Touch sensor panel with multi-power domain chip configuration

Abstract

Embodiments of the present disclosure relate to a touch sensor panel with a multi-power domain chip configuration. The present invention discloses a touch sensing system. The touch sensing system includes a protection signal generating chip operating in a first power domain referenced to a first voltage, and the protection signal generating chip is configured to generate a protection signal. A touch sensing chip operates in a second power domain referenced to the protection signal different from the first power domain, and the touch sensing chip is configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip is a chip different from the protection signal generating chip. A voltage regulator is configured to selectively adjust the voltage of the protection signal at the touch sensing chip.

Description

[0001] This application is a divisional application of an invention patent application with an international application date of July 28, 2017, which entered the Chinese national stage on January 28, 2019, with Chinese national application number 201780046939.3, and invention name “Touch sensor panel with multi-power domain chip configuration”. Technical Field

[0002] The present invention relates generally to touch sensor panels, and more particularly to touch sensor panels in which a touch sensing chip operates in a different power domain than other chips in the touch sensing system. Background Art

[0003] Many types of input devices are currently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens, and the like. In particular, touch screens have become increasingly popular due to their ease and flexibility in operation and their ever-decreasing prices. A touch screen may include a touch sensor panel and a display device such as a liquid crystal display (LCD), the touch sensor panel may be a transparent panel with a touch-sensitive surface, the display device may be partially or completely positioned behind the panel, so that the touch-sensitive surface may cover at least a portion of the visible area of ​​the display device. A touch screen may allow a user to perform various functions by touching the touch sensor panel at a location often indicated by a user interface (UI) displayed by the display device using a finger, stylus, or other object. Generally speaking, a touch screen may identify a touch and the location of the touch on the touch sensor panel, and the computing system may then interpret the touch according to the display content that appears when the touch occurs, and may then perform one or more actions based on the touch. With some touch sensing systems, a physical touch on the display is not required to detect a touch. For example, in some capacitive touch sensing systems, the fringe electric field used to detect a touch may extend beyond the surface of the display, and an object approaching the surface may be detected as being near the surface without actually contacting the surface.

[0004] Capacitive touch sensor panels can be formed from a matrix of substantially transparent or opaque conductive plates (e.g., touch electrodes) made of a material such as indium tin oxide (ITO). As described above, in part because of their substantial transparency, some capacitive touch sensor panels can be overlaid on a display to form a touch screen. Some touch screens can be formed by at least partially integrating touch sensing circuitry into the display pixel stack structure (i.e., the stacked material layers that form the display pixels).

[0005] In some cases, parasitic or stray capacitances may exist between touch electrodes used to sense touches on a touch sensor panel and other components of a device including the touch sensor panel, which are referenced to a frame or ground. These parasitic or stray capacitances may introduce errors and / or offsets into the touch outputs of the touch sensor panel, and thus may reduce the touch sensing dynamic range. Therefore, it may be beneficial to reduce or eliminate such parasitic or stray capacitances. Summary of the invention

[0006] As previously described, there may be parasitic or stray capacitance between the touch electrodes on the touch sensor panel and other components of the device including the touch sensor panel, which may introduce errors and / or offsets into the touch output of the touch sensor panel, thereby reducing the touch sensing dynamic range. Examples of the present disclosure provide various touch sensing system configurations in which the touch sensing chip can operate in a different power domain than other chips in the touch sensing system (i.e., the touch sensing chip can be referenced to a protective ground, which can be different from the chassis or ground ground that can be referenced to other chips in the system). Doing so can reduce or eliminate stray or parasitic capacitance that may exist between the touch electrodes and the chassis or ground ground. This, in turn, can improve the touch sensing performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figures 1A to 1D An exemplary mobile phone, an exemplary media player, an exemplary personal computer, and an exemplary tablet computer are shown, which may each include an exemplary touch screen according to examples of the present disclosure.

[0008] Figure 2 is a block diagram of an exemplary computing system illustrating one specific implementation of an exemplary self-capacitive touch screen according to examples of the present disclosure.

[0009] Figure 3A An exemplary touch sensor circuit corresponding to self-capacitance touch node electrodes and sensing circuits according to examples of the present disclosure is shown.

[0010] Figure 3B An exemplary touch sensor circuit corresponding to mutual capacitance drive, sense lines, and sense circuits according to examples of the present disclosure is shown.

[0011] Figure 4A A touch screen having touch electrodes arranged in rows and columns according to an example of the present disclosure is shown.

[0012] Figure 4B A touch screen having touch node electrodes arranged in a pixelated touch node electrode configuration is shown according to examples of the present disclosure.

[0013] FIG. 5A to FIG. 5BAn exemplary touch sensor panel configuration is shown according to an example of the present disclosure, wherein the touch sensing circuitry of the touch sensor panel is included in an electronic chip (eg, an integrated circuit, etc.) referenced to a ground or chassis ground.

[0014] FIG. 6A to FIG. 6E An exemplary touch sensor panel configuration is shown according to examples of the present disclosure, in which touch sensing circuitry of the touch sensor panel is included in an electronic chip (e.g., an integrated circuit, etc.) that is referenced to a protective ground rather than a chassis or ground ground.

[0015] Fig. 7A An exemplary guard excitation voltage delivery configuration for delivering a guard excitation voltage to a touch sensing chip according to examples of the present disclosure is shown.

[0016] Figure 7B An example according to the present disclosure is shown. Fig. 7A An exemplary protection signal at node A in FIG.

[0017] Fig. 8A An exemplary protection excitation voltage delivery configuration for delivering a protection excitation voltage to a touch sensing chip using a voltage regulator according to an example of the present disclosure is shown.

[0018] Figure 8B Exemplary details of a protection source and a voltage regulator according to examples of the present disclosure are shown.

[0019] Figure 8C The example of the present disclosure shows the voltage regulation generated by the low-side and / or high-side voltage regulation. FIG. 8A to FIG. 8B An exemplary protection signal at node A of FIG.

[0020] Fig.8D Another exemplary protection excitation voltage delivery configuration for delivering a protection excitation voltage to a touch sensing chip according to an example of the present disclosure is shown, wherein a capacitor is selectively coupled to Fig. 7A Node A.

[0021] Fig. 8E An exemplary timing diagram involving a protection signal, a RESET signal, and an output of a sensing circuit during a DC recovery mode according to an example of the present disclosure is shown.

[0022] Figure 8F An exemplary timing diagram involving a protection signal, a RESET signal, and an output of a sensing circuit during a scan step RESET mode according to an example of the present disclosure is shown.

[0023] Fig. 9 An exemplary level shifter configuration according to examples of the present disclosure is shown. DETAILED DESCRIPTION

[0024] In the following description of the examples, reference will be made to the accompanying drawings which form a part of the following description and in which are shown by way of example specific examples that can be implemented. It should be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples.

[0025] Some capacitive touch sensor panels can be formed by a matrix of substantially transparent or opaque conductive plates (e.g., touch electrodes) made of materials such as indium tin oxide (ITO), and some touch screens can be formed by integrating touch sensing circuitry at least partially into a display pixel stack structure (i.e., stacked material layers forming display pixels). In some cases, there may be parasitic or stray capacitance between touch electrodes used to sense touch on a touch sensor panel and other components of a device including the touch sensor panel, which may be referenced to a frame or ground. These parasitic or stray capacitances may introduce errors and / or offsets into the touch output of the touch sensor panel, thereby reducing the touch sensing dynamic range. Therefore, it may be beneficial to reduce or eliminate such parasitic or stray capacitances. Examples of the present disclosure provide various touch sensing system configurations in which a touch sensing chip may operate in a power domain different from other chips in the touch sensing system (i.e., the touch sensing chip may be referenced to a protective ground, which may be different from the chassis or ground ground of other chips that may be referenced to the system). Doing so may reduce or eliminate stray or parasitic capacitances that may exist between the touch electrodes and the chassis or ground ground. This in turn can improve the touch sensing performance of the system.

[0026] Figures 1A to 1D An exemplary system is shown in which a touch screen according to examples of the present disclosure may be implemented. Figure 1A An exemplary mobile phone 136 including a touch screen 124 is shown. Figure 1B An example digital media player 140 including a touch screen 126 is shown. Figure 1C An exemplary personal computer 144 including a touch screen 128 is shown. Figure 1D An exemplary tablet computer 148 is shown that includes a touch screen 130. It should be understood that the above-described touch screen may also be implemented in other devices, including in wearable devices.

[0027] In some examples, touch screens 124, 126, 128, and 130 can be based on self-capacitance. A touch system based on self-capacitance can include a matrix of small individual plates of conductive material, which can be referred to as touch node electrodes (as described below with reference to Figure 2220 in the embodiment of the present invention). For example, the touch screen may include multiple individual touch node electrodes, each touch node electrode identifying or representing a unique location on the touch screen where touch or proximity (i.e., a touch event or proximity event) is to be sensed, and each touch node electrode is electrically isolated from other touch node electrodes in the touch screen / panel. Such a touch screen may be referred to as a pixelated self-capacitance touch screen, but it should be understood that in some examples, the touch node electrodes on the touch screen may be used to perform scans other than self-capacitance scans (e.g., mutual capacitance scans) on the touch screen. During operation, the touch node electrodes may be stimulated with an AC waveform, and the ground self-capacitance of the touch node electrodes may be measured. When an object approaches the touch node electrodes, the self-capacitance to the ground portion of the touch node electrodes may change. Such changes in the self-capacitance of the touch node electrodes may be detected and measured by the touch sensing system to determine the locations of multiple objects when they touch or approach the touch screen. In some examples, the electrodes of a self-capacitance-based touch system may be formed by rows and columns of conductive material, and similar to the above, changes in the self-capacitance to the ground portion of the rows and columns may be detected. In some examples, the touch screen can be multi-touch, single-touch, projection scanning, full-imaging multi-touch, capacitive touch, etc.

[0028] In some examples, touch screens 124, 126, 128, and 130 can be based on mutual capacitance. A touch system based on mutual capacitance can include drive and sense lines that can cross each other on different layers or can be adjacent to each other on the same layer. The crossing or adjacent positions can be referred to as touch nodes. During operation, the drive lines can be excited using an AC waveform, and the mutual capacitance of the touch nodes can be measured. When an object approaches a touch node, the mutual capacitance of the touch node can change. This change in the mutual capacitance of the touch nodes can be detected and measured by the touch sensing system to determine the location of multiple objects when they touch or approach the touch screen.

[0029] Figure 22 is a block diagram of an exemplary computing system 200, which shows a specific implementation of an exemplary self-capacitive touch screen 220 according to an example of the present disclosure. It should be understood that the computing system 200 may alternatively include a mutual capacitance touch screen, as described above, but the examples of the present disclosure will be described assuming that a self-capacitive touch screen is provided. The computing system 200 may be included, for example, in a mobile phone 136, a digital media player 140, a personal computer 144, a tablet computer 148, or any mobile computing device or non-mobile computing device (including wearable devices) including a touch screen. The computing system 200 may include a touch sensing system, which includes one or more touch processors 202, peripherals 204, a touch controller 206, and a touch sensing circuit (described in more detail below). The peripherals 204 may include, but are not limited to, random access memory (RAM) or other types of memory or storage devices, a watchdog timer, and the like. The touch controller 206 may include, but is not limited to, one or more sensing channels 208 and a channel scanning logic component 210. The channel scanning logic component 210 may access the RAM 212, autonomously read data from the sensing channel 208, and provide control for the sensing channel. In some examples, RAM 212 can contain various configuration information for a particular touch screen 220 scan performed by channel scan logic 210 (e.g., specific configuration information for scanning sense channels 208), can receive and / or store touch data from sense channels 208, and can be managed by channel scan logic 210. In addition, channel scan logic 210 can control sense channels 208 to generate stimulus signals of various frequencies and phases that can be selectively applied to touch nodes of touch screen 220, as described in more detail below. In some examples, touch controller 206, touch processor 202, and peripherals 204 can be integrated into a single application specific integrated circuit (ASIC), and in some examples can be integrated with touch screen 220 itself.

[0030] The touch screen 220 may include touch sensing circuitry that may include a capacitive sensing medium (e.g., a pixelated self-capacitance touch screen) having a plurality of electrically isolated touch node electrodes 222. The touch node electrodes 222 may be coupled to the sensing channels 208 in the touch controller 206, may be driven by excitation signals from the sensing channels through the drive / sense interface 225, and may also be sensed by the sensing channels through the drive / sense interface, as described above. In some examples, the drive / sense interface 225 may be implemented in the touch controller 206, or may be implemented in a chip separate from the touch controller 206. Additional exemplary details of how to implement the drive / sense interface 225 may be found in U.S. Patent Application No. 15 / 009,774, filed on January 28, 2016, entitled “Flexible Self Capacitance and Mutual Capacitance Touch Sensing System Architecture,” the entire contents of which are incorporated herein by reference for all purposes. Labeling the conductive plates used to detect touches (i.e., touch node electrodes 222) as "touch node" electrodes may be particularly useful when the touch screen 220 is viewed as capturing an "image" of a touch (e.g., a "touch image"). In other words, after the touch controller 206 has determined the amount of touch detected at each touch node electrode 222 in the touch screen 220, the pattern of touch node electrodes in the touch screen where touches occur may be viewed as a touch image (e.g., a pattern of fingers touching the touch screen).

[0031] The computing system 200 may also include a host processor 228 for receiving output from the touch processor 202 and performing actions based on the output. For example, the host processor 228 may be connected to a program storage device 232 and a display controller such as an LCD driver 234. The LCD driver 234 may provide a voltage to each pixel transistor on a select (e.g., gate) line and may provide data signals to these same transistors along data lines to control the pixels to display an image, as described in more detail below. The host processor 228 may use the LCD driver 234 to generate a display image such as a display image of a user interface (UI) on the touch screen 220, and may use the touch processor 202 and the touch controller 206 to detect a touch on or near the touch screen 220. The touch input may be used by a computer program stored in the program storage device 232 to perform actions, which may include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting a control setting, opening a file or document, viewing a menu, making a selection, executing an instruction, operating a peripheral device connected to the host device, answering a phone call, placing a phone call, terminating a phone call, changing volume or audio settings, storing information related to phone communications (such as addresses, frequently dialed numbers, received calls, missed calls), logging into a computer or computer network, allowing authorized individuals to access restricted areas of a computer or computer network, loading a user profile associated with a user's preferred computer desktop layout, allowing access to web page content, launching a specific program, encrypting or decrypting a message, and the like. The host processor 228 may also perform additional functions that may not be related to touch processing. It should be understood that in some examples, the touch screen 220 need not be integrated into the display module or stacked structure (e.g., need not be within the unit), but may instead be separate from the display module or stacked structure (e.g., a discrete touch sensor panel that is not part of the display and only covers the display or is separate from the display).

[0032] Note that one or more of the functions described herein (including configuration of switches) may be performed by firmware stored in a memory (e.g., Figure 2The firmware may be stored in one of the peripheral devices 204 in the touch processor 202 or stored in the program memory 232 and executed by the host processor 228. The firmware may also be stored and / or delivered in any non-transitory computer-readable storage medium for use or in conjunction with an instruction execution system, device or apparatus such as a computer-based system, a system including a processor, or other system that can obtain instructions from an instruction execution system, device or apparatus and execute the instructions. In the context of this document, a "non-transitory computer-readable storage medium" may be any medium (excluding signals) that can contain or store a program for use or in conjunction with an instruction execution system, device or apparatus. Computer-readable storage media may include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, apparatuses or devices, portable computer disks (magnetic), random access memory (RAM) (magnetic), read-only memory (ROM) (magnetic), erasable programmable read-only memory (EPROM) (magnetic), portable optical disks such as CD, CD-R, CD-RW, DVD, DVD-R or DVD-RW, or flash memory such as compact flash cards, secure digital cards, USB storage devices, memory sticks, etc.

[0033] The firmware may also be transmitted in any transmission medium for use or in conjunction with an instruction execution system, device or apparatus such as a computer-based system, a system including a processor, or other system that can obtain instructions from an instruction execution system, device or apparatus and execute instructions. In the context of this article, a "transmission medium" can be any medium that can transmit, propagate or transmit a program for use or in conjunction with an instruction execution system, device or apparatus. Transmission media may include, but are not limited to, electronic, magnetic, optical, electromagnetic or infrared wired or wireless transmission media.

[0034] Figure 3AAn exemplary touch sensor circuit 300 corresponding to a self-capacitive touch node electrode 302 and a sensing circuit 314 according to an example of the present disclosure is shown. The touch node electrode 302 may correspond to the touch node electrode 222. The touch node electrode 302 may have an inherent self-capacitance C stray 307 to ground associated therewith, and also have an additional self-capacitance C 304 to ground formed when an object such as a finger 305 approaches or contacts the electrode. The total self-capacitance to ground of the touch node electrode 302 may be shown as capacitance C 304 + C stray 307. The finger 305 may have a capacitance C body 309 to ground. Note that C body 309 may typically be much larger than C 304, so that the total series capacitance of C 304 and C stray 307 may be approximately C 304. The touch node electrode 302 may be coupled to the sensing circuit 314. Although other configurations may be used, the sensing circuit 314 may include an operational amplifier 308, a feedback resistor 312, and a feedback capacitor 310. For example, feedback resistor 312 may be replaced by a switched capacitor resistor to minimize parasitic capacitance effects that may be caused by a variable feedback resistor. In some examples, switch 315 may be coupled to feedback resistor 312 (e.g., in parallel with feedback resistor 312 and / or feedback capacitor 310), and switch 315 may be controlled by signal RESET (e.g., the RESET signal may control whether switch 315 is open or closed). By closing and opening switch 315, the touch sensing system of the present disclosure may dynamically change the feedback impedance of sensing circuit 314, which may change its operating characteristics. Details regarding the operation of switch 315 and the RESET signal will be provided later.

[0035] The touch node electrode 302 may be coupled to the inverting input (-) of the operational amplifier 308. The Ac voltage source 306 (Vac) may be coupled to the non-inverting input (+) of the operational amplifier 308. In this way, the touch sensor circuit 300 may be configured to sense changes in the total self-capacitance 304 of the touch node electrode 302 caused by a finger or object touching or approaching the touch sensor panel. The output Vo of the sensing circuit 314 may be filtered and heterodyned or synchronized by feeding to a multiplier 328, where Vo may be multiplied by a local oscillator 330 to obtain V detection. V detection may be input to a filter 332. Those skilled in the art will recognize that the placement of the filter 332 may be varied; thus, the filter may be placed after the multiplier 328, as shown, or two filters may be employed: one before the multiplier and one after the multiplier. In some examples, there is no filter at all. The DC portion of the V detection can be used to determine whether a touch event or proximity event has occurred; for example, the DC portion of the V detection can be used by a processor to determine whether a proximity event or touch event exists, or the output can be input into a discrete logic network to determine whether a proximity event or touch event exists. Note that although Figure 3A The demodulation at the indicator multiplier 328 occurs in the analog domain, but the output Vo can be digitized by an analog-to-digital converter (ADC), and blocks 328, 332 and 330 can be implemented digitally (e.g., 328 can be a digital demodulator, 332 can be a digital filter, and 330 can be a digital NCO (numerically controlled oscillator)).

[0036] Figure 3B An exemplary touch sensor circuit 350 corresponding to mutual capacitance drive 322, sense line 326, and sense circuit 314 according to an example of the present disclosure is shown. Drive line 322 can be excited by an excitation signal 306 (e.g., an AC voltage signal). Excitation signal 306 can be capacitively coupled to sense line 326 via mutual capacitance 324 between drive line 322 and sense line. When a finger or object 305 approaches a touch node created by the intersection of drive line 322 and sense line 326, mutual capacitance 324 can be changed (e.g., capacitance C FD 311 and C FS313), the two capacitors may be formed between the drive line 322, the finger 305, and the sense line 326. Such changes in mutual capacitance 324 may be detected to indicate a touch event or proximity event at the touch node, as previously and below. The sense signal coupled to the sense line 326 may be received by the sense circuit 314. The sense circuit 314 may include an operational amplifier 308 and at least one of a feedback resistor 312 and a feedback capacitor 310. In some examples, a switch 315 may be coupled to the feedback resistor 312 (e.g., in parallel with the feedback resistor 312 and / or the feedback capacitor 310), and the switch 315 may be controlled by a signal RESET (e.g., the RESET signal may control whether the switch 315 is open or closed). By closing and opening the switch 315, the touch sensing system of the present disclosure may dynamically change the feedback impedance of the sense circuit 314, which may change its operating characteristics. Details regarding the operation of the switch 315 and the RESET signal will be provided later.

[0037] Figure 3B The general case of using both resistive and capacitive feedback elements is shown. The sense signal (referred to as Vinput) can be input to the inverting input of the operational amplifier 308, and the non-inverting input of the operational amplifier can be coupled to a reference voltage V 基准 The operational amplifier 308 can drive its output to the voltage Vo to maintain V 输入端 Basically equal to V 基准 , and thus V 输入端 constant or nearly grounded. Thus, the gain of the sensing circuit 314 can be primarily a function of the ratio of the mutual capacitance 324 to the feedback impedance (comprising the resistor 312 and / or the capacitor 310). The output Vo of the sensing circuit 314 can be filtered and heterodyned or synchronized by feeding into a multiplier 328, where Vo can be multiplied by a local oscillator 330 to obtain Vdetect. Vdetect can be input into a filter 332. Those skilled in the art will recognize that the placement of the filter 332 can be varied; thus, the filter can be placed after the multiplier 328, as shown, or two filters can be employed: one before the multiplier and one after the multiplier. In some examples, there is no filter at all. The direct current (DC) portion of Vdetect can be used to determine whether a touch event or proximity event has occurred. Note that although Figure 3B The demodulation at the indicator multiplier 328 occurs in the analog domain, but the output Vo may be digitized by an ADC and blocks 328, 332 and 330 may be implemented digitally (e.g., 328 may be a digital demodulator, 332 may be a digital filter, and 330 may be a digital NCO (numerically controlled oscillator)).

[0038] Refer again Figure 2In some examples, touch screen 220 can be an integrated touch screen in which the touch sensing circuit elements of the touch sensing system can be integrated into the display pixel stacking structure of the display. The circuit elements in touch screen 220 may include, for example, elements that may be present in an LCD or other display, such as one or more pixel transistors (e.g., thin film transistors (TFTs)), gate lines, data lines, pixel electrodes, and common electrodes. In a given display pixel, the voltage between the pixel electrode and the common electrode can control the brightness of the display pixel. The voltage on the pixel electrode can be provided by the data line through the pixel transistor, which can be controlled by the gate line. It should be noted that the circuit element is not limited to the entire circuit component, such as the entire capacitor, the entire transistor, etc., but may include a portion of the circuit, such as one of the two plates of a parallel plate capacitor.

[0039] Figure 4A A touch screen 400 with touch electrodes 404 and 406 arranged in rows and columns is shown according to an example of the present disclosure. Specifically, the touch screen 400 may include a plurality of touch electrodes 404 arranged in rows, and a plurality of touch electrodes 406 arranged in columns. The touch electrodes 404 and the touch electrodes 406 may be located on the same or different material layers on the touch screen 400, and may intersect each other while remaining electrically isolated from each other, such as Figure 4A In some examples, touch screen 400 may sense self-capacitance of touch electrodes 404 and 406 to detect touch activity and / or proximity activity on touch screen 400, and in some examples, touch screen 400 may sense mutual capacitance between touch electrodes 404 and 406 to detect touch activity and / or proximity activity on touch screen 400.

[0040] Figure 4B A touch screen 402 having touch node electrodes 408 arranged in a pixelated touch node electrode configuration is shown according to an example of the present disclosure. Specifically, the touch screen 402 may include a plurality of individual touch node electrodes 408, each of which identifies or represents a unique location on the touch screen where a touch or proximity (i.e., a touch event or proximity event) is to be sensed, and each of which is electrically isolated from other touch node electrodes in the touch screen / panel, as previously described. The touch node electrodes 408 may be located on the same or different material layers on the touch screen 400. In some examples, the touch screen 400 may sense the self-capacitance of the touch node electrodes 408 to detect touch activity and / or proximity activity on the touch screen 400, and in some examples, the touch screen 400 may sense mutual capacitance between the touch node electrodes 408 to detect touch activity and / or proximity activity on the touch screen 400.

[0041] In some examples, the touch sensing circuitry of a touch screen or touch sensor panel (e.g., reference Figure 2 and FIG. 3A to FIG. 3B The touch sensing circuit described herein can be manufactured in an electronic chip (e.g., an integrated circuit, etc.), and the electronic chip and / or the circuit included in the electronic chip can be used with respect to an electronic device (e.g., a touch screen or a touch sensor panel) including the touch screen or the touch sensor panel. Figures 1A to 1D In some examples, the chassis ground can be a ground path from the chassis through a user operating the electronic device to the ground. In some examples, the chassis ground can be the same as the ground ground. However, in some examples, operating the electronic chip and / or the circuits included in the electronic chip relative to the chassis or ground ground may result in undesirable touch sensing performance, as will be described in more detail below.

[0042] FIG. 5A to FIG. 5B An exemplary touch sensor panel configuration 500 is shown according to an example of the present disclosure, wherein the touch sensing circuitry of the touch sensor panel is included in an electronic chip (e.g., an integrated circuit, etc.) referenced to a ground or chassis ground. Figure 5A In configuration 500, the touch sensor panel includes a device having a device chassis 502 (e.g., Figures 1A to 1D Chassis 502 may be grounded to ground 506 (e.g., by a user holding the device or otherwise making contact with the device), or may be grounded to a separate device ground (not shown). Chassis 502 may include electronic chip 504, which may include a chip for sensing information included in the device. Figure 5A For example, chip 504 may include a touch sensing circuit for sensing a touch on a touch sensor panel in a device. Figure 2 The touch controller 206, the drive / sensing interface 225 and / or the touch processor 202 and / or FIG. 3A to FIG. 3B Chip 504 and / or the touch sensing circuitry in chip 504 may be referenced to chassis 502 (e.g., reference ground 506). Chip 504 may be coupled to touch node electrodes 508 via one or more traces, which may be included in Figure 5A Chip 504 may also be coupled to other touch node electrodes included in the touch sensor panel, but only a single touch node electrode 508 is shown for ease of description. Chip 504 may measure the self-capacitance of touch node electrode 508 to detect proximity activity at touch node electrode 508, as described in reference to FIG. Figure 3A discussed.

[0043] Figure 5B An example of using the present disclosure is shown. Figure 5AThe various capacitances associated with proximity detection of the touch sensor panel configuration 500. Specifically, a finger (or object) 510 can approach a touch node electrode 508. The finger 510 can be detected by a capacitance 512 (e.g., C 身体 ) is grounded to ground 506, which may represent the capacitance from finger 510 through the user's body to ground 506. Capacitor 514 (e.g., C 触摸 ) may represent the capacitance between the finger 510 and the touch node electrode 508, and may be a target capacitance for determining the extent to which the finger 510 contacts the node electrode 508. The capacitance 514 may be determined by a sensing circuit 522 (e.g., as shown in FIG. 5B ) included in the chip 504. Figure 3A ) to determine the amount of touch at touch node electrode 508. However, because touch node electrode 508 may be proximate to chassis 502 (e.g., due to being included in a device of which chassis 502 is a part), which chassis may be grounded to ground 506, a capacitor 516 (e.g., C ) may be provided between touch node electrode 508 and chassis 502. p ) and / or between the trace connecting the touch node electrode 508 to the sensing circuit 522 and the chassis 502 (represented by the capacitor 518 (e.g., C s ) indicates that parasitic or stray capacitances may be present. These stray capacitances 516 and 518 may also be measured by the sensing circuit 522 and may produce an offset in the output signal of the sensing circuit 522 (e.g., an output signal away from zero), which may reduce the touch signal-to-noise ratio (or touch dynamic range) of the sensing circuit 522. This, in turn, may reduce the touch-related capacitance (e.g., C 触摸 514), thereby possibly limiting the touch sensing performance of the touch sensor panel including the touch node electrode 508.

[0044] In order to reduce or eliminate parasitic or stray capacitance that can be measured by the sensing circuit in the touch sensing chip of the touch sensor panel, a guard plane can be established between the touch-related components of the touch sensor panel (e.g., touch node electrodes 508, touch sensing chip 504, etc.) and one or more portions of the chassis 502 (e.g., the surface of the chassis 502 corresponding to the backplane of the device). The guard plane including the touch sensing chip (e.g., integrated circuit, etc.) can be referenced to a guard potential that can be mirrored or identical to the excitation signal used to excite the touch node electrodes on the touch sensor panel. In this way, the voltages on both sides of the above-mentioned parasitic or stray capacitance can be mirrored to each other, so that those capacitances are out of touch sensing measurements performed by the touch sensing circuit in the touch sensing chip. Therefore, the signal portion (outside of the readout amplifier 522) associated with the undesired stray capacitance can be greatly reduced, thereby improving the touch dynamic range and touch sensing performance of the touch sensor panel. It should be understood that a "guard plane" need not refer to a planar element or electrode; rather, the guard plane of the present disclosure may be implemented in any number of ways, including being non-planar, being comprised of one or more portions of the device that are driven / held at a guard potential, and being implemented in different ways in different portions of the device (e.g., as part of a flexible circuit in one portion of the device, as part of a touch sensor panel in another portion of the device, etc.).

[0045] FIG. 6A to FIG. 6C An exemplary touch sensor panel configuration 600 is shown according to an example of the present disclosure, wherein the touch sensing circuitry of the touch sensor panel is included in an electronic chip (e.g., an integrated circuit, etc.) that is referenced to a protective ground instead of a chassis or ground. Fig. 6A In the configuration 600 of FIG. 6A , a touch sensing chip 604 (e.g., corresponding to the touch sensing chip 504) is disposed or fabricated on a guard plane 620, which can represent a virtual ground plane of the touch sensing chip 604 that is distinct from a chassis or ground ground 606. Specifically, an excitation source 626 (“guard source”) can reference the chassis or ground ground 606 and can output a guard voltage (e.g., a guard excitation signal, such as a square wave) that can establish a voltage at the guard plane 620. The excitation source 626 can be included on the chip, separate from the touch sensing chip 604. Because the touch sensing chip 604 can be built on the guard plane 620, circuits (e.g., touch sensing circuits) included in the touch sensing chip 604 can reference the guard signal and can be isolated from the chassis or ground ground 606 by the guard plane 620. In other words, the touch sensing chip 604 and the chip including the protection source 626 may operate in different “power domains”: the touch sensing chip 604 may operate in the protection power domain, and the protection source 626 may operate in the chassis or ground power domain.

[0046] In addition, guard plane 624 can be disposed between touch node electrodes 608 and chassis 602 (or, more generally, ground 606), and guard plane 628 can be disposed between traces coupling touch node electrodes 608 to touch sensing chip 604 and chassis 602 (or, more generally, ground 606). Guard plane 624 and guard plane 628 can also be excited by the same guard voltage as guard plane 620. These guard planes 624 and 628 can similarly isolate touch node electrodes 608 and traces coupling touch node electrodes 608 to touch sensing chip 604 from chassis or ground 606. One or more of guard planes 620, 624, and 628 can reduce or eliminate parasitic or stray capacitance that may exist between touch node electrodes 608 and chassis or ground 606, as will be described below.

[0047] Figure 6B An example for implementing the present disclosure is shown. Fig. 6A601. Specifically, as previously described, the protection source 626 can provide a protection excitation voltage to the protection plane 620, on which the touch sensing chip 604 can be disposed or manufactured and can be referred to. The protection plane 620 can be any conductive material (e.g., silver, copper, gold, etc.) on which the touch sensing chip 604 can be disposed or manufactured. For example, the touch sensing chip 604 can be assembled on a flexible circuit or printed circuit board (PCB), and can be referred to as a flexible circuit or PCB ground layer 620 driven by the protection source 626. The protection source 626 can be manufactured in an electronic chip that is different from and separate from the touch sensing chip 604, and the electronic chip that manufactures the protection source 626 can be referred to as a chassis or ground ground 606. The touch sensing chip 604 (e.g., the touch sensing circuit in the touch sensing chip 604) can be coupled to the touch node electrodes 608A, 608B, 608C, and 608D (and other touch node electrodes included in the touch electrode and wiring layer 634 of the touch sensor panel 630, collectively referred to as 608) in the touch sensor panel 630 via traces 632 included on the flexible circuit that couples the touch sensing chip 604 to the touch sensor panel 630. The flexible circuit can include top 628A and bottom 628B shields that sandwich the traces 632 on both sides and can also be coupled to the protection source 626. Finally, the touch sensor panel 630 can also include top 624A and bottom 624B shields that sandwich the touch node electrodes 608 on the touch electrode and wiring layer 634 on both sides and can also be coupled to the protection source 626. In some examples, the material of the shield 628 in the flexible circuit can be different from the material of the shield 624 in the touch sensor panel 630. For example, shield 624 in touch sensor panel 630 can be made of the same material as the material from which touch node electrodes 608 are made (e.g., ITO or other substantially transparent conductors), and shield 628 in the flex circuit can be made of a different conductor, such as copper, aluminum, or other transparent or opaque conductors. Top shield 624A can include openings 609A (e.g., corresponding to touch node electrodes 608A), 609B (e.g., corresponding to touch node electrodes 608B), 609C (e.g., corresponding to touch node electrodes 608C), and 609D (e.g., corresponding to touch node electrodes 608D), which allow touch node electrodes 608A, 608B, 608C, and 608D, respectively, to detect touch activity on touch sensor panel 630 from above while protecting the touch electrodes and routing on routing layer 634 from stray capacitance that may be formed due to a touch or other stray capacitance. Thus, the touch signal path from the touch sensor panel 630 to the flexible circuit of the touch sensing chip 604 can be referenced to the protection potential provided by the protection source 626 and can be isolated from the chassis or ground ground 606.

[0048] Figure 6C An example of the present disclosure is shown. Fig. 6A The touch sensor panel configuration 600 and / or Figure 6B The various capacitances associated with proximity detection of the touch sensor panel configuration 601. Except as otherwise described below, Figure 6C The configuration 602 can be used with Figure 5B Specifically, a finger (or object) 610 may approach a touch node electrode 608. The finger 610 may be moved through a capacitor 612 (e.g., C 身体 ) is grounded to ground 606, which may represent the capacitance from finger 610 through the user's body to ground 606. Capacitor 614 (e.g., C 触摸 ) may represent the capacitance between the finger 610 and the touch node electrode 608, and may be a target capacitance for determining the extent to which the finger 610 contacts the node electrode 608. Typically, C 身体 612 can be significantly greater than C 触摸 614, so that the equivalent series capacitance through the finger 610 seen at the touch node electrode 608 can be approximated as C 触摸 614. Capacitor 616 may represent the touch node electrode 608 and the shield 624 (e.g., Figure 6B 624A and 624B in FIG. 1 ), and capacitance 618 may represent the capacitance between trace 632 and shield 628 (eg, Figure 6B The capacitance between the shields 628A and 628B in the printed circuit board 623). The touch sensing chip 604 can be mounted on (e.g., arranged or manufactured on) a printed circuit board 623, which can have a ground layer 620, and the touch sensing chip 604 and the touch sensor panel can refer to the ground layer. In some examples, the ground layer 620 can be included in the printed circuit board 623 (e.g., as a conductive layer in a printed circuit board layer), or the ground layer 620 can be a separate conductive plate, and the printed circuit board 623 can be mounted on the conductive plate. In the case where the ground layer 620 is included in the printed circuit board 623, the output of the protection source 626 can be directly input into the ground layer 620 within the printed circuit board 623. The protection plane 620 and the shields 624 and 628 can be excited by the protection power supply 626 at a protection voltage, as referenced FIG. 6A to FIG. 6B The protection source 626 can also be used to drive the touch node electrode 608 through the touch sensing circuit 622 (e.g., because the virtual ground coupled to the inverting input of the sense amplifier 622 and / or the touch node electrode 608 can follow the voltage reference of the sense amplifier 622, which can be the protection voltage provided by the protection source 626 coupled to the non-inverting input of the sense amplifier 622) to detect a touch at the touch node electrode 608 (e.g., as referenced Figure 3A as described), Figure 6C Because the voltage at the touch node electrode 608 and the trace 632 can mirror or follow the voltage at the shields 624 and 628, the capacitances 616 and 618 for touch measurements performed by the touch sensing circuit 622 can be reduced or eliminated. In this way, the touch sensing circuit 622 can simply detect C 触摸 614, which can be represented as a virtual mutual capacitance between the finger 610 and the touch node electrode 608, such as Fig.6D As shown. Without stray capacitances 616 and 618 affecting touch measurements performed by touch sensing circuit 622, offsets in the output signal of sensing circuit 622 (e.g., when no touch is detected at touch node electrode 608) can be greatly reduced or eliminated, which can increase the signal-to-noise ratio and / or the dynamic range of sensing circuit 622. This in turn can improve the ability of touch sensing circuit 622 to detect a wider range of touches at touch node electrode 608 and accurately detect smaller capacitances C 触摸 614 (and therefore, accurately detect hovering activity at touch node electrodes 608 at larger distances). In addition, with a near-zero offset output signal from the touch sensing circuit 622, the effects of drift due to environmental changes (e.g., temperature changes) can be greatly reduced. For example, if the signal outside the sense amplifier 622 consumes 50% of its dynamic range due to undesired / unprotected stray capacitance in the system, and the analog front end (AFE) gain varies by 10% due to temperature, the output of the sense amplifier 622 will drift by 5% and the effective signal-to-noise ratio (SNR) can be limited to 26 dB. By reducing the undesired / unprotected stray capacitance by 20 dB, the effective SNR can be improved from 26 dB to 46 dB.

[0049] Additionally, as described in the present disclosure, implementing the touch sensing chip 604 as a separate chip from the protection source 626 may provide benefits in addition to those described above. Specifically, separating the touch sensing chip 604 from the protection source 626 may enable higher protection signal voltage levels (which may also be used to stimulate the touch node electrodes 608) that may be beyond the range possible with a single chip implementation (e.g., an implementation in which the touch sensing chip 604 and the protection source 626 are included in a single chip).

[0050] Fig.6D FIG. 1 shows a graph depicting C as a virtual mutual capacitance between a finger 610 and a touch node electrode 608 as described above according to an example of the present disclosure. 触摸 614. Specifically, due to the shielding provided by shields 624 and 628, the Figure 6C The capacitances 616 and 618, C, of ​​the touch measurement performed by the touch sensing circuit 622 触摸614 can appear as a virtual mutual capacitance between the finger 610 and the touch node electrode 608, which can be coupled to the inverting input of the sensing circuit 622. Specifically, the finger 610 can be connected to the protection source 626 via C 身体 612 excitation, and the finger 610 may have C between it and the inverting input terminal of the sensing circuit 622 触摸 614. Therefore, C can be sensed by sensing circuit 622 触摸 614, as the virtual mutual capacitance C between the finger 610 and the sensing circuit 622 触摸 614. In this way, the offset in the output signal of the sensing circuit 622 (e.g., when no touch is detected at the touch node electrode 608) can be greatly reduced or eliminated, as described above. As a result, the sensing circuit 622 (e.g., the input stage of the sensing circuit 622) does not need to support the self-capacitance sensing circuit (e.g., Figure 3A The sensing circuit 314 in may additionally need to support a dynamic input range in environments / configurations that do not exhibit the virtual mutual capacitance effects described herein.

[0051] Because the self-capacitance measurement of the touch node electrodes in the touch screen configuration of the present disclosure can exhibit the virtual mutual capacitance characteristics as described above, in some examples, the touch sensing chip 604 does not need to be a chip that supports self-capacitance measurement (for example, the touch sensing chip 604 may not include a self-capacitance sensor such as a touch sensor chip 604). Figure 3A In contrast, the touch sensing chip 604 may be a standard mutual capacitance touch sensing chip that only supports mutual capacitance measurement (eg, the touch sensing chip 604 may include a touch sensing circuit 314 as described in FIG. 1 ). Figure 3B The sensing circuit 314 described in Figure 3A In such an example, although the touch sensing chip 604 is a mutual capacitance touch sensing chip rather than a self capacitance touch sensing chip, the protection source 626 can be appropriately designed and used with the mutual capacitance touch sensing chip in various configurations (e.g., configuration 600) of the present disclosure to effectively implement the protection self capacitance function of the present disclosure. Figure 3B , the excitation source 306 (e.g., the guard source 626) can excite the guard plane of the present disclosure, which can be used as a drive electrode in the virtual mutual capacitance configuration described herein. The touch node electrodes of the touch sensor panel can then be regarded as sense electrodes in the virtual mutual capacitance configuration described herein and can be coupled to Figure 3B The input terminal of the sense amplifier 308 in. Then, Figure 3B The touch sensing circuit 314 in the embodiment can sense the mutual capacitance between the guard plane and the touch node electrode, which can be represented by Fig.6D The circuit configuration is shown in FIG.

[0052] Fig. 6E An exemplary configuration of a protection source 626 according to an example of the present disclosure is shown. Specifically, the protection source 626 may include a direct digital synthesizer (DDS) 650 (e.g., a direct waveform synthesis generator), which may generate an arbitrary waveform (such as a square wave) and may be referenced to a ground 606. The output of the DDS 650 may be input to a digital-to-analog converter (DAC) 652, which may convert the output of the DDS 650 into a corresponding analog signal. The output of the DAC 652 may be input to a non-inverting input of a linear buffer 654 (e.g., a unity gain buffer, but it should be understood that the buffer 654 may alternatively have a non-unity gain configuration). The output of the linear buffer 654 may correspond to the output of the protection source 626, as previously described, and may provide a protection signal to the protection plane 620. The inverting input of the linear buffer 654 may be coupled to the output of the linear buffer 654 to facilitate the feedback function of the linear buffer 654. In some examples, the inverting input of the linear buffer 654 may be coupled to the output of the linear buffer 654 at a location away from the protection source 626; for example, Fig. 6E As shown, the inverting input of the linear buffer 654 may be coupled to the node A at the guard plane 620. In this way, the effect of a resistance that may exist between the output of the linear buffer 654 and the node A at the guard plane 620 may be reduced (e.g., because the resistance may be included in the feedback loop of the linear buffer 654, which in turn may improve the accuracy of the voltage delivered by the protection source 626 to the guard plane 620).

[0053] It should be understood that Fig. 6E The example of FIG. 650 may show a voltage mode DAC (e.g., DAC 652) and a subsequent buffer (e.g., buffer 654). However, in some examples, DAC 652 may be a current mode DAC (iDAC), and buffer 652 may be a transimpedance amplifier (TIA) type buffer that may convert the current from the iDAC to a buffer output voltage (e.g., similar to the above description of FIG. 651 ). Fig. 6E described).

[0054] Because the protection signal provided to the touch sensing chip of the present disclosure can be used as an excitation signal for sensing touch on the touch node electrodes on the touch sensor panel, it may be important to have a known protection signal that is noise stable and / or noise-free because noise in the protection signal can directly introduce errors into the measured touch values ​​at the touch node electrodes. In addition, because the touch sensing chip can be separated from the protection source chip, the resistance of the bonding pads, wires, or other coupling circuits / components between the touch sensing chip and the protection source chip may be large. This substantial resistance can cause the protection signal reaching the touch sensing chip to be different from the protection signal output by the protection source, such as referring to FIG. 7A to FIG. 7B as described.

[0055] Specifically, Fig. 7A An exemplary guard excitation voltage delivery configuration 700 for delivering a guard excitation voltage to a touch sensing chip 704 according to an example of the present disclosure is shown. The touch sensing chip 704 may be referenced, disposed, and / or fabricated on a guard plane 720, as previously described. The guard ground 707 may represent a virtual ground provided by the guard plane 720. The guard source 726 may be a buffer or other amplifier circuit having an output coupled to the guard plane 720 and outputting a guard signal 721. The guard source 726 may be included in a reference chassis or ground ground 706 chip and may be coupled to the guard plane 720 via one or more of bonding pads, wires, traces, and the like.

[0056] Circuits in the touch sensing chip 704, such as the touch sensing circuit 622 described above (e.g., amplifier 308, multiplier 328, filter 332, etc.), may require two voltage rails to operate—a low voltage rail (e.g., provided by the guard plane 720 stimulated by the guard signal 721) and a high voltage rail (e.g., a voltage rail having a higher or more positive voltage than the guard plane 720). As described above, the voltage of the low voltage rail may be provided to the touch sensing chip 704 by the guard source 726, which may stimulate the guard plane 720 with the guard signal 721. In order to provide the high voltage rail to the touch sensing chip 704, a capacitor 730 may be coupled between the guard plane 720 and a high voltage input terminal 732 of the touch sensing chip 704. The capacitor 730 may be charged until a specified direct current (DC) voltage is established across the capacitor 730, which may provide a high voltage (referenced to the guard signal 721 on the guard plane 720) to the touch sensing chip 704. For example, one terminal of the capacitor 730 may be coupled to the guard plane 720 at node A, and the other terminal of the capacitor 730 may be coupled to a switch 734, which may be coupled to a DC voltage source 736 referenced to a chassis or ground ground 706. When the guard signal 721 output by the guard source 726 is low (e.g., substantially the voltage at the chassis or ground ground 706, such as 0V), the switch 734 may be closed (e.g., the device may be configured to close the switch 734 through a control signal when the guard signal 721 is low, or the switch 734 may be configured to close itself when the guard signal 721 is low), and the DC voltage source 736 may charge the capacitor 730 to a desired DC voltage offset between a low voltage rail (e.g., the guard plane 720) and a high voltage rail of the touch sensing chip 704. For example, the DC voltage offset may be on the order of 3V or 4V, but other voltages are also within the scope of the present disclosure. In some examples, capacitor 730 can be charged beyond a desired DC voltage offset between a low voltage rail and a high voltage rail of touch sensing chip 704, and the excess DC voltage on capacitor 730 can be regulated by a regulator 738 (e.g., a low dropout or LDO regulator) in touch sensing chip 704 to a final desired voltage of the high voltage rail for use by circuits in the touch sensing chip (e.g., touch sensing circuit 622).

[0057] When the protection signal 721 output by the protection source 726 is high (e.g., a voltage greater or more positive than the chassis or ground 706, such as 2V, 3V, 4V, etc.), the switch 734 can be opened (e.g., the device can be configured to open the switch 734 through a control signal when the protection signal 721 is high, or the switch 734 can be configured to open itself when the protection signal 721 is high). In other words, the switch 734 can be opened when the protection signal 721 changes from low to high, and the switch 734 can be closed when the protection signal 721 changes from high to low. When the switch 734 is open, the capacitor 730 can provide its voltage to the high voltage input terminal 732, which can be adjusted by the regulator 738 to the final desired voltage of the high voltage rail in the touch sensing chip 704. In this way, a voltage appropriately offset from the protection signal 721 can be provided to the high voltage rail of the touch sensing chip 704 during various states of the protection signal 721. Because the voltage regulator 738 can be referenced to the ground 707, which can be referenced to the protection signal, the operation of the voltage regulator 738 does not need to change when the protection signal transitions between low and high—the voltage rails of the voltage regulator 738 (e.g., the ground 707 and the high voltage rail of the touch sensing chip 704) can maintain their predetermined relationship, and the voltage regulator 738 can operate without regard to the voltage transition in the protection signal. In some examples, the switch 734 can be current limited or otherwise regulated to reduce or minimize the inrush current into the capacitor 730 (e.g., limited to only allow current below a current threshold), and / or reduce or minimize load current changes from the voltage source 736. The low voltage rail and the high voltage rail of the touch sensing chip 704 (e.g., provided by the protection source 626) can have a predetermined relationship relative to the “ground” 707 of the touch sensing chip 704. Thus, when the voltage output by protection source 626 alternates (e.g., between a low voltage and a high voltage), the voltages on the low voltage and high voltage rails of touch sensing chip 704 can similarly alternate so that a predetermined relationship of those voltages relative to ground 707 can be maintained.

[0058] In some examples, voltage source 736, switch 734, and protection source 726 may be included in one chip (e.g., a protection source chip), and capacitor 730 may be a discrete component (e.g., separate from touch sensing chip 704 and the chip including protection source 726) coupled in an electrical path between the protection source chip and touch sensing chip 704. In some examples, capacitor 730 may be included in touch sensing chip 704 if the current requirements of capacitor 730 / touch sensing chip 704 are small enough.

[0059] In some examples, especially when the touch sensing chip 704 is separated from the chip on which the protection source 726 is disposed or fabricated, the resistance between the protection source 726 and the output of the node A (e.g., the node is on or near the touch sensing chip 704, where the protection plane 720 and the capacitor 730 can be coupled) can be large. These resistances (which may include resistances such as the output resistance of the protection source 726, the trace resistance between the protection source 726 and the touch sensing chip 704, the resistance of the bonding pad, etc.) can be determined by Fig. 7A 728 in. In addition, during the time period when the protection signal 721 is low and when the switch 734 is closed to charge the capacitor 730, a current may flow from the DC voltage source 736, through the capacitor 730, the resistor 728 and the protection source 726 to the chassis or ground ground 706 via the current path 740. This current that may flow through the resistor 728 may cause the voltage at the node A to be different (e.g., higher or more positive) than the voltage at the output of the protection source 726. In addition, the current may vary over time, and as the capacitor 730 is charged to the desired DC voltage by the DC voltage source 736, the current may decrease. Therefore, the amount by which the voltage at the node A differs from the voltage at the output of the protection source 726 may also vary as a function of time when the protection signal 721 is low.

[0060] Figure 7B An example according to the present disclosure is shown. Fig. 7A An exemplary protection signal 721 at node A in FIG. A solid line 723 may represent a signal to be provided to Fig. 7A 721 at node A in FIG. 700 . When the protection signal 721 transitions from high to low, due to the resistor 728 and the current path 740, instead of reaching the desired low voltage point immediately, the protection signal at node A may gradually reach the desired low voltage point over time, as shown by the dotted line 725. In some examples, when the protection signal transitions from low to high, the protection signal 721 at node A may not reach the desired low voltage point. Therefore, the protection signal 721 at node A may be unknown and may change over time, which may cause errors in touch sensing performance, as described above. In other words, because the protection signal 721 at node A can be used by the touch sensing circuit in the touch sensing chip 704 to sense the touch on the touch sensor panel, the error in the protection signal voltage at node A may directly introduce errors into the touch signal output by the touch sensing circuit. Therefore, it may be desirable to include a mechanism for better regulating the voltage at node A in the configuration 700, especially when the protection source 726 and the touch sensing circuit are included in separate and different chips.

[0061] Fig. 8AAn exemplary voltage delivery configuration 800 is shown for delivering voltage to a touch sensing chip 804 using a voltage regulator 842 according to an example of the present disclosure. In addition to the configuration 800 including a voltage regulator 842 coupled between node A and a protection source 826, Fig. 8A The configuration 800 can be used with Fig. 7A 826). For example, switch 834 (similar to switch 734) can be current limited or otherwise regulated to reduce or minimize inrush current into capacitor 830 (e.g., limited to only allow current below a current threshold), and / or reduce or minimize load current variations from voltage source 836. Other components of configuration 800 can be similarly the same as those of configuration 700. Regulator 842 can regulate the voltage at node A when protection signal 821 is low and / or high, as will be described in more detail below, to provide a stable and known protection signal for protection plane 820 and used by touch sensing chip 804.

[0062] Figure 8B 858 (although other configurations of the protection source 826 may also be used), wherein the source of the P-FET 856 may be coupled to the high voltage rail 854, the drain of the P-FET 856 may be coupled to the drain of the N-FET 858, and the source of the N-FET 858 may be coupled to the chassis or ground ground 806. The protection source 826 may have an input terminal 846 and an input terminal 848, which may provide input voltage signals to the P-FET 856 and the N-FET 858, respectively. For example, when the protection source 826 is to output a high voltage, the input terminals 846 and 848 may be low voltages, causing the P-FET 856 to turn on and the N-FET 858 to turn off. Similarly, when the protection source 826 is to output a low voltage, the input terminals 846 and 848 may be high voltages, causing the P-FET 856 to be turned off and the N-FET 858 to be turned on. Node B may represent the output node of the protection source 826. Node B may be coupled to node A (corresponding to Fig. 8A Node A in the resistor R 输出端 828A and R 迹线 828B (which may correspond to the output resistance of the protection source 826 and the resistance of the trace coupling the protection source 826 and the node A, respectively) may represent the resistance between the node A and the protection source 826 .

[0063] The voltage regulator 842 may be coupled between the node A and the protection source 826. Specifically, the voltage regulator 842 may include an amplifier 844 having two inputs: an input from the node A coupled to the non-inverting input of the amplifier 844, and a V coupled to the inverting input of the amplifier 844. 目标保护 , which may be the desired protection voltage at node A. The output of amplifier 844 (and regulator 842) may be coupled to input 848 via adder 852. In addition, regulator 842 may receive an enable signal that may control whether amplifier 844 is operable, as will be discussed below. The enable signal may be timed to protect signal 821 output by protection source 826 (e.g., using appropriate circuitry to provide precise timing control), such that when protection signal 821 is low, the enable signal may be active (e.g., high), which may cause amplifier 844 to be operable (e.g., amplifier 844 may output a signal), and when protection signal 821 is high, the enable signal may be inactive (e.g., low), which may cause amplifier 844 to be inoperable (e.g., amplifier 844 may not output a signal).

[0064] The operation of the voltage regulator 842 and the protection source 826 will now be described. The voltage regulator 842 can perform low-side and / or high-side voltage regulation at node A. Figure 8B Although low-side voltage regulation (e.g., regulating the voltage at node A when the protection signal 821 is low) is described, it should be understood that high-side voltage regulation (e.g., regulating the voltage at node A when the protection signal 821 is high) can be similarly implemented. For example, when the protection signal 821 output by the protection source 826 is low, the regulator 842 can regulate the voltage at node A. Specifically, the output terminal of the regulator 842 can be coupled to the input terminal 848, such as Figure 8B As shown, when the protection signal 821 is low, V 目标保护 Set to the desired voltage at node A. For example, V 目标保护 It can be a voltage slightly above chassis or ground 806, such as 0.1V or 0.2V. When protection signal 821 is low, the enable signal input to regulator 842 can be active, which can make amplifier 844 operational, but if the voltage at node A deviates from V 目标保护 , the amplifier 844 can output a signal corresponding to the deviation, which can be added to the input terminal 848 through the adder 852 to change the gate voltage of the N-FET 858 until the voltage at the node A reaches V 目标保护 . In this way, even if the current can flow through R 输出端 828A and R 迹线 828B, and even if the current varies with time (e.g., as shown in reference Fig. 7A), the voltage regulator 842 can also maintain the voltage at node A at V 目标保护 It should be noted that due to R 输出端 828A and R 迹线 The existence of 828B, V 目标保护 may not be set to a voltage (e.g., 0 V) ​​at the chassis or ground ground 806. Thus, the voltage at node A may not reach the chassis or ground ground 806 when the protection signal is low, but may instead remain at a level slightly above the chassis or ground ground 806 (e.g., 0.1 V, 0.2 V, etc.).

[0065] As previously described, the voltage regulator 842 (or an independent voltage regulating circuit similarly constructed and / or operating as the voltage regulator 842) may additionally or alternatively perform high-side voltage regulation at the node A. For example, when the protection signal 821 output by the protection source 826 is high, such a voltage regulating circuit may regulate the voltage at the node A. Specifically, the output terminal of such a voltage regulating circuit may be coupled to the input terminal 846, and when the protection signal 821 is high, the V used for the voltage regulating circuit may be increased. 目标保护 Set to the desired voltage at node A. For example, V 目标保护 It can be a voltage slightly higher than the high voltage rail 854 (e.g., 0.1V, 0.2V, etc. higher than the high voltage rail). 目标保护 , the voltage regulation circuit can output a signal corresponding to the deviation, which can be added to the input terminal 846 through the adder to change the gate voltage of the P-FET 856 until the voltage at the node A reaches V 目标保护 . In this way, even if the current can flow through R 输出端 828A and R 迹线 828B, and even if the current varies with time (e.g., as shown in reference Fig. 7A The voltage regulation circuit can also maintain the voltage at node A at V 目标保护 It should be noted that due to the existence of R 输出端 828A and R 迹线 828B, V 目标保护 may not be set to the voltage at high voltage rail 854 (e.g., current can flow from node A through R 输出端 828A and R 迹线 828B to high voltage rail 854). Therefore, when the protection signal is high, the voltage at node A may not reach the voltage at high voltage rail 854, but may be maintained at a level slightly higher than the voltage at high voltage rail 854 (e.g., higher than 0.1V, 0.2V, etc.).

[0066] Figure 8C The example of the present disclosure shows the voltage regulation generated by the low side voltage regulation. FIG. 8A to FIG. 8B An exemplary protection signal 821 at node A of FIG. 823 may represent an example protection signal 821 at node A of FIG. FIG. 8A to FIG. 8B 821, and the dashed line 825 may correspond to the voltage at node A maintained by the voltage regulator 842. As shown, the voltage maintained by the voltage regulator 842 at node A during the time period when the protection signal 821 is low may deviate slightly from the ideal voltage; however, the voltage at node A may be stable and known, and therefore may not interfere with accurate touch detection by the touch sensing chip 804. In the case of implementing high-side voltage regulation, the voltage maintained at node A during the time period when the protection signal is high may similarly deviate slightly from the ideal voltage (e.g., slightly higher than the ideal voltage), as described above.

[0067] Fig.8D Another exemplary voltage delivery configuration 801 for delivering voltage to a touch sensing chip 804 according to an example of the present disclosure is shown, wherein a capacitor 830 is selectively coupled to a node A. In addition to the configuration 801 including a switch 835 coupled between the capacitor 830 and the node A, Fig.8D The configuration 801 can be used with Fig. 7A Specifically, as described above, when the protection signal 821 is low, the current flowing from the voltage source 836 through the capacitor 830 and the resistor 828 to the protection source 826 may cause the voltage at the node A to fluctuate from the desired or known protection voltage. To address this issue, in the configuration 801, the switch 835 may be coupled between the capacitor 830 and the node A, such as Fig.8D As shown. When the protection signal 821 is low (e.g., at or near the ground or chassis ground 806), the switch 835 can couple the capacitor 830 to the node B, which can be coupled to the ground or chassis ground 806, and can decouple the capacitor 830 from the node A. In this way, the capacitor 830 can continue to be coupled to the low voltage level of the protection signal 821 (e.g., at or near the ground or chassis ground 806), which can be provided by the node B instead of the protection source 826. When the protection signal 821 is high, the switch 835 can couple the capacitor 830 to the node A, and can decouple the capacitor 830 from the node B. Therefore, when the protection signal 821 is low, there is no path for current to flow from the voltage source 836 through the capacitor 830 and the resistor 828 to the protection source 826 because the switch 835 can decouple the capacitor 830 from the node A when the protection signal 821 is low. Conversely, when the protection signal 821 is low, current can flow from the voltage source 836 through the capacitor 830 directly to the ground or chassis ground 806 through the node B, to which the switch 835 can couple the capacitor 830 when the protection signal 821 is low. FIG. 8B to FIG. 8CIn the case of the voltage regulator 842 in FIG. 8 , the effect of this current on the voltage at node A is reduced or eliminated. More generally, the voltage at node B can be the expected low voltage output of the protection source 826 (e.g., chassis ground, 1V below chassis ground, 1V above chassis ground, etc.), except that the voltage at node B is not provided by the protection source 826, but rather by another separate voltage source that outputs a low voltage value corresponding to the low side of the protection signal 821 to node B.

[0068] The switch 835 can be implemented as a physical switch, a solid-state switch (e.g., including one or more transistors), or any other design for performing the above functions. In some examples, the switch 835 can be current-limited or otherwise regulated to reduce or minimize the inrush current into / through the capacitor 830 (e.g., limited to only allow current below a current threshold), and / or reduce or minimize the load current variation from the voltage source 836. In addition, in some examples, the switch 835 can switch between nodes A and B synchronously with the protection signal 821 switching between low and high (e.g., the switch 835 can switch from node A to node B at the same time as the protection signal 821 transitions from high to low, etc.). However, in other examples, the switch 835 may switch between nodes A and B simultaneously but slightly delayed relative to the transition of the protection signal 821 between low and high (e.g., the switch 835 may switch from node A to node B at a predetermined time after the protection signal 821 transitions from high to low, etc.) so as to reduce spikes or other fluctuations in voltage that may occur at node A when the switch 835 decouples the capacitor 830 from nodes A or B and couples the capacitor 830 to nodes B or A, respectively. In such examples, the timing delay of the switch 835 switching between nodes A and B may be predetermined (e.g., a predetermined time, a predetermined change in the voltage of the protection signal 821 during the transition between low and high, etc.). In some examples, as described above, circuitry external to the switch 835 may control the switching of the switch 835 between nodes A and B (e.g., by monitoring the elapse of time since the protection signal transitions from low to high, by monitoring the voltage of the protection signal 821 and / or the voltage at node A since the protection signal transitions from low to high, etc.).

[0069] As indicated above, the protection buffer of the present disclosure (eg, Fig. 6E Protection source 626 or Figure 8B However, in some examples, the protection buffer of the present disclosure may be a push-pull buffer disclosed in the present application (e.g., Figure 8B ) and linear buffers (e.g., Fig. 6EThe protection buffer may be a mixture of a linear buffer and a push-pull buffer (e.g., a linear buffer may have good linearity but may require more power than a push-pull buffer due to internal structures such as the output headroom and / or bias current required for the input / output stage). In contrast, the protection buffer may be operated as a push-pull buffer during the period when the protection signal is high (e.g., the PMOS in the output stage of the protection buffer may be fully turned on instead of being regulated). The push-pull buffer may have worse linearity than the linear buffer, but may require less power than the linear buffer because it may not require the output headroom of the linear buffer and / or the quiescent current budget of the linear buffer. An advantage of the above operation may be that during the stage when the protection signal is high, the output headroom of the protection buffer may not have to be allocated (e.g., relative to the headroom required for the protection signal low and / or high voltage) because the protection buffer may be operated as a push-pull buffer. In this way, the positive power supply of the protection buffer may be reduced, thereby saving power.

[0070] In some examples, the touch sensing system of the present disclosure may configure the touch sensing circuitry to operate in different operating modes to sense touches at different times. For example, the touch sensing circuitry is capable of operating in one of two or more operating modes and can switch between these operating modes in response to various criteria being met. In some examples, the touch sensing circuitry is capable of operating in one of three modes: 1) a reset off mode, 2) a DC recovery mode, and 3) a scan step reset mode, as will now be referenced. FIG. 3A to FIG. 3B Specifically, in the reset off mode, the reset control signal can keep the switch 315 in the open position throughout the touch scanning step, and in the DC recovery mode and the scanning step reset mode, the reset control signal can close the switch 315 at different times in the touch scanning step, as described below.

[0071] With respect to the reset-off mode, as described above, the switch 315 may remain open during the touch scanning step of the touch screen (e.g., which may extend one or more protection signal 721 and / or 821 cycles). In this mode, the amplifier 308 in the sensing circuit 314 may be configured as a transimpedance amplifier having a feedback impedance including the resistor 312 and / or the capacitor 310. In such a configuration, the resistor 312 may dominate the overall feedback impedance of the amplifier 308. Thus, the output (e.g., Vo) of the amplifier 308 may stabilize relatively quickly. The touch sensing system may configure the sensing circuit 314 to operate in the reset-off mode when the sensing circuit 314 simultaneously senses touches of a greater number of touch electrodes (e.g., greater than two, five, or ten touch node electrodes 302), and may configure the sensing circuit 314 to operate in a different mode (e.g., a DC recovery mode or a scanning step reset mode) when the sensing circuit 314 simultaneously senses touches of less than or equal to a threshold number of touch electrodes. The reason for configuring the sensing circuit 314 to operate in the reset-off mode when the sensing circuit 314 simultaneously senses touches to greater than a threshold number of touch electrodes may be that, in this case, the input signal from those touch electrodes to the amplifier 308 may be more absorbent than the capacitor 310 without saturating the amplifier 308. Therefore, to reduce the feedback impedance of the amplifier 308, the resistor 312 may be maintained in the feedback loop of the amplifier 308 (e.g., by maintaining the switch 315 in an open position) so that the feedback impedance may be dominated by the resistor 312, which may cause the output of the sensing circuit 314 to settle relatively quickly.

[0072] With respect to the DC recovery mode, amplifier 308 in sensing circuit 314 may be configured as a charge amplifier, and switch 315 may remain open during a touch scan step of the touch screen, except during periods of protection signals 721 and / or 821, during which switch 315 may be closed one or more times (e.g., multiple times during a touch scan step of the touch screen) to facilitate maintaining a desired common-mode voltage of output Vo of amplifier 308 throughout the touch scan step of the touch screen. For example, Fig. 8E An exemplary timing diagram associating the protection signal 821, the reset signal 862, and the output 864 of the sensing circuit 314 during the DC recovery mode is shown. As shown, the reset signal 862 (and the closed switch 315) can be asserted before each transition (e.g., a transition from low to high, and a transition from high to low) of the protection signal 821, such as during time t0 before the protection signal 821 transitions from low to high. The reset signal 862 can then be de-asserted at time t1 before the low-to-high transition of the protection signal 821. In some examples, such assertion / de-assertion can continue before each transition of the protection signal 821, such as Fig. 8EWhen the reset signal 862 is asserted, the switch 315 may be closed, which may help the output of the sensing circuit 314 return to the desired common-mode voltage of the sensing circuit (eg, Fig. 8E V 偏置 ).

[0073] With respect to the scan step reset mode, the amplifier 308 in the sensing circuit 314 may be configured as a charge amplifier and the switch 315 may remain open during a touch scan step of the touch screen, except that the switch 315 may be closed once at the beginning of the touch scan step (e.g., which may extend one or more periods of the protection signal 721 and / or 821) to facilitate rapid stabilization of the amplifier 308 before touch sensing begins, which may otherwise be limited by the RC time constant attributable to the resistor 312 and capacitor 310 in the sensing circuit 314. For example, Figure 8F An exemplary timing diagram associating the protection signal 821, the reset signal 862, and the output 864 of the sensing circuit 314 during the scan step reset mode is shown. As shown, the reset signal 862 can be asserted (and thus close the switch 315) at point 1 at time t0. During time t0, at point 2, the protection signal 821 can transition from low to the programmed common mode level V MID , and can reach V at point 3 according to the programmed rise time MID The protection signal 821 can be maintained at V from point 3 to point 5. MID At point 4 between points 3 and 5, reset signal 862 may be de-asserted, and time t1 later, at point 5, protection signal 821 may be de-asserted from V MID 864 is turned high and can reach high at point 6 according to the programmed rise time. As shown, reset signal 862 can remain de-asserted during the remainder of touch scanning step 866. In this way, it can be facilitated to stabilize the output terminal 864 of amplifier 308 to V before performing touch sensing. 偏置 If output 864 does not stabilize to V before touch sensing begins at the start of scanning step 866, 偏置 , the unsettled portion of output 864 may consume the dynamic range of sensing circuit 314, which may reduce the interference / noise suppression of the touch sensing system.

[0074] The touch sensing system's configuration of the sensing circuit 314 to operate in the DC recovery mode or the scan step reset mode may depend on the results of a spectral analysis step performed by the touch sensing system (e.g., performing a touch scanning step during a time when there is no touch activity on the touch screen, wherein the touch sensing system senses signals from touch electrodes on the touch screen, thereby capturing and identifying noise or other interference sources). For example, the touch sensing system may perform a spectral analysis step and may identify a noise distribution present at the touch screen. Based on the noise distribution, the touch sensing system may configure the sensing circuit 314 to operate in the DC recovery mode or the scan step reset mode (when it is not operating in the reset shutdown mode). For certain protection signal excitation frequencies (e.g., 60 Hz or 120 Hz), the DC recovery mode may provide better low-frequency interference suppression than the scan step reset mode; therefore, if the spectral analysis indicates the presence of low-frequency (e.g., below a threshold frequency) noise or interference, the touch sensing system may select the DC recovery mode. However, the DC recovery mode may cause aliasing at the amplifier 308, which may reduce interference suppression at other frequencies. Thus, the touch sensing system can determine, based on these and / or other factors, which of the DC recovery mode and the scan step RESET mode to configure the sensing circuit 314. For example, if the spectrum analysis indicates that noise or interference is present at a high frequency (e.g., above a threshold frequency), the touch sensing system can select the scan step reset mode. FIG. 8E to FIG. 8F The touch system operation shown can be compared with FIG. 1 to FIG. Fig. 9 Any of the touch sensing system configurations described may be used together.

[0075] refer to FIG. 8E to FIG. 8F In some examples, one or more touch node electrodes on a touch sensor panel can be driven at a reference voltage (e.g., at a protection signal voltage) while one or more other touch node electrodes are touch sensed. The sensed touch node electrodes can be coupled to a touch sensing circuit (e.g., such as a reference FIG. 3A to FIG. 3B As described), the touch sensing circuit can be based on Fig. 8E and / or Figure 8F The touch node electrodes driven with the reference voltage but not sensed may not be coupled to the touch sensing circuitry but to the drive circuitry (e.g., a buffered drive amplifier)—the separate drive circuitry may not include the reset switch 315 and may therefore be independent of the touch sensing circuitry. Fig. 8E and / or Figure 8F Reset 862 operation in.

[0076] As previously described, in some examples, the touch sensing chip of the present disclosure may be a separate and distinct chip from other chips in the touch sensing system (e.g., a protection source chip, a touch processor chip, a host system chip, etc.). In addition, the touch sensing chip may be protected by a protection plane reference voltage that may be different from a chassis or ground ground to which other chips in the touch sensing system may be grounded. In some examples, other chips in the touch sensing system may need to communicate with the touch sensing chip, in which case a level shifter may need to be included in the communication link between the touch sensing chip and the other chips to account for the different power domains in which the touch sensing chip and other chips in the touch sensing system operate.

[0077] Fig. 9 An exemplary level shifter configuration 900 is shown according to an example of the present disclosure. The touch sensing chip 904 may reference a protection reference 907 as described in the present disclosure (e.g., operating in a protection power domain). The touch sensing chip 904 may also include a touch microcontroller 912, which may correspond to Figure 2 904 for controlling and / or processing touch sensing performed by the touch sensing chip 904. The touch microcontroller 912 may include various logic components, memory, touch sensing circuitry, etc. for sensing touches on the touch sensor panel. The touch microcontroller 912 may be communicatively coupled to a host 902, which may reference a chassis or ground ground 906 (e.g., operating in a chassis or ground ground power domain). The host 902 may correspond to a host processor and / or system (e.g., Figures 1A to 1D 136, 140, 144 and 148) and may include Figure 2 The host processor 228 and / or program memory 232 in the touch sensing chip 904 and / or the protection signal generating chip 926. The host 902 can be a different and separate chip from the touch sensing chip 904 and / or the protection signal generating chip 926, but in some examples, the host 902 can be on the same chip as the protection signal generating chip 926.

[0078] The host 902 may need to communicate data with the touch microcontroller 912. For example, when first powering on a device including configuration 900, the host 902 may send information about touch scanning (e.g., information about how the touch microcontroller 912 should sense a touch on the touch sensor panel, such as information about which touch node electrodes are being sensed, grounded, biased, etc. at any given moment) to the touch microcontroller 912 to appropriately configure the touch microcontroller 912. Because the host 902 and the touch sensing chip 904 (and therefore, the touch microcontroller 912) may be in different power domains (e.g., grounded to chassis / ground ground 906 and grounded to protective ground 907), communications between the host 902 and the touch microcontroller 912 may be appropriately level-shifted between power domains by the level shifter 908. In some examples, the host 902 may be communicatively coupled to the touch microcontroller 904 via a protective signal chip 926, which may also reference the chassis or ground ground 906. Thus, in some examples, the level shifter 908 that may be included in the communication link between the host 902 and the touch sensing chip 904 may be included in the protection signal chip 926 .

[0079] In some examples, the amount of data that the host 902 needs to communicate with the touch sensing chip 904 may be large, and level shifting the data between the power domains of the host 902 and the touch sensing chip 904 may slow down the speed of such communication between the two chips. Therefore, in some examples, the protection signal chip 926 may include a bypass switch 910 that can selectively bypass the level shifter 908 on the communication link between the host 902 and the touch sensing chip 904 when appropriate. For example, when the protection signal chip 926 is not generating a protection signal for the protection plane of the touch sensing chip 904, or when the protection signal is in a low state (and therefore, the voltage of the protection signal is substantially the same as the voltage at the chassis or ground 906), the switch 910 can be closed to bypass the level shifter 908 and increase the possible communication rate between the host 902 and the touch sensing chip 904. Otherwise (eg, when the protection signal is in a high state), the switch 910 may be open, and the host 902 may communicate with the touch sensing chip 904 through the level shifter 908 (ie, the level shifter 908 may not be bypassed).

[0080] Thus, examples of the present disclosure provide various configurations for operating a touch sensing chip in a different power domain than other chips in a touch sensing system, which may improve the touch sensing performance of the system.

[0081] Therefore, according to the above, some examples of the present disclosure relate to a touch sensing system, which includes: a protection signal generating chip operating in a first power domain referenced to a first voltage, the protection signal generating chip being configured to generate a protection signal; a touch sensing chip operating in a second power domain as a protection signal different from the referenced first power domain, the touch sensing chip being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a chip different from the protection signal generating chip; and a voltage regulator configured to selectively adjust the voltage of the protection signal at the touch sensing chip. In addition to or as an alternative to one or more examples disclosed above, in some examples, the first power domain reference includes a chassis ground or a ground ground of an electronic device of the touch sensing system. In addition to or as an alternative to one or more examples disclosed above, in some examples, the reference potential includes an AC voltage. In addition to or as an alternative to one or more examples disclosed above, in some examples, the touch sensing chip is disposed on a protection plane, the protection plane being electrically connected to the protection signal generating chip and being configured to be driven with a protection signal. In addition to or as an alternative to one or more examples disclosed above, in some examples, the touch sensing chip includes a touch sensing circuit configured to sense a touch at one or more touch electrodes using a protection signal. In addition to or as an alternative to one or more examples disclosed above, in some examples, the touch sensing system further includes: a flexible circuit, the flexible circuit including: one or more traces configured to electrically couple the touch sensing chip to the touch sensor panel; and one or more shields configured to isolate the one or more traces from the first power domain, wherein: the touch sensing chip is disposed on a protection plane configured to isolate the touch sensing chip from the first power domain, the touch sensor panel includes one or more shields configured to separate the one or more touch electrodes from the first power domain and the protection plane, the one or more shields are included in the flexible circuit, and the one or more shields included in the touch sensor panel are electrically connected to the protection signal generating chip and are configured to be driven by the protection signal. In addition to or as an alternative to one or more examples disclosed above, in some examples, the regulator is configured to: when the protection signal is in a first state, adjust the voltage of the protection signal at the touch sensing chip to a corresponding voltage, and when the protection signal is in a second state different from the first state, abandon adjusting the voltage of the protection signal at the touch sensing chip to a corresponding voltage. In addition to or as an alternative to one or more examples disclosed above, in some examples, when the protection signal is in a low voltage state, the protection signal is in a first state, and when the protection signal is in a high voltage state, the protection signal is in a second state.In addition to or as an alternative to one or more examples disclosed above, in some examples, the corresponding voltage is a low voltage. In addition to or as an alternative to one or more examples disclosed above, in some examples, when the protection signal is in a high voltage state, the protection signal is in a first state, and when the protection signal is in a low voltage state, the protection signal is in a second state. In addition to or as an alternative to one or more examples disclosed above, in some examples, the corresponding voltage is a high voltage. In addition to or as an alternative to one or more examples disclosed above, in some examples, the regulator includes an amplifier, which includes: an input terminal electrically coupled to the protection signal at the touch sensing chip; and an output terminal electrically coupled to the protection signal generating chip. In addition to or as an alternative to one or more examples disclosed above, in some examples, the regulator is configured to adjust the output terminal of the amplifier based on the deviation of the protection signal at the touch sensing chip from the target voltage, thereby adjusting the output terminal of the amplifier so that the protection signal generating chip adjusts the protection signal. In addition to or as an alternative to one or more examples disclosed above, in some examples, the touch sensing system further includes: a host chip operating in a first power domain, the host chip being communicatively coupled to the touch sensing chip via a communication link, and the host chip being configured to transmit data to the touch sensing chip via the communication link. In addition to or as an alternative to one or more examples disclosed above, in some examples, the touch sensing system further includes one or more level shifters included in the communication link, the one or more level shifters being configured to adjust the level of data from the first power domain to the second power domain. In addition to or as an alternative to one or more examples disclosed above, in some examples, the one or more level shifters are configured to be selectively bypassed during data communication from the host chip to the touch sensing chip. In addition to or as an alternative to one or more examples disclosed above, in some examples, the one or more level shifters are configured to be bypassed during data communication from the host chip to the touch sensing chip: when the protection signal generating chip does not generate a protection signal, and when the protection signal generating chip generates a protection signal, it is not bypassed. In addition to or as an alternative to one or more of the examples disclosed above, in some examples, one or more level shifters are configured to be bypassed when the protection signal is in a low state and not bypassed when the protection signal is in a high state during data communication from the host chip to the touch sensing chip. In addition to or as an alternative to one or more of the examples disclosed above, in some examples, the protection signal generation chip includes a direct digital synthesizer, a digital-to-analog converter, and a buffer, the output of the direct digital synthesizer is coupled to the input of the digital-to-analog converter, the output of the digital-to-analog converter is coupled to the input of the buffer, and the output of the buffer outputs the protection signal generated by the protection signal generation chip.In addition to or as an alternative to one or more of the examples disclosed above, in some examples, the touch sensing chip is configured to receive a low voltage and a high voltage, the low voltage corresponding to the protection signal, the high voltage is based on the low voltage and is generated using a capacitor and a switch, the switch is configured to limit the amount of current flowing into the capacitor to less than a threshold amount. In addition to or as an alternative to one or more of the examples disclosed above, in some examples, the protection signal generation chip includes a circuit configured to generate a protection signal, the circuit is configured to operate as a linear buffer when the protection signal is in a low state, and the circuit is configured to operate as a push-pull buffer when the protection signal is in a high state. In addition to or as an alternative to one or more of the examples disclosed above, in some examples, the touch sensing chip is configured to selectively reset a sense amplifier, which is configured to sense a touch at one or more touch electrodes based on one or more of the multiple touch electrodes simultaneously sensed by the sense amplifier and a spectral scan of the touch sensor panel.

[0082] Some examples of the present disclosure relate to an electronic device, which includes: a touch sensor panel including one or more touch electrodes; a protection signal generating chip operating in a first power domain referenced to a first voltage, the protection signal generating chip being configured to generate a protection signal; a touch sensing chip operating in a second power domain referenced to a protection signal different from the first power domain, the touch sensing chip being configured to sense touch at one or more touch electrodes included in the touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a different chip from the protection signal generating chip; and a regulator configured to selectively adjust the voltage of the protection signal at the touch sensing chip.

[0083] Some examples of the present disclosure relate to a method for operating a touch sensing system, the method comprising: operating a protection signal generating chip configured to generate a protection signal in a first power domain referenced to a first voltage; operating a touch sensing chip in a second power domain referenced to the protection signal different from the first power domain, the touch sensing chip being configured to sense touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a chip different from the protection signal generating chip; and selectively adjusting the voltage of the protection signal at the touch sensing chip.

[0084] Some examples of the present disclosure relate to a touch sensing system, which includes: a protection signal generating chip operating in a first power domain referenced to a first voltage, the protection signal generating chip being configured to generate a protection signal; a touch sensing chip operating in a second power domain referenced to the protection signal and different from the first power domain, the touch sensing chip being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a chip different from the protection signal generating chip; and a switching circuit configured to selectively couple a voltage input terminal of the touch sensing chip to the protection signal generating chip based on a state of the protection signal. In addition to or as an alternative to one or more examples disclosed above, in some examples, the switching circuit is configured to: couple the voltage input terminal of the touch sensing chip to the protection signal when the state of the protection signal is a first state, and couple the voltage input terminal of the touch sensing chip to the first voltage when the state of the protection signal is a second state different from the first state.

[0085] Although the examples of the present disclosure have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. It should be understood that such changes and modifications are considered to be included within the scope of the examples of the present disclosure defined by the appended claims.

Claims

1. A system, include: a first circuit operating in a first power domain referenced to a first voltage; a touch sensing circuit communicatively coupled to the first circuit and operating in a second power domain referenced to a guard signal, the second power domain being different from the first power domain, the guard signal being different from the first voltage, the touch sensing circuit being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the guard signal; as well as A level shifting circuit is coupled between the first circuit and the touch sensing circuit, wherein the level shifting circuit is configured to selectively level shift communications between the first circuit and the touch sensing circuit.

2. The system of claim 1, wherein the first voltage is chassis or earth ground and the protection signal is an AC voltage. 3 . The system of claim 1 , wherein the touch sensing circuit is disposed on a first chip referenced to the protection signal, and the first circuit is disposed on a second chip referenced to the first voltage, the second chip being different from the first chip. 4 . The system of claim 1 , wherein the touch sensing circuit comprises a touch processor for processing touch sensing performed by the touch sensing circuit.

5. The system of claim 1, wherein the first circuit comprises a host processor of a device comprising the system.

6. The system according to claim 1, further comprising: include: The protection signal is generated by a protection signal circuit, The protection signal circuit is arranged on the first chip, The first circuit is disposed on a second chip, the second chip being different from the first chip, and The touch sensing circuit is disposed on a third chip, and the third chip is different from the first chip and the second chip.

7. The system according to claim 1, further comprising: include: The protection signal is generated by a protection signal circuit, The protection signal circuit is arranged on the first chip, The first circuit is disposed on the first chip, and The touch sensing circuit is disposed on a second chip, and the second chip is different from the first chip.

8. The system of claim 1, wherein the communication between the first circuit and the touch sensing circuit comprises instructions for configuring the touch sensing circuit to sense a touch on the touch sensor panel.

9. The system of claim 1, wherein the level shifting circuit is referenced to the first voltage.

10. The system of claim 1, wherein the level shifting circuit comprises a switch configured to selectively bypass the level shifting circuit.

11. The system of claim 1 , wherein the level shifting circuit is configured to: If it is determined that the protection signal is in a first state, level shifting the communication between the first circuit and the touch sensing circuit; and If it is determined that the protection signal is in a second state different from the first state, the communication between the level shifting first circuit and the touch sensing circuit is abandoned.

12. The system of claim 1, wherein the level shifting circuit is configured to: If it is determined that the protection signal is being generated, level shifting the communication between the first circuit and the touch sensing circuit; and If it is determined that the protection signal is not being generated, the communication between the level shifting first circuit and the touch sensing circuit is abandoned.

13. A method for operating a system, the method include: operating a first circuit in a first power domain referenced to a first voltage; communicatively coupling a touch sensing circuit to the first circuit and operating the touch sensing circuit in a second power domain referenced to a guard signal, the second power domain being different from the first power domain, the guard signal being different from the first voltage, the touch sensing circuit being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the guard signal; as well as Communications between the first circuit and the touch sensing circuit are selectively level shifted.

14. The method of claim 13, wherein the first voltage is chassis or earth ground and the protection signal is an AC voltage.

15. The method of claim 13, wherein the level shifting is performed by a level shifting circuit, and the level shifting circuit is referenced to the first voltage. 16 . The method of claim 13 , wherein the level shifting is performed by a level shifting circuit, and the level shifting circuit comprises a switch configured to selectively bypass the level shifting circuit.

17. The method of claim 13, wherein the selectively level shifting include: level shifting the communication between the first circuit and the touch sensing circuit if it is determined that the protection signal is in a first state; as well as If it is determined that the protection signal is in a second state different from the first state, the communication between the level shifting first circuit and the touch sensing circuit is abandoned.

18. The method of claim 13, wherein the selectively level shifting include: level shifting the communication between the first circuit and the touch sensing circuit if it is determined that the protection signal is being generated; as well as If it is determined that the protection signal is not being generated, the communication between the level shifting first circuit and the touch sensing circuit is abandoned.

19. A touch sensing system, include: a protection signal generating chip, the protection signal generating chip operating in a first power domain with reference to a first voltage, the protection signal generating chip being configured to generate a protection signal; as well as a touch sensing chip, the touch sensing chip operating in a second power domain referenced to the protection signal, the second power domain being different from the first power domain, the touch sensing chip being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a chip different from the protection signal generating chip, wherein: The touch sensing chip is configured to receive a low voltage at a low voltage input node of the touch sensing chip and to receive a high voltage at a high voltage input node of the touch sensing chip, The low voltage corresponds to the protection signal, and The high voltage is generated based on at least the protection signal, and the high voltage refers to the protection signal.

20. A touch sensing system, include: a protection signal generating chip, the protection signal generating chip operating in a first power domain with reference to a first voltage, the protection signal generating chip being configured to generate a protection signal; a touch sensing chip, the touch sensing chip operating in a second power domain referenced to the protection signal, the second power domain being different from the first power domain, the touch sensing chip being configured to sense a touch at one or more touch electrodes included in a touch sensor panel operating in the second power domain referenced to the protection signal, and the touch sensing chip being a different chip from the protection signal generating chip; as well as A switch circuit is configured to selectively couple a voltage input of the touch sensing chip to the protection signal generating chip based on a state of the protection signal.

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