output of the reconstruction block 1008, and more specifically, to the uncorrected reconstructed differential signals r0, r1, r2, and r3 via respective summation blocks to generate reconstructed differential signals r0', r1', r2', and r3'.

[0107] The filter block 1012 receives each of the reconstructed differential signals r0', r1', r2', and r3' and, at least in part, generates filtered reconstructed differential signals t0', t1', t2', and t3' in response thereto. In one or more embodiments, the filter block 1012 may apply common-mode noise filtering, artifact filtering, or both to each of the corrected reconstructed differential signals r0', r1', r2', and r3'. In one or more embodiments, the filter block 1012 may filter all or a subset of the reconstructed differential signals r0', r1', r2', and r3'. As a non-limiting example, the subset of the reconstructed differential signals may correspond to channels associated with the periphery of a touch sensor or touch display.

[0108] The signal amplification block 1014 includes respective signal amplifiers for amplifying (i.e., increasing or increasing the signal-to-noise ratio of) the target signal in each of the filtered reconstructed differential signals t0', t1', t2', and t3' to generate respective differential target signals t0, t1, t2, and t3.

[0109] 11 is a block diagram of a target signal amplifier 1100 according to one or more embodiments. Target signal amplifier 1100 is a non-limiting example of target signal amplifier 222 of FIG. 2 or signal amplifier block 1014 of FIG.

[0110] The sequence "τ+αb" represents a reconstructed differential signal (e.g., without limitation, r0', r1', r2', and r3' in FIG. 10). The reconstructed differential signal τ+αb includes a combination "+" of the target signal "τ" and a moving average "α" bending noise "b" component "αb." Here, the "bending noise b" represents the amount by which the target signal τ can be reduced by the equalization process in the reconstruction block 1008 (e.g., without limitation, based on an average). The symbol "m" represents a multiplier, and the symbol "d" represents a divisor. The relationship between the multiplier m and the moving average α is m=1 / α. The relationship between the divisor d and the moving average α is d=α.

[0111] The reconstructed differential signal τ+αb is multiplied by a multiplier m to produce “mτ+mαb”, which is fed to the input of the bending block of the lens.

[0112] The first bend b and the multiplied target signal mτ (the target signal is labeled "touch" in FIG. 11) are generated separately at the output of the lens bending block. The first bend "b" is a low-frequency component that can be obtained by fitting a low-order polynomial (7th order) to the reconstructed differential signal τ+αb multiplied by the multiplier m.

[0113] The first bending b produced at the output of the lens bending block is multiplied by a divisor d to produce a second bending db.

[0114] The reconstructed differential signal τ+αb is subtracted from the multiplied second bending db to generate the filtered target signal τ+αb−db.

[0115] The multiplier m and divisor d may be independently specified parameters (e.g., without limitation, predetermined parameters or user-provided parameters), may be in any suitable format, or may be expressed according to any suitable notation for representing integers, non-integers, or both.

[0116] As a specific, non-limiting example, one or more of the multiplier m and the divisor d may be in 8.8 format (i.e., a 16-bit fixed notation), where the most significant 8 bits represent the integer portion of the number and the least significant 8 bits represent the fractional portion of the number in units of 1 / 256.

[0117] <Background for mutual capacitance measurement> Mutual capacitance is the capacitive coupling between objects; in the case of a touch sensor, it is the capacitive coupling between the intersection of an electrode that acts as a transmitter (the transmitter electrode, also called the "X electrode") and an electrode that acts as a receiver (the receiver electrode, also called the "Y electrode").

[0118] In a typical layout of a touch sensor, the X lines of the X electrodes and the Y lines of the Y electrodes are arranged in a grid of rows and columns, respectively. Each intersection of the X and Y lines is referred to herein as a "sensor node." In mutual capacitance measurements, the X electrodes measure the mutual capacitance (C M ) coupling into the capacitance of the Y electrode. The amount of injected current is indicative of the mutual capacitance between the X and Y electrodes. When the grounded object is not in adequate proximity to the sensor node, the injected current represents the baseline mutual capacitance of the Y electrode. When the grounded object is in adequate proximity to the sensor node, the grounded object shunts some of the charge (e.g., current) through the capacitively coupled ground path, thereby appearing to an observer (i.e., measurement circuitry) to change (e.g., decrease, without limitation) the mutual capacitance between the X and Y electrodes that intersect at that sensor node.

[0119] An integrated circuit (IC) coupled to each X and Y electrode may control mutual capacitance measurement and touch sensing. A touch processor in the IC may observe changes in mutual capacitance and, by way of non-limiting example, use the changes to determine that a touch event has occurred at the sensor node. In mutual capacitance measurement, the measurement signal may include a touch signal and noise. The noise in the measurement signal may include system noise and environmental noise. In the case of a touch display, sources of system noise may include the display ("display noise source"), such as, but not limited to, the underlying hardware or electronics that drive the display. Non-limiting examples of displays include a liquid crystal display (LCD) and the hardware or electronics that drive the LCD. Thus, the noise in the measurement signal may include display noise, and the measurement signal may include the touch signal, the display noise signal, and environmental noise.

[0120] When the X and Y lines of a touch sensor are laid out in a rectangular pattern, the X lines typically have uniform lengths and the Y lines typically have uniform lengths, so they typically exhibit a uniform degree of noise coupling, which can be canceled out.

[0121] When the X and Y lines of a touch sensor are laid out in a non-rectangular manner (a "non-rectangular touch sensor"), physical asymmetries may exist between the respective X or Y lines, which cause channel effects such as differential-mode noise. As a non-limiting example, in a non-rectangular touch sensor, one or more of the X or Y lines may have non-uniform lengths. As another non-limiting example, assuming uniform distances between sensor nodes, a non-rectangular touch sensor may include a non-uniform number of nodes per X electrode, Y electrode, or both. Stated another way, in a non-rectangular touch sensor, some X electrodes may include a different number of sensor nodes than other X electrodes, or some Y electrodes may include a different number of sensor nodes than other Y electrodes.

[0122] The length of the X or Y lines and the number of sensor nodes per electrode can affect the degree of noise coupling and the amount of noise included in the measurement signal. Uneven line lengths or uneven numbers of nodes can cause uneven noise coupling with one or more noise sources.

[0123] In addition to or as an alternative to physical asymmetries, non-uniform spatial distributions of noise strength or characteristics (also referred to herein as "spatial variation") (where noise coupling depends on the position of the receiver relative to the noise source) can cause non-uniform degrees of noise coupling. Spatial variation can be caused by, by way of non-limiting examples, the directionality of noise emission by the noise source (where the noise source emits noise more strongly or differently in certain directions than in others), non-uniform interference patterns, non-uniform attenuation, or non-uniform propagation patterns. Non-uniform interference patterns, attenuation, or propagation can depend, by way of non-limiting examples, on what obstacles exist between the receiver and the noise source (e.g., without limitation, whether they are physically or electrically present), material properties, or the frequencies involved.

[0124] In mutual capacitance measurements, because capacitance is measured between adjacent lines, non-uniform noise coupling can introduce differential-mode noise that affects the mutual capacitance measurement. Accordingly, noise in the measurement signal, including but not limited to display noise, can be affected by the shape of the touch sensor, and such shape-induced effects on the measurement signal can cause inaccurate capacitance determinations or inaccurate touch detection (inaccurate touch detection can cause, by way of non-limiting examples, phantom touches, mistouches, or inaccurate touch locations). By way of non-limiting example, such shape-induced effects on the measurement signal can reduce the capacitance value determined based on the measurement signal or the signal strength of a detected touch event (e.g., by having an unknown effect on the measurement signal). For rectangular or non-rectangular touch sensors, spatial variation-induced effects on the measurement signal can reduce the determined capacitance value or the signal strength of a detected touch event (in addition to, or as an alternative to, shape-induced effects).

[0125] Noise equalization can be used in mutual capacitance measurements to compensate for differences in noise coupling between adjacent lines of a touch sensor. In the context of mutual capacitance measurements, noise equalization can involve equalizing (or balancing) noise so that it does not disproportionately affect certain areas of the touch sensor or its mutual capacitance measurements.

[0126] One or more embodiments generally relate to pseudo-inverse-matrix-based noise equalization in mutual capacitance measurements. In one or more embodiments, the channel matrix on which the pseudo-inverse channel matrix of the noise equalizer is based at least in part may characterize channel effects in terms of capacitive coupling with display noise sources. Such a pseudo-inverse-matrix-based noise equalizer may reduce channel effects (e.g., channel effects based on, but not limited to, line length, number of nodes, spacing between nodes, or a combination thereof). Such a pseudo-inverse-matrix-based noise equalizer may reduce noise that is differential mode noise, including, but not limited to, display noise that is differential mode noise.

[0127] FIG. 12 is a schematic block diagram depicting a touch display system portion 1200 utilizing pseudoinverse-based equalization of noise, according to one or more embodiments.

[0128] The touch display system portion 1200 includes connections 1202 , 1204 , a display driver 1206 , display lines 1216 , a touch driver 1208 , X lines 1218 , Y lines 1214 , and an equalization system 1220 .

[0129] When the touch driver 1208 applies the drive signal 1212 as a driven drive signal to one or more of the X lines 1218 via the respective connections 1204, the touch signal associated with the driven drive signal 1212 is determined by the mutual capacitance c m0 , c m1 , c m2 , or c m3 When the display driver 1206 applies the synchronization signal 1210 as a driven synchronization signal to one or more of the display lines 1216 via the connection 1202, the display noise corresponding to the driven synchronization signal 1210 is injected into the Y line 1214 via the mutual capacitance C y0 , C y1 , C y2 , and C y3is injected into each Y-line 1214 via coupling via

[0130] The equalization system 1220 equalizes the mutual capacitance measurement signal received via the Y line 1214 in the manner discussed with respect to the device 100, the equalization system 200, the equalization system 300, or the system 1000, as non-limiting examples, to generate an equalized mutual capacitance measurement signal 1222.

[0131] In one or more embodiments, the touch display system portion 1200 may apply the pseudo-inverse matrix based noise equalization discussed herein to the mutual capacitance measurement signals received from the entire Y-lines 1214, or may apply the pseudo-inverse matrix based noise equalization only to a subset of the Y-lines 1214, such as, by way of non-limiting example, each of the Y-lines 1214 having a node number or line length different from a predetermined baseline node number or line length.

[0132] 13, 14, 15, and 16 are graphs depicting the delta (Δ) signal (“Δ”), the reconstructed signal (“Reconstruction”), the scaled reconstructed signal (“Scaled Reconstruction”), and the boosted touch signal (“Boosted Touch”) in several different touch scenarios in a mutual capacitance measurement system in accordance with one or more embodiments.

[0133] In this diagram, the "delta" signal is the mutual capacitance measurement signal. When the system starts up, the mutual capacitance measurement signal is captured and stored (for example, but not limited to, in a storage device). This represents the capacitance across the touch sensor in the absence of a touch (also referred to herein as the "baseline capacitance" and the measurement is also referred to as the "baseline measurement"). Subsequent measurements are made with respect to the baseline measurement and are therefore referred to as deltas.

[0134] The reconstructed signal is the reconstructed corrected differential mutual capacitance measurement signal (e.g., reconstructed differential signals r0', r1', r2', and r3' of FIG. 10). The scaled reconstructed signal is the filtered reconstructed differential signal (e.g., filtered reconstructed differential signals t0', t1', t2', and t3' of FIG. 10). The boosted touch is the differential target signal (e.g., differential target signals t0, t1, t2, and t3 of FIG. 10).

[0135] In the scenario depicted by FIG. 13, a touch event is indicated by the scaled reconstructed signal and a boosted touch signal with an amplitude much larger than the reconstructed signal. In the scenario depicted by FIG. 14, a non-touch event is indicated by the scaled reconstructed signal and a boosted touch signal that closely matches the reconstructed signal. In the scenario depicted by FIG. 15, a touch event is indicated by the scaled reconstructed signal and a boosted touch signal with an amplitude larger than the reconstructed signal. FIG. 15 depicts some touch superimposed on a "common" signal at approximately -300 (located around Y line 5). However, this common signal is not flat, but rather "U" shaped. The common signal is "U" shaped because noise is not realized equally across the sensor (channel effect). It can be seen (in this particular non-limiting example) that the Y line to the left of the touch has less noise than the Y line to the right of the touch. The common-mode noise signal can be filtered out, but if done without noise equalization, it will cause the "reconstructed" signal waveform depicted in FIG. 15. The U-shape of the common-mode noise is visible and looks the same as the touch signal. This has the potential to be misclassified as a touch, i.e., a false touch. In the specific, non-limiting example depicted in Figure 15, equalization is applied to achieve (in this specific, non-limiting example) a "scaled reconstruction" signal. While there is no signal that can be considered a false touch, a side effect of the equalization process is that the touch signal amplitude is reduced. When the touch signal is boosted, a boosted touch signal is obtained, which (in this specific, non-limiting example) has the same amplitude as the original touch signal, but is not U-shaped.

[0136] Those skilled in the art will appreciate that the functional elements (e.g., functions, operations, acts, processes, and / or methods) of the embodiments disclosed herein can be implemented in any suitable hardware, software, firmware, or combination thereof. Figure 17 shows a non-limiting example of an implementation of the functional elements disclosed herein. In some embodiments, some or all of the functional elements disclosed herein may be performed by hardware capable of executing the functional elements.

[0137] 17 is a block diagram of a circuit 1700 that may, in some examples, be used to implement various functions, operations, acts, processes, or methods disclosed herein. The circuit 1700 includes one or more processors 1702 (sometimes referred to herein as “processors 1702”) operably coupled to one or more data storage devices 1704 (sometimes referred to herein as “storage devices 1704”). The storage devices 1704 include machine-executable code 1706 stored thereon, and the processors 1702 include logic circuitry 1708. The machine-executable code 1706 includes information describing functional elements that may be implemented (e.g., executed) by the logic circuitry 1708. The logic circuitry 1708 is adapted to implement (e.g., execute) the functional elements described by the machine-executable code 1706. The circuitry 1700, when executing the functional elements described by the machine-executable code 1706, should be considered dedicated hardware for executing the functional elements disclosed herein. In one or more embodiments, processor 1702 may execute the functional elements described by machine-executable code 1706 sequentially, simultaneously (e.g., on one or more different hardware platforms), or in one or more parallel processing streams.

[0138] When implemented by logic circuitry 1708 of processor 1702, machine-executable code 1706 causes processor 1702 to perform the operations of embodiments disclosed herein. As a non-limiting example, machine-executable code 1706 may cause processor 1702 to perform some or all of the operations of one or more of process 500, process 600, process 700, process 800, or process 900.

[0139] Also, as a non-limiting example, machine-executable code 1706 may adapt processor 1702 to perform some or all of the features, functions, or operations disclosed herein for one or more of device 100, equalization system 200, equalization system 300, system 400, system 1000, filter 1100, and touch display system portion 1200. More specifically, the features, functions, or operations disclosed herein for one or more of the differential measurement system portion 102, the equalization system 104, the differential signal reconstructor 210, the noise equalizer 214, the filter 218, the target signal amplifier 222, the first noise equalizer 314, the second noise equalizer 334, the differential driver 310, the summer 416, the summer 418, the subtractor 414, the equalization system 424, the connection block 1002, the differential amplification block 1004, the A / D block 1006, the reconstruction block 1008, the correction block 1010, the filter block 1012, the signal amplification block 1014, the matrix 1016, the pseudo-inverse channel matrix 1018, and the matrix 1020. Also, by way of non-limiting example, the machine-executable code 1706 may cause the processor 1702 to perform some or all of the features, functions, or operations disclosed herein with respect to one or more of the logical blocks of FIG. 11, including the multiplier parameter m, the divisor parameter d, the lens bending block, and the multiplication and addition block depicted in the figure.

[0140] The processor 1702 may include a general-purpose processor, a special-purpose processor, a central processing unit (CPU), a microcontroller, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, other programmable devices, or any combination thereof designed to perform the functions disclosed herein. A general-purpose computer including one or more processors 1702, including a general-purpose processor, is considered a special-purpose computer, at least while the general-purpose computer executes functional elements corresponding to machine-executable code 1706 (e.g., but not limited to, software code, firmware code, configuration data, hardware descriptions) associated with examples of the present disclosure. It should be noted that the general-purpose processor (sometimes referred to herein as a host processor or simply a host) may be a microprocessor, but alternatively, a general-purpose processor within the processor 1702 may include any conventional processor, controller, microcontroller, or state machine. The FPGA or other PLD of processor 1702 may be configured (e.g., without limitation, programmed) with configuration data to perform the functions disclosed herein, or may additionally or alternatively be capable of being configured or reconfigured (e.g., without limitation, programmable or reprogrammable) with configuration data to perform the functions disclosed herein. Processor 1702 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0141] In one or more embodiments, the memory device 1704 includes a volatile data storage device (e.g., without limitation, random-access memory (RAM), static RAM (SRAM)), a non-volatile data storage device (e.g., without limitation, flash memory, hard disk drive, solid-state drive, erasable programmable read-only memory (EPROM)). In some embodiments, the processor 1702 and the memory device 1704 may be implemented in a single device (e.g., without limitation, a semiconductor device product, a system on chip (SOC)). In some embodiments, the processor 1702 and the memory device 1704 may be implemented in separate devices.

[0142] In one or more embodiments, machine-executable code 1706 may include computer-readable instructions (e.g., software code, firmware code). As a non-limiting example, the computer-readable instructions may be stored by memory device 1704, accessed directly by processor 1702, and executed by processor 1702 using at least logic circuitry 1708. Also, as a non-limiting example, the computer-readable instructions may be stored in memory device 1704, transferred for execution to a memory device (not shown), and executed by processor 1702 using at least logic circuitry 1708. Processor 1702 or its logic circuitry 1708 may be coupled to or include such memory devices (e.g., without limitation, configuration memory cells). Thus, in some embodiments, logic circuitry 1708 includes electrically configurable logic circuitry 1708.

[0143] In one or more embodiments, machine-executable code 1706 may describe hardware (e.g., circuits) to be implemented in logic circuitry 1708 to perform the functional elements. This hardware may be described at any of a variety of levels of abstraction, from low-level transistor layouts to high-level description languages. At high levels of abstraction, a hardware description language (HDL) such as the IEEE standard hardware description language (HDL) may be used. As non-limiting examples, VERILOG®, SYSTEMVERILOG™, or very large scale integration (VLSI) hardware description language (VHDL) may be used.

[0144] The HDL description may be converted into a description at any of a number of other levels of abstraction, as desired. As a non-limiting example, the high-level description may be converted into a logic-level description, such as a register-transfer language (RTL), a gate-level (GL) description, a layout-level description, or a mask-level description. As a non-limiting example, the micro-operations performed by hardware logic circuits (e.g., without limitation, gates, flip-flops, registers) of logic circuit 1708 may be described in RTL and then converted by a synthesis tool into a GL description, which may be converted by a place-and-route tool into a layout-level description that corresponds to the physical layout of an integrated circuit of programmable logic devices, discrete gate or transistor logic, discrete hardware components, or combinations thereof. Thus, in some embodiments, machine-executable code 1706 may include HDL, RTL, a GL description, a mask-level description, other hardware descriptions, or any combination thereof.

[0145] In embodiments in which machine-executable code 1706 includes a hardware description (at any level of abstraction), a system (not shown, but including storage 1704) implements the hardware description described by machine-executable code 1706. As a non-limiting example, processor 1702 may include a programmable logic device (e.g., without limitation, an FPGA or a PLC), and logic circuitry 1708 may be electronically controlled (e.g., without limitation, via configuration data) to implement circuitry in logic circuitry 1708 corresponding to the hardware description. Also, as a non-limiting example, logic circuitry 1708 may include hardwired logic manufactured by a manufacturing system (not shown, but including storage 1704) according to the hardware description in machine-executable code 1706.

[0146] Regardless of whether machine-executable code 1706 includes computer-readable instructions or a hardware description, logic circuitry 1708, when implementing the functional elements of machine-executable code 1706, is adapted to perform the functional elements described by machine-executable code 1706. Note that the hardware description need not directly describe the functional elements, but rather the hardware description indirectly describes the functional elements that the hardware elements described by the hardware description can perform.

[0147] As used in this disclosure, the term "module" or "component" may refer to a module or component and / or a specific hardware implementation for performing the actions of a software object or software routine that may be stored on and / or executed by general-purpose hardware (e.g., without limitation, computer-readable media, processing device) of a computing system. In some embodiments, different components, modules, engines, and services described in this disclosure may be implemented as objects or processes (e.g., as separate threads) executing on a computing system. While some of the systems and methods described in this disclosure are generally described as being implemented in software (stored and / or executed on general-purpose hardware), specific hardware implementations, or a combination of software and specific hardware implementations, are also possible and contemplated.

[0148] As used in this disclosure, the term "combination," referring to multiple elements, can include a combination of all elements or any of various different subcombinations of elements. For example, the phrase "A, B, C, D, or combinations thereof" can refer to A, B, C, or D; each combination of A, B, C, and D; and any subcombination of A, B, C, or D, such as any one of A, B, and C; A, B, and D; A, C, and D; B, C, and D; A and B; A and C; A and D; B and C; B and D; or C and D.

[0149] The terms used in this disclosure, and particularly in the appended claims (including, but not limited to, the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," and the term "includes" should be interpreted as "including, but not limited to," without limitation). As used herein, the term "each" means "in part or in whole." As used herein, the term "each and all" means "in whole."

[0150] Additionally, if a specific number of introduced claim recitations is intended, such intent will be expressly recited in the claim; absent such recitation, no such intent exists. For example, as an aid to understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed as limiting any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even if the same claim also includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., without limitation, "a" and / or "an" should be construed to mean "at least one" or "one or more")). The same applies to the use of express articles used to introduce claim recitations.

[0151] Additionally, even when a particular number recited in an introduced claim is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., an express recitation of "two recitations" without other modifiers means, but is not limited to, at least two recitations or more than two recitations). Furthermore, when conventions similar to "including but not limited to, at least one of A, B, and C" or "including but not limited to, one or more of A, B, and C" are used, such structures are generally intended to include, but are not limited to, A only, B only, C only, A and B together, A and C together, B and C together, or A, B, and C together.

[0152] Furthermore, any disjunction or phrase presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" should be understood to include the possibilities of "A" or "B" or "A and B."

[0153] Further non-limiting examples include the following: Example 1: An apparatus comprising: a differential measurement system portion for providing a first single-ended measurement signal and a second single-ended measurement signal; and an equalization system for applying pseudo-inverse matrix based noise equalization to one or more of the first single-ended measurement signal or the second single-ended measurement signal.

[0154] Example 2: The apparatus described in Example 1, wherein the equalization system generates an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal or the second single-ended measurement signal.

[0155] Example 3: The apparatus described in Example 1 or 2, wherein the equalization system includes: a differential signal reconstructor for generating a preliminary differential measurement signal based at least in part on a single-ended measurement input signal, the single-ended measurement input signal being based at least in part on a difference between a first single-ended measurement signal and a second single-ended measurement signal; and a noise equalizer for generating a differential measurement signal based at least in part on the preliminary differential measurement signal and a predetermined pseudo-inverse channel matrix.

[0156] Example 4: The apparatus of any of Examples 1-3, wherein the equalization system comprises an artifact filter for reducing artifacts in the differential measurement signal generated by the noise equalizer.

[0157] Example 5: An apparatus described in any of Examples 1 to 4, wherein the equalization system includes a target signal amplifier for amplifying a target signal within the filtered differential measurement signal generated by the artifact filter to generate an amplified differential measurement signal.

[0158] Example 6: The apparatus of any of Examples 1-5, wherein coefficients of the predetermined pseudo-inverse channel matrix are set to reduce channel effects.

[0159] Example 7: An apparatus described in any of Examples 1 to 6, wherein the equalization system multiplies one or more of the first single-ended measurement signal or the second single-ended measurement signal with the predetermined pseudo-inverse channel matrix to generate an equalized measurement signal based at least in part on the predetermined pseudo-inverse channel matrix.

[0160] Example 8: The apparatus of any of Examples 1-7, wherein one or more channels of the differential measurement system portion include a physical asymmetry.

[0161] Example 9: The apparatus of any of Examples 1 to 8, wherein the equalization system includes: a first noise equalizer for generating an equalized first single-ended measurement signal based at least in part on the first single-ended measurement signal; a second noise equalizer for generating an equalized second single-ended measurement signal based at least in part on the second single-ended measurement signal; and a differential driver for generating a differential measurement signal based at least in part on the equalized first single-ended measurement signal and the equalized second single-ended measurement signal.

[0162] Example 10: An apparatus described in any of Examples 1 to 9, wherein the first noise equalizer generates an equalized first single-ended measurement signal based at least in part on a first predetermined pseudo-inverse channel matrix, and the second noise equalizer generates an equalized second single-ended measurement signal based at least in part on a second predetermined pseudo-inverse channel matrix.

[0163] Example 11: An apparatus described in any of Examples 1 to 10, wherein the differential measurement system portion includes a differential amplification block for generating an analog single-ended difference signal based at least in part on a difference between the first single-ended measurement signal and the second single-ended measurement signal.

[0164] Example 12: The apparatus of any of Examples 1 to 11, wherein the differential measurement system portion includes a connection block for receiving the first single-ended measurement signal and the second single-ended measurement signal.

[0165] Example 13: An apparatus described in any of Examples 1 to 12, wherein the differential measurement system portion includes physical channels for carrying a first single-ended measurement signal and a second single-ended measurement signal, respectively, and the connection block is operable to be coupled to the physical channels.

[0166] Example 14: An apparatus described in any of Examples 1 to 13, wherein the equalization system includes an analog-to-digital conversion block for generating a digital single-ended differential signal based at least in part on the analog single-ended differential signal, a reconstruction block for generating an uncorrected reconstructed differential signal based at least in part on the digital single-ended differential signal, and a correction block for generating a differential measurement signal based at least in part on the uncorrected reconstructed differential signal.

[0167] Example 15: A method comprising: acquiring a first single-ended measurement signal and a second single-ended measurement signal; and generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal and the second single-ended measurement signal.

[0168] Example 16: The method of example 15, wherein coefficients of the predetermined pseudo-inverse channel matrix are set to reduce channel effects.

[0169] Example 17: A method as described in Example 15 or 16, comprising: generating a single-ended measurement input signal based at least in part on a relationship between a first single-ended measurement signal and a second single-ended measurement signal; and generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and the single-ended measurement input signal.

[0170] Example 18: The method of any one of Examples 15 to 17, wherein the step of generating the equalized measurement signal includes the steps of: generating a first single-ended equalized measurement signal based at least in part on the first single-ended measurement signal and a first predetermined pseudo-inverse channel matrix of the predetermined pseudo-inverse channel matrix; generating a second single-ended equalized measurement signal based at least in part on the second single-ended measurement signal and a second predetermined pseudo-inverse channel matrix of the predetermined pseudo-inverse channel matrix; and generating a differential measurement signal based at least in part on the first single-ended equalized measurement signal and the second single-ended equalized measurement signal.

[0171] Example 19: The method of any of Examples 15 to 18, wherein the step of generating the first single-ended equalized measurement signal includes the step of multiplying the first single-ended measurement signal by a first predetermined pseudo-inverse channel matrix.

[0172] Example 20: The method of any of Examples 15 to 19, wherein the step of generating the second single-ended equalized measurement signal includes the step of multiplying the second single-ended measurement signal by a second predetermined pseudo-inverse channel matrix.

[0173] Example 21: A system comprising: a display; a touch sensor having X electrodes and Y electrodes; and an equalization system for generating an equalized mutual capacitance measurement signal based at least in part on a single-ended measurement signal received via the Y electrodes of the touch sensor during a mutual capacitance measurement.

[0174] Example 22: The system of example 21, wherein at least some of the lines of X electrodes or the lines of Y electrodes exhibit a non-uniform spatial distribution of noise intensity or noise characteristics.

[0175] Example 23: The system of example 21 or 22, wherein the X electrode or the Y electrode comprises a line of non-uniform length.

[0176] Example 24: The system of any of Examples 21 to 23, wherein the X electrodes or Y electrodes include a non-uniform number of sensor nodes.

[0177] While the present disclosure has been described herein with reference to certain illustrated embodiments, those skilled in the art will recognize and appreciate that the present invention is not so limited. Rather, numerous additions, deletions, and modifications can be made to the illustrated and described embodiments without departing from the scope of the invention as claimed below, along with their legal equivalents. In addition, features of one embodiment can be combined, as contemplated by the inventor, with features of other disclosed embodiments and still fall within the scope of the present disclosure.

Claims

1. 1. An apparatus comprising: a differential measurement system portion for providing a first single-ended measurement signal and a second single-ended measurement signal; an equalization system for applying pseudo-inverse matrix based noise equalization to one or more of the first single-ended measurement signal or the second single-ended measurement signal.

2. The equalization system comprises:

10. The apparatus of claim 1, wherein the apparatus generates an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal or the second single-ended measurement signal.

3. The equalization system comprises: a differential signal reconstructor for generating a preliminary differential measurement signal based at least in part on a single-ended measurement input signal, the single-ended measurement input signal being based at least in part on a difference between the first single-ended measurement signal and the second single-ended measurement signal; 3. The apparatus of claim 2, further comprising: a noise equalizer for generating a differential measurement signal based at least in part on the preliminary differential measurement signal and a predetermined pseudo-inverse channel matrix.

4. The equalization system comprises: The apparatus of claim 3 , comprising an artifact filter for reducing artifacts in the differential measurement signal produced by the noise equalizer.

5. The equalization system comprises:

5. The apparatus of claim 4, comprising a target signal amplifier for amplifying a target signal in the filtered differential measurement signal produced by the artifact filter to produce an amplified differential measurement signal.

6. The apparatus of claim 2 , wherein coefficients of the predetermined pseudo-inverse channel matrix are set to reduce channel effects.

7. 3. The apparatus of claim 2, wherein the equalization system multiplies the predetermined pseudo-inverse channel matrix with one or more of the first single-ended measurement signal or the second single-ended measurement signal to generate the equalized measurement signal based at least in part on the predetermined pseudo-inverse channel matrix.

8. The apparatus of claim 1 , wherein one or more channels of the differential measurement system portion include a physical asymmetry.

9. The equalization system comprises: a first noise equalizer for generating an equalized first single-ended measurement signal based at least in part on the first single-ended measurement signal; a second noise equalizer for generating an equalized second single-ended measurement signal based at least in part on the second single-ended measurement signal; a differential driver for generating a differential measurement signal based at least in part on the equalized first single-ended measurement signal and the equalized second single-ended measurement signal.

10. 10. The apparatus of claim 9, wherein the first noise equalizer generates the equalized first single-ended measurement signal based at least in part on a first predetermined pseudo-inverse channel matrix, and the second noise equalizer generates the equalized second single-ended measurement signal based at least in part on a second predetermined pseudo-inverse channel matrix.

11. 2. The apparatus of claim 1, wherein the differential measurement system portion includes a differential amplifier block for generating an analog single-ended difference signal based at least in part on a difference between the first single-ended measurement signal and the second single-ended measurement signal.

12. 12. The apparatus of claim 11, wherein the differential measurement system portion includes a connection block for receiving the first single-ended measurement signal and the second single-ended measurement signal.

13. the differential measurement system portion includes physical channels for carrying the first single-ended measurement signal and the second single-ended measurement signal, respectively; The apparatus of claim 12 , wherein the connection block is operable to be coupled to the physical channel.

14. The equalization system comprises: an analog-to-digital conversion block for generating a digital single-ended differential signal based at least in part on the analog single-ended differential signal; a reconstruction block for generating an uncorrected reconstructed differential signal based at least in part on the digital single-ended difference signal; a correction block for generating a differential measurement signal based at least in part on the uncorrected reconstructed differential signal.

15. 1. A method comprising: obtaining a first single-ended measurement signal and a second single-ended measurement signal; generating an equalized measurement signal based at least in part on a predetermined pseudo-inverse channel matrix and one or more of the first single-ended measurement signal and the second single-ended measurement signal.

16. The method of claim 15 , wherein coefficients of the predetermined pseudo-inverse channel matrix are set to reduce channel effects.

17. generating a single-ended measurement input signal based at least in part on a relationship between the first single-ended measurement signal and the second single-ended measurement signal; generating the equalized measurement signal based at least in part on the predetermined pseudo-inverse channel matrix and the single-ended measurement input signal.

18. generating the equalized measurement signal comprises: generating a first single-ended equalized measurement signal based at least in part on the first single-ended measurement signal and a first predetermined pseudo-inverse channel matrix of the predetermined pseudo-inverse channel matrix; generating a second single-ended equalized measurement signal based at least in part on the second single-ended measurement signal and a second predetermined pseudo-inverse channel matrix of the predetermined pseudo-inverse channel matrix; generating a differential measurement signal based at least in part on the first single-ended equalized measurement signal and the second single-ended equalized measurement signal.

19. 20. The method of claim 18, wherein generating a first single-ended equalized measurement signal comprises multiplying the first single-ended measurement signal with the first predetermined pseudo-inverse channel matrix.

20. 20. The method of claim 18, wherein generating a second single-ended equalized measurement signal comprises multiplying the second single-ended measurement signal with the second predetermined pseudo-inverse channel matrix.

21. 1. A system comprising: The display and a touch sensor including an X electrode and a Y electrode; an equalization system for generating an equalized mutual capacitance measurement signal based at least in part on a single-ended measurement signal received via the Y electrodes of the touch sensor during a mutual capacitance measurement.

22. 22. The system of claim 21, wherein at least some of the lines of X electrodes or the lines of Y electrodes exhibit a non-uniform spatial distribution of noise intensity or noise characteristics.

23. 22. The system of claim 21, wherein the X or Y electrodes comprise lines of non-uniform length.

24. 22. The system of claim 21, wherein the X or Y electrodes comprise a non-uniform number of sensor nodes.

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