Spread spectrum switching power conversion circuit, clock generation circuit, and clock generation method

Abstract

A spread spectrum switching power conversion circuit, a clock generation circuit and a clock generation method. The spread spectrum switching power conversion circuit includes: a power stage circuit including an inductor and a power switch for switching the power switch to perform power conversion according to a switching signal with spread spectrum; a variable frequency oscillator for generating a spread spectrum clock signal according to a spread spectrum control signal; a spread spectrum control circuit for generating the spread spectrum control signal according to a first clock signal and a second clock signal; and a pulse width modulation circuit for generating the switching signal according to a feedback signal based on the spread spectrum clock signal; wherein the spread spectrum control circuit samples and operates a first periodic waveform with periodicity and a first random waveform with randomness to generate the spread spectrum control signal. The first random waveform is generated according to the first clock signal, and the first periodic waveform is generated according to the second clock signal.

Description

Technical Field

[0001] This invention relates to a switching power conversion circuit, and more particularly to a spreading-spectrum switching power conversion circuit that can effectively improve the spreading effect and expand the applicable frequency range of spreading. This invention also relates to a clock generation circuit and method for realizing spreading. Background Technology

[0002] Figure 1A , Figure 1B Display the modulation waveforms of known spread spectrum modulation methods, where Figure 1A , Figure 1B The switching frequency Fsw is spread spectrumd using sawtooth wave signal and triangular wave signal respectively, and the switching frequency varies within the range of Δf. Figure 2 This displays the modulation waveform of another known spread spectrum modulation method, where... Figure 2 The switching frequency Fsw is spread spectrumd using a pseudo random waveform.

[0003] Figure 1A , Figure 1B and Figure 2 The known spread spectrum modulation method has the following drawbacks: Figure 1A , Figure 1B The periodic analog spread spectrum modulation method shown is only effective in the 150kHz~30MHz frequency band, while Figure 2 The frequency hopping spread spectrum modulation method shown is only effective in the 30MHz~1GHz frequency band. In other words, neither of these spread spectrum modulation methods is applicable to both low-frequency and high-frequency bands simultaneously.

[0004] In view of this, the present invention addresses the shortcomings of the prior art by proposing a spread spectrum switching power conversion circuit, a clock generation circuit, and a clock generation method that can effectively improve the spread spectrum effect and expand the applicable frequency range of spread spectrum. Summary of the Invention

[0005] In one viewpoint, the present invention provides a spread-frequency switching power conversion circuit, comprising: a variable-frequency oscillator for generating a spread-frequency clock signal according to a spread-frequency control signal, wherein the spread-frequency clock signal has a fundamental frequency and a switching frequency variation range under the control of the spread-frequency control signal; a spread-frequency control circuit for generating the spread-frequency control signal according to a first clock signal and a second clock signal; and a pulse-width modulation (PWM) circuit for generating a spread-frequency switching signal according to a feedback signal based on the spread-frequency clock signal; wherein the switching signal is used to control a power stage circuit, the power stage circuit including an inductor and at least one power switch coupled to each other, for switching the power switch according to the spread-frequency switching signal to perform power conversion; The spread spectrum control circuit includes: a first periodic waveform generator for generating a periodic first periodic waveform according to the second clock signal; a first random waveform generator for generating a random first random waveform according to the first clock signal; and a processing unit for sampling the first random waveform and the first periodic waveform, and performing operations to generate the spread spectrum control signal.

[0006] In another viewpoint, the present invention provides a clock generation circuit for generating a spread-spectrum clock signal based on a first clock signal and a second clock signal, wherein the spread-spectrum clock signal has a fundamental frequency and a switching frequency variation range; the clock generation circuit includes: a variable frequency oscillator for generating the spread-spectrum clock signal based on a spread-spectrum control signal; and a spread-spectrum control circuit for generating the spread-spectrum control signal based on the first clock signal and the second clock signal; wherein the spread-spectrum control circuit includes: a first periodic waveform generator for generating a periodic first periodic waveform based on the second clock signal; a first random waveform generator for generating a random first random waveform based on the first clock signal; and a processing unit for sampling the first random waveform and the first periodic waveform, and performing operations to generate the spread-spectrum control signal.

[0007] In another viewpoint, the present invention provides a clock generation method for generating a spread-spectrum clock signal based on a first clock signal and a second clock signal, wherein the spread-spectrum clock signal has a fundamental frequency and a switching frequency variation range; the clock generation method includes: generating the spread-spectrum clock signal based on a spread-spectrum control signal; and generating the spread-spectrum control signal based on the first clock signal and the second clock signal; wherein the step of generating the spread-spectrum control signal includes: generating a first periodic waveform based on the second clock signal; generating a first random waveform based on the first clock signal; and sampling the first random waveform and the first periodic waveform, and performing calculations to generate the spread-spectrum control signal.

[0008] In one embodiment, the first periodic waveform is a triangular wave, a sawtooth wave, or a sine wave.

[0009] In one embodiment, the first random waveform is a virtual random step wave.

[0010] In one embodiment, the first periodic waveform generator includes an up-down counter or a lookup table circuit to generate the first periodic waveform by counting or looking up a table according to the second clock signal.

[0011] In one embodiment, the first clock signal is the spread spectrum clock signal, and the first random waveform is generated in a feedback manner, wherein the first clock signal and the second clock signal come from different sources and are independent of each other; the arithmetic unit includes: a sampling synchronization circuit for generating a sampled periodic waveform based on the first clock signal by sampling the first periodic waveform, thereby synchronizing the sampled periodic waveform with a sampling frequency of the first random waveform; and an operator unit for generating the spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform.

[0012] In one embodiment, the feature is that: (1) the operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and the first random waveform; or (2) the operator unit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform, wherein the operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and the downsampling random waveform.

[0013] In one embodiment, the arithmetic unit further includes a frequency division unit, wherein the arithmetic unit generates a forward spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform, wherein the frequency division unit down-clocks the forward spread spectrum control signal by a factor of m to generate the spread spectrum control signal, where m is a positive integer.

[0014] In one embodiment, the arithmetic unit further includes a control signal generator for generating a control switching signal with random properties, wherein the arithmetic unit generates an arithmetic result by randomly adding or subtracting the sampled periodic waveform from a signal related to the first random waveform based on the control switching signal, and generates the spread spectrum control signal according to the arithmetic result.

[0015] In one embodiment, the arithmetic unit includes: a control signal generator for generating a control switching signal, wherein the control switching signal is random; and an operator unit for randomly adding or subtracting the first periodic waveform from a signal related to the first random waveform based on the control switching signal to generate an arithmetic result, and generating the spread spectrum control signal according to the arithmetic result.

[0016] In one embodiment, the spread spectrum control circuit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform, wherein the operator unit is used to randomly add or subtract the first periodic waveform from the downsampling random waveform based on the control switching signal to generate a calculation result, and to generate the spread spectrum control signal based on the calculation result.

[0017] In one embodiment, the first clock signal used to generate the first random waveform is different from and independent of a clock signal used to generate the control switching signal.

[0018] The advantages of this invention are that it can improve the spread spectrum effect and expand the applicable frequency range of spread spectrum by mixing two different spread spectrum techniques, and the spread spectrum effect can be further improved by controlling the timing of triggering the first random waveform generator to update the random seed through the sampling control circuit.

[0019] The following detailed description through specific embodiments will make it easier to understand the purpose, technical content, features, and effects achieved by the present invention. Attached Figure Description

[0020] Figure 1A and Figure 1B It displays the modulation waveform of a known spread spectrum modulation method.

[0021] Figure 2 It is a frequency hopping waveform diagram showing another known spread spectrum modulation method.

[0022] Figure 3 This is a circuit block diagram showing a spread spectrum switching power conversion circuit according to an embodiment of the present invention.

[0023] Figure 4 This is a circuit block diagram showing a spread spectrum control circuit according to an embodiment of the present invention.

[0024] Figure 5 This is a circuit block diagram showing a spread spectrum control circuit according to an embodiment of the present invention.

[0025] Figure 6 This is a circuit block diagram showing a spread spectrum control circuit according to an embodiment of the present invention.

[0026] Figures 7A-7B This is a circuit block diagram of a first-cycle waveform generator according to a more specific embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of an embodiment of the present invention showing a first periodic waveform (triangular wave) and a first random waveform (virtual random waveform) and the resulting spread spectrum control signal.

[0028] Figure 9 This is a schematic diagram of an embodiment of the invention showing a first periodic waveform (sawtooth wave) and a first random waveform (virtual random waveform) and the resulting spread spectrum control signal.

[0029] Figure 10 This is an embodiment of displaying a first periodic waveform (sine wave) according to yet another embodiment of the present invention.

[0030] Figure 11A This invention relates to an embodiment of the present invention and shows a comparison between the power spectrum of an unmodulated narrowband interference signal and the spectrum after downward low-frequency spread-out.

[0031] Figure 11B This invention relates to an embodiment of the present invention and shows a comparison between the power spectrum of an unmodulated narrowband interference signal and its spectrum spread outward from the center.

[0032] Figures 12A to 12K It is a synchronous or asynchronous buck, boost, reverse, buck-boost, boost-reverse, and flyback power stage circuit for display spread spectrum switching power conversion circuits.

[0033] Figure 13 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit according to a more specific embodiment of the present invention.

[0034] Figure 14 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit according to a more specific embodiment of the present invention.

[0035] Figure 15 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit according to a more specific embodiment of the present invention.

[0036] Figure 16This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit according to a more specific embodiment of the present invention.

[0037] Figure 17 This is a comparison table showing the simulation results of Fast Fourier Transform (FFT) of the clock signals for various spread spectrum modulation methods.

[0038] Explanation of symbols in the diagram

[0039] 10: Spread spectrum switching power conversion circuit

[0040] 11: Power stage circuit

[0041] 12: Pulse Width Modulation (PWM) Circuit

[0042] 13: Spread spectrum control circuit

[0043] 131, 731A, 731B: First-cycle waveform generator

[0044] 132: First Random Waveform Generator

[0045] 133: Control signal generator

[0046] 134: Addition and Subtraction Unit

[0047] 135: Addition Unit

[0048] 136: Sampling control circuit

[0049] 137: Sampling Synchronization Circuit

[0050] 14: Variable frequency oscillator

[0051] 1413, 1513, 1613, 1713: Spread spectrum control circuit

[0052] 15, 1415, 1515, 1615, 1715: Clock generation circuit

[0053] 438, 538, 638, 738: Arithmetic Units

[0054] 7311: Counter

[0055] 7312: Lookup table circuit

[0056] BC, BC1, BC2: Basic clock signals

[0057] CLK1, CLK2: Clock signals

[0058] CKSYS: System Clock

[0059] CKSW: Spread Spectrum Clock Signal

[0060] CS1: Control switching signal

[0061] SSC, SSC': Spread spectrum control signals

[0062] FB: Feedback Signal

[0063] Fsw: Switching frequency

[0064] Ff: Fundamental frequency

[0065] Iout: Output current

[0066] L: Inductor

[0067] LG, UG: Switching signals

[0068] LX: Switch Node

[0069] PW1: Waveform of the first cycle

[0070] PW1': Periodic waveform after sampling

[0071] QU, QL: Power switch

[0072] RW1, RW1': First random waveform

[0073] Vin: Input power

[0074] VLX: Switching node voltage

[0075] Vout: Output power

[0076] Δf: Switching frequency variation range Detailed Implementation

[0077] The accompanying drawings in this invention are all schematic and are mainly intended to show the coupling relationship between various circuits and the relationship between various signal waveforms. The circuits, signal waveforms and frequencies are not drawn to scale.

[0078] Figure 3 This is a circuit block diagram showing a spread spectrum switching power conversion circuit according to an embodiment of the present invention. Figure 3As shown, the spread spectrum switching power conversion circuit 10 of the present invention includes a power stage circuit 11, a pulse width modulation (PWM) circuit 12, a spread spectrum control circuit 13, and a variable frequency oscillator 14. The power stage circuit 11 includes an inductor L and at least one power switch. This embodiment includes synchronously switching power switches QU and QL. Power switches QU and QL are used to switch power switches according to switching signals UG and LG, respectively, to perform power conversion. Power switch QU is coupled between the input power supply Vin and the switching node LX, power switch QL is coupled between the switching node LX and ground potential, and inductor L is coupled between the switching node LX and the output power supply Vout, thereby converting the input power supply Vin to the output power supply Vout. In other words, the power stage circuit 11 of this embodiment is configured as a synchronous buck power stage circuit.

[0079] It should be noted that this embodiment is for illustrative purposes only and is not intended to limit the scope of the invention. Figures 12A to 12K As shown, in other embodiments, the power stage circuit 11 may also be a boost, reverse, buck-boost, boost-reverse, or flyback power stage circuit.

[0080] The variable frequency oscillator 14 is used to generate a spread-spectrum clock signal CKSW according to a spread-spectrum control signal SSC, wherein the spread-spectrum clock signal CKSW has a fundamental frequency Ff and, under the control of the spread-spectrum control signal SSC, has a switching frequency variation range Δf. In one embodiment, the variable frequency oscillator 14 can control the frequency of the spread-spectrum clock signal CKSW according to the level of the spread-spectrum control signal SSC, wherein the level of the spread-spectrum control signal SSC can be, for example, a voltage level or a current level; in other words, the variable frequency oscillator can be, for example, a voltage-controlled oscillator or a current-controlled oscillator.

[0081] The spread spectrum control circuit 13 is used to generate a spread spectrum control signal SSC based on the first clock signal CLK1 and the second clock signal CLK2, the details of which will be described later. In one embodiment, the spread spectrum control circuit 13 and the variable frequency oscillator 14 can be integrated into a clock generation circuit 15 to generate a spread spectrum clock signal CKSW based on the first clock signal CLK1 and the second clock signal CLK2.

[0082] The PWM circuit 12 is used to generate switching signals UG and LG based on the spread spectrum clock signal CKSW and the feedback signal FB. In one embodiment, the feedback signal FB is related to the output power supply Vout, as shown in the figure. In one embodiment, it may be, for example, a voltage divider of the output power supply Vout.

[0083] Since the spread spectrum clock signal CKSW has spread spectrum characteristics under the control of the spread spectrum control signal SSC, the switching signals UG and LG, as well as the voltages (e.g., the voltage VLX on the switching node LX) and currents (e.g., the inductor current IL or the switching current IHS, ILS) generated by the switching of the power stage circuit 11 also have spread spectrum characteristics. Therefore, the electromagnetic interference caused by the switching of the power stage circuit 11 can be effectively reduced.

[0084] Figure 4 This is a circuit block diagram showing a spread spectrum control circuit (spread spectrum control circuit 413) according to an embodiment of the present invention. Figure 4 As shown, in one embodiment, the spread spectrum control circuit 413 includes a first periodic waveform generator 131, a first random waveform generator 132, and an arithmetic unit 138. The first random waveform generator 132 generates a first random waveform RW1 with random characteristics based on a first clock signal CLK1, and the first periodic waveform generator 131 generates a first periodic waveform PW1 with periodic variations based on a second clock signal CLK2. The arithmetic unit 138 samples the first random waveform RW1 and the first periodic waveform PW1, and performs calculations to generate a spread spectrum control signal SSC. In one embodiment, the first periodic waveform PW1 is, for example, a triangular wave (e.g.,...). Figure 8 ), sawtooth wave (such as Figure 9 ) or sine wave (such as Figure 10 In one embodiment, the first random waveform RW1 is, for example, a random stepped waveform. In another embodiment, the first random waveform RW1 is, for example, a pseudorandom stepped waveform.

[0085] Figure 5 This is a circuit block diagram showing the spread spectrum control circuit according to a more specific embodiment of the present invention. In this embodiment, as shown... Figure 5 As shown, the arithmetic unit 138 in the spread spectrum control circuit 513 includes a control signal generator 133 and an addition / subtraction unit 134.

[0086] In one embodiment, the first clock signal CLK1 and the second clock signal CLK2 are different clocks, respectively coupled to the basic clock signals BC1 and BC2. In one embodiment, the first clock signal CLK1 and the second clock signal CLK2 are, for example, directly connected to the basic clock signals BC1 and BC2, respectively, or obtained after frequency division. In one embodiment, the first clock signal CLK1 is the basic clock signal BC1, and the second clock signal CLK2 is obtained by frequency division of the basic clock signal BC2. It should be noted that the basic clock signal BC1 used to generate the first random waveform RW1 is different from and independent of the basic clock signal (such as BC2) used to generate the control switching signal CS1.

[0087] In one embodiment, the control signal generator 133 is used to generate a control switching signal CS1. In another embodiment, the control signal generator 133 is used to generate the control switching signal CS1 (e.g., obtained based on the basic clock signal BC2). The addition / subtraction unit 134 is used to randomly add or subtract the first periodic waveform PW1 and the first random waveform RW1 according to the control switching signal CS1 to generate a spread spectrum control signal SSC.

[0088] Figure 6 This is a circuit block diagram showing a spread spectrum control circuit according to an embodiment of the present invention. The spread spectrum control circuit 613 is similar to the spread spectrum control circuit 513, as shown below. Figure 6 As shown, the spread spectrum control circuit 613 further includes a sampling control circuit 136, used to downsample the first random waveform RW1, for example, sampling once every n cycles of the second clock signal CLK2 to generate a downsampled random waveform RW1', where n is a positive integer. In this embodiment, the addition / subtraction unit 134 is used to randomly add or subtract the first periodic waveform PW1 and the downsampled random waveform RW1' according to the control switching signal CS1 to generate a spread spectrum control signal SSC. In one embodiment, the sampling period n is, for example, but not limited to, 1, 2, 4, or 8, preferably, for example, 8. Different spread spectrum effects can be obtained under different sampling periods n. In this embodiment, the control signal generator 133, the addition / subtraction unit 134, and the sampling control circuit 136 form, for example, the arithmetic unit 138 corresponding to the aforementioned embodiment.

[0089] Figure 7A This is a circuit block diagram of a first period waveform generator (first period waveform generator 731A) according to a more specific embodiment of the present invention. In one embodiment, the first period waveform generator 731A includes an up-down counter 7311 for up-down counting according to a second clock signal CLK2 to generate the aforementioned first period waveform PW1.

[0090] Figure 7B This is a circuit block diagram of a first periodic waveform generator (first periodic waveform generator 731B) according to a more specific embodiment of the present invention. In one embodiment, the first periodic waveform generator 731B includes a lookup table circuit 7312 for storing a preset periodic waveform. The lookup table circuit 7312 reads the preset periodic waveform by performing a lookup table according to a second clock signal CLK2 to generate the aforementioned first periodic waveform PW1.

[0091] Figure 8 This is a schematic diagram showing an embodiment of the present invention, displaying a first periodic waveform and a first random waveform, and the resulting spread spectrum control signal. In one embodiment, as... Figure 8As shown, the first periodic waveform PW1 generated by the first periodic waveform generator can be a triangular wave, while the first random waveform RW1 generated by the first random waveform generator can be a virtual random waveform. The first periodic waveform PW1 and the first random waveform RW1 are randomly added or subtracted by the addition / subtraction unit 134 according to the control switching signal CS1 to generate the spread spectrum control signal SSC, as shown below. Figure 8 As shown.

[0092] It is worth noting that, by Figure 8 It can be seen that the spread spectrum control signal generated in this embodiment has both some characteristics of a triangular wave and some characteristics of a virtual random waveform. In addition, since the addition or subtraction of the first periodic waveform PW1 and the first random waveform RW1 is also determined by the control switching signal CS1 which has random properties, the spread spectrum effect can be improved.

[0093] It should be noted that the levels of the first periodic waveform PW1, the first random waveform RW1, and the spread spectrum control signal SSC can be voltage, current, or digital values, which can be used to indicate the corresponding switching frequency. In one embodiment, the intermediate values ​​of the first periodic waveform PW1 and the first random waveform RW1 both correspond to the fundamental frequency Ff, and the intermediate value of the spread spectrum control signal SSC also corresponds to the fundamental frequency Ff, wherein the switching frequency varies within a range of Δf.

[0094] Figure 9 This is a schematic diagram showing an embodiment of a first periodic waveform and a first random waveform according to another embodiment of the present invention, and the resulting spread spectrum control signal. In one embodiment, as... Figure 9 As shown, the first periodic waveform PW1 generated by the first periodic waveform generator can be a sawtooth wave, while the first random waveform RW1 generated by the first random waveform generator can be a virtual random waveform. The first periodic waveform PW1 and the first random waveform RW1 are randomly added or subtracted by the addition / subtraction unit according to the control switching signal CS1 to generate a spread spectrum control signal, as shown below. Figure 9 As shown. By Figure 9 It can be seen that the spread spectrum control signal generated in this embodiment has both some sawtooth wave characteristics and some virtual random waveform characteristics.

[0095] Figure 10 This is another embodiment of the invention, displaying a first periodic waveform. For example... Figure 10 As shown, the first-cycle waveform generated by the first-cycle waveform generator can also be a sine wave. Similarly, as mentioned above, the sine wave can also be randomly added to or subtracted from the virtual random waveform generated by the first random waveform generator via an addition / subtraction unit to generate a spread spectrum control signal.

[0096] Figure 11AThis invention relates to an embodiment of the present invention and shows a comparison between the power spectrum of an unmodulated narrowband interference signal and the spectrum after downward low-frequency spread-out. Figure 11B This invention illustrates a comparison between the power spectrum of an unmodulated narrowband interference signal and its center-to-outward spread spectrum, according to an embodiment of the present invention. According to the CISPR 25 standard, electromagnetic interference measurements are performed with a 9kHz bandwidth resolution in the 150kHz–30MHz band and a 120kHz bandwidth resolution in the 30MHz–1GHz band. As is well known in the art, periodic analog spread spectrum is more effective at reducing peak energy in the 150kHz–30MHz band. Furthermore, based on the Carlson bandwidth rule, periodic analog spread spectrum can modify the switching frequency variation range Δf to improve the suppression effect. On the other hand, frequency-hopping spread spectrum technology randomly changes the frequency and is therefore not limited by the 120kHz bandwidth resolution. Therefore, frequency-hopping spread spectrum technology is more effective at reducing peak energy in the 30MHz–1GHz band.

[0097] The spread spectrum switching power conversion circuit of this invention randomly adds or subtracts two different spread spectrum techniques. This circuit not only retains the characteristics of each technique simultaneously but also provides electromagnetic interference reduction performance in the 150kHz~1GHz frequency band. Furthermore, as mentioned above, the spread spectrum switching power conversion circuit can also utilize a sampling control circuit to sample the first random waveform RW1 at different sampling periods n to achieve different levels of electromagnetic interference reduction performance.

[0098] Figure 13 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit (clock generation circuit 1415, spread spectrum control circuit 1413) according to a more specific embodiment of the present invention. In one embodiment, as... Figure 13 As shown, the spread spectrum control circuit 1413 includes a first periodic waveform generator 131, a first random waveform generator 132, and an arithmetic unit 438. In one embodiment, the arithmetic unit 438 includes a sampling synchronization circuit 137 and an addition unit 135.

[0099] In this embodiment, the first random waveform generator 132 generates a first random waveform RW1 based on a first clock signal CLK1. In this embodiment, the first clock signal CLK1 is coupled to the spread spectrum clock signal CKSW; in other words, the first clock signal CLK1 is the spread spectrum clock signal CKSW. The first periodic waveform generator 131 generates a first periodic waveform PW1 based on a second clock signal CLK2 (e.g., coupled to a system clock CKSYS). The arithmetic unit 438 performs operations on the first random waveform RW1 and the first periodic waveform PW1 to generate a spread spectrum control signal SSC. Details of the first periodic waveform generator 131 can be found in [reference needed]. Figures 7A-7B Related narratives.

[0100] In one embodiment, the first periodic waveform PW1 is, for example, a triangular wave (e.g., Figure 8 ), sawtooth wave (such as Figure 9 ) or sine wave (such as Figure 10 In one embodiment, the first random waveform RW1 is, for example, a random stepped waveform. In another embodiment, the first random waveform RW1 is, for example, a pseudo random stepped waveform.

[0101] It is worth noting that, in one embodiment, the first clock signal CLK1 and the second clock signal CLK2 are clock signal sources from different sources and independent of each other. Specifically, the first clock signal CLK1 has spread spectrum characteristics because it is coupled to the spread spectrum clock signal CKSW. On the other hand, the second clock signal CLK2 (system clock CKSYS) may be a clock that does not have spread spectrum characteristics.

[0102] In this embodiment, the sampling synchronization circuit 137 is used to sample the first periodic waveform PW1 based on the first clock signal CLK1 (spread spectrum clock signal CKSW) to generate the sampled periodic waveform PW1', thereby enabling the sampled periodic waveform PW1' to be synchronized with the sampling frequency of the first random waveform RW1. Then, the addition unit 135 is used to add the sampled periodic waveform PW1' to the first random waveform RW1 to generate the spread spectrum control signal SSC. The variable frequency oscillator 14 is used to generate the spread spectrum clock signal CKSW according to the spread spectrum control signal SSC.

[0103] From one perspective, in this embodiment, the spread spectrum clock signal CKSW is fed back to the spread spectrum control circuit 1413 used to control the spread spectrum characteristics to generate the spread spectrum control signal SSC, which in turn controls the variable frequency oscillator 14 to generate the spread spectrum clock signal CKSW in a feedback manner, thereby making the spread spectrum effect better.

[0104] Figure 14This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit (clock generation circuit 1515, spread spectrum control circuit 1513) according to a more specific embodiment of the present invention. This embodiment is similar to... Figure 13 In one embodiment, the arithmetic unit 538 in the spread spectrum control circuit 1513 further includes a sampling control circuit 136 for down-sampling the first random waveform RW1 to generate a down-frequency random waveform RW1'. Its operation can be found in [reference needed]. Figure 6 According to the relevant description, in this embodiment, the addition unit 135 is used to add the sampled periodic waveform PW1' to the down-frequency random waveform RW1' to generate the spread spectrum control signal SSC.

[0105] Figure 15 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit (clock generation circuit 1615, spread spectrum control circuit 1613) according to a more specific embodiment of the present invention. This embodiment is similar to... Figure 14 In one embodiment, the arithmetic unit 638 in the spread spectrum control circuit 1613 further includes a frequency divider unit 139, used to add the sampled periodic waveform PW1' to the down-frequency random waveform RW1' to generate the spread spectrum control signal SSC', down-frequency it by a factor of m to generate the spread spectrum control signal SSC, and then control the variable frequency oscillator 14 to generate the spread spectrum clock signal CKSW, where m is a positive integer. In one embodiment, as... Figure 15 The sampling control circuit 136 can be omitted, and the sampled periodic waveform PW1' can be directly added to the first random waveform RW1 to generate the spread spectrum control signal SSC'.

[0106] Figure 16 This is a block diagram of a clock generation circuit and a circuit block diagram of a spread spectrum control circuit (clock generation circuit 1715, spread spectrum control circuit 1713) according to a more specific embodiment of the present invention. This embodiment is similar to... Figure 15 In one embodiment, the arithmetic unit 738 in the spread spectrum control circuit 1713 further includes a control signal generator 133, and the addition unit 135 is replaced by an addition / subtraction unit 134. The control signal generator 133 is used to generate a control switching signal CS1, wherein the control switching signal CS1 has a random nature, and its generation method can be found in [reference needed]. Figure 5 This embodiment describes an example where the addition / subtraction unit 134 randomly adds or subtracts the sampled periodic waveform PW1' from the down-frequency random waveform RW1' based on the control switching signal CS1 to generate a spread spectrum control signal SSC'. In this embodiment, the control signal generator 133 generates the random control switching signal CS1 based on the basic clock signal BC. It should be noted that the first clock signal CLK1 used to generate the first random waveform RW1 is different from and independent of the clock signal (such as BC) used to generate the control switching signal CS1.

[0107] Furthermore, in one embodiment, such as Figure 16 The sampling control circuit 136 can be omitted, and the sampled periodic waveform PW1' can be directly added to the first random waveform RW1 to generate the spread spectrum control signal SSC'. In one embodiment, as shown... Figure 16 The frequency division unit 139 can be omitted, and the result of the addition and subtraction unit 134 can be directly used as the spread spectrum control signal SSC.

[0108] Figure 17 Is it displayed corresponding to Figure 5 , Figure 6 A comparison table of measurement results for spread spectrum modulation methods using different waveform combinations is provided. The input power supply Vin is 7V, the output current Iout is 2A, the switching frequency Fsw is 2.1MHz, the output power supply Vout is 5.2V, and the switching frequency variation range Δf is ±6%. Figure 17 It is understood that the spread spectrum switching power conversion circuit of the present invention combines two different spread spectrum techniques, such as, but not limited to, those mentioned above. Figure 17 The triangular wave mixed virtual random waveform, sawtooth wave mixed virtual random waveform, triangular wave mixed virtual random waveform with a sampling period of 8, and sawtooth wave mixed virtual random waveform with a sampling period of 8 shown can all make the spread spectrum effect better than using a single spread spectrum technique (such as virtual random waveform) and can expand the applicable frequency range of spread spectrum.

[0109] As described above, the spread spectrum switching power conversion circuit / spread spectrum control method of the present invention can improve the spread spectrum effect and expand the applicable frequency range of spread spectrum by mixing two different spread spectrum techniques, and can further improve the spread spectrum effect by controlling the sampling period of the first random waveform generator through the sampling control circuit.

[0110] The present invention has been described above with reference to preferred embodiments. However, the above description is only intended to facilitate understanding of the invention by those skilled in the art and is not intended to limit the broadest scope of the invention. The described embodiments are not limited to individual application and can also be used in combination. For example, two or more embodiments can be used in combination, and some components of one embodiment can be used to replace corresponding components in another embodiment. Furthermore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations. For example, the phrase "processing or calculating based on a signal or generating an output result" in the present invention is not limited to the signal itself, but also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and / or proportional conversion on the signal, and then processing or calculating based on the converted signal to generate an output result. Therefore, within the same spirit of the invention, those skilled in the art can conceive of various equivalent changes and combinations, and there are many combinations, which will not be listed here. Therefore, the scope of the present invention should cover the above and all other equivalent changes.

Claims

1. A spread spectrum switching power supply conversion circuit, characterized by comprising: Include: A variable frequency oscillator is used to generate a spread-frequency clock signal with spread frequency according to a spread-frequency control signal, wherein the spread-frequency clock signal has a fundamental frequency and has a switching frequency variation range under the control of the spread-frequency control signal; A spread spectrum control circuit is used to generate the spread spectrum control signal based on a first clock signal and a second clock signal; as well as A pulse width modulation circuit is used to generate a spread-spectrum switching signal based on the spread-spectrum clock signal and a feedback signal. The switching signal is used to control a power stage circuit, which includes an inductor and at least one power switch coupled to each other, and is used to switch the power switch according to the switching signal having spread spectrum to perform power conversion. The spread spectrum control circuit includes: A first-period waveform generator is used to generate a periodic first-period waveform according to the second clock signal; A first random waveform generator for generating a first random waveform with randomness according to the first clock signal; and A processing unit is used to sample the first random waveform and the first periodic waveform, and perform calculations to generate the spread spectrum control signal; The first clock signal is the spread spectrum clock signal, and the first random waveform is generated in a feedback manner. The first clock signal and the second clock signal come from different sources and are independent of each other.

2. The spread spectrum switching power supply conversion circuit of claim 1 wherein, The waveform of the first cycle is a triangular wave, a sawtooth wave, or a sine wave.

3. The spread spectrum switching power conversion circuit as described in claim 1, wherein, The first random waveform is a virtual random ladder wave.

4. The spread spectrum switching power conversion circuit as described in claim 1, wherein, The first-cycle waveform generator includes an up-and-down counter or a lookup table circuit to generate the first-cycle waveform by counting or looking up a table according to the second clock signal.

5. The spread spectrum switching power conversion circuit as described in claim 1, wherein the arithmetic unit comprises: A sampling synchronization circuit is configured to generate a sampled post-period waveform by sampling the first periodic waveform based on the first clock signal, thereby synchronizing the sampled post-period waveform with a sampling frequency of the first random waveform; and An operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform.

6. The spread spectrum switching power conversion circuit as described in claim 5, in, It is characterized by one of the following: (1) Wherein the operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and the first random waveform; or (2) The arithmetic unit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform, wherein the arithmetic unit generates the spread spectrum control signal based on the sum of the sampled periodic waveform and the downsampling random waveform.

7. The spread spectrum switching power conversion circuit as described in claim 5, wherein, The arithmetic unit further includes a frequency division unit, wherein the arithmetic unit generates a forward spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform, wherein the frequency division unit down-frequencys the forward spread spectrum control signal by a factor of m to generate the spread spectrum control signal, where m is a positive integer.

8. The spread spectrum switching power conversion circuit as described in claim 5, wherein, The arithmetic unit further includes a control signal generator for generating a control switching signal with random properties, wherein the arithmetic unit generates an arithmetic result by randomly adding or subtracting the sampled periodic waveform from a signal related to the first random waveform based on the control switching signal, and generates the spread spectrum control signal based on the arithmetic result.

9. The spread spectrum switching power conversion circuit as described in claim 1, wherein, This arithmetic unit includes: A control signal generator for generating a control switching signal, wherein the control switching signal is random; and An operator unit is configured to randomly add or subtract the first periodic waveform from a signal associated with the first random waveform based on the control switching signal, thereby generating a calculation result, and to generate the spread spectrum control signal based on the calculation result.

10. The spread spectrum switching power conversion circuit as described in claim 9, wherein, The spread spectrum control circuit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform. The operator unit is used to randomly add or subtract the first periodic waveform from the downsampling random waveform based on the control switching signal to generate a calculation result, and generates the spread spectrum control signal based on the calculation result.

11. The spread spectrum switching power conversion circuit as described in claim 9, wherein, The first clock signal used to generate the first random waveform is different from and independent of the clock signal used to generate the control switching signal.

12. A clock generation circuit for generating a spread-spectrum clock signal based on a first clock signal and a second clock signal, wherein the spread-spectrum clock signal has a fundamental frequency and a switching frequency variation range; characterized in that, The clock generation circuit includes: A variable frequency oscillator for generating a spread-spectrum clock signal based on a spread-spectrum control signal; and A spread spectrum control circuit is used to generate the spread spectrum control signal according to the first clock signal and the second clock signal; The spread spectrum control circuit includes: A first-period waveform generator is used to generate a periodic first-period waveform according to the second clock signal; A first random waveform generator for generating a first random waveform with randomness according to the first clock signal; and A processing unit is used to sample the first random waveform and the first periodic waveform, and perform calculations to generate the spread spectrum control signal; The first clock signal is the spread spectrum clock signal, and the first random waveform is generated in a feedback manner. The first clock signal and the second clock signal come from different sources and are independent of each other.

13. The clock generation circuit as described in claim 12, wherein, The waveform of the first cycle is a triangular wave, a sawtooth wave, or a sine wave.

14. The clock generation circuit as described in claim 12, wherein, The first random waveform is a virtual random ladder wave.

15. The clock generation circuit as described in claim 12, wherein, The first-cycle waveform generator includes an up-and-down counter or a lookup table circuit to generate the first-cycle waveform by counting or looking up a table according to the second clock signal.

16. The clock generation circuit of claim 12, wherein the arithmetic unit comprises: A sampling synchronization circuit is configured to generate a sampled post-period waveform by sampling the first periodic waveform based on the first clock signal, thereby synchronizing the sampled post-period waveform with a sampling frequency of the first random waveform; and An operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform.

17. The clock generating circuit as claimed in claim 16, wherein, characterized in that... One of the following: (1) Wherein the operator unit is used to generate the spread spectrum control signal based on the sum of the sampled periodic waveform and the first random waveform; or (2) The arithmetic unit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform, wherein the arithmetic unit generates the spread spectrum control signal based on the sum of the sampled periodic waveform and the downsampling random waveform.

18. The clock generating circuit as described in claim 16, wherein, The arithmetic unit further includes a frequency division unit, wherein the arithmetic unit generates a forward spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform, wherein the frequency division unit down-frequencys the forward spread spectrum control signal by a factor of m to generate the spread spectrum control signal, where m is a positive integer.

19. The clock generating circuit as described in claim 16, wherein, The arithmetic unit further includes a control signal generator for generating a control switching signal with random properties, wherein the arithmetic unit generates an arithmetic result by randomly adding or subtracting the sampled periodic waveform from a signal related to the first random waveform based on the control switching signal, and generates the spread spectrum control signal based on the arithmetic result.

20. The clock generation circuit as claimed in claim 12, wherein, This arithmetic unit includes: A control signal generator for generating a control switching signal, wherein the control switching signal is random; and An operator unit is configured to randomly add or subtract the first periodic waveform from a signal associated with the first random waveform based on the control switching signal, thereby generating a calculation result, and to generate the spread spectrum control signal based on the calculation result.

21. The clock generating circuit as described in claim 20, wherein, The spread spectrum control circuit further includes a sampling control circuit for downsampling the first random waveform to generate a downsampling random waveform. The operator unit is used to randomly add or subtract the first periodic waveform from the downsampling random waveform based on the control switching signal to generate a calculation result, and generates the spread spectrum control signal based on the calculation result.

22. The clock generating circuit as described in claim 20, wherein, The first clock signal used to generate the first random waveform is different from and independent of the clock signal used to generate the control switching signal.

23. A clock generation method for generating a spread-spectrum clock signal based on a first clock signal and a second clock signal, wherein the spread-spectrum clock signal has a fundamental frequency and a switching frequency variation range; characterized in that, The clock generation method includes: A spread-spectrum clock signal is generated based on a spread-spectrum control signal; and The spread spectrum control signal is generated based on the first clock signal and the second clock signal; The steps for generating the spread spectrum control signal include: A first-cycle waveform with periodicity is generated based on the second clock signal; A first random waveform with randomness is generated according to the first clock signal; and The first random waveform and the first periodic waveform are sampled and processed to generate the spread spectrum control signal; The first clock signal is the spread spectrum clock signal, and the first random waveform is generated in a feedback manner. The first clock signal and the second clock signal come from different sources and are independent of each other.

24. The clock generation method as described in claim 23, wherein, The waveform of the first cycle is a triangular wave, a sawtooth wave, or a sine wave.

25. The clock generation method as described in claim 23, wherein, The first random waveform is a virtual random ladder wave.

26. The clock generation method as described in claim 23, wherein, The steps for generating the first periodic waveform include: generating the first periodic waveform by either counting or looking up a table according to the second clock signal.

27. The clock generation method of claim 23, wherein the step of generating the spread spectrum control signal comprises: A sampled periodic waveform is generated based on the first clock signal by sampling the first periodic waveform, thereby synchronizing the sampled periodic waveform with a sampling frequency of the first random waveform; and The spread spectrum control signal is generated based on the sum of the sampled periodic waveform and a signal related to the first random waveform.

28. The clock generation method as described in claim 27, wherein, characterized in that... One of the following: (1) The spread spectrum control signal is generated based on the sum of the sampled periodic waveform and the first random waveform; or (2) The first random waveform is downsampled to generate a downsampled random waveform, and the spread spectrum control signal is generated based on the sum of the sampled periodic waveform and the downsampled random waveform.

29. The clock generation method as described in claim 27, wherein, The step of generating the spread spectrum control signal further includes: generating a pre-spread spectrum control signal based on the sum of the sampled periodic waveform and a signal related to the first random waveform, and down-clocking the pre-spread spectrum control signal by a factor of m to generate the spread spectrum control signal, where m is a positive integer.

30. The clock generation method as described in claim 27, wherein, The steps for generating the spread spectrum control signal also include: Generate a control switching signal with random properties; and Based on the control switching signal, the sampled periodic waveform is randomly added or subtracted from a signal related to the first random waveform to generate a calculation result, and the spread spectrum control signal is generated based on the calculation result.

31. The clock generation method as described in claim 23, wherein, The steps for generating the spread spectrum control signal include: Generate a control switching signal, wherein the control switching signal is random; and Based on the control switching signal, the first periodic waveform is randomly added or subtracted from a signal related to the first random waveform to generate a calculation result, and the spread spectrum control signal is generated according to the calculation result.

32. The clock generation method as described in claim 31, wherein, The steps for generating the spread spectrum control signal also include: The first random waveform is downsampled to generate a downsampled random waveform; and Based on the control switching signal, the first period waveform is randomly added to or subtracted from the down-frequency random waveform to generate a calculation result, and the spread spectrum control signal is generated according to the calculation result.

33. The clock generation method as described in claim 31, wherein, The first clock signal used to generate the first random waveform is different from and independent of the clock signal used to generate the control switching signal.

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