Pre-charge circuit and method, chip, display device

Abstract

The application discloses a pre-charge circuit and method, a chip and a display device. The pre-charge circuit comprises a resistor string having a plurality of voltage output nodes; a threshold voltage adjusting unit coupled with a threshold node in the voltage output nodes, configured to adjust the voltage value of the threshold node according to a set bit in a selection signal; a current source configured to provide a branch current flowing through the resistor string; and a multiplexer configured to select one of the plurality of voltage output nodes to provide a pre-charge voltage according to the remaining bits in the selection signal. The voltage value of the resistor string is adjusted according to a part of the selection signal to adjust the accuracy of the pre-charge voltage, and the corresponding pre-charge voltage is provided according to the remaining part of the selection signal, so that the accuracy of the pre-charge voltage can be improved without increasing the circuit area.

Description

Technical Field

[0001] This application relates to the field of integrated circuit technology, and in particular to a pre-charging circuit and method, a chip, and a display device. Background Technology

[0002] During the display process of an LED screen, problems such as coupling and ghosting can occur due to the parasitic capacitance of the LED beads and the parasitic capacitance on the row and column traces. Therefore, a pre-charging voltage is usually provided to the LED beads before they are turned on to release the charge stored on the parasitic capacitance, thereby reducing coupling and ghosting phenomena.

[0003] To accommodate different LED on-state voltages and parasitic capacitance parameters, a pre-charge circuit provides different levels of pre-charge voltage. Figure 1 A circuit diagram of a pre-charging circuit in the prior art is shown. (Reference) Figure 1 The existing pre-charge circuit mainly consists of a multiplexer MUX, a current source IS connected in series between ground voltage GND and power supply voltage VDD, and multiple resistors Rm~R0. The current provided by the current source IS flows through different resistors, generating different node voltages. The multiplexer selects the N+1 bit selection signal S. <n:0>Choose one of these node voltages as the pre-charge voltage VOUT. N is a positive integer.

[0004] It is easy to understand that, under the same adjustable range of precharge voltage, the more series resistors there are, the more node voltages are provided, the more precharge voltage levels there are, the higher the adjustment accuracy of the precharge voltage, and the better the decoupling and ghosting effects.

[0005] However, as the number of resistors increases, the input terminals and wiring of the multiplexer (MUX) grow exponentially. This exponential growth significantly increases the circuit layout area and wiring complexity, leading to increased chip cost and layout design difficulties. Summary of the Invention

[0006] In view of the above problems, the purpose of this application is to provide a pre-charging circuit and method, chip, and display device that can improve the accuracy of the pre-charging voltage while taking into account the circuit area.

[0007] According to one aspect of this application, a pre-charge circuit is provided, comprising: a resistor string having a plurality of voltage output nodes; a threshold voltage adjustment unit coupled to a threshold node among the voltage output nodes for adjusting the voltage value of the threshold node according to a set bit in a selection signal; a current source for providing branch current flowing through the resistor string; and a multiplexer for selecting one of the plurality of voltage output nodes to provide a pre-charge voltage according to the remaining bits in the selection signal.

[0008] Optionally, the pre-charging circuit further includes a control unit for controlling the magnitude of the branch current.

[0009] Optionally, the threshold voltage adjustment unit includes: a first resistor, with a first end coupled to a first supply voltage and a second end coupled to a first end of the resistor string, the threshold node being the first end of the resistor string; and a mirror branch coupled between the second end of the first resistor and the second supply voltage, each of the mirror branches being turned on / off according to a corresponding bit in the setting bit, and the mirror branch providing a mirror current of the branch current when it is turned on.

[0010] Optionally, the current source includes: a switching transistor coupled between the second end of the resistor string and the second supply voltage, and a control terminal coupled to the control unit; each of the mirror branches includes: a first path switch and a mirror transistor connected in series, the first path switch being turned on / off according to a corresponding bit in the setting bit, the control terminal of the mirror transistor being coupled to the control terminal of the switching transistor, and the mirror transistor being used to proportionally replicate the branch current to provide the mirror current.

[0011] Optionally, the control unit includes: an adjustable current source and a first transistor connected in series, wherein the control terminal of the first transistor is coupled to the control terminal of the switching transistor.

[0012] Optionally, the resistance value of the first resistor is the same as the resistance value of each resistor in the resistor string, the total number of bits in the setting bits is X, where X is a positive integer, and the ratio of the mirrored current corresponding to each setting bit is 1 / 2 in order from the least significant bit to the most significant bit. X : 1 / 2 X-1 :...:1 / 2.

[0013] Optionally, the threshold voltage adjustment unit includes an adjustable resistor, and the set position is used to adjust the resistance value of the adjustable resistor.

[0014] Optionally, the adjustable resistor includes: a second resistor coupled between a first supply voltage and a first end of the resistor string and at least one series structure, the threshold node being the first end of the resistor string; and a second path switch, each of the series structures being connected in parallel with a corresponding second path switch, the second path switch being turned on / off according to a corresponding bit in the set bit.

[0015] Optionally, each of the series structures includes a third resistor.

[0016] Optionally, each of the series structures includes: a third resistor and a third path switch connected in series, wherein the on / off state of the second path switch is opposite to the on / off state of the third path switch in the series structure connected in parallel, and any third path switch and any second path switch have the same width-to-length ratio.

[0017] Optionally, the resistance value of the second resistor is the same as the resistance value of each resistor in the resistor string. The total number of bits in the setting position is X, where X is a positive integer. Following the order from least significant bit to most significant bit, the resistance ratio of the third resistor corresponding to each setting position is 1 / 2. X : 1 / 2 X-1 :...:1 / 2.

[0018] Optionally, the current source includes: a switching transistor coupled between the second end of the resistor string and the second supply voltage; the control unit includes: a sampling resistor coupled between the switching transistor and the second supply voltage for providing a sampling voltage based on the branch current; and an operational amplifier with a first input terminal coupled to the reference voltage, a second input terminal coupled to the sampling voltage, and an output terminal coupled to the control terminal of the switching transistor.

[0019] According to another aspect of this application, a chip is provided, comprising: the pre-charge circuit described above.

[0020] According to another aspect of this application, a display device is provided, comprising: a display panel including a plurality of pixels; a driving circuit for driving the pixels to be turned on and displayed according to image data; and the aforementioned pre-charging circuit for providing a pre-charging voltage to the pixels before they are turned on.

[0021] According to another aspect of this application, a pre-charging method is provided, comprising: providing a branch current to a resistor string having a plurality of voltage output nodes; adjusting the voltage value of a threshold node among the voltage output nodes according to a set bit in a selection signal; and selecting one of the plurality of voltage output nodes to provide a pre-charging voltage according to the remaining bits in the selection signal.

[0022] Optionally, the step of adjusting the voltage value of the threshold node includes: connecting a resistor to the threshold node, wherein the resistor and the resistor are connected in series between a first supply voltage and a second supply voltage; and adjusting the resistance value of the resistor according to the setting position, or providing a mirror current of the branch current to the resistor according to the setting position.

[0023] According to the pre-charging circuit, method, chip, and display device provided in this application, a threshold voltage adjustment unit is set up, and the threshold voltage adjustment unit adjusts the voltage value of the threshold node according to a portion of the selection signal. Under the condition of a constant branch current, the voltage value of each voltage output node will change with the change of the threshold node voltage value. Therefore, precise adjustment of the pre-charging voltage can be achieved. Combined with a multiplexer selecting the corresponding voltage output node to provide the pre-charging voltage according to another portion of the selection signal, the original single-level pre-charging voltage can be expanded into multiple levels of pre-charging voltage. Thus, the accuracy of pre-charging voltage adjustment is improved without increasing the number of resistors, the area of ​​the multiplexer, or the wiring between the resistors and the multiplexer. Attached Figure Description

[0024] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0025] Figure 1 A circuit diagram of a pre-charging circuit in the prior art is shown;

[0026] Figure 2 This invention provides a schematic diagram of the structure of a display device according to an embodiment of the present application.

[0027] Figure 3 The following are schematic diagrams of the pre-charging circuit in some embodiments of this application;

[0028] Figure 4 This application shows schematic diagrams of the control unit structure in different embodiments;

[0029] Figures 5 to 7 The circuit diagrams of the pre-charging circuits in different embodiments of this application are shown;

[0030] Figure 8 This application shows a schematic diagram of the pre-charging circuit structure in some other embodiments;

[0031] Figure 9 This is a schematic flowchart illustrating the pre-charging method according to an embodiment of this application. Detailed Implementation

[0032] Various embodiments of the present application will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0033] Furthermore, certain terms are used in this specification and claims to refer to specific components. Those skilled in the art will understand that manufacturers may use different names to refer to the same component. This specification and claims do not use differences in name to distinguish components.

[0034] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0035] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] It should also be noted that in the various methods and processes of this application, the order of the steps does not imply the order of execution, nor does it constitute any limitation on the implementation process of the embodiments of this application.

[0037] Figure 2 A schematic diagram of the display device according to an embodiment of this application is shown. (Reference) Figure 2 The display device 10 provided in this application includes: a pre-charging circuit 100, a driving circuit 200, and a display panel 300 in any embodiment of this application.

[0038] The display panel 300 includes, for example, a plurality of pixels arranged in an array. The driving circuit 200 is used to drive the pixels to turn on and display according to image data DATA. The pre-charge circuit 100 is used to pre-charge the pixels according to an N+1 bit selection signal S before the pixels are turned on.<N:0> Provide it with a pre-charge voltage, where N is a positive integer.

[0039] Taking an LED display device as an example, the pixels of the display panel 300 refer to LED beads. The driving circuit 200 is a constant current driving circuit, used to provide the driving current flowing through the LED beads. The pre-charging circuit 100 is used to provide a pre-charging voltage to the LED beads before they are lit, so as to release the charge stored in the parasitic capacitance of the LED beads and the parasitic capacitance on the row and column lines, thereby making the state of different LED beads consistent when they are turned on, reducing coupling and ghosting phenomena caused by parasitic capacitance during the display process, and thus improving the display quality.

[0040] It should be understood that the aforementioned LED display device can be an LED display device under any conditions, including any type of LED bead (such as Mini LED, MicroLED, etc.), any LED bead spacing (such as conventional spacing or small spacing with a dot spacing of less than P2.5), and any usage environment (such as indoor LED, outdoor LED).

[0041] Furthermore, in some embodiments, the pre-charging circuit provided in this application can also be used in voltage generation circuits that require high precision, such as shadow removal voltage.

[0042] Figure 3 A schematic diagram of the pre-charging circuit 100 in an embodiment of this application is shown. (Reference) Figure 3 The pre-charge circuit 100 includes at least: a current source 110, a resistor string 120, a threshold voltage adjustment unit 130, and a multiplexer MUX.

[0043] The resistor string 120 includes multiple resistors R1~Rm and provides multiple voltage output nodes.

[0044] exist Figure 3 In the example, we will use the case where both ends of each resistor in the resistor string 120 are used as voltage output nodes. That is, the number of voltage output nodes provided by the M resistors R1~Rm is M+1, where M is a positive integer.

[0045] The threshold voltage adjustment unit 130 is connected between the first supply voltage and the threshold node of the resistor string 120. In different embodiments, the threshold node is the output node corresponding to the maximum or minimum voltage value among the multiple voltage output nodes of the resistor string 120, corresponding to the voltage value of the first supply voltage.

[0046] exist Figure 3 In the example, the first supply voltage is the power supply voltage VDD, and the threshold node is the output node corresponding to the maximum voltage value. Under the condition that M+1 voltage output nodes are provided by M resistors as described above, the first end of resistor R1 can be used as the threshold node, and the second end of resistor R1 can be connected to the remaining resistors in the resistor string 120.

[0047] The threshold voltage adjustment unit 130 is used to adjust the voltage value of the threshold node according to the setting bit in the selection signal S. The selection signal S has N+1 bits, and the total number of setting bits is X. Both N and X are positive integers, and X ≤ N.

[0048] In the following embodiments, the set bit is always the low X bit S in the selection signal S. <x-1:0>Let's take an example. For instance, with N=5 and X=2, two of the six selection signals are setting bits. If we refer to the least significant bit to the most significant bit of this six-bit selection signal S as the first to the sixth bit, then these two setting bits are the first and second bits.

[0049] Current source 110 is connected between resistor string 120 and the second supply voltage to provide branch current I0 flowing through resistor string 120.

[0050] exist Figure 3 In the example, the second supply voltage is ground voltage GND. With the first supply voltage being power supply voltage VDD and the second supply voltage being ground voltage GND, the pre-charging circuit can provide a pre-charging voltage to the display panel 300 with common anode LED connection.

[0051] The multiplexer (MUX) includes multiple inputs. Each input is connected to a voltage output node via a 120Ω resistor series. The multiplexer (MUX) selects the voltage output node based on the remaining bits S in the selection signal S. <n:x>Select one of multiple voltage output nodes to provide the pre-charge voltage VOUT.

[0052] By setting a threshold voltage adjustment unit, which adjusts the voltage value of the threshold node based on a portion of the selection signal, and under the condition of a constant branch current, the voltage values ​​of each voltage output node will change with the threshold node voltage value, thus achieving precise adjustment of the pre-charge voltage. Combined with a multiplexer that selects the corresponding voltage output node based on the remaining portion of the selection signal to provide the pre-charge voltage, the original single-level pre-charge voltage can be expanded into multiple levels. This improves the precision of pre-charge voltage adjustment without increasing the number of resistors, the area of ​​the multiplexer, or the wiring between the resistors and the multiplexer.

[0053] In some embodiments, such as Figure 3 As shown, in order to provide an accurate pre-charge voltage, the pre-charge circuit 100 also includes a control unit 140. The control unit 140 is used to control the branch current I0 provided by the current source 110.

[0054] Depending on the driving type of the current source 110, the control unit 140 can have different structures. Figure 4 A schematic diagram of the control unit 140 in different embodiments is shown.

[0055] In some embodiments, the current source 110 can be a current-driven current source. The control unit 140 can be as follows: Figure 4 As shown in Figure (a), the system includes a reference current generation module 141, a current calibration module 142, and a drive module 143. The reference current generation module 141 provides a reference current, the current calibration module 142 calibrates the reference current, and the drive module 143 drives the current source 110 to provide the branch current I0 based on the calibrated reference current IREF.

[0056] In some embodiments, the calibration of the reference current refers to adjusting the reference current through the current calibration module 142, while keeping other conditions unchanged, until the output node of the resistor string 120 provides a preset voltage value, so that the pre-charge circuit can provide an accurate pre-charge voltage in subsequent operation. It is easy to understand that, under the condition that other conditions remain unchanged, when any output node of the resistor string 120 provides the corresponding preset voltage value, the voltage values ​​provided by other output nodes should also be accurate.

[0057] In some other embodiments, the current source 110 can be a voltage-driven current source. When the current source 110 is a voltage-driven current source, the control unit 140 can also be as follows: Figure 4 As shown in Figure (b), the system includes a reference voltage generation module 144, a voltage calibration module 145, and a control voltage generation module 146. The reference voltage generation module 144 generates a reference voltage, the voltage calibration module 145 calibrates the reference voltage, and the control voltage generation module 146 generates a control voltage based on the calibrated reference voltage VREF, thereby driving the current source 110 to generate a branch current I0.

[0058] In some embodiments, reference voltage calibration refers to adjusting the reference voltage through the voltage calibration module 145 while keeping other conditions unchanged until the output node of the resistor string 120 provides a preset voltage value, thereby enabling the pre-charge circuit to provide an accurate pre-charge voltage in subsequent operation. It is easy to understand that, under the condition that other conditions remain unchanged, when any output node of the resistor string 120 provides the corresponding preset voltage value, the voltage values ​​provided by other output nodes should also be accurate.

[0059] In some other embodiments, the reference current generation module 141 and the reference voltage generation module 144 described above can both reuse existing related structures in the system, thereby saving circuit area and system power consumption.

[0060] Figures 5 to 7 The diagram shows circuit schematics of pre-charge circuits in different embodiments of this application. In the following embodiments, the number of bits for the selection signal S is N+1 bits, and the least significant bit S of the selection signal S is... <0> and the second lowest S <1> This explanation uses a setting as an example.

[0061] Combination Figures 3 to 5 In some embodiments, the pre-charge circuit 100a includes a current source 110, a control unit 140a, a resistor string 120, a threshold voltage adjustment unit 130a, and a multiplexer MUX.

[0062] The resistor string 120 consists of M resistors R1 to Rm connected in series, where M is a positive integer. The two ends of any resistor in this resistor string 120 serve as voltage output nodes. That is, these M resistors provide M+1 voltage output nodes. The multiplexer MUX selects the remaining bits S in the selection signal...<N:2> Select one of the M+1 voltage output nodes to provide the pre-charge voltage VOUT.

[0063] It's easy to understand that, given a resistor series of 120V where M resistors provide M+1 voltage output nodes, the condition M+1=2 must be met. N+1-X Where M+1 is the number of voltage output nodes, N+1 is the total number of bits in the selection signal, X is the total number of bits in the setting bit, and M, N, and X are positive integers, with X ≤ N.

[0064] The first end of the resistor string 120 is connected to the power supply voltage VDD via the threshold voltage adjustment unit 130a, and the second end is connected to the ground voltage GND via the current source 110.

[0065] exist Figure 5 In the illustrated embodiment, the current source 110 includes a switching transistor MS. The first terminal of the switching transistor MS is connected to the second terminal of the resistor string 120, the second terminal is connected to ground voltage GND, and the control terminal is connected to the control unit 140a.

[0066] In some other embodiments, particularly when the current source 110 is a current-driven current source, the current source 110 may further include a mirror structure of the switching transistor MS. This mirror structure can be used to replace, for example... Figure 4 The current calibration module 142 in Figure (a) is shown. That is, the drive module 143 directly drives the switch transistor MS according to the reference current and adjusts the magnitude of the branch current I0 through these mirror structures, so that the pre-charge circuit can provide an accurate pre-charge voltage.

[0067] Control unit 140a corresponds to Figure 4 The embodiment shown in Figure (a) includes an adjustable current source IK connected in series and a first transistor M1.

[0068] exist Figure 5 In the example, the adjustable current source IK and the first transistor M1 are connected in series between the power supply voltage VDD and the ground voltage GND.

[0069] The circuit structure of the adjustable current source IK includes, for example, Figure 4 (a) includes a reference current generation module 141 and a current calibration module 142, which provide a calibrated reference current IREF.

[0070] The drive module 143 includes a first transistor M1. The control terminal of the first transistor M1 is shorted to the first terminal and connected to the control terminal of the switching transistor MS.

[0071] In other words, the first transistor M1 and the switching transistor MS form a current mirror. The switching transistor MS acts as a current mirror transistor, and proportionally replicates the current IEF to obtain the branch current I0.

[0072] The voltage regulation circuit 130a includes a first resistor Ra and a mirror branch.

[0073] The first terminal of the first resistor Ra is connected to the power supply voltage VDD, and the second terminal is connected to the first terminal of the resistor string 120. The resistance value of the first resistor Ra can be the same as the resistance values ​​of each resistor in the resistor string 120.

[0074] The number of mirror branches is the same as the total number of bits in the setting bits. Mirror branches are turned on / off according to the corresponding bit in the setting bits. Specifically, each mirror branch includes a first path switch and a mirror transistor connected in series. The first path switch is turned on / off according to the corresponding bit in the setting bits. When the first path switch is on, its mirror branch provides a mirror current to the first resistor Ra for the branch current I0.

[0075] The state in which the aforementioned threshold voltage adjustment unit 130a is not working can specifically refer to the state in which all mirror branches are turned off.

[0076] Each mirror branch is connected between the second terminal of the first resistor Ra and the ground voltage GND.

[0077] Assuming the resistance value of the first resistor Ra is the same as that of all resistors in the resistor string 120, the ratio of the mirror current corresponding to each set bit, from least significant bit to most significant bit, is 1 / 2. X : 1 / 2 X-1 :...:1 / 2.

[0078] exist Figure 5 In the example, corresponding to the 2-bit setting bit, two mirror branches 131 and 132 are shown. Mirror branch 131 includes a first path switch K11 and a first mirror transistor MM1 connected in series, and mirror branch 132 includes a first path switch K12 and a second mirror transistor MM2 connected in series.

[0079] The first path switch K11 selects the least significant bit S of the selection signal. <0> When the first path switch K11 is turned on, the first mirror current I1 = 1 / 4 × I0 provided by its mirror branch 131 is turned off.

[0080] The first path switch K12 is based on the second least significant bit S of the selection signal S. <1> When the first path switch K12 is turned on, the second mirror current I2 = 1 / 2 × I0 provided by its mirror branch 132 is turned off.

[0081] The following example illustrates the following: the selection signal is a 6-bit selection signal S<5:0>, the lower 2 bits S<1:0> of the selection signal are set bits, the larger the overall value of the remaining bits, the smaller the pre-charge voltage VOUT, the first path switches K11 and K12 are both turned on when the corresponding bit value is 1 and turned off when the corresponding bit value is 0, the first resistor Ra and the resistance value of each resistor in the resistor series 120 are all R, and the branch current value is I0.

[0082] When the 6-bit selection signal is 000000, both the first path switches K11 and K12 are off, and the current flowing through the first resistor Ra and each resistor R1~Rm in the resistor string 120 is I0. The multiplexer MUX connects to the common node of the first resistor Ra and resistor R1, that is, the first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage V1 = VDD - I0 × R.

[0083] When the 6-bit selection signal is 000001, the first path switch K11 is turned on, the first path switch K12 is turned off, the current flowing through the first resistor Ra is I0 + I1, and the current flowing through the resistor series 120 is still I0. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage is V2 = VDD - (I0 + I1) × R = VDD - 5 / 4 × I0 × R. Since the accuracy of the pre-charge voltage is the difference between the pre-charge voltages of adjacent gears, the accuracy of the pre-charge voltage at this time is STEP1 = V2 - V1 = -1 / 4 × I0 × R.

[0084] When the 6-bit selection signal is 000010, the first path switch K11 is off, the first path switch K12 is on, the current flowing through the first resistor Ra is I0 + I2, and the current flowing through the resistor series 120 is still I0. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage V3 = VDD - (I0 + I2) × R = VDD - 3 / 2 × I0 × R. The accuracy of the pre-charge voltage STEP2 = V3 - V2 = -1 / 4 × I0 × R.

[0085] When the 6-bit selection signal is 000011, both first path switches K11 and K12 are turned on. The current flowing through the first resistor Ra is I0 + I1 + I2, and the current flowing through resistor series 120 is still I0. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage is V4 = VDD - (I0 + I1 + I2) × R = VDD - 7 / 4 × I0 × R. The accuracy of the pre-charge voltage is STEP3 = V4 - V3 = -1 / 4 × I0 × R.

[0086] When the 6-bit selection signal is 000100, both the first path switches K11 and K12 are off, and the current flowing through the first resistor Ra and each resistor R1~Rm in the resistor string 120 is I0. The multiplexer MUX connects the common node of resistors R1 and R2, that is, the first terminal of resistor R2 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage V5 = VDD - I0 × (Ra + R1) = VDD - 2 × I0 × R. The accuracy of the pre-charge voltage STEP4 = V5 - V4 = -1 / 4 × I0 × R.

[0087] Based on the above analysis, when the selection signal is 6 bits and the total number of bits in the setting position is 2 bits, the pre-charge circuit 100a can provide a pre-charge voltage with an accuracy of -I0*R / 4 through the first resistor Ra and the 15 resistors in the resistor string 120.

[0088] In such Figure 1 In the conventional precharge circuit shown, at least 63 resistors with a resistance of R / 4 are required in the resistor string to provide 64 voltage output nodes. A multiplexer selects one of these 64 voltage output nodes to provide the precharge voltage based on a 6-bit selection signal, so that the accuracy of the precharge voltage is -I0*R / 4.

[0089] Therefore, compared to traditional pre-charge circuits, the pre-charge circuit 100a of this application can exponentially reduce the number of resistors in the resistor string and the number of traces between the multiplexer and the resistor string while maintaining the same accuracy. It can also effectively reduce the area of ​​the multiplexer. Thus, both circuit miniaturization and high accuracy of the pre-charge voltage can be achieved.

[0090] Combination Figure 3 , 4 6. In some embodiments, the pre-charging circuit 100b includes a current source 110 and a control unit 140b (in... Figure 6 Only the control voltage generation module 146, resistor string 120, threshold voltage adjustment unit 130b, and multiplexer MUX in the control unit 140b are shown.

[0091] For details regarding the structure and interconnections of resistor string 120, multiplexer MUX, current source 110, and switching transistor MS, please refer to [link to documentation / reference]. Figure 5 The relevant explanations. In Figure 6 In one embodiment, the control voltage generation module 146 includes a sampling resistor and an operational amplifier AMP.

[0092] The sampling resistor is connected between the switching transistor MS and ground voltage GND to provide the sampling voltage VS for the branch current I0. Figure 6 In the example, the sampling resistors include a first sampling resistor Rc1 and a second sampling resistor Rc2 connected in series. The intermediate node between the first sampling resistor Rc1 and the second sampling resistor Rc2 provides the sampling voltage VS.

[0093] However, it should be understood that this application is not limited thereto. For example, in some other embodiments, only a sampling resistor may be included between the switch MS and the ground voltage GND. The common node of this sampling resistor and the switch MS provides the sampling voltage VS.

[0094] The first input terminal of the operational amplifier AMP (e.g., the non-inverting input terminal) is connected to the reference voltage VREF, the second input terminal (e.g., the inverting input terminal) is connected to the sampling voltage VS, and the output terminal is connected to the control terminal of the switching transistor MS, providing the control voltage.

[0095] In this design, the control terminal voltage of the switching transistor MS is adjusted by forming a feedback loop through the operational amplifier AMP and the sampling resistor, thereby adjusting the gate-source voltage of the switching transistor MS, so that the switching transistor MS is equivalent to a voltage-controlled current source and provides branch current I0.

[0096] The voltage regulation circuit 130b is, for example, an adjustable resistor. The set position in the selection signal is used to adjust the resistance value of the adjustable resistor. That is, the voltage regulation circuit 130b adjusts the voltage value of the resistor series 120 by adjusting its voltage divider.

[0097] exist Figure 6 In one example, the adjustable resistor may include a second resistor Rb connected between the power supply voltage VDD and the resistor string 120, multiple series structures, and a second path switch connected in parallel with each series structure.

[0098] The resistance value of the second resistor Rb can be the same as the resistance values ​​of each resistor in the resistor series 120.

[0099] The number of series structures and the number of second-path switches can both be the same as the total number of bits in the setting position.

[0100] exist Figure 6 In the example, each series structure includes a corresponding third resistor. Assuming the second resistor Rb has the same resistance value as all resistors in resistor string 120, the ratio of the resistance values ​​of the third resistors corresponding to each set bit, from least significant bit to most significant bit, is 1 / 2. X : 1 / 2 X-1 :...:1 / 2.

[0101] exist Figure 6 In this embodiment, the total number of bits corresponding to the setting bit is 2, and the second resistor Rb is connected in series with two series structures. These two series structures are the third resistor R0a and the third resistor R0b, respectively. The second path switch includes a second path switch K22 connected in parallel with resistor R0a and a second path switch K21 connected in parallel with resistor R0b.

[0102] Each second path switch is turned on / off according to the corresponding bit in the setting bit.

[0103] exist Figure 6 In the example, the second path switch K21 is based on the least significant bit S of the selection signal. <0> When the circuit is on / off, the resistance ratio of resistor R0b to the resistance ratio of the second resistor Rb is 1 / 4:1. The second path switch K22 operates based on the second lowest bit of the selection signal S. <1> On / Off. The resistance ratio of resistor R0a to the resistance ratio of the second resistor Rb is 1 / 2:1.

[0104] The following example illustrates the following: the selection signal is a 6-bit selection signal S<5:0>, the lower 2 bits S<1:0> of the selection signal are the set bits, the larger the overall value of the remaining bits, the smaller the pre-charge voltage VOUT, the second path switches K21 and K22 are both turned on when the corresponding bit value is 0 and turned off when the corresponding bit value is 1, the second resistor Rb and the resistance value of each resistor in the resistor series 120 are all R, and the branch current value is I0.

[0105] When the 6-bit selection signal is 000000, both second-path switches K21 and K22 are turned on. The equivalent resistance of the adjustable resistor R01 = R + R / 2||R K22O +R / 4||R K21O Where R / 2||R K22O This is the equivalent resistance of the second-path switch K22 when it is turned on, after its resistance and resistance R0a are connected in parallel. R / 4||R K21O This is the equivalent resistance of the second-path switch K21 when it is turned on, after its resistance is connected in parallel with the resistor R0b. The multiplexer MUX connects the common node of the adjustable resistor 130b and the resistor R1, that is, the first terminal of the resistor R1 provides the pre-charge voltage VOUT. At this time, the voltage value of the pre-charge voltage V1 = VDD - I0 × R01.

[0106] When the 6-bit selection signal is 000001, the second path switch K21 is off, and the second path switch K22 is on. The equivalent resistance of the adjustable resistor R02 = R + R / 2||R K22O +R / 4||R K21F Where R / 2||R K22O This is the equivalent resistance of the second-path switch K22 when it is turned on, after its resistance and resistance R0a are connected in parallel. R / 4||R K21F When the second-path switch K21 is turned off, the equivalent resistance of its resistor and resistor R0b in parallel is approximately R / 4. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the pre-charge voltage value V2 = VDD - I0 × R02. The accuracy of the pre-charge voltage at this time is STEP1 = V2 - V1 = -I0 × (R / 4 - R / 4||R K21O ).

[0107] When the 6-bit selection signal is 000010, the second path switch K21 is turned on, and the second path switch K22 is turned off. The equivalent resistance of the adjustable resistor R03 = R + R / 2||R K22F +R / 4||R K21O Where R / 2||R K22F The equivalent resistance of the second-path switch K22 when it is turned off, after its resistance and the resistor R0a are connected in parallel, is approximately R / 2. R / 4||R K21O This is the equivalent resistance of the resistor R1 connected in parallel with resistor R0b when the second path switch K21 is turned on. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the pre-charge voltage value V3 = VDD - I0 × R03. The accuracy of the pre-charge voltage at this time is STEP2 = V3 - V2 = -I0 × (R / 4 + R / 4||R K21O -R / 2||R K22O ).

[0108] When the 6-bit selection signal is 000011, both second-path switches K21 and K22 are turned off. The equivalent resistance of the adjustable resistor R04 = R + R / 2||R K22F +R / 4||R K21F Where R / 2||R K22F The equivalent resistance of the second-path switch K22 when it is turned off, after its resistance and the resistor R0a are connected in parallel, is approximately R / 2. R / 4||R K21F When the second-path switch K21 is turned off, the equivalent resistance of its resistor and resistor R0b in parallel is approximately R / 4. The first terminal of resistor R1 provides the pre-charge voltage VOUT. At this time, the pre-charge voltage value V4 = VDD - I0 × R04. The accuracy of the pre-charge voltage at this time is STEP3 = V4 - V3 = -I0 × (R / 4 - R / 4||R K21O ).

[0109] When the 6-bit selection signal is 000100, both second-path switches K21 and K22 are turned on. The equivalent resistance of the adjustable resistor R05 = R + R / 2||R K22O +R / 4||R K21O Where R / 2||R K22O This is the equivalent resistance of the second-path switch K22 when it is turned on, after its resistance and resistance R0a are connected in parallel. R / 4||R K21O This is the equivalent resistance of the resistor R1 and resistor R0b connected in parallel when the second path switch K21 is turned on. The multiplexer MUX connects the common node of resistors R1 and R2, i.e., the first terminal of resistor R2, providing a pre-charge voltage. At this time, the pre-charge voltage value V5 = VDD - I0 × (R + R05). The accuracy of the pre-charge voltage at this time is STEP4 = V5 - V4 = -I0 × (R / 4 + R / 2||R K22O +R / 4||R K21O Based on the above analysis, Figure 6 When the on-resistance of the second path switch is sufficiently small, the pre-charge circuit 100b shown can be ignored, and the accuracy of the pre-charge voltage is approximately -I0*R / 4. Therefore, compared with traditional pre-charge circuits, pre-charge circuit 100b can also achieve both circuit miniaturization and high accuracy of the pre-charge voltage.

[0110] It's easy to understand that the on-resistance of a switch is negatively correlated with its switching area. In the above embodiment, the larger the path switch area, the smaller its on-resistance, and the closer the accuracy of the pre-charge voltage is to -I0*R / 4. Therefore, in actual operating conditions, the switch size can be adjusted by combining the accuracy requirements of the pre-charge voltage and the requirements of the circuit area.

[0111] Combination Figure 3 and Figure 7 In some embodiments, the pre-charge circuit 100c includes a current source 110, a control voltage generation module 146, a resistor string 120, a threshold voltage adjustment unit 130c, and a multiplexer MUX.

[0112] The descriptions of resistor string 120, multiplexer MUX, current source 110, switching transistor MS, control voltage generation module 146, operational amplifier AMP, first sampling resistor Rc1, second sampling resistor Rc2, reference voltage VREF, and sampling voltage VS can be found in [reference needed]. Figure 6 Related explanations.

[0113] exist Figure 7 In the example, the threshold voltage adjustment unit 130c can be an adjustable resistor. The set bit in the selection signal is used to adjust the resistance value of this adjustable resistor. That is, the voltage adjustment circuit 130c adjusts the voltage value of the resistor string 120 by adjusting its voltage divider.

[0114] exist Figure 7 In one example, the adjustable resistor may include a second resistor Rb connected between the power supply voltage VDD and the resistor string 120, multiple series structures, and a second path switch connected in parallel with each series structure.

[0115] exist Figure 7 In the example, each series structure includes a third resistor and a third-path switch connected in series. For an explanation of the third resistor and the second-path switch, please refer to [reference needed]. Figure 5 Related explanations.

[0116] exist Figure 7 In the example, the on / off state of the second path switch is opposite to that of the third path switch in its parallel series structure. The width-to-length ratio of any third path switch is the same as that of the second path switch.

[0117] exist Figure 7 In one embodiment, corresponding to a total of 2 bits for the setting bit, two series structures 133 and 134 are shown. Series structure 133 includes a third resistor R0a and a third path switch K32 connected in series. Series structure 134 includes a third resistor R0b and a third path switch K31 connected in series.

[0118] The second path switch K21 and the third path switch K31 are selected based on the least significant bit S of the selection signal. <0> The circuit is switched on / off, and the on / off states of the second path switch K21 and the third path switch K31 are opposite. The resistance ratio of resistor R0b to the resistance ratio of the second resistor Rb is 1 / 4:1.

[0119] The second path switch K22 and the third path switch K32 are selected based on the second least significant bit S of the selection signal. <1> The circuit is switched on / off, and the on / off states of the second path switch K22 and the third path switch K32 are opposite. The resistance ratio of resistor R0a to the resistance ratio of the second resistor Rb is 1 / 2:1.

[0120] The following example illustrates the following: a 6-bit selection signal S<5:0>, with the lower 2 bits S<1:0> as the set bits, the larger the overall value of the remaining bits, the smaller the pre-charge voltage VOUT, the second path switch is turned on when the corresponding bit value is 0 and turned off when the corresponding bit value is 1, the third path switch is turned on when the corresponding bit value is 1 and turned off when the corresponding bit value is 0, the second resistor Rb and the resistance of each resistor in the resistor series 120 are all R, and the branch current is I0.

[0121] When the 6-bit selection signal is 000000, both second-path switches K21 and K22 are turned on, and both third-path switches K31 and K32 are turned off. The equivalent resistance of the adjustable resistor R01 = R + (R / 2 + R K32F )||R K22O +(R / 4+R K31F )||R K21O Among them, R K21O R K22O These are the equivalent resistances R when the second path switches K21 and K22 are turned on. K31F R K32F These are the equivalent resistance values ​​when the third path switches K31 and K32 are turned off, respectively. Therefore, R01 can be equivalent to R+R K21O +R K22O The multiplexer MUX connects the common node of the adjustable resistor and resistor R1, meaning that the first terminal of resistor R1 provides the pre-charge voltage. At this point, the pre-charge voltage value V1 = VDD - I0 × R01.

[0122] When the 6-bit selection signal is 000001, the second path switch K21 is off, the second path switch K22 is on, the third path switch K31 is on, and the third path switch K32 is off. The equivalent resistance R02 of the adjustable resistor can be equivalent to R + R / 4 + R K31O +R K22O R K31O R K22O These are the equivalent resistance values ​​when the third path switch K31 and the second path switch K22 are turned on, respectively. The first terminal of resistor R1 provides the pre-charge voltage. At this time, the pre-charge voltage value V2 = VDD - I0 × R02. The accuracy of the pre-charge voltage at this time is STEP1 = V2 - V1 = -I0 × (R / 4 + R...). K31O -R K21O When transistors with the same width-to-length ratio are selected for each of the second-path and third-path switches, it can be assumed that each of the second-path and third-path switches has the same on-resistance. Therefore, the simplified result is STEP1 = -I0 × R / 4.

[0123] Similarly, when the 6-bit selection signal is 000010, the equivalent resistance R03 of the adjustable resistor is R + R / 2 + R K32O +R K21O R K32O R K21O These are the equivalent resistance values ​​when the third-path switch K32 and the second-path switch K21 are turned on, respectively. The first terminal of resistor R1 provides the pre-charge voltage. At this time, the pre-charge voltage value V3 = VDD - I0 × R03. The accuracy of the pre-charge voltage at this time is STEP2 = V3 - V2. When transistors with the same aspect ratio are used in both the second-path and third-path switches, STEP2 = -I0 × R / 4.

[0124] When the 6-bit selection signal is 000011, the equivalent resistance R04 of the adjustable resistor is R + R / 2 + R / 4 + R K31O +R K32O R K31O R K32O These are the equivalent resistance values ​​when the third-path switches K31 and K32 are turned on, respectively. The first terminal of resistor R1 provides the pre-charge voltage. At this time, the pre-charge voltage value V4 = VDD - I0 × R04. The accuracy of the pre-charge voltage at this time is STEP3 = V4 - V3. When transistors with the same aspect ratio are used for each of the second and third-path switches, STEP3 = -I0 × R / 4.

[0125] When the 6-bit selection signal is 000100, the equivalent resistance R05 of the adjustable resistor is R+R. K21O +R K22O R K21O R K22O These are the equivalent resistance values ​​when the second-path switches K21 and K22 are turned on, respectively. The common node of the multiplexer MUX connecting resistors R1 and R2, i.e., the first terminal of resistor R2, provides the pre-charge voltage. At this time, the pre-charge voltage value V5 = VDD - I0 × R05. The accuracy of the pre-charge voltage at this time is STEP4 = V5 - V4. When transistors with the same aspect ratio are used in each of the second-path and third-path switches, STEP4 = -I0 × R / 4.

[0126] Therefore, compared to traditional pre-charge circuits, the pre-charge circuit 100c can also achieve both circuit miniaturization and high precision in pre-charge voltage. Furthermore, in Figure 7 In the illustrated embodiment, by selecting second and third path switches of the same specification, the accuracy of the pre-charge voltage can be ensured to be -I0×R / 4. Therefore, in Figure 7 In the illustrated embodiment, circuit area can be saved by using smaller path switches.

[0127] Figure 8 This paper shows a schematic diagram of the pre-charging circuit 100' in some embodiments of this application. Figure 8 The pre-charge circuit of the illustrated embodiment also includes a current source 110, a resistor string 120, a threshold voltage adjustment unit 130, and a control unit 140.

[0128] exist Figure 8 In the example, the threshold voltage adjustment unit 130 is connected to the threshold node corresponding to the minimum voltage value of the resistor string 120. Figure 8 This is manifested in that the current source 110, resistor string 120, and threshold voltage adjustment unit 130 are connected in series between the power supply voltage VDD and the ground voltage GND. With this design, the pre-charge circuit can provide a pre-charge voltage for the LED common cathode connected display panel.

[0129] For the remaining descriptions of the current source 110, resistor string 120, threshold voltage adjustment unit 130, and control unit 140, please refer to the descriptions of the other components. Figures 3 to 7 The description.

[0130] This application also provides a chip including any of the pre-charge circuits described above.

[0131] According to the pre-charging circuit, chip, and display device provided in this application, a threshold voltage adjustment unit is set up, and the threshold voltage adjustment unit adjusts the voltage value of the threshold node according to a portion of the selection signal. Under the condition of a constant branch current, the voltage value of each voltage output node will change with the change of the threshold node voltage value. Therefore, precise adjustment of the pre-charging voltage can be achieved. Combined with a multiplexer selecting the corresponding voltage output node to provide the pre-charging voltage according to another portion of the selection signal, the original single-level pre-charging voltage can be expanded into multiple levels. Thus, without increasing the number of resistors, the area of ​​the multiplexer, or the wiring between the resistors and the multiplexer, the precision of pre-charging voltage adjustment is improved.

[0132] Figure 9 A flowchart illustrating the pre-charging method in an embodiment of this application is shown. This pre-charging method can be implemented using any of the pre-charging circuits described above.

[0133] refer to Figure 9 The pre-charging method in this application includes:

[0134] Step S11: Provide branch current to the resistor string, which has multiple voltage output nodes;

[0135] Step S12: Adjust the voltage value of the threshold node in the voltage output node according to the set position in the selection signal; and

[0136] Step S13: Select one of the multiple voltage output nodes to provide the pre-charge voltage based on the remaining bits in the selection signal.

[0137] A threshold node is the node corresponding to the maximum or minimum voltage value among multiple voltage output nodes in a resistor series. Specifically, when the LEDs on the display panel are connected in a common anode configuration, the threshold node is the output node corresponding to the maximum voltage value; when the LEDs on the display panel are connected in a common cathode configuration, the threshold node is the output node corresponding to the minimum voltage value.

[0138] With a constant branch current, the voltage values ​​of each output node will change according to the threshold node voltage value. Therefore, precise adjustment of the pre-charge voltage can be achieved. By combining a multiplexer to select the corresponding voltage output node based on another part of the selection signal to provide the pre-charge voltage, the original single-level pre-charge voltage can be expanded into multiple levels. This improves the precision of pre-charge voltage adjustment without increasing the number of resistors, the area of ​​the multiplexer, or the wiring between the resistors and the multiplexer.

[0139] In some embodiments, the pre-charging method further includes calibrating the branch current. Specifically, the step of calibrating the branch current may include adjusting the branch current to achieve a preset value, while keeping other conditions unchanged. Calibration of the branch current can improve the accuracy of the pre-charging voltage. In some embodiments, the step of adjusting the voltage value of the threshold node may include: coupling a first resistor to the threshold node, the first resistor and the resistor string being connected in series between a first supply voltage and a second supply voltage; and providing a mirror current of the branch current to the first resistor according to a setting bit.

[0140] That is, by adjusting the voltage of the first resistor by adjusting the current flowing through the first resistor while keeping the branch current flowing through the resistor string constant, the voltage value of the threshold node can be adjusted.

[0141] In some embodiments, adjusting the current flowing through the first resistor can be achieved as described above. Figure 5 The circuit shown is used to implement this.

[0142] In some other embodiments, the step of adjusting the voltage value of the threshold node may include: coupling an adjustable resistor to the threshold node, wherein the adjustable resistor and the resistor string are connected in series between a first supply voltage and a second supply voltage; and adjusting the resistance value of the adjustable resistor according to a setting position in a selection signal. That is, by adjusting the resistance value of the adjustable resistor, the voltage division ratio of the adjustable resistor and the resistor string is adjusted, thereby achieving the adjustment of the voltage value of the threshold node.

[0143] In some embodiments, adjusting the resistance value of the adjustable resistor can be specifically achieved as described above. Figure 6 or Figure 7 The circuit shown is used to implement this.

[0144] According to the pre-charging circuit, method, chip, and display device provided in this application, a threshold voltage adjustment unit is set up, and the threshold voltage adjustment unit adjusts the voltage value of the threshold node according to a portion of the selection signal. Under the condition of a constant branch current, the voltage value of each voltage output node will change with the change of the threshold node voltage value. Therefore, precise adjustment of the pre-charging voltage can be achieved. Combined with a multiplexer selecting the corresponding voltage output node to provide the pre-charging voltage according to another portion of the selection signal, the original single-level pre-charging voltage can be expanded into multiple levels of pre-charging voltage. Thus, the accuracy of pre-charging voltage adjustment is improved without increasing the number of resistors, the area of ​​the multiplexer, or the wiring between the resistors and the multiplexer.

[0145] As described above, these embodiments of this application do not exhaustively cover all details, nor do they limit this application to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to effectively utilize this application and its modifications. The scope of protection of this application should be determined by the scope defined in the claims of this application.< / n:x>

Claims

1. A pre-charging circuit, wherein, include: A resistor string with multiple voltage output nodes; A threshold voltage adjustment unit, coupled to the threshold node in the voltage output node, is used to adjust the voltage value of the threshold node according to the setting bit in the selection signal; A current source is used to provide branch current flowing through the resistor string; as well as A multiplexer is used to select one of the plurality of voltage output nodes to provide a pre-charge voltage based on the remaining bits in the selection signal.

2. The pre-charging circuit according to claim 1, wherein, The pre-charging circuit also includes: A control unit is used to control the magnitude of the branch current.

3. The pre-charging circuit according to claim 2, wherein, The threshold voltage adjustment unit includes: A first resistor, with a first end coupled to a first supply voltage and a second end coupled to the first end of the resistor string, wherein the threshold node is the first end of the resistor string; and A mirror branch is coupled between the second terminal of the first resistor and the second supply voltage. Each mirror branch is turned on / off according to the corresponding bit in the setting bit. When the mirror branch is turned on, it provides a mirror current of the branch current.

4. The pre-charging circuit according to claim 3, wherein, The current source includes: A switching transistor is coupled between the second end of the resistor string and the second power supply voltage, and a control terminal is coupled to the control unit. Each of the aforementioned mirrored branches includes: The first-path switch and the mirror transistor are connected in series. The first path switch is turned on / off according to the corresponding bit in the set bit. The control terminal of the mirror transistor is coupled to the control terminal of the switching transistor, and the mirror transistor is used to proportionally replicate the branch current to provide the mirror current.

5. The pre-charging circuit according to claim 4, wherein, The control unit includes: An adjustable current source and a first transistor are connected in series, wherein the control terminal of the first transistor is coupled to the control terminal of the switching transistor.

6. The pre-charging circuit according to claim 4, wherein, The resistance value of the first resistor is the same as the resistance values ​​of each resistor in the resistor string. The total number of bits in the set position is X, where X is a positive integer. The ratio of the mirrored currents corresponding to each set bit, from least significant bit to most significant bit, is 1 / 2. X : 1 / 2 X -1 :...:1 / 2.

7. The pre-charging circuit according to claim 2, wherein, The threshold voltage adjustment unit includes: An adjustable resistor, wherein the setting position is used to adjust the resistance value of the adjustable resistor.

8. The pre-charging circuit according to claim 7, wherein, The adjustable resistor includes: A second resistor coupled between a first supply voltage and a first end of the resistor string, and at least one series structure, wherein the threshold node is the first end of the resistor string; and The second path switch, each of the series structures is connected in parallel with the corresponding second path switch, the second path switch being turned on / off according to the corresponding bit in the set bit.

9. The pre-charging circuit according to claim 8, wherein, Each of the series structures includes a third resistor.

10. The pre-charging circuit according to claim 8, wherein, Each of the series structures includes: a third resistor and a third path switch connected in series. The on / off state of the second path switch is opposite to the on / off state of the third path switch in the series structure connected in parallel with it. The width-to-length ratio of any of the third path switches and any of the second path switches is the same.

11. The pre-charging circuit according to claim 9 or 10, wherein, The resistance value of the second resistor is the same as the resistance values ​​of each resistor in the resistor string. The total number of bits in the set position is X, where X is a positive integer. The resistance ratio of the third resistor corresponding to each set bit, in order from least significant bit to most significant bit, is 1 / 2. X : 1 / 2 X-1 :...:1 / 2.

12. The pre-charging circuit according to claim 7, wherein, The current source includes: The switching transistor is coupled between the second terminal of the resistor string and the second supply voltage. The control unit includes: A sampling resistor, coupled between the switching transistor and the second supply voltage, is used to provide a sampling voltage based on the branch current; and The operational amplifier has a first input terminal coupled to the reference voltage, a second input terminal coupled to the sampled voltage, and an output terminal coupled to the control terminal of the switching transistor.

13. A chip, wherein, include: The pre-charge circuit as described in any one of claims 1-12.

14. A display device, wherein, include: The display panel includes multiple pixels; A driving circuit is used to drive the pixels to be turned on and displayed according to image data; as well as The pre-charge circuit as described in any one of claims 1-12 is used to provide a pre-charge voltage to the pixel before it is turned on.

15. A pre-charging method, wherein, include: Provide branch current for the resistor string, which has multiple voltage output nodes; Adjust the voltage value of the threshold node in the voltage output node according to the setting bit in the selection signal; as well as One of the plurality of voltage output nodes is selected based on the remaining bits in the selection signal to provide a pre-charge voltage.

16. The pre-charging method according to claim 15, wherein, The steps for adjusting the voltage value of the threshold node include: A threshold node coupling resistor is connected in series between a first supply voltage and a second supply voltage; and The resistance value of the resistor is adjusted according to the setting position, or a mirror current of the branch current is provided to the resistor according to the setting position.

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