Spread spectrum circuit, power supply system, chip and electronic device

Abstract

The application provides a spread spectrum circuit, a power supply system, a chip and an electronic device. The closed loop controlled oscillator comprises a closed loop control module and a voltage controlled oscillator for generating a first clock signal; the spread spectrum circuit comprises a spread spectrum module and a frequency divider for generating a second clock signal with a preset frequency according to the first clock signal; the input end of the spread spectrum module is coupled to the output end of the frequency divider, the output end of the spread spectrum module is coupled to the first input end of the closed loop control module, the output end of the closed loop control module is coupled to the input end of the voltage controlled oscillator, the output end of the voltage controlled oscillator is coupled to the second input end of the closed loop control module and the input end of the frequency divider; the spread spectrum module generates a triangular wave signal according to the second clock signal, and the closed loop control module generates a control signal for driving the oscillator according to the first clock signal and the triangular wave signal. The application can achieve linear frequency modulation effect without complex digital modules, the spectrum energy is uniform, the chip design can be effectively simplified, and the cost can be significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of circuit design technology, and in particular to a spread spectrum circuit, power supply system, chip, and electronic device. Background Technology

[0002] In high-frequency scenarios of tens or even hundreds of MHz, traditional open-loop oscillators composed of current sources charging and discharging capacitors and comparators are gradually failing to meet the requirements. This is because, firstly, the comparator consumes a great deal of power at such frequencies, and secondly, the open-loop control method is susceptible to random errors in the components, which may lead to significant differences in frequency between chips (in actual large-scale applications, due to random errors in the chip manufacturing process, the actual dimensions of various components in the chip will have a certain degree of random deviation, causing changes in chip performance), making it difficult to meet the high-precision requirements of the chips.

[0003] To address this issue, existing high-frequency oscillators often employ closed-loop control schemes. Please refer to [link / reference]. Figure 1 , Figure 1 This is a block diagram of a closed-loop oscillator using a spread spectrum module in the prior art. Figure 1 As shown, the output of the voltage-controlled oscillator 110 is fed back to switches 1211 and 1212 of the switched capacitor 121 in the closed-loop control module 120. When the frequency of the voltage-controlled oscillator 110 changes, the equivalent impedance of the switched capacitor 121 changes, causing a change in the voltage at the negative input terminal of the operational amplifier 122. The voltage of the output signal Vctrl of the operational amplifier 122 changes accordingly, adjusting the frequency of the closed-loop oscillator to achieve negative feedback and stabilize the frequency. Based on this theoretical analysis, the frequency of the closed-loop oscillator is only related to the resistor 123 and capacitor 1213 of the closed-loop control module 120 (closed-loop network) and the supply voltage VDD, which can significantly improve the inter-chip consistency. The theoretical analysis yields the following expression:

[0004] (1)

[0005] In equation (1), The power supply voltage, The resistance value of resistor 123. Here is the impedance expression for the switched capacitor. The reference voltage for operational amplifier 122 comes from spread spectrum module 200, which is typically a pseudo-random resistor array or a triangular wave circuit.

[0006] Further derivation yields the following equation (2):

[0007] (2)

[0008] In the above formula (2), Here is the capacitance value of capacitor 1213. For other parameters, please refer to the above explanation of equation (1).

[0009] To meet the demands of chip miniaturization, higher drive frequencies are often used to reduce the size of passive components. Therefore, switching power supply chips often require high-frequency oscillators of tens or even hundreds of MHz to drive the power stage. As the drive frequency continues to increase, the larger dv / dt ratio leads to EMI (Electromagnetic Interference), necessitating dedicated spread spectrum circuits to broaden the oscillator frequency and reduce single-point radiation. In existing technologies, pseudo-random codes or triangular wave generators are often used to control the reference voltage of the oscillator's operational amplifier. Modulation is performed to change the frequency.

[0010] However, research has found that while the pseudo-random code scheme is relatively simpler than the triangular wave scheme, the number of frequency points generated is related to the circuit size, and the uniformity of frequency point energy is positively correlated with the number of frequency points. In other words, achieving a good spread spectrum effect means that the circuit complexity and cost will increase accordingly. The triangular wave generator scheme directly modulates the reference voltage, which cannot achieve linear frequency adjustment or relatively fine-tuned level adjustment. It also suffers from uneven frequency point energy distribution and reduced spread spectrum effect.

[0011] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0012] The purpose of this invention is to provide a spread spectrum circuit, a power supply system, a chip, and an electronic device. The spread spectrum circuit provided by this invention can achieve linear frequency modulation without complex digital modules, and the spectrum energy is uniform, which can effectively simplify chip design and significantly reduce costs.

[0013] To achieve the above objectives, the present invention provides the following technical solution: a spread spectrum circuit for an oscillator used in closed-loop control, wherein the closed-loop controlled oscillator includes a closed-loop control module and a voltage-controlled oscillator (VCO) for generating a first clock signal; the spread spectrum circuit includes a spread spectrum module and a frequency divider for generating a second clock signal of a preset frequency based on the first clock signal; the input terminal of the spread spectrum module is coupled to the output terminal of the frequency divider, the output terminal of the spread spectrum module is coupled to the first input terminal of the closed-loop control module, the output terminal of the closed-loop control module is coupled to the input terminal of the VCO, and the output terminal of the VCO is coupled to the second input terminal of the closed-loop control module and the input terminal of the frequency divider;

[0014] The spread spectrum module is configured to generate a triangular wave signal based on the second clock signal, and the closed-loop control module generates a control signal for driving the oscillator based on the first clock signal and the triangular wave signal.

[0015] Optionally, the spread spectrum module includes an integrator and a first operational amplifier. The first end of the integrator is coupled to the output of the frequency divider, the second end of the integrator is coupled to the negative input of the first operational amplifier, and the third end of the integrator and the output of the first operational amplifier are coupled to the first input of the closed-loop control module. The positive input of the first operational amplifier receives a triangular wave reference voltage.

[0016] Optionally, the integration unit includes a first resistor, a second resistor, and a first capacitor. The first end of the first resistor is coupled to the output terminal of the frequency divider. The second end of the first resistor, the negative inverting input terminal of the first operational amplifier, the first end of the second resistor, and the first end of the first capacitor are coupled together. The second end of the second resistor, the second end of the first capacitor, and the output terminal of the first operational amplifier are coupled together.

[0017] Optionally, the closed-loop control module includes a voltage divider adjustment unit and a second operational amplifier. The first input terminal of the voltage divider adjustment unit is coupled to the output terminal of the spread spectrum module, the output terminal of the voltage divider adjustment unit is coupled to the negative input terminal of the second operational amplifier, the second input terminal of the voltage divider adjustment unit is coupled to the output terminal of the voltage-controlled oscillator, and the positive input terminal of the second operational amplifier receives a reference voltage.

[0018] Optionally, the voltage divider adjustment unit includes a third resistor and a switched capacitor sub-circuit. The first end of the third resistor is coupled to the output end of the spread spectrum module, the second end of the third resistor and the first end of the switched capacitor sub-circuit are coupled to the negative phase input end of the second operational amplifier, the second end of the switched capacitor sub-circuit is coupled to the output end of the voltage-controlled oscillator, and the third end of the switched capacitor sub-circuit is coupled to reference ground.

[0019] Optionally, the switched capacitor sub-circuit includes a first switch, a second switch, a second capacitor, and an inverter. The first terminal of the first switch is coupled to the second terminal of the third resistor and the negative input terminal of the second operational amplifier. The second terminal of the first switch, the first terminal of the second switch, and the first terminal of the second capacitor are coupled together. The second terminal of the second capacitor and the second terminal of the second switch are coupled to a reference ground. The control terminal of the first switch and the input terminal of the inverter are coupled to the output terminal of the voltage-controlled oscillator. The control terminal of the second switch is coupled to the output terminal of the inverter.

[0020] Optionally, the voltage-controlled oscillator includes a first MOS current source to an eighth MOS current source, and a first MOS transistor to a sixth MOS transistor. The first terminal of the first MOS current source to the first terminal of the fourth MOS current source receives the supply voltage. The control terminal of the first MOS current source to the control terminal of the fourth MOS current source is coupled to the output terminal of the closed-loop control module. The second terminal of the first MOS current source, the first terminal of the fifth MOS current source, and the control terminal of the fifth MOS current source are coupled to the control terminal of the eighth MOS current source. The second terminal of the second MOS current source is coupled to the first terminal of the first MOS transistor. The second terminal of the first MOS transistor, the control terminal of the second MOS transistor, the first terminal of the fourth MOS transistor, and the control terminal of the fifth MOS transistor are coupled. The control terminal of the first MOS transistor, the first terminal of the fourth MOS transistor, and the control terminal of the fifth MOS transistor are coupled. The control terminal of the fourth MOS transistor, the second terminal of the third MOS transistor, and the first terminal of the sixth MOS transistor are coupled to the second input terminal of the closed-loop control module; the second terminal of the third MOS current source is coupled to the first terminal of the second MOS transistor, and the second terminal of the second MOS transistor, the first terminal of the fifth MOS transistor, the control terminal of the third MOS transistor, and the control terminal of the sixth MOS transistor are coupled; the second terminal of the fourth MOS current source is coupled to the first terminal of the third MOS transistor; the second terminal of the fourth MOS transistor is coupled to the first terminal of the sixth MOS current source, the second terminal of the fifth MOS transistor is coupled to the first terminal of the seventh MOS current source, the second terminal of the sixth MOS transistor is coupled to the first terminal of the eighth MOS current source, and the second terminal of the fifth MOS current source to the second terminal of the eighth MOS current source are coupled to reference ground.

[0021] To achieve the above objectives, the present invention also provides a power supply system, the power supply system including a high-frequency oscillator and the spread spectrum circuit described in any of the above claims.

[0022] To achieve the above objectives, the present invention also provides a chip, wherein the chip integrates the spread spectrum circuit or the power supply system described above.

[0023] To achieve the above objectives, the present invention also provides an electronic device, which includes the spread spectrum circuit described in any of the above claims, or the power supply system described in the above claims, or the chip described in the above claims.

[0024] Compared with existing technologies, the spread spectrum circuit, power supply system, chip, and electronic equipment provided by this invention have the following advantages: The spread spectrum circuit for a closed-loop controlled oscillator provided by this invention includes a spread spectrum module and a frequency divider. The spread spectrum module can generate an analog triangular wave signal with driving capability based on the second clock signal output by the frequency divider. This not only directly drives the closed-loop control module, thereby achieving continuous and linear frequency adjustment, but also results in more uniform spectral energy and significantly improved spread spectrum effect. Furthermore, compared with pseudo-random code schemes, the input signal (i.e., the second clock signal) of the spread spectrum module in the spread spectrum circuit provided by this invention is provided by the frequency divider. Therefore, the spread spectrum module does not need to generate a low-frequency clock separately, which can significantly simplify circuit design and greatly reduce chip area. It not only has high reliability but also significantly reduces costs. In summary, by using the spread spectrum circuit provided by this invention, the high-precision, low-EMI power supply system for a closed-loop controlled high-frequency oscillator can achieve a linear frequency modulation effect without complex digital modules, and the spectral energy is more uniform.

[0025] Furthermore, since the power supply system, chip, and electronic device provided by this invention belong to the same inventive concept as the spread spectrum circuit provided by this invention, the power supply system, chip, and electronic device provided by this invention have at least all the advantages of the spread spectrum circuit provided by this invention. For details on the beneficial effects of the power supply system, chip, and electronic device provided by this invention, please refer to the above description of the beneficial effects of the spread spectrum circuit provided by this invention, which will not be repeated here. Attached Figure Description

[0026] Figure 1 This is a block diagram of a closed-loop oscillator using a spread spectrum module in the prior art.

[0027] Figure 2 This is a block diagram of an oscillator with closed-loop control and spread spectrum circuit provided by the present invention.

[0028] Figure 3 This is a schematic diagram of the topology of a spread spectrum circuit provided in one embodiment of the present invention.

[0029] Figure 4 The diagram shows the signal waveforms of each key node in the spread spectrum circuit provided by this invention. Detailed Implementation

[0030] The following detailed description, in conjunction with the accompanying drawings, provides a further detailed account of the spread spectrum circuit, power supply system, chip, and electronic device proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clearly illustrate the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes and to enable those skilled in the art to understand and read them, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, provided they produce the same or similar effects and achieve the same objectives as this invention, should still fall within the scope of the technical content disclosed in this invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and usage environment. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, omitting repeated descriptions. In this specification, similar reference numerals and letters are used to denote similar items, so once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0031] 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. Furthermore, 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. The singular forms “a,” “an,” and “the” include plural objects. The term “or” is generally used to mean “and / or,” the term “several” is generally used to mean “at least one,” and the term “at least two” is generally used to mean “two or more.” Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0032] It should be understood that when a component is referred to as "connected," "connected to," or "coupled to" other components, it may be directly connected to other components, or there may be intermediary components. Conversely, when a component is referred to as "directly connected" or "directly connected to" other components, there are no intermediary components.

[0033] The core idea of ​​this invention is to provide a spread spectrum circuit, a power supply system, a chip, and an electronic device. The spread spectrum circuit provided by this invention can achieve linear frequency modulation without complex digital modules, and the spectrum energy is uniform, which can effectively simplify chip design and significantly reduce costs.

[0034] It should be noted that the spread spectrum circuit, power supply system, and chip provided by this invention can be used in the electronic devices provided by this invention. Furthermore, the spread spectrum circuit provided by this invention is particularly suitable for high-precision, low-EMI power supply systems. The electronic devices described herein include, but are not limited to, mobile phones, laptops, tablets, and in-vehicle computers.

[0035] To achieve the above-mentioned ideas, one embodiment of the present invention provides a spread spectrum circuit for an oscillator used in closed-loop control. For example, please refer to... Figure 2 , Figure 2 This is a block diagram of the oscillator used for closed-loop control in the spread spectrum circuit provided by the present invention. Figure 2 As can be seen, the closed-loop controlled oscillator 100 includes a closed-loop control module 140 and a voltage-controlled oscillator 130 for generating a first clock signal Vosc. The spread spectrum circuit 300 includes a spread spectrum module 310 and a frequency divider 320 for generating a second clock signal Vclk with a preset frequency based on the first clock signal Vosc. The input terminal of the spread spectrum module 310 is coupled to the output terminal of the frequency divider 320, the output terminal of the spread spectrum module 310 is coupled to the first input terminal of the closed-loop control module 140, the output terminal of the closed-loop control module 140 is coupled to the input terminal of the voltage-controlled oscillator 130, and the output terminal of the voltage-controlled oscillator 130 is coupled to the second input terminal of the closed-loop control module 140 and the input terminal of the frequency divider 320. Further, the spread spectrum module 310 is configured to generate a triangular wave signal Vtri based on the second clock signal Vclk, and the closed-loop control module 140 generates a control signal Vctrl for driving the oscillator based on the first clock signal Vosc and the triangular wave signal Vtri.

[0036] The spread spectrum circuit 300 for a closed-loop controlled oscillator provided by this invention includes a spread spectrum module 310 and a frequency divider 320. The spread spectrum module 310 can generate an analog triangular wave signal Vtri with driving capability based on the second clock signal Vclk output by the frequency divider 320. This not only directly drives the closed-loop control module 140, thereby achieving continuous and linear frequency adjustment, but also results in more uniform spectral energy and significantly improved spread spectrum effect. Furthermore, compared to the pseudo-random code scheme, the input signal (i.e., the second clock signal Vclk) of the spread spectrum module 310 in the spread spectrum circuit 300 provided by this invention is provided by the frequency divider 320. Therefore, the spread spectrum module 310 does not need to generate a low-frequency clock separately, which can significantly simplify circuit design and greatly reduce chip area, resulting in high reliability and significantly reduced cost. In summary, by using the spread spectrum circuit 300 provided by this invention, the high-precision, low-EMI power supply system of the closed-loop controlled high-frequency oscillator can achieve linear frequency modulation effect without complex digital modules, and the spectral energy is more uniform.

[0037] It should be noted that in spread spectrum circuit design, the modulation frequency often depends on the resolution bandwidth of the testing instrument in the EMI test standard. Therefore, the frequency of the second clock signal Vclk generated by the frequency divider 320 is a preset value. As a preferred embodiment, it can be obtained by dividing the first clock signal Vosc generated by the voltage-controlled oscillator 130 of the present invention by the frequency divider 320. For details regarding the frequency divider 320 and how it generates the second clock signal Vclk based on the first clock signal Vosc generated by the voltage-controlled oscillator 130, please refer to the relevant content about voltage-controlled oscillators known to those skilled in the art. Due to space limitations, this article will not elaborate further. However, it is clear that the present invention does not impose excessive limitations on the specific implementation of the frequency divider 320. For example, the frequency divider 320 can adopt design methods including but not limited to phase-locked loop frequency division and frequency division chips.

[0038] For example, please see Figure 3 , Figure 3 This is a schematic diagram of the topology of a spread spectrum circuit provided in one embodiment of the present invention. (See diagram below.) Figure 3 As shown, in some exemplary embodiments, the spread spectrum module 310 includes an integrator 311 and a first operational amplifier 312. The first terminal of the integrator 311 is coupled to the output terminal of the frequency divider 320, the second terminal of the integrator 311 is coupled to the negative input terminal of the first operational amplifier 312, and the third terminal of the integrator 311 and the output terminal of the first operational amplifier 312 are coupled to the first input terminal of the closed-loop control module 140. The positive input terminal of the first operational amplifier 312 receives a triangular wave reference voltage Vref_tri.

[0039] Therefore, the spread spectrum circuit 300 provided by the present invention, wherein the spread spectrum module 310 adopts the design of an integrator 311 and a first operational amplifier 312, can achieve a linear adjustment effect on the frequency through the integrator 311, so that the energy is evenly distributed at each frequency point, thereby improving the spread spectrum effect, and can improve the driving capability of the triangular wave signal Vtri through the first operational amplifier 312; at the same time, the structure is simple and easy to implement.

[0040] For example, please continue to see Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the integration unit 311 includes a first resistor R1, a second resistor R2, and a first capacitor C1. The first end of the first resistor R1 is coupled to the output of the frequency divider 320. The second end of the first resistor R1, the negative inverting input of the first operational amplifier 312, the first end of the second resistor R2, and the first end of the first capacitor C1 are coupled together. The second end of the second resistor R2, the second end of the first capacitor C1, and the output of the first operational amplifier 312 are coupled together.

[0041] The spread spectrum circuit 300 provided by this invention includes a spread spectrum module 310 that forms an RC integrator unit 311 through a first resistor R1, a second resistor R2, and a first capacitor C1, and combines it with a first operational amplifier 312 to form an integrator network structure. Thus, by reasonably selecting the first resistor R1, the second resistor R2, and the first capacitor C1, a triangular wave signal Vtri with a corresponding voltage range can be generated. The linear change of the voltage of the triangular wave signal Vtri can achieve the effect of linear frequency adjustment, so that the energy is evenly distributed at each frequency point, significantly improving the spread spectrum effect. Moreover, the structure is simple, which can significantly simplify the circuit design and reduce the circuit area, and it is low in cost and easy to implement.

[0042] It should be noted that the present invention does not impose excessive limitations on the performance parameters of the first resistor R1, the second resistor R2, and the first capacitor C1. When implementing the present invention, these parameters should be selected reasonably according to actual needs. It should also be noted that those skilled in the art should understand that the use of resistors and capacitors to implement the integration unit 311 in this document is merely an illustrative example of a preferred embodiment and not a limitation of the present invention. The present invention does not impose excessive limitations on the specific implementation of the integration unit 311. For example, in some other embodiments, the integration unit 311 can also be implemented using methods including, but not limited to, switched-capacitor integrators. These will not be elaborated upon here. For more implementation methods of the integration unit 311, please refer to the relevant descriptions of integration networks known to those skilled in the art.

[0043] For example, please continue to see Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the closed-loop control module 140 includes a voltage divider adjustment unit 141 and a second operational amplifier 142. The first input terminal of the voltage divider adjustment unit 141 is coupled to the output terminal of the spread spectrum module 310, the output terminal of the voltage divider adjustment unit 141 is coupled to the negative input terminal of the second operational amplifier 142, the second input terminal of the voltage divider adjustment unit 141 is coupled to the output terminal of the voltage-controlled oscillator 130, and the positive input terminal of the second operational amplifier 142 receives a reference voltage Vref.

[0044] Therefore, the closed-loop control module 140 adopts a design of voltage divider adjustment unit 141 and second operational amplifier 142. The voltage divider adjustment unit 141 can maintain the frequency of the control signal Vctrl generated by the second operational amplifier 142, thereby stabilizing the frequency of the first clock signal Vosc generated by the voltage-controlled oscillator 130.

[0045] For example, the voltage divider adjustment unit 141 is configured to reduce the voltage at the negative phase input terminal of the second operational amplifier 142 when the frequency of the first clock signal Vosc output by the voltage-controlled oscillator 130 increases, thereby adjusting the control signal Vctrl output by the second operational amplifier 142 to decrease the frequency of the first clock signal Vosc output by the voltage-controlled oscillator 130; and to increase the voltage at the negative phase input terminal of the second operational amplifier 142 when the frequency of the first clock signal Vosc output by the voltage-controlled oscillator 130 decreases, thereby adjusting the control signal Vctrl output by the second operational amplifier 142 to increase the frequency of the first clock signal Vosc output by the voltage-controlled oscillator 130.

[0046] For example, please continue to see Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the voltage divider adjustment unit 141 includes a third resistor R3 and a switched capacitor sub-circuit 1411. The first end of the third resistor R3 is coupled to the output of the spread spectrum module 310, the second end of the third resistor R3 and the first end of the switched capacitor sub-circuit 1411 are coupled to the negative inverting input of the second operational amplifier 142, the second end of the switched capacitor sub-circuit 1411 is coupled to the output of the voltage-controlled oscillator 130, and the third end of the switched capacitor sub-circuit 1411 is coupled to reference ground. Therefore, the voltage divider adjustment unit 141, using the third resistor R3 and the switched capacitor sub-circuit 1411, has simple logic and is easy to implement.

[0047] Exemplary, in some exemplary embodiments, the switched capacitor sub-circuit 1411 includes a first switch S1, a second switch S2, a second capacitor C2, and an inverter N1. The first terminal of the first switch S1 is coupled to the second terminal of the third resistor R3 and the negative input terminal of the second operational amplifier 142. The second terminal of the first switch S1, the first terminal of the second switch S2, and the first terminal of the second capacitor C2 are coupled together. The second terminal of the second capacitor C2 and the second terminal of the second switch S2 are coupled to reference ground. The control terminal of the first switch S1 and the input terminal of the inverter N1 are coupled to the output terminal of the voltage-controlled oscillator 130. The control terminal of the second switch S2 is coupled to the output terminal of the inverter N1.

[0048] It should be understood that the voltage divider adjustment unit 141 described in this article, which uses a third resistor R3 and a switched capacitor sub-circuit 1411, and the switched capacitor sub-circuit 1411 uses a first switch S1, a second switch S2, a second capacitor C2, and an inverter N1, is only an illustrative description of a preferred embodiment and not a limitation of the present invention. The present invention does not impose too many limitations on the specific implementation of the voltage divider adjustment unit 141. For example, in some other exemplary embodiments, the voltage divider adjustment unit 141 may also be implemented using an adjustable resistor or the like.

[0049] For example, please continue to see Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the voltage-controlled oscillator 130 includes a first MOS current source I1 to an eighth MOS current source I8, and a first MOS transistor M1 to a sixth MOS transistor M6, wherein the first terminal of the first MOS current source I1 ( Figure 3 (Example: using the source of PMOS transistor I1) to the first terminal of the fourth MOS current source I4 ( Figure 3 (Taking the source of PMOS transistor I4 as an example) receives the supply voltage VDD. The control terminal of the first MOS current source I1 to the control terminal of the fourth MOS current source I4 are coupled to the output terminal of the closed-loop control module 140. The second terminal of the first MOS current source I1 ( Figure 3 Example of the drain of PMOS transistor I1), and the first terminal of the fifth MOS current source I5 ( Figure 3 (Example: the drain of NMOS transistor I5), and the control terminal of the fifth MOS current source I5 is coupled to the control terminal of the eighth MOS current source I8; the second terminal of the second MOS current source I2 ( Figure 3 (Example: Drain of PMOS transistor I2) is coupled to the first terminal of the first MOS transistor M1. Figure 3 Taking the source of PMOS transistor M1 as an example), the second terminal of the first MOS transistor M1 ( Figure 3(Example: drain of PMOS transistor M1), control terminal of second MOS transistor M2, first terminal of fourth MOS transistor M4) Figure 3 (Example: Drain of NMOS transistor M4) and control terminal of fifth MOS transistor M5 are coupled together. Control terminal of first MOS transistor M1, control terminal of fourth MOS transistor M4, and second terminal of third MOS transistor M3 (… Figure 3 Example of the drain of PMOS transistor M3) and the first terminal of the sixth MOS transistor M6 (using the drain of PMOS transistor M3 as an example) Figure 3 (Example: the drain of NMOS transistor M6) is coupled to the second input terminal of the closed-loop control module 140; the second terminal of the third MOS current source I3 (… Figure 3 (Example: Drain of PMOS transistor I3) is coupled to the first terminal of the second MOS transistor M2. Figure 3 Taking the source of PMOS transistor M2 as an example), the second terminal of the second MOS transistor M2 ( Figure 3 (Example: drain of PMOS transistor M2), first terminal of the fifth MOS transistor M5 (...) Figure 3 (Example: the drain of NMOS transistor M5), the control terminal of the third MOS transistor M3, and the control terminal of the sixth MOS transistor M6 are coupled; the second terminal of the fourth MOS current source I4 (… Figure 3 (Example: Drain of PMOS transistor I4) is coupled to the first terminal of the third MOS transistor M3. Figure 3 Example of the source of PMOS transistor M3); the second terminal of the fourth MOS transistor M4 ( Figure 3 (Example: The source of NMOS transistor M4 is coupled to the first terminal of the sixth MOS current source I6) Figure 3 (Example: the drain of NMOS transistor I6), the second terminal of the fifth MOS transistor M5 (…) Figure 3 (Example: The source of NMOS transistor M5 is coupled to the first terminal of the seventh MOS current source I7) Figure 3 (Example: the drain of NMOS transistor I7), the second terminal of the sixth MOS transistor M6 (…) Figure 3 (Example: The source of NMOS transistor M6 is coupled to the first terminal of the eighth MOS current source I8.) Figure 3 Taking the drain of NMOS transistor I8 as an example, the second terminal of the fifth MOS current source I5 ( Figure 3 (Example: the source of NMOS transistor I5) to the second terminal of the eighth MOS current source I8 (using the source of NMOS transistor I5 as an example) Figure 3 (Example of the source of NMOS transistor I8) is coupled to reference ground.

[0050] Therefore, the voltage-controlled oscillator 130 is a current-type ring oscillator formed by the first MOS current source I1 to the eighth MOS current source I8 and the first MOS transistor M1 to the sixth MOS transistor M6, which has the advantages of easy integration and wide tuning range.

[0051] It should be noted that those skilled in the art should understand that the design of the voltage-controlled oscillator 130 described herein, employing the first MOS current source I1 to the eighth MOS current source I8 and the first MOS transistor M1 to the sixth MOS transistor M6, is merely an illustrative example of a preferred embodiment and not a limitation of the present invention. The present invention does not impose excessive limitations on the specific implementation of the voltage-controlled oscillator 130. When implementing the present invention, appropriate selection should be made according to the actual application scenario. For example, in other embodiments, a resonant circuit composed of LC circuits can also be used to achieve frequency modulation. Due to space limitations, the voltage-controlled oscillator 130 will not be described in detail here; for more detailed information, please refer to the relevant descriptions of the voltage-controlled oscillator 130 known to those skilled in the art.

[0052] Please continue reading Figure 3 and Figure 4 ,in, Figure 4 This is a schematic diagram of the signal waveforms at key nodes of the spread spectrum circuit 300 provided by the present invention. The following is in conjunction with... Figure 3 and Figure 4 The working principle of the spread spectrum circuit 300 for closed-loop control of the oscillator provided by the present invention will be explained.

[0053] As mentioned above, the spread spectrum circuit 300 provided by the present invention generates a triangular wave signal Vtri with driving capability through the spread spectrum module 310, which serves as the input to the third resistor R3 and the switched capacitor sub-circuit 1411. Combining the expression of formula (2), the frequency expression of the voltage-controlled oscillator 130 in the present invention is as shown in formula (3):

[0054] (3)

[0055] In the above formula (3), where The voltage of the triangular wave signal Vtri output by the spread spectrum module 310. The reference voltage Vref, Let R3 be the resistance value of the third resistor. This is the capacitance value of the second capacitor C2.

[0056] From equation (3) above, it can be seen that if the voltage of the triangular wave signal Vtri is... Linear variation allows for linear frequency adjustment, ensuring even energy distribution across all frequency points and significantly improving the spread spectrum effect. Furthermore, since the input to the spread spectrum module 310 is provided by the frequency divider 320, the spread spectrum module 310 does not need to generate a separate low-frequency clock. By designing the first resistor R1, the second resistor R2, and the first capacitor C1, a triangular wave signal Vtri with a corresponding voltage range can be generated, greatly simplifying circuit design and reducing area. The theoretical analysis of the voltage variation range of the triangular wave signal Vtri is as follows:

[0057] Let the triangular wave input signal be a square wave signal with frequency f, duty cycle of 50%, amplitude VDD, and period T. Within one period, it can be divided into the following two segments:

[0058] (a) When the input is high level VDD ( )

[0059] Because the op-amp is virtually open, the current flowing through the first resistor R1 is shown in equation (4-1), the current flowing through the first capacitor C1 is shown in equation (4-2), and the current flowing through the second resistor R2 is shown in equation (4-3). Furthermore, according to Kirchhoff's current law, the current flowing through the first resistor R1 is equal to the sum of the currents flowing through the first capacitor C1 and the second resistor R2, which gives equation (5-1):

[0060] (4-1)

[0061] (4-2)

[0062] (4-3)

[0063] (5-1)

[0064] (ii) When the input is low level 0 ( )

[0065] Based on the foregoing analysis, we can obtain the following equation (5-2):

[0066] (5-2)

[0067] In the above equations (4-1), (4-2), (4-3), and (5-1) and (5-2), The high level of the input square wave. The current flowing through the first resistor R1, The current flowing through the first capacitor C1, The current flowing through the second resistor R2, Let R1 be the resistance value of the first resistor. The capacitance value of the first capacitor C1. Let R2 be the resistance value of the second resistor. The real-time voltage of the triangular wave signal Vtri is given.

[0068] Solving the first-order linear nonhomogeneous differential equations in both cases yields the piecewise function expressions under steady state as shown in equations (6) and (7) below:

[0069] when hour,

[0070] (6)

[0071] when hour,

[0072] (7)

[0073] In equations (6) and (7) above, n = 0, 1, 2, ...

[0074] To ensure the linearity of the triangular wave signal Vtri, the time constant of R2C1 is very large, meaning R2 is also very large and can be approximately ignored. Therefore, the peak voltage of the triangular wave signal Vtri can be approximately obtained. As shown in equation (8):

[0075] (8)

[0076] In the design of the spread spectrum circuit 300, the modulation frequency often depends on the resolution bandwidth of the testing instrument in the EMI test standard. Therefore, the frequency f is a specified value, which can be obtained by dividing the voltage-controlled oscillator 130 in this invention by the frequency divider 320. When the system gives the required spread spectrum range of the oscillator, the spread spectrum circuit 300 (triangular wave circuit) can be designed by combining it with formula (8).

[0077] like Figure 4 As shown, Figure 4 The waveforms of key nodes in signal transmission are shown. Figure 4 In the diagram, Vtri is the waveform diagram of the triangular wave signal output by the spread spectrum circuit 300, Vosc is the waveform diagram of the first clock signal output by the voltage-controlled oscillator 130, Vclk is the waveform diagram of the input signal of the spread spectrum circuit 300 (that is, the waveform diagram of the second clock signal Vclk obtained by dividing the first clock signal Vosc output by the voltage-controlled oscillator 130 by the frequency divider 320), and fosc is the waveform diagram of the frequency of the first clock signal output by the voltage-controlled oscillator 130. Figure 4It can be seen that since the frequency of the voltage-controlled oscillator 130 is significantly different from the frequency of the triangular wave signal Vtri, the triangular wave signal Vtri can be approximately changed at a fixed frequency within a certain voltage range. Therefore, the frequency of the voltage-controlled oscillator 130 also changes accordingly, which effectively achieves linear frequency modulation and uniform spectral energy.

[0078] Another embodiment of the present invention provides a power supply system, the power supply system including a high-frequency oscillator and the spread spectrum circuit described in any of the above embodiments.

[0079] Another embodiment of the present invention provides a chip on which the spread spectrum circuit described in any of the above embodiments or the power supply system provided by the present invention is integrated.

[0080] This invention does not limit the manufacturing process, application field, or function of the chip. For example, the chip may be, but is not limited to, a 7nm chip, a 14nm chip, or a 28nm chip; the chip may be, but is not limited to, automotive chips, consumer electronics chips, and medical chips.

[0081] This embodiment provides an electronic device. In some embodiments, the electronic device includes a spread spectrum circuit provided by any embodiment of the present invention; in other embodiments, the electronic device includes a power supply system provided by any embodiment of the present invention; and in still other embodiments, the electronic device includes a chip provided by the present invention.

[0082] Since the electronic device provided by this invention belongs to the same inventive concept as the spread spectrum circuit, power supply system, or chip provided by this invention, and the power supply system and chip provided by this invention belong to the same inventive concept as the spread spectrum circuit provided by this invention, the electronic device provided by this invention has at least all the advantages of the spread spectrum circuit provided by this invention. For details on the beneficial effects of the power supply system, chip, and electronic device provided by this invention, please refer to the above description of the beneficial effects of the spread spectrum circuit provided by this invention, which will not be repeated here.

[0083] More specifically, the electronic device provided in this embodiment, in addition to at least a processor and a memory, may further include display components, communication components, sensor components, power supply components, multimedia components, and input / output interfaces, etc., as needed. The display components, memory, communication components, sensor components, power supply components, multimedia components, and input / output interfaces are all connected to the processor. The memory can be static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, etc. The processor can be a central processing unit (CPU), graphics processing unit (GPU), field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), digital signal processing (DSP) chip, etc. Other communication components, sensor components, power supply components, multimedia components, etc., can all be implemented using general-purpose components; due to space limitations, they will not be described in detail here. For more detailed information, please refer to the relevant technical adaptation understanding known to those skilled in the art.

[0084] It should be noted that the functional modules in the various embodiments of this article can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0085] Compared with the prior art, the spread spectrum circuit, power supply system, chip, and electronic device provided by the present invention have the following advantages:

[0086] The spread spectrum circuit for a closed-loop controlled oscillator provided by this invention includes a spread spectrum module and a frequency divider. The spread spectrum module generates an analog triangular wave signal with driving capability based on the second clock signal output by the frequency divider. This not only directly drives the closed-loop control module, thus achieving continuous and linear frequency adjustment, but also results in more uniform spectral energy and significantly improved spread spectrum effect. Furthermore, compared to pseudo-random code schemes, the input signal (i.e., the second clock signal) of the spread spectrum module in the spread spectrum circuit provided by this invention is provided by the frequency divider. Therefore, the spread spectrum module does not need to generate a low-frequency clock separately, which can significantly simplify circuit design and greatly reduce chip area. This not only results in high reliability but also significantly reduces cost. In summary, by using the spread spectrum circuit provided by this invention, a high-precision, low-EMI power supply system for a closed-loop controlled high-frequency oscillator can achieve linear frequency modulation effect without complex digital modules, and the spectral energy is more uniform.

[0087] The above description is merely a description of preferred embodiments of the spread spectrum circuit, power supply system, chip, and electronic device provided by the present invention, and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Therefore, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A spread spectrum circuit for an oscillator used in closed-loop control, characterized in that, The closed-loop controlled oscillator includes a closed-loop control module and a voltage-controlled oscillator for generating a first clock signal. The spread spectrum circuit includes a spread spectrum module and a frequency divider for generating a second clock signal with a preset frequency according to the first clock signal. The input terminal of the spread spectrum module is coupled to the output terminal of the frequency divider, the output terminal of the spread spectrum module is coupled to the first input terminal of the closed-loop control module, the output terminal of the closed-loop control module is coupled to the input terminal of the voltage-controlled oscillator, and the output terminal of the voltage-controlled oscillator is coupled to the second input terminal of the closed-loop control module and the input terminal of the frequency divider. The spread spectrum module is configured to generate a triangular wave signal based on the second clock signal, and the closed-loop control module generates a control signal for driving the oscillator based on the first clock signal and the triangular wave signal.

2. The spread spectrum circuit according to claim 1, characterized in that, The spread spectrum module includes an integrator and a first operational amplifier. The first end of the integrator is coupled to the output of the frequency divider, the second end of the integrator is coupled to the negative input of the first operational amplifier, and the third end of the integrator and the output of the first operational amplifier are coupled to the first input of the closed-loop control module. The positive input of the first operational amplifier receives a triangular wave reference voltage.

3. The spread spectrum circuit according to claim 2, characterized in that, The integration unit includes a first resistor, a second resistor, and a first capacitor. The first end of the first resistor is coupled to the output terminal of the frequency divider. The second end of the first resistor, the negative inverting input terminal of the first operational amplifier, the first end of the second resistor, and the first end of the first capacitor are coupled together. The second end of the second resistor, the second end of the first capacitor, and the output terminal of the first operational amplifier are coupled together.

4. The spread spectrum circuit according to claim 1, characterized in that, The closed-loop control module includes a voltage divider adjustment unit and a second operational amplifier. The first input terminal of the voltage divider adjustment unit is coupled to the output terminal of the spread spectrum module, the output terminal of the voltage divider adjustment unit is coupled to the negative input terminal of the second operational amplifier, the second input terminal of the voltage divider adjustment unit is coupled to the output terminal of the voltage-controlled oscillator, and the positive input terminal of the second operational amplifier receives a reference voltage.

5. The spread spectrum circuit according to claim 4, characterized in that, The voltage divider adjustment unit includes a third resistor and a switched capacitor sub-circuit. The first end of the third resistor is coupled to the output end of the spread spectrum module. The second end of the third resistor and the first end of the switched capacitor sub-circuit are coupled to the negative phase input end of the second operational amplifier. The second end of the switched capacitor sub-circuit is coupled to the output end of the voltage-controlled oscillator. The third end of the switched capacitor sub-circuit is coupled to reference ground.

6. The spread spectrum circuit according to claim 5, characterized in that, The switched capacitor sub-circuit includes a first switch, a second switch, a second capacitor, and an inverter. The first terminal of the first switch is coupled to the second terminal of the third resistor and the negative input terminal of the second operational amplifier. The second terminal of the first switch, the first terminal of the second switch, and the first terminal of the second capacitor are coupled together. The second terminal of the second capacitor and the second terminal of the second switch are coupled to a reference ground. The control terminal of the first switch and the input terminal of the inverter are coupled to the output terminal of the voltage-controlled oscillator. The control terminal of the second switch is coupled to the output terminal of the inverter.

7. The spread spectrum circuit according to claim 1, characterized in that, The voltage-controlled oscillator includes a first MOS current source to an eighth MOS current source, and a first MOS transistor to a sixth MOS transistor. The first terminal of the first MOS current source to the first terminal of the fourth MOS current source receives the supply voltage. The control terminal of the first MOS current source to the control terminal of the fourth MOS current source is coupled to the output terminal of the closed-loop control module. The second terminal of the first MOS current source, the first terminal of the fifth MOS current source, and the control terminal of the fifth MOS current source to the control terminal of the eighth MOS current source are coupled. The second terminal of the second MOS current source is coupled to the first terminal of the first MOS transistor. The second terminal of the first MOS transistor, the control terminal of the second MOS transistor, the first terminal of the fourth MOS transistor, and the control terminal of the fifth MOS transistor are coupled. The control terminal of the first MOS transistor and the control terminal of the fourth MOS transistor are coupled. The control terminal of the OS transistor, the second terminal of the third MOS transistor, and the first terminal of the sixth MOS transistor are coupled to the second input terminal of the closed-loop control module; the second terminal of the third MOS current source is coupled to the first terminal of the second MOS transistor, and the second terminal of the second MOS transistor, the first terminal of the fifth MOS transistor, the control terminal of the third MOS transistor, and the control terminal of the sixth MOS transistor are coupled; the second terminal of the fourth MOS current source is coupled to the first terminal of the third MOS transistor; the second terminal of the fourth MOS transistor is coupled to the first terminal of the sixth MOS current source, the second terminal of the fifth MOS transistor is coupled to the first terminal of the seventh MOS current source, the second terminal of the sixth MOS transistor is coupled to the first terminal of the eighth MOS current source, and the second terminal of the fifth MOS current source to the second terminal of the eighth MOS current source are coupled to reference ground.

8. A power supply system, characterized in that, The power supply system includes a high-frequency oscillator and a spread spectrum circuit as described in any one of claims 1 to 7.

9. A chip, characterized in that, It integrates a spread spectrum circuit as described in any one of claims 1 to 7 or a power supply system as described in claim 8.

10. An electronic device, characterized in that, It includes the spread spectrum circuit as described in any one of claims 1 to 7, the power supply system as described in claim 8, or the chip as described in claim 9.

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