Signal generation circuit, touch-control chip and active stylus

Abstract

Provided in the embodiments of the present application are a signal generation circuit, a chip and an active stylus. The signal generation circuit comprises: a boost circuit, a charge pump and an encoding circuit, wherein an input end of the boost circuit is connected to a power supply, an output end of the boost circuit is connected to an input end of the charge pump, and an output end of the charge pump is connected to the encoding circuit; the boost circuit is used for boosting a power supply voltage, which is provided by the power supply, to a preset voltage; the charge pump is used for raising the preset voltage by a preset integer factor to generate a target voltage; and the encoding circuit is used for receiving the target voltage and generating an encoding signal at least on the basis of the target voltage. On the basis of the above solution, the signal generation circuit provided in the embodiments of the present application can have relatively low design and use costs and a relatively high working efficiency.

Description

Signal generating circuit, touch chip and active pen Technical Field

[0001] The embodiments of the present application relate to the field of touch technology, and in particular to a signal generating circuit, a touch chip, and an active pen. Background Art

[0002] With the development of touch technology and mobile terminal technology, more and more mobile terminals are adopting touch for human-computer interaction. Currently, the touch screens used in mobile terminals are primarily capacitive touch screens. In addition to direct finger touch operation, capacitive touch screens can also be operated using an active stylus (hereinafter referred to as an active stylus) instead of a finger. When using an active stylus for touch operation, the active stylus typically needs to output a high coding voltage to enable communication between the active stylus and the terminal device.

[0003] In related technologies, active pens typically use a step-up chopper circuit (also known as a Boost circuit) to boost the low-voltage power supply voltage to a higher target voltage to provide a higher coding voltage. This results in the components in the Boost circuit needing to withstand a higher voltage rating, which increases the cost of the components. In addition, since the voltage amplification factor is high during the boosting process using the Boost circuit, and the load current in active pen applications is usually very low, this results in a low boost efficiency of the Boost circuit, resulting in low operating efficiency of the entire circuit.

[0004] Summary of the Invention

[0005] In view of this, one of the technical problems solved by the embodiments of the present application is to provide a signal generating circuit, a touch chip and an active pen, which are used to at least partially solve the above technical problems.

[0006] In a first aspect, embodiments of the present application provide a signal generating circuit comprising: a boost circuit, a charge pump, and a coding circuit. The boost circuit has an input connected to a power supply, an output connected to an input of the charge pump, and an output connected to the coding circuit. The boost circuit is configured to boost a power supply voltage provided by the power supply to a preset voltage; the charge pump is configured to increase the preset voltage by a preset integer multiple to generate a target voltage. The coding circuit is configured to receive the target voltage and generate a coding signal based at least on the target voltage.

[0007] In a second aspect, an embodiment of the present application further provides a touch control chip, comprising the signal generating circuit provided in the first aspect.

[0008] In a third aspect, an embodiment of the present application further provides an active pen, comprising the chip provided in the second aspect.

[0009] In the technical solution provided by the embodiment of the present application, a boost circuit is used as the first stage of boosting to increase the power supply voltage to a preset voltage, and a charge pump is used as the second stage of boosting to further increase the preset voltage to the target voltage and provide it to the coding circuit. Since a two-stage boost is achieved by using a boost circuit and a charge pump, the withstand voltage requirements of the components in the boost circuit and the charge pump are greatly reduced compared to the one-stage boost solution using only a boost circuit in the related art, thereby reducing the design and use cost of the signal generating circuit. In addition, due to the use of the charge pump, the output voltage of the boost circuit is a preset voltage that is smaller than the target voltage, so the boost multiple of the boost circuit can be lower, and the boost efficiency of the boost circuit is correspondingly improved. At the same time, the charge pump path loss is small and the efficiency is high. Therefore, the signal generating circuit provided by the present application can have a high working efficiency while having a low design and use cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Hereinafter, some specific embodiments of the present application will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the drawings:

[0011] FIG1 is a schematic structural diagram of a signal generating circuit provided by a related art;

[0012] FIG2 is a schematic structural diagram of a signal generating circuit provided in an embodiment of the present application;

[0013] FIG3 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0014] FIG4 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0015] FIG5 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0016] FIG6 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application;

[0017] FIG7 is a schematic diagram of a coding signal of a signal generating circuit provided in an embodiment of the present application;

[0018] FIG8 is a schematic structural diagram of a signal generating circuit provided in an embodiment of the present application;

[0019] FIG9 is a schematic diagram of a coding signal of a signal generating circuit provided in an embodiment of the present application;

[0020] FIG10 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application; and

[0021] FIG11 is a circuit structure diagram of a signal generating circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0023] Capacitive touch screens are widely used as touch screens for mobile terminals due to their good clarity, light transmittance and touch feel. In addition to being able to be operated directly by fingers, capacitive touch screens can also be operated by an active touch stylus (hereinafter referred to as an active pen) instead of fingers. In the application scenario where the active pen is used in conjunction with a terminal device, the active pen is used to write or input instructions to a terminal device with a capacitive touch screen, such as a mobile terminal device, a computer screen, a drawing board, etc., to achieve human-computer interaction. In order to achieve communication between the active pen and the terminal device, the active pen needs to output a coding signal. The coding signal is usually a high-voltage signal to ensure that the communication signal between the active pen and the terminal device has a high signal-to-noise ratio. In order for the active pen to output such a coding signal, the signal generating circuit in the active pen needs to boost the power voltage provided by the power supply to the target voltage, and generate a coding signal based on such a target voltage and provide it to the active pen (for example, the tip of the active pen), and the active pen outputs the coding signal.

[0024] FIG1 is a structural diagram of a signal generating circuit provided by the related art. As shown in FIG1 , the signal generating circuit includes a Boost circuit and a coding circuit. The input end of the Boost circuit is connected to a power supply (also referred to as an input power supply) to receive the power supply voltage of the input power supply and directly convert the power supply voltage into a desired DC voltage (i.e., a target voltage) to provide to the coding circuit. The input power supply typically has a relatively low DC voltage, for example, the power supply voltage of the input power supply is typically 1.0V to 5V. The target voltage is typically a relatively high DC voltage, for example, it can be 60V, 40V, or 20V. The input end of the coding circuit is connected to the output end of the Boost circuit, and the output end of the coding circuit is connected to a drive electrode, which is typically located in the pen tip of an active pen. The coding circuit generates a coding signal based on the target voltage to provide to the drive electrode.

[0025] In the signal generating circuit shown in Figure 1, a boost circuit is used to directly boost the power supply voltage to a target voltage. The boost circuit includes an inductor L01, a main power tube Q01, a freewheeling diode D01, and a capacitor C01. The first end of the inductor L01 is connected to a power supply, wherein the power supply can be a battery, providing a power supply voltage V (also referred to as VBAT). The second end of the inductor L01 is connected to the first end of the main power tube Q01 and the positive pole of the freewheeling diode D01. The second end of the main power tube Q01 is connected to ground, and the third end of the main power tube Q01 is connected to a control module (not shown) to receive a control signal. The negative pole of the freewheeling diode D01 is connected to the input end of the coding circuit and the first end of the capacitor C01, and the second end of the capacitor C01 is connected to ground.

[0026] Among them, the inductor L01 and the main power tube Q01 constitute a basic energy conversion unit. When the main power tube Q01 is turned on, the inductor L01 is charged, and the energy stored in the inductor L01 gradually increases. When the main power tube is turned off, the inductor L01 is discharged, and the energy stored in the inductor L01 flows to the capacitor C01 through the freewheeling diode D01. The control module intermittently controls the number of times the main power tube Q01 is turned on and off by applying a control signal to the third end of the main power tube Q01, so that the voltage on the capacitor C01 gradually increases to the target voltage HV to be provided to the coding circuit. The coding circuit includes a first switch S1 and a second switch S2. The first switch S1 and the second switch S2 are alternately turned on, so that the output end of the coding circuit outputs a coding signal to the drive electrode TX.

[0027] In the signal generation circuit shown in Figure 1, the main power transistor Q01, freewheeling diode D01, and capacitor C01 all need to have a high withstand voltage—that is, they all need to be greater than HV. The higher the withstand voltage of a device, the larger the package size and, accordingly, the more expensive the device. Furthermore, the high withstand voltage of a device also limits its selection. Therefore, the design and use costs of the signal generation circuit shown in Figure 1 are relatively high.

[0028] In addition, in the signal generating circuit shown in FIG1 , a Boost circuit is used to increase the low-voltage DC power supply voltage to a target voltage, and the voltage amplification factor is large. As known to those skilled in the art, for a Boost circuit, the greater the voltage amplification factor, the greater the various losses such as the conduction loss of the main power tube and the freewheeling diode in the Boost circuit, and the lower the boost efficiency of the Boost circuit (i.e., the energy conversion efficiency between the input and output of the Boost circuit). In addition, in active pen applications, the load is a smaller capacitive load (i.e., a smaller capacitor), and the current flowing through the load is usually very low, which makes the boost efficiency of the Boost circuit even lower. For example, in an active pen application, the Boost circuit increases the power supply voltage of 3.6V to a target voltage of 60V, and the boost efficiency of the boost circuit is only 40%-60%.

[0029] To this end, an embodiment of the present application provides a signal generating circuit, which uses a boost circuit and a charge pump to increase the power supply voltage to a target voltage through two-stage boosting, and provides it to a coding circuit. The coding circuit generates a coding signal based on the target voltage, thereby reducing the voltage resistance requirements of the devices in the signal generating circuit while improving their working efficiency, thereby realizing a signal generating circuit with lower design and use costs and higher efficiency.

[0030] The specific implementation of the embodiment of the present application is further explained below in conjunction with the accompanying drawings of the embodiment of the present application.

[0031] Figure 2 shows a schematic diagram of the structure of a signal generating circuit provided according to an embodiment of the present application. As shown in Figure 2, the signal generating circuit 200 includes: a boost circuit 202, a charge pump 204 and a coding circuit 206;

[0032] The input end of the boost circuit 202 is connected to the power supply 100 , the output end of the boost circuit 202 is connected to the input end of the charge pump 204 , and the output end of the charge pump 204 is connected to the coding circuit 206 ;

[0033] The boost circuit 202 is used to boost the power voltage V provided by the power supply 100 to a preset voltage V1;

[0034] a charge pump 204 for increasing the preset voltage V1 by a preset integer multiple to generate a target voltage HV;

[0035] The coding circuit 206 is configured to receive the target voltage HV and generate a coding signal based at least on the target voltage HV.

[0036] The power supply 100 may be a battery. For example, in an active pen application, the power supply may be a battery of the active pen.

[0037] The input of boost circuit 202 is connected to power supply 100 to receive the power supply voltage V provided by power supply 100. Boost circuit 202 can be an energy storage and release circuit composed of an inductor and a switching element. When the switching element is on, the inductor stores energy; when the switching element is off, the inductor releases energy and provides a predetermined voltage that is greater than the power supply voltage.

[0038] The boost circuit 202 can gradually adjust the power supply voltage V to a preset voltage V1 by storing and releasing energy in the inductor. In one implementation of the present application, the boost circuit 202 is a boost circuit, and the structure of the boost circuit can be similar to the structure of the boost circuit shown in Figure 1, which will not be repeated here.

[0039] The charge pump 204 uses the charging and discharging principle of a capacitor to achieve voltage boosting. In this embodiment, the charge pump 204 can boost the preset voltage by a preset integer multiple to generate a target voltage. The preset integer multiple can be any one of 2, 4, or 6. That is, the charge pump 204 can be any one of a 2x voltage charge pump, a 4x voltage charge pump, or a 6x voltage charge pump. When the preset integer multiple is 2, the boost circuit 202 needs to boost the power supply voltage to 1 / 2 times the target voltage, that is, the preset voltage is equal to 1 / 2 times the target voltage. Similarly, when the preset integer multiple is 4, the boost circuit 202 needs to boost the power supply voltage to 1 / 4 times the target voltage, that is, the preset voltage is equal to 1 / 4 times the target voltage. When the preset integer multiple is 6, the boost circuit 202 needs to boost the power supply voltage to 1 / 6 times the target voltage, that is, the preset voltage is equal to 1 / 6 times the target voltage.

[0040] As the boost multiple that charge pump 204 can achieve increases, more energy storage capacitors are required in the charge pump, which means that the number of capacitors in the charge pump also increases, and the charge pump efficiency may decrease. Therefore, in one implementation of the present application, the preset integer multiple is 2. That is, the charge pump is a 2x charge pump. Typically, under light load conditions (i.e., low load factor), the efficiency of a 2x charge pump is greater than 90%.

[0041] An output terminal of the charge pump 204 is connected to the coding circuit 206 to provide a target voltage to the coding circuit. The coding circuit generates a coding signal based on at least the target voltage.

[0042] In an embodiment of the present application, a boost circuit is used as a first-stage boost to increase the power supply voltage to a preset voltage, and a charge pump is used as a second-stage boost to further increase the preset voltage to a target voltage and provide it to the coding circuit. Since a two-stage boost is achieved using a boost circuit and a charge pump, the withstand voltage requirements of the components in the boost circuit and the charge pump are significantly reduced compared to a solution using only a single-stage boost, thereby reducing the overall design and use cost of the signal generating circuit provided in this application. In addition, since the output voltage of the boost circuit is a preset voltage that is lower than the target voltage, the boost multiple of the boost circuit can be lower. The smaller the boost multiple of the boost circuit, the smaller its loss, and thus the boost efficiency of the boost circuit is improved. At the same time, since the charge pump path loss is small and the efficiency is high, the signal generating circuit provided in this application has high efficiency while having low cost.

[0043] For example, for an active pen application with a 3.6V power supply voltage and a 60V target voltage, if the boost circuit employs the boost circuit shown in Figure 1 and the charge pump is a 2x charge pump, the boost circuit only needs to boost the 3.6V power supply voltage to 30V. The charge pump then doubles the 30V preset voltage to 60V. Because the efficiency of a boost circuit is related to the voltage gain, the voltage gain of 8.3 for boosting the 3.6V power supply voltage to 30V is lower than the voltage gain of 16.7 for boosting the 3.6V power supply voltage to 60V. The efficiency of a 16.7x voltage gain is lower than the efficiency of an 8.3x voltage gain, typically by approximately 20%. Therefore, in this embodiment, by boosting the 3.6V power supply voltage to 30V, the boost circuit's efficiency can be increased from 40-60% to 60-80%. Furthermore, under light loads, the efficiency of the 2x charge pump exceeds 90%. The combined efficiency of the two can reach over 54-73%, significantly higher than the 40-60% achieved by direct voltage boosting using a boost circuit as shown in Figure 1. Furthermore, due to the two-stage boost, the withstand voltage requirement for at least some components in the boost circuit and the 2x charge pump is reduced from greater than 60V to greater than 30V. This significantly reduces the withstand voltage requirement for the components, thereby lowering component costs, expanding the selection range, and ultimately reducing the design and use costs of the entire signal generation circuit.

[0044] Based on the signal generating circuit shown in FIG2 , FIG3 shows a schematic diagram of the structure of a signal generating circuit according to an embodiment of the present application. The boost circuit 302 and coding circuit 306 in the signal generating circuit 300 shown in FIG3 have the same structure and operating principle as the boost circuit 202 and coding circuit 206 in the signal generating circuit 200 shown in FIG2 . The signal generating circuit 300 shown in FIG3 provides a circuit implementation of the charge pump in the signal generating circuit 200 shown in FIG2 .

[0045] As shown in Figure 3, the charge pump 304 includes a first capacitor C1, a second capacitor C2, a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first switch Q1 and the second switch Q2 are connected in series between the output of the boost circuit 302 and the input of the coding circuit 306, and the third switch Q3 and the fourth switch Q4 are connected in series between the output of the boost circuit 302 and ground. The first end of the first capacitor C1 is connected to the common terminal of the first and second switches Q1 and Q2, and the second end of the first capacitor C1 is connected to the common terminal of the third and fourth switches Q3 and Q4. The first end of the second capacitor C2 is connected to the input of the coding circuit 306, and the second end of the second capacitor C2 is grounded.

[0046] In this embodiment, the first switch tube Q1 and the fourth switch tube Q4 form a group of switches, and the second switch tube Q2 and the third switch tube Q3 form a group of switches, and the two groups of switches are mutually exclusive turned on or off at a certain frequency. Specifically, the control ends of the first switch tube Q1 to the fourth switch tube Q4 are connected to a control module (not shown). The control module mutually exclusively turns on or off a group of switches consisting of the first switch tube Q1 and the fourth switch tube Q4 and a group of switches consisting of the second switch tube Q2 and the third switch tube Q3 at a certain frequency so that the charge pump 304 boosts the received preset voltage V1 to HV, where V1=1 / 2HV. In this embodiment, the first switch tube Q1 to the fourth switch tube Q4 can be a field effect transistor. The control module may include a micro control unit (not shown) and a drive module (not shown). The drive module is connected to the control ends of the first switch tube Q1 to the fourth switch tube Q4 for driving the first switch tube Q1 to the fourth switch tube Q4. The micro control unit is connected to the driving module and controls the driving mode of the driving module so that the driving module generates a square wave with a certain duty cycle to control the on and off of the first to fourth switching tubes Q1 to Q4.

[0047] In this embodiment, when the first switch tube Q1 and the fourth switch tube Q4 are turned on, and the second switch tube Q2 and the third switch tube Q3 are turned off, the voltages across the first capacitor C1 are 1 / 2HV and 0V, respectively. At this time, the voltage difference across the second switch tube and the third switch tube is 1 / 2HV. Then, when the second switch tube Q2 and the third switch tube Q3 are turned on, and the first switch tube Q1 and the fourth switch tube Q4 are turned off, the voltages across the first capacitor C1 are HV and 1 / 2HV, respectively. At this time, the voltage difference across the first switch tube Q1 and the fourth switch tube Q4 is also only 1 / 2HV. That is, during the entire operation, the withstand voltage of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4 and the first capacitor C1 only needs to meet 1 / 2HV. Compared to the one-stage boost scheme in the signal generation circuit shown in Figure 1, the device does not need to withstand the high voltage HV, which reduces the requirements for the device and reduces the circuit design cost of the signal generation circuit.

[0048] In the charge pump 304 shown in FIG3 , the withstand voltage of the second capacitor C2 needs to meet HV. To optimize the withstand voltage of the second capacitor C2, FIG4 provides a schematic diagram of the structure of a signal generating circuit according to an embodiment of the present application. The difference between the signal generating circuit 400 shown in FIG4 and the signal generating circuit 300 shown in FIG3 lies in the different circuit implementation of the charge pump.

[0049] In the signal generating circuit 400 shown in FIG4 , the charge pump 404 includes a first capacitor C1, a second capacitor C2, a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The first switch Q1 and the second switch Q2 are connected in series between the output of the boost circuit 302 and the input of the coding circuit 306, and the third switch Q3 and the fourth switch Q4 are connected in series between the output of the boost circuit 302 and ground. The first end of the first capacitor C1 is connected to the common terminal of the first and second switches Q1 and Q2, and the second end of the first capacitor C1 is connected to the common terminal of the third and fourth switches Q3 and Q4. The first end of the second capacitor C2 is connected to the input of the coding circuit 306, and the second end of the second capacitor C2 is connected to the output of the boost circuit 302.

[0050] The charge pump 400 in this embodiment has the same control process and working principle as the charge pump 300 in the embodiment shown in FIG3 , with the only difference being that in FIG4 , the second end of the second capacitor C2 is connected to the output end of the boost circuit 302, so that the withstand voltage value of the second capacitor C2 is also reduced from HV to 1 / 2HV. That is, in the embodiment shown in FIG4 , the withstand voltage values ​​of all devices in the charge pump only need to meet 1 / 2HV. Compared with the first-level boost scheme in the signal generating circuit shown in FIG1 , the devices do not need to withstand the high voltage HV, which reduces the withstand voltage requirements for the devices and reduces the circuit design cost of the signal generating circuit.

[0051] In the signal generating circuits shown in Figures 2 to 4, the boost circuit may include a boost circuit. As shown in Figures 5 and 6, the boost circuit is a boost circuit 502 and 602, and the boost circuit 502 and 602 include: an inductor L1, a switch tube Q5, a freewheeling diode D1 and a third capacitor C3. The first end of the inductor L1 is connected to the power supply 100, and the second end of the inductor L1 is connected to the first end of the switch tube Q5 and the positive pole of the freewheeling diode D1. The second end of the switch tube Q5 is connected to ground, and the third end of the switch tube Q5 is connected to a control module (not shown) to receive a control signal. The negative pole of the freewheeling diode D1 is connected to the input end of the charge pump 504 and 604 and the first end of the third capacitor C3, and the second end of the third capacitor C3 is connected to ground.

[0052] In this embodiment, the switch tube Q5 can be a field effect transistor. The control module connected to the switch tube Q5 can be the control module in the embodiments shown in Figures 3 and 4. The control module intermittently controls the conduction and shutdown of the switch tube Q5. By controlling the number of times the switch tube Q5 is turned on and off, the voltage on the third capacitor C3 can be increased to V1, V1=1 / 2HV. The freewheeling diode D1 can prevent the energy on the third capacitor C3 from flowing back to the power supply. The specific process of Boost in this embodiment refers to the specific process of the boost circuit shown in Figure 1, and will not be repeated here.

[0053] Because the boost circuit in this embodiment only needs to boost the power supply voltage V to 1 / 2HV, the switch Q5, freewheeling diode D1, and third capacitor C3 in the boost circuit only need to meet 1 / 2HV. Compared with the single-stage boost solution in the signal generation circuit shown in Figure 1, this reduces the need for components to withstand the high voltage HV, lowering the component requirements and reducing the circuit design cost of the signal generation circuit.

[0054] The embodiments shown in Figures 5 and 6 further illustrate a circuit structure diagram of a coding circuit provided in an embodiment of the present application. As shown in Figures 5 and 6, the coding circuits 506 and 606 include a switch module and a control module (not shown) connected to the control end of the switch module. The switch module includes: a first switch S1 and a second switch S2, the first switch S1 and the second switch S2 are connected in series between the output end of the charge pump 504 and 604 and the ground, and the common end between the first switch S1 and the second switch S2 is connected to the output end of the coding circuit 506 and 606;

[0055] The control module (not shown) is used to control the state of the switches in the switch module so that the output terminals of the coding circuits 506 and 606 output coding signals, wherein the coding signals include two voltage levels with amplitudes of ground voltage and target voltage.

[0056] The control module in this embodiment can be designed to be integrated with the control modules for controlling the boost circuit and each switching tube in the charge pump, or it can be designed independently of the control modules for controlling the boost circuit and each switching tube in the charge pump. This embodiment does not limit this.

[0057] In a specific implementation, the control module controls the switches in the switch module including: a first stage and a second stage;

[0058] In the first stage, the first switch S1 is in a closed state and the second switch S2 is in an open state, and the output terminals of the coding circuits 506 and 606 output the target voltage;

[0059] In the second stage, when the first switch S1 is in the open state and the second switch S2 is in the closed state, the output terminals of the coding circuits 506 and 606 output the ground voltage.

[0060] The control module periodically executes the first stage and the second stage in the above manner, thereby simply controlling and generating the coding signal as shown in FIG7 , where 0 represents the ground voltage and HV represents the target voltage.

[0061] Since the load in the active pen application is a capacitive load, energy loss is inevitable when charging the capacitive load. The energy loss is proportional to the square of the charging voltage difference. In order to reduce the loss of the coding signal when charging the capacitive load and improve the coding efficiency, a signal generating circuit as shown in Figure 8 is provided. The difference between the signal generating circuit shown in Figure 8 and the signal generating circuit shown in Figures 2 to 7 is that in the signal generating circuit shown in Figure 8, the coding circuit 806 includes a first input terminal and a second input terminal, the first input terminal of the coding circuit 806 is connected to the output terminal of the charge pump 804, and the second input terminal of the coding circuit 806 is connected to the output terminal of the boost circuit 802. The coding circuit is used to receive the preset voltage output by the boost circuit and the target voltage output by the charge pump to generate a coding signal based on the preset voltage and the target voltage. Among them, the coding signal is a step signal and includes three voltage levels with amplitudes of ground voltage, preset voltage and target voltage.

[0062] In this embodiment, the structures and operating principles of the boost circuit 802 and the charge pump 804 are the same as those of the boost circuit and the charge pump in the embodiments shown in FIG. 2 to FIG. 6 , and are not described again here.

[0063] In this embodiment, by connecting the first input of coding circuit 806 to the output of charge pump 804 and the second input of coding circuit 806 to the output of boost circuit 802, the coding circuit can generate a step coding signal as shown in FIG9 . For capacitive loads, the lower the single charge voltage, the lower the power loss. Specifically, energy loss is proportional to the square of the charge voltage difference. Therefore, compared with the coding signal shown in FIG7 , the voltage difference between the two voltage levels in the step coding signal shown in FIG9 is significantly reduced, thereby significantly reducing energy loss and improving coding efficiency. For example, when the preset voltage is 1 / 2 of the target voltage, using the step coding signal shown in FIG9 can save 50% of energy, achieving higher coding efficiency.

[0064] Figures 10 and 11 show two structural schematic diagrams of the signal generating circuit provided according to an embodiment of the present application. The boost circuit and charge pump in Figures 10 and 11 have the same structure and working principle as the boost circuit and charge pump in the aforementioned embodiment, and will not be repeated here. The difference between the signal generating circuit shown in Figures 10 and 11 and the signal generating circuit in the aforementioned embodiment is that the structure of the coding circuit is different. Specifically, as shown in Figures 10 and 11, the coding circuit 906 and 1006 includes a switch module and a control module connected to the control end of the switch module; the switch module includes: a first switch S1, a second switch S2 and a third switch S3, the first switch S1 and the second switch S2 are connected in series between the output end of the charge pump 904 and 1004 and the ground, the common end between the first switch S1 and the second switch S2 is connected to the output end of the coding circuit 906 and 1006, the first end of the third switch S3 is connected to the output end of the boost circuit 902 and 1002, and the second end of the third switch S3 is connected to the output end of the coding circuit 906 and 1006. The control module (not shown) is used to control the states of the switches in the switch module so that the output terminals of the coding circuits 906 and 1006 output coding signals.

[0065] The control module in this embodiment can be designed to be integrated with the control modules for controlling the boost circuit and each switch tube in the charge pump, or it can be designed independently of the control modules for controlling the boost circuit and each switch tube in the charge pump. This embodiment does not limit this.

[0066] In a specific implementation, the control module controls the switches in the switch module in the following stages: a first stage, a second stage, a third stage, and a fourth stage;

[0067] In the first stage, the third switch S3 is in a closed state, and the first switch S1 and the second switch S2 are in an open state, and the output terminals of the coding circuits 906 and 1006 have a preset voltage;

[0068] In the second stage, the first switch S1 is in the closed state, and the second switch S2 and the third switch S3 are in the open state, and the output terminals of the coding circuits 906 and 1006 output the target voltage;

[0069] In the third stage, the third switch S3 is in a closed state, and the first switch S1 and the second switch S2 are in an open state, and the output terminals of the coding circuits 906 and 1006 have a preset voltage;

[0070] In the fourth stage, the second switch S2 is in a closed state, and the first switch S1 and the third switch S3 are in an open state, and the output terminals of the coding circuits 906 and 1006 output a ground voltage.

[0071] In this embodiment, the control module controls the conduction and closure of the first switch S1, the second switch S2, and the third switch S3 in this manner to implement the staircase coding signal shown in Figure 9. Because energy loss for capacitive loads is proportional to the square of the charge voltage difference, the voltage difference between the two levels in the staircase coding signal shown in Figure 9 is significantly smaller than that in the coding signal shown in Figure 7. Consequently, energy loss is significantly reduced, thereby improving coding efficiency.

[0072] An embodiment of the present application provides a touch control chip, including the signal generating circuit in any embodiment of the present application.

[0073] The present application also provides an active pen, which includes the touch chip provided in the above embodiment. When the active pen touches the capacitive touch screen of the terminal device, the touch chip provides a coding signal to the tip of the active pen.

[0074] The terminal devices of the embodiments of the present application exist in various forms, including but not limited to:

[0075] (1) Mobile communication devices: These devices are characterized by their mobile communication capabilities and are primarily designed to provide voice and data communications. These terminals include smartphones (e.g., iPhones), multimedia phones, feature phones, and low-end phones.

[0076] (2) Ultra-mobile personal computer devices: These devices fall under the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access. These terminals include PDAs, MIDs, and UMPCs, such as the iPad.

[0077] (3) Portable entertainment devices: These devices can display and play multimedia content. These devices include audio and video players (such as iPods), handheld game consoles, e-books, smart toys, and portable car navigation devices.

[0078] (4) Server: A device that provides computing services. The server consists of a processor 810, a hard disk, memory, a system bus, etc. The server is similar to a general computer architecture, but because it needs to provide highly reliable services, it has higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0079] (5) Other electronic devices with data interaction functions.

[0080] Thus far, specific embodiments of the present subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing may be advantageous.

[0081] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0082] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A signal generating circuit comprising: Boost circuit, charge pump and coding circuit; The input end of the boost circuit is connected to the power supply, the output end of the boost circuit is connected to the input end of the charge pump, and the output end of the charge pump is connected to the coding circuit; The boost circuit is used to boost the power voltage provided by the power supply to a preset voltage; The charge pump is configured to increase the preset voltage by a preset integer multiple to generate a target voltage; The coding circuit is configured to receive the target voltage and generate a coding signal based at least on the target voltage.

2. The signal generating circuit according to claim 1, wherein: The preset integer multiple is 2.

3. The signal generating circuit according to claim 2, wherein: The charge pump includes a first capacitor, a second capacitor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; The first switch tube and the second switch tube are connected in series between the output end of the boost circuit and the first input end of the coding circuit, and the third switch and the fourth switch are connected in series between the output end of the boost circuit and the ground; The first end of the first capacitor is connected to the common end of the first switching tube and the second switching tube, and the second end of the first capacitor is connected to the common end of the third switching tube and the fourth switching tube; and the first end of the second capacitor is connected to the first input end of the coding circuit, and the second end of the second capacitor is grounded.

4. The signal generating circuit according to claim 2, wherein: The charge pump includes a first capacitor, a second capacitor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; The first switch tube and the second switch tube are connected in series between the output end of the boost circuit and the first input end of the coding circuit, and the third switch and the fourth switch are connected in series between the output end of the boost circuit and the ground; The first end of the first capacitor is connected to the common end of the first switching tube and the second switching tube, and the second end of the first capacitor is connected to the common end of the third switching tube and the fourth switching tube; the first end of the second capacitor is connected to the input end of the coding circuit, and the second end of the second capacitor is connected to the output end of the boost circuit. The signal generating circuit according to claim 1 , wherein the voltage increasing circuit comprises a boost circuit. The signal generating circuit according to claim 1 , wherein: The coding circuit includes a switch module and a control module connected to a control end of the switch module; The switch module includes a first switch and a second switch, wherein the first switch and the second switch are connected in series between the output terminal of the charge pump and the ground. The common end is connected to the output end of the coding circuit; The control module is used to control the state of the switch in the switch module so that the output end of the coding circuit outputs the coding signal, wherein the coding signal includes two voltage levels with amplitudes of ground voltage and the target voltage.

7. The signal generating circuit according to claim 6, wherein: The control of the switches in the switch module by the control module includes: a first stage and a second stage; In the first stage, the first switch is in a closed state and the second switch is in an open state, and the output end of the coding circuit outputs the target voltage; In the second stage, when the first switch is in an open state and the second switch is in a closed state, the output end of the coding circuit outputs a ground voltage.

8. The signal generating circuit according to claim 1, wherein: The coding circuit includes a first input terminal and a second input terminal, the first input terminal of the coding circuit is connected to the output terminal of the charge pump, and the second input terminal of the coding circuit is connected to the output terminal of the boost circuit; The coding circuit is used to receive the preset voltage and the target voltage to generate the coding signal based on the preset voltage and the target voltage, wherein the coding signal is a step signal and includes three levels of voltage with amplitudes of ground voltage, the preset voltage and the target voltage.

9. The signal generating circuit according to claim 8, wherein: The coding circuit includes a switch module and a control module connected to a control end of the switch module; The switch module includes: a first switch, a second switch, and a third switch, wherein the first switch and the second switch are connected in series between the output terminal of the charge pump and the ground, a common terminal between the first switch and the second switch is connected to the output terminal of the coding circuit, a first terminal of the third switch is connected to the output terminal of the boost circuit, and a second terminal of the third switch is connected to the output terminal of the coding circuit; The control module is used to control the state of the switch in the switch module so that the output end of the coding circuit outputs the coding signal.

10. The signal generating circuit according to claim 8, wherein: The control of the switches in the switch module by the control module includes: a first stage, a second stage, a third stage and a fourth stage; In the first stage, the third switch is in a closed state, and the first switch and the second switch are in an open state, and the output end of the coding circuit is at the preset voltage; In the second stage, the first switch is in a closed state, and the second switch and the third switch are in an open state, and the output end of the coding circuit outputs the target voltage; In the third stage, the third switch is in a closed state, and the first switch and the second switch are The switch is in the off state, and the output end of the coding circuit has the preset voltage; In the fourth stage, the second switch is in a closed state, and the first switch and the third switch are in an open state, and the output end of the coding circuit outputs the ground voltage.

11. A touch control chip comprising the signal generating circuit according to any one of claims 1 to 10. 12 . An active pen comprising the touch chip according to claim 11 .

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