Ripple injection circuit with integrated slope compensation, and buck converter

Abstract

Provided in the embodiments of the present disclosure are a ripple injection circuit with integrated slope compensation, and a buck converter. The ripple injection circuit comprises: a first charging module, a second charging module, a first capacitor, a switch and an impedance module, wherein the first charging module is configured to provide a charging current for a ripple output node after an upper power tube of a switch power source is turned on, such that the ripple output node outputs a ripple voltage with integrated slope compensation; the second charging module is configured to provide a charging current for the ripple output node after the upper power tube is turned on; the first capacitor is configured to cooperate with the first charging module or the second charging module to form a charging path; the switch is configured to control the second charging module to provide the charging current for the ripple output node, and control the ripple output node to discharge by means of the first charging module after the upper power tube is turned off; and the impedance module is configured to provide a direct-current operating point for the ripple output node. The present disclosure solves the problem of the high design complexity of existing fixed-frequency control architectures based on ripple injection.

Description

Ripple injection circuit integrated with slope compensation, buck converter

[0001] Cross Reference to Related Applications

[0002] This application claims priority to the Chinese Patent Application No. 202410804440.6, filed on June 20, 2024, entitled “Ripple injection circuit integrated with slope compensation, buck converter”, the entire disclosure of which is incorporated herein by reference. TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to the field of integrated circuit technology, and in particular, to a ripple injection circuit integrated with slope compensation, buck converter. BACKGROUND

[0004] Constant on-time (COT) control topology is one of the mainstream control modes of switching power supply at present, which has the advantage of fast response, but the switching frequency is not fixed and cannot be synchronized with the external clock. Therefore, for applications that require fixed switching frequency, an oscillator needs to be added to ensure that the switching frequency does not change, but this will cause the occurrence of sub-harmonic oscillation phenomenon. Generally, switching power supply (such as BUCK) under fixed frequency control mode needs to add a slope voltage with appropriate polarity to the input end of the pulse width modulation comparator (PWM comparator) to avoid the occurrence of sub-harmonic oscillation phenomenon.

[0005] In the prior art, to solve the problem of sub-harmonic oscillation in fixed frequency control, a slope compensation circuit is combined with a multiple-input summing comparator to solve the problem of sub-harmonic oscillation. As shown in FIG. 1, it is a fixed frequency BUCK control architecture based on ripple injection in the prior art, and the specific working principle is as follows: close the upper tube Q1 and open the lower tube Q2 every time the oscillator clock signal arrives. The ripple signal V RAMP is generated by resistor R1 and capacitor C1, the slope voltage V Slope is generated by the slope compensation circuit, and the ripple injection circuit and the slope compensation circuit are independent, and their output signals need to be added and summed by the multiple-input summing comparator (PWM COMP) and compared with the output signal COMP of the transconductance amplifier OTA. When the PWM comparator (PWM COMP) outputs high level, the upper tube Q1 is opened and the lower tube Q2 is closed. As can be seen from the circuit structure of FIG. 1, the ripple injection circuit and the slope compensation circuit in the prior art are independent, and a multiple-input summing comparator is needed, which has high design complexity. SUMMARY

[0006] The embodiments described herein provide a ripple injection circuit integrated with slope compensation, a buck converter, to solve the problem of high design complexity of existing ripple injection based fixed frequency control architecture.

[0007] According to a first aspect of the present disclosure, a ripple injection circuit integrated with slope compensation is provided, the ripple injection circuit is coupled between a switching node and an output voltage of a switching power supply, and is configured to generate a ripple voltage integrated with slope compensation, the ripple injection circuit comprises: a first charging module, a second charging module, a first capacitor, a switch, and an impedance module, wherein the first charging module is configured to provide a charging current for a ripple output node after a high-side power tube of the switching power supply is closed, the ripple output node outputs the ripple voltage integrated with slope compensation, and the switching node is a node between the high-side power tube and a low-side power tube of the switching power supply; the second charging module is configured to provide a charging current for the ripple output node after the high-side power tube is closed; the first capacitor is configured to form a charging path together with the first charging module or the second charging module; the switch is coupled between the second charging module and a ground terminal, and is configured to control the second charging module to provide the charging current for the ripple output node, and to control the ripple output node to discharge through the first charging module after the high-side power tube is opened; and the impedance module is configured to provide a DC operating point for the ripple output node.

[0008] Optionally, the first charging module comprises a first resistor and a second capacitor, wherein one end of the first resistor is coupled to the switching node, and the other end of the first resistor is coupled to one end of the second capacitor; and the other end of the second capacitor is coupled to one end of the first capacitor, the second charging module, and the impedance module, respectively.

[0009] Optionally, the first charging module comprises a first resistor, wherein one end of the first resistor is coupled to the switching node, and the other end of the first resistor is coupled to one end of the first capacitor, the second charging module, and the impedance module.

[0010] Optionally, the second charging module comprises a second resistor and a third capacitor, wherein one end of the second resistor is coupled to the output voltage and the other end of the first capacitor, respectively, and the other end of the second resistor is coupled to one end of the third capacitor and one end of the switch, respectively; the other end of the third capacitor is coupled to one end of the first capacitor, the first charging module, and the impedance module, respectively; and the other end of the switch is coupled to a ground terminal.

[0011] Optionally, the impedance module comprises a third resistor and a fourth resistor, wherein one end of the third resistor is coupled to the output voltage, the other end of the third resistor is coupled to one end of the first capacitor, the first charging module, the ripple output node and one end of the fourth resistor respectively; the other end of the fourth resistor is coupled to a ground terminal.

[0012] Optionally, the impedance module comprises a third resistor, a fourth resistor and a fourth capacitor, and the impedance module is further configured to constitute a high-pass filter, wherein one end of the third resistor is coupled to the output voltage and the other end of the first capacitor respectively, the other end of the third resistor is coupled to the ripple output node, one end of the fourth resistor and one end of the fourth capacitor respectively; the other end of the fourth resistor is coupled to a ground terminal; the other end of the fourth capacitor is coupled to the first charging module and one end of the first capacitor respectively.

[0013] Optionally, the ripple injection circuit further comprises a switch signal control module, wherein the switch signal control module is configured to generate a switch signal according to a pulse width modulation signal in the switch power supply, and the switch signal is used to control the opening and closing of the switch.

[0014] Optionally, the switch signal control module comprises a delay circuit and a NOR gate, wherein the input end of the delay circuit is coupled to the pulse width modulation signal and the first input end of the NOR gate respectively, the output end of the delay circuit is coupled to the second input end of the NOR gate; and the output end of the NOR gate outputs the switch signal.

[0015] Optionally, the rising slope of the ripple output voltage is S n , and the falling slope of the ripple output voltage is S f : S n ≈(Vin-Vout) / (R1×C1)+Vout / (R2×C1); S f ≈Vout / (R1×(C1+C3)); wherein Vin is the input voltage of the switch power supply, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, C1 is the capacitance value of the first capacitor, and C3 is the capacitance value of the third capacitor.

[0016] Optionally, when the capacitance value of the third capacitor is less than one tenth of the capacitance value of the first capacitor, the falling slope S f of the ripple output voltage is approximately Vout / (R1×C1).

[0017] Optionally, the resistance value of the second resistor is twice the resistance value of the first resistor.

[0018] According to a second aspect of this disclosure, a buck converter is provided, comprising at least one of the integrated slope-compensated ripple injection circuits described in any of the first aspects above, and a two-input pulse width modulation comparator, wherein the positive input terminal of the two-input pulse width modulation comparator is coupled to the integrated slope-compensated ripple voltage output by the integrated slope-compensated ripple injection circuit, the negative input terminal of the two-input pulse width modulation comparator is coupled to the comparison signal output by the transconductance amplifier of the buck converter, and the output terminal of the two-input pulse width modulation comparator outputs a signal for controlling the switching of the power transistor of the buck converter.

[0019] In the integrated slope-compensated ripple injection circuit of the embodiments of this disclosure, when the state of the upper power transistor is continuously switched through the circuit structure composed of the first charging module, the second charging module, the first capacitor, the switch, and the impedance module, an integrated slope-compensated ripple voltage with rising and falling slopes is output. This realizes the integration of the ripple injection circuit and the slope compensation circuit together. Compared with the prior art, the circuit is simplified. Moreover, when comparing with the OTA output signal COMP in the future, a multi-input summing comparator is not required. Only a normal two-input comparator is needed, which further simplifies the circuit design. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure, wherein:

[0021] Figure 1 illustrates a fixed-frequency BUCK control architecture based on ripple injection in the prior art;

[0022] Figure 2 shows a schematic block diagram of an integrated slope-compensated ripple injection circuit according to an embodiment of the present disclosure;

[0023] Figure 3 shows an exemplary circuit diagram of an integrated slope-compensated ripple injection circuit according to an embodiment of the present disclosure;

[0024] Figure 4-6 shows three simplified circuit diagrams corresponding to Figure 3;

[0025] Figure 7 shows an exemplary circuit diagram of another integrated slope-compensated ripple injection circuit according to an embodiment of the present disclosure;

[0026] Figure 8-11 shows four simplified circuit diagrams corresponding to Figure 7;

[0027] Figure 12 shows an exemplary circuit diagram of the switching control module of the integrated slope-compensated ripple injection circuit according to an embodiment of the present disclosure;

[0028] Figure 13 shows a circuit timing diagram of the integrated slope-compensated ripple injection circuit according to an embodiment of the present disclosure;

[0029] The elements in the attached diagram are schematic and not drawn to scale. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are also within the scope of protection of this disclosure.

[0031] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the specification and in the relevant art, and shall not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, the statement of “connecting” or “coupling” two or more parts together shall mean that these parts are directly joined together or joined through one or more intermediate components.

[0032] In all embodiments of this disclosure, terms such as “first” and “second” are used only to distinguish one component (or part of a component) from another component (or another part of a component).

[0033] To address the high design complexity of existing fixed-frequency control architectures based on ripple injection, a ripple injection circuit with integrated slope compensation is proposed. The ripple injection circuit with integrated slope compensation in this disclosure integrates the ripple injection circuit and the slope compensation circuit, simplifying the circuit design. Furthermore, when comparing with the OTA output signal COMP, a multi-input summation comparator is not required; a standard two-input comparator suffices, further simplifying the circuit design. The ripple injection circuit 100 with integrated slope compensation of this disclosure will be described in detail below.

[0034] Figure 2 shows a schematic block diagram of the integrated slope-compensated ripple injection circuit 100 according to an embodiment of this disclosure. Figure 2 also shows other circuit structures in the switching power supply S1, including a pulse width modulation comparator (PWM COMP), an upper power transistor Q1, a lower power transistor Q2, an inductor L, an output capacitor (Co), a load (RL), a logic and driver circuit, and a transconductance amplifier (OTA). As shown in Figure 2, the ripple injection circuit 100 is coupled between the switching node SW and the output voltage Vout of the switching power supply to generate an integrated slope-compensated ripple voltage Vramp. The ripple injection circuit 100 includes: a first charging module 110, a second charging module 120, a first capacitor C1, a switch S1, and an impedance module 130.

[0035] The first charging module 110 is configured to provide charging current to the ripple output node P after the upper power transistor Q1 of the switching power supply is closed, causing the voltage at point P to rise. The ripple output node P outputs the integrated slope-compensated ripple voltage Vramp. The switching node SW is the node between the upper power transistor Q1 and the lower power transistor Q2 of the switching power supply. The second charging module 120 is configured to provide charging current to the ripple output node P after the upper power transistor Q1 is closed, causing the voltage at point P to rise. The first capacitor C1 is configured to cooperate with the first charging module 110 or the second charging module SW. Two charging modules 120 form a charging path; the switch S1 is coupled between the second charging module 120 and the ground terminal, and is configured to control the second charging module 120 to provide charging current to the ripple output node P, and after the upper power transistor Q1 is turned off, control the ripple output node P to discharge through the first charging module 110, causing the voltage at point P to drop; the impedance module 130 is coupled to the first charging module 110, the second charging module 120, the first capacitor C1, the output voltage Vout, and the ripple output node P, respectively, and the impedance module 130 is configured to provide a DC operating point to the ripple output node P. Additionally, the switching signal V controls the opening and closing of the switch S1. RST This is related to the switching of the upper power transistor Q1. Specifically, when the upper power transistor Q1 is closed, the switching signal V... RST When the power transistor Q1 is off, the switching signal V is at a low level. RST It is a high level.

[0036] The ripple injection circuit 100 in Figure 2 operates as follows in steady state: After the upper power transistor Q1 is closed, the switching node SW is at a high level, and the switch S1 is open. The switching node SW and the output voltage Vout provide charging current to the ripple output node P through the first charging module 110 and the second charging module 120, respectively, causing the voltage at point P to rise. After the upper power transistor Q1 is open, the switching node SW is at a low level, and the switch S1 is closed. The ripple output node P discharges through the first charging module 110, causing the voltage at point P to drop. When the switching node SW continuously switches between high and low levels, the ripple output node P can output a ripple voltage Vramp with integrated slope compensation and a certain rising and falling slope. The basic design idea of ​​this embodiment is to use two charging modules to replace the two parts of ripple injection and slope compensation in the prior art, thereby achieving the integration of ripple injection and slope compensation.

[0037] Furthermore, the composition of each module in the ripple injection circuit 100 is described. As shown in Figure 3, the first charging module 110 includes: a first resistor R1 and a second capacitor C2, wherein one end of the first resistor R1 is coupled to the switching node SW, and the other end of the first resistor R1 is coupled to one end of the second capacitor C2; the other end of the second capacitor C2 is coupled to the impedance module 130, one end of the first capacitor C1, and the second charging module 120, respectively.

[0038] The second charging module 120 includes: a second resistor R2 and a third capacitor C3, wherein one end of the second resistor R2 is coupled to the output voltage Vout and the other end of the first capacitor C1, and the other end of the second resistor R2 is coupled to one end of the third capacitor C3 and one end of the switch S1, and the other end of the switch S1 is coupled to the ground terminal; the other end of the third capacitor C3 is coupled to one end of the first capacitor C1, the first charging module 110, and the impedance module 130.

[0039] The impedance module includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is coupled to the output voltage Vout, and the other end of the third resistor R3 is coupled to one end of the first capacitor C1, the first charging module 110, the ripple output node P, and one end of the fourth resistor R4. The other end of the fourth resistor R4 is coupled to the ground terminal.

[0040] The working principle of the ripple injection circuit 100 in the embodiments of this disclosure will be explained with reference to Figure 3:

[0041] When the upper power transistor Q1 is closed and the lower power transistor Q2 is open, the potential of the switching node SW is equal to the power supply voltage Vin, and the ripple output node P is in the charging phase. Assuming only the charging paths are R1, C2, and C1, the circuit diagram simplifies to the diagram shown in Figure 4. Based on the circuit principle in Figure 4, we can obtain:

[0042] Time-domain voltage V at node A A The expression for (t) is:

[0043] Where t is time and e is the natural constant.

[0044] According to V A From the expression for (t), we can obtain the rising slope of the voltage at node A:

[0045] when At that time, the rising slope of the voltage at node A is approximately:

[0046] The rising slope of the Vramp is approximately:

[0047] Assuming there are only charging paths for R2, C3, and C1, the circuit diagram simplifies to the diagram shown in Figure 5. Similarly, based on the circuit principle in Figure 5, we can obtain:

[0048] The rising slope of the voltage at node B is:

[0049] when At that time, the rising slope of the voltage at node B is approximately:

[0050] The rising slope of the Vramp is approximately:

[0051] In summary, by merging the two charging paths, in At that time, the rising slope S of the ripple output node P n Approximately:

[0052] When the upper power transistor Q1 is off and the lower power transistor Q2 is closed, the potential of the switching node SW is 0V, and the ripple output node P is in the discharge phase. A simplified circuit diagram is shown in Figure 6. Based on the circuit principle in Figure 6, we can obtain:

[0053] The voltage drop slope at node A is:

[0054] when At that time, the slope of the voltage drop at node A is approximately:

[0055] The descent slope of the Vramp can then be expressed as:

[0056] The descent slope of the ripple output node P can be approximated as:

[0057] In summary, the rising slope S of the ripple output node P with integrated slope compensation can be obtained. n and the descending slope S f It can be represented as follows:

[0058] When C3 is less than 1 / 10 of C1, the effect of the third capacitor C3 can be ignored, and the decreasing slope can be expressed as:

[0059] For the prior art shown in Figure 1, the rising slope S of the ripple voltage Vramp n0 and the descending slope S f0 for:

[0060] The rising slope S of the ripple voltage Vramp with integrated slope compensation in this embodiment of the disclosure. n and the descending slope S f Compared with the rising slope S in the prior art n0 and the descending slope S f0 In comparison, it can be seen that the ripple voltage Vramp with integrated slope compensation in this embodiment is equivalent to reducing the rising slope to a certain value. The slope compensation voltage with zero descent slope is integrated into the ripple circuit, resulting in an integrated slope compensation ripple injection circuit, which simplifies the circuit design. Furthermore, when comparing the Vramp with the OTA output signal COMP, a multi-input summation comparator is not required; only a standard two-input comparator is needed, further simplifying the circuit design.

[0061] In practical engineering, as a preferred circuit design, the slope of the slope compensation is set to 1 / 2 of the ripple descent slope, i.e. Therefore, we get R2 = 2R1, which means that the resistance of the second resistor R2 is twice the resistance of the first resistor R1.

[0062] Additionally, the third resistor R3 and the fourth resistor R4 in the impedance module 130 are used to determine the DC operating point V of the ripple output node P. ramp,dc :

[0063] Furthermore, as shown in Figure 7, this disclosure also provides an exemplary circuit diagram of another ripple injection circuit. The difference between Figure 7 and Figure 3 lies in the different circuit structures of the first charging module 110 and the impedance module 130; all other structures are the same. Specifically, as shown in Figure 7, the first charging module 110 includes: a first resistor R1, wherein one end of the first resistor R1 is coupled to the switching node SW, and the other end of the first resistor R1 is coupled to one end of the first capacitor C1, the second charging module 120, and the impedance module 130. The impedance module 130 includes a third resistor R3, a fourth resistor R4, and a fourth capacitor C4. Besides providing a DC operating point for the ripple output node P, the impedance module 130 also forms a high-pass filter. One end of the third resistor R3 is coupled to the output voltage Vout and the other end of the first capacitor C1. The other end of the third resistor R3 is coupled to the ripple output node P, one end of the fourth resistor R4, and one end of the fourth capacitor C4. The other end of the fourth resistor R4 is coupled to ground. The other end of the fourth capacitor C4 is coupled to the first charging module 110 and one end of the first capacitor C1.

[0064] The working principle of the ripple injection circuit 100 in the embodiments of this disclosure will be explained with reference to Figure 7:

[0065] When the upper power transistor Q1 is closed and the lower power transistor Q2 is open, the potential of the switching node SW is equal to the power supply voltage Vin, node A is in the charging stage, and the voltage of the ripple output node P is in the rising stage. Assuming only the charging path of R1 and C1 exists, the circuit diagram simplifies to the circuit diagram shown in Figure 8. According to the circuit principle in Figure 8, we can obtain:

[0066] Time-domain voltage V at node A A The expression for (t) is:

[0067] Where t is time and e is the natural constant.

[0068] According to V A From the expression for (t), we can obtain the rising slope of the voltage at node A:

[0069] When t << R1·C1, the rising slope of the voltage at node A is approximately:

[0070] Assuming there are only charging paths for R2, C3, and C1, the circuit diagram simplifies to the diagram shown in Figure 9. Similarly, based on the circuit principle in Figure 9, we can obtain:

[0071] The rising slope of the voltage at node B is:

[0072] when At that time, the rising slope of the voltage at node B is approximately:

[0073] The approximate slope of node A is:

[0074] In summary, by merging the two charging paths, in At that time, the rising slope S of node A nA Approximately:

[0075] When the upper power transistor Q1 is off and the lower power transistor Q2 is closed, the potential of the switching node SW is 0V, node A is in the discharge phase, and the voltage of the ripple output node P is in the decreasing phase. A simplified circuit diagram is shown in Figure 10. Based on the circuit principle in Figure 10, we can obtain:

[0076] The voltage drop slope at node A is:

[0077] When t << R1·(C1+C3), the slope of the voltage drop at node A is approximately:

[0078] The descent slope S of node A fA It can be represented as:

[0079] Based on the above analysis, we can obtain the slope S of ascent at point A. nA and the descending slope S fA It can be represented as follows:

[0080] Since the AC equivalent circuit from node A to node P is equivalent to a high-pass filter, and Vout is considered a DC signal during AC small-signal equivalence, Vout can be considered AC ground. Therefore, R3 and R4 can be considered to be connected in parallel, as shown in Figure 11, which is the AC equivalent circuit diagram from node A to node P. Here, R3 / / R4 represents the equivalent resistance of R3 and R4 connected in parallel. Based on the circuit principle in Figure 11, we can obtain:

[0081] The time-domain voltage expression for node P is:

[0082] When t << C4·(R3 / / R4), V ramp (t)≈V A (t)

[0083] Therefore, the rising slope S of the ripple output node P with integrated slope compensation can be obtained. n and the descending slope S fIt can be represented as follows:

[0084] Similar to the previous embodiment, when C3 is less than 1 / 10 of C1, the effect of capacitor C3 can be ignored, and the slope S will decrease. f It can be represented as:

[0085] In practical engineering, R2 = 2R1 is a preferred circuit design. The DC operating point of the ripple output node P.

[0086] In summary, although the circuit structures of Figures 3 and 7 differ, the resulting Vramp's rising and falling slopes are consistent. From a circuit principle perspective, in Figure 3, the first charging module 110 and the second charging module 120 directly charge the ripple output node P, and the discharging process involves P discharging directly through 110. In Figure 7, the first charging module 110 and the second charging module 120 directly charge node A, and the discharging process involves A discharging directly through 110, then coupling the AC information of node A to P through the fourth capacitor C4. Whether directly charging and discharging P or coupling the AC information to P through C4, the charging process is equivalent to the charging current being provided by the charging modules (110 and 120), and the discharging process is equivalent to P discharging through 110.

[0087] Furthermore, as shown in Figure 12, the ripple injection circuit further includes a switching signal control module 140, wherein the switching signal control module 140 is configured to generate a switching signal V based on the pulse width modulation signal (PWM signal in Figure 2) in the switching power supply. RST The switching signal V RST Used to control the opening and closing of the switch S1. Further, the switch signal V... RST The control module includes a delay circuit (Delay) and a NOR gate, wherein the input terminals of the delay circuit (Delay) are coupled to the pulse width modulation signal (PWM) and the first input terminal of the NOR gate, respectively, and the output terminal of the delay circuit (Delay) is coupled to the second input terminal of the NOR gate; the output terminal of the NOR gate outputs the switching signal V. RST Switch signal V RST When the value is low, switch S1 is open, and the switch signal V... RST When the signal is high, switch S1 is closed. The switch signal control module receives the pulse width modulation signal PWM output from the SR latch, and then outputs the switch signal V through the delay circuit Delay and the NOR gate. RST The obtained switching signal V RST The timing diagram is shown in Figure 13, and the switching signal V RSTAfter the potential of the switching node SW goes high, it immediately goes low, but V RST After the switching node SW potential goes low, it is delayed for a period of time before going high (the change in SW potential is synchronized with the change in PWM potential). This delay is to ensure that the input signal at the R terminal of the SR latch has sufficient pulse width, increasing the circuit's anti-interference capability. Additionally, Figure 13 also shows the timing diagram of other signals corresponding to the ripple injection circuit in this embodiment. As shown in Figure 13, from top to bottom, they correspond to the switching node SW, the switching signal V... RST The timing diagram corresponding to the ripple voltage Vramp is shown in Figure 13. It should be noted that in the initial stage of the falling portion of the Vramp timing diagram, there is a short section where the slope is not S. f This is caused by the on-resistance of switch S1. In order to reduce the impact, the on-resistance of switch S1 needs to be small enough in practical applications.

[0088] Another embodiment of this disclosure provides a buck converter, which includes at least the integrated slope-compensated ripple injection circuit 100 described in the above embodiments, and a two-input pulse width modulation comparator (PWM COMP). Referring to FIG2, the positive input terminal of the two-input PWM COMP is coupled to the integrated slope-compensated ripple voltage Vramp output by the integrated slope-compensated ripple injection circuit 100, and the negative input terminal of the two-input PWM COMP is coupled to the comparison signal COMP output by the transconductance amplifier OTA of the buck converter. The output terminal of the two-input PWM COMP outputs a signal V for controlling the switching of the power transistors (Q1, Q2) of the buck converter. PWM_OUT V PWM_OUT The pulse width modulation (PWM) signal is obtained through the latch SR. Compared with the circuit diagram in Figure 1, this embodiment not only integrates ripple injection and slope compensation, but also simplifies the circuit design by requiring only a standard two-input comparator for the PWM COMP.

[0089] In summary, the integrated slope-compensated ripple injection circuit 100 in this embodiment integrates the ripple injection circuit and the slope compensation circuit, simplifying the circuit design. Furthermore, when comparing it with the OTA output signal COMP, a multi-input summation comparator is not required; only a standard two-input comparator is needed, further simplifying the circuit design.

[0090] Unless otherwise expressly indicated by the context, the singular form of words used herein and in the appended claims includes the plural form, and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the terms “comprising” and “including” shall be interpreted as including rather than exclusively. Likewise, the terms “including” and “or” shall be interpreted as including unless such interpretation is expressly prohibited herein. Where the term “example” is used herein, particularly when it follows a set of terms, “example” is merely exemplary and illustrative and should not be considered exclusive or extensive.

[0091] Further aspects and scope of adaptation become apparent from the description provided herein. It should be understood that various aspects of this disclosure may be implemented individually or in combination with one or more other aspects. It should also be understood that the descriptions and specific embodiments herein are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0092] Several embodiments of this disclosure have been described in detail above. However, it is obvious that those skilled in the art can make various modifications and variations to the embodiments of this disclosure without departing from the spirit and scope of this disclosure. The scope of protection of this disclosure is defined by the appended claims.

Claims

1. An integrated slope-compensated ripple injection circuit, characterized by, The ripple injection circuit is coupled between a switching node of a switching power supply and an output voltage, and is configured to generate a ripple voltage integrated with slope compensation, the ripple injection circuit comprising: a first charging module, a second charging module, a first capacitor, a switch, an impedance module, The first charging module is configured to provide a charging current for the ripple output node after the upper power tube of the switching power supply is closed, the ripple output node outputs the ripple voltage integrated with slope compensation, and the switching node is a node between the upper power tube and a lower power tube of the switching power supply. The second charging module is configured to provide a charging current for the ripple output node after the upper power tube is closed. The first capacitor is configured to form a charging path with the first charging module or the second charging module. The switch is coupled between the second charging module and a ground terminal, and is configured to control the second charging module to provide a charging current for the ripple output node, and control the ripple output node to discharge through the first charging module after the upper power tube is opened. The impedance module is configured to provide a DC operating point for the ripple output node.

2. The integrated slope-compensated ripple injection circuit of claim 1, wherein, The first charging module comprises a first resistor and a second capacitor, One end of the first resistor is coupled to the switching node, and the other end of the first resistor is coupled to one end of the second capacitor. The other end of the second capacitor is coupled to one end of the first capacitor, the second charging module and the impedance module, respectively.

3. The integrated slope-compensated ripple injection circuit of claim 1, wherein, The first charging module comprises a first resistor, One end of the first resistor is coupled to the switching node, and the other end of the first resistor is coupled to one end of the first capacitor, the second charging module and the impedance module.

4. The integrated slope-compensated ripple injection circuit of claim 1, wherein, The second charging module comprises a second resistor and a third capacitor, One end of the second resistor is coupled to the output voltage and the other end of the first capacitor, respectively, and the other end of the second resistor is coupled to one end of the third capacitor and one end of the switch, respectively, and the other end of the switch is coupled to a ground terminal. The other end of the third capacitor is coupled to one end of the first capacitor, the first charging module and the impedance module, respectively.

5. The integrated slope-compensated ripple injection circuit of claim 2, wherein, The impedance module comprises a third resistor and a fourth resistor, One end of the third resistor is coupled to the output voltage, and the other end of the third resistor is coupled to one end of the first capacitor, the first charging module, the ripple output node and one end of the fourth resistor, respectively. The other end of the fourth resistor is coupled to a ground terminal.

6. The integrated slope-compensated ripple injection circuit of claim 3, wherein, The impedance module comprises a third resistor, a fourth resistor and a fourth capacitor, and the impedance module is further configured to form a high-pass filter, One end of the third resistor is coupled to the output voltage and the other end of the first capacitor, respectively, and the other end of the third resistor is coupled to the ripple output node, one end of the fourth resistor and one end of the fourth capacitor, respectively. The other end of the fourth resistor is coupled to a ground terminal. The other end of the fourth capacitor is coupled to one end of the first capacitor and the first charging module, respectively.

7. The integrated slope-compensated ripple injection circuit of claim 1, wherein, The ripple injection circuit further comprises a switch signal control module, The switch signal control module is configured to generate a switch signal according to a pulse width modulation signal in the switch power supply, and the switch signal is used to control opening and closing of the switch.

8. The integrated slope-compensated ripple injection circuit of claim 7, wherein, The switch signal control module comprises a delay circuit and a NOR gate. The input end of the delay circuit is coupled with the pulse width modulation signal and the first input end of the NOR gate, and the output end of the delay circuit is coupled with the second input end of the NOR gate. The output end of the NOR gate outputs the switch signal.

9. The integrated slope-compensated ripple injection circuit of claim 4, wherein, The rising slope of the ripple output voltage is S n The falling slope of the ripple output voltage is S f : S n ≈(Vin-Vout) / (R1×C1)+Vout / (R2×C1); S f ≈Vout / (R1×(C1+C3)); Vin is an input voltage of the switch power supply, R1 is a resistance value of the first resistor, R2 is a resistance value of the second resistor, C1 is a capacitance value of the first capacitor, and C3 is a capacitance value of the third capacitor.

10. The integrated slope-compensated ripple injection circuit of claim 9, wherein, When the capacitance of the third capacitor is less than one-tenth of the capacitance of the first capacitor, the falling slope S of the ripple output voltage f ≈Vout / (R1×C1).

11. The integrated slope-compensated ripple injection circuit of claim 9, wherein, The resistance value of the second resistor is twice the resistance value of the first resistor.

12. A step-down converter, characterized by The buck converter at least comprises the integrated slope compensated ripple injection circuit, the two-input pulse width modulation comparator, the delay circuit and the NOR gate. The positive input end of the two-input pulse width modulation comparator is coupled with the integrated slope compensated ripple voltage output by the integrated slope compensated ripple injection circuit, the negative input end of the two-input pulse width modulation comparator is coupled with the comparison signal output by the transconductance amplifier of the buck converter, and the output end of the two-input pulse width modulation comparator outputs a signal used to control switching of the power tube of the buck converter.

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