A high frequency ripple filter circuit and apparatus thereof

Abstract

The application provides a high-frequency ripple filtering circuit and a device thereof, comprising an error feedback control sub-circuit, a DC biasing sub-circuit and a ripple cancellation sub-circuit, wherein: the DC biasing sub-circuit generates a DC biasing voltage and transmits the DC biasing voltage to the error feedback control sub-circuit, and makes the error feedback control sub-circuit perform frequency domain separation on an external mixed current to obtain an AC ripple component, and simultaneously obtain the DC biasing voltage, so as to perform error operation on the AC ripple component and the DC biasing voltage to obtain a first voltage control signal; the ripple cancellation sub-circuit is used for adjusting an AC ripple absorption degree according to the first voltage control signal, and filtering high-frequency ripples of the external mixed current based on the AC ripple absorption degree. The high-frequency ripple filtering circuit and the device thereof provided by the application can deeply filter high-frequency ripple noise while keeping high efficiency of a switching power supply.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to a high-frequency ripple filtering circuit and device thereof. Background Technology

[0002] Switching power supplies are widely used in various electronic devices due to their high efficiency and small size. However, their inherent switching action results in ripple in the output voltage, which includes the switching frequency and its higher harmonics. In applications requiring extremely high power purity, such as high-precision analog circuits, radio frequency circuits, and medical equipment, this ripple can severely interfere with normal system operation and even lead to equipment failure. Currently, conventional ripple suppression methods include the following three: using a series LDO regulator to suppress low-frequency ripple; using passive LC filtering to suppress ripple by increasing the output filter inductance and capacitance; and using multi-phase interleaved parallel technology to cancel out ripple through multiple phase-staggered switching circuits.

[0003] Under the current technological background, the aforementioned conventional ripple suppression methods all have their own limitations: although the series-connected LDO regulator can effectively suppress low-frequency ripple, the LDO itself needs to withstand the input / output voltage difference, which leads to a significant reduction in the efficiency of the switching power supply. At the same time, the power supply rejection ratio (PSRR) of the LDO for high-frequency switching noise drops sharply, and the high-frequency ripple suppression effect is limited; passive LC filtering will slow down the dynamic response of the power supply and has limited ripple suppression effect for specific frequencies; multiphase interleaved parallel technology cannot completely eliminate all ripple components. Summary of the Invention

[0004] The present invention aims to provide a high-frequency ripple filtering circuit and device to solve the above-mentioned technical problems. By separating the DC component and the AC ripple component in the frequency domain and processing only the AC ripple component, the high-frequency ripple noise can be deeply filtered out while maintaining the high efficiency of the switching power supply.

[0005] To address the aforementioned technical problems, this invention provides a high-frequency ripple filtering circuit, comprising a first inductor, an error feedback control sub-circuit, a DC bias sub-circuit, a ripple cancellation sub-circuit, and a load sub-circuit, wherein: The first inductor is used to receive external mixed current and perform frequency domain separation on the received external mixed current to obtain AC ripple component and DC component; The load sub-circuit is used to transmit the DC component to the error feedback control sub-circuit; The DC bias sub-circuit is used to generate a DC bias voltage and transmit it to the error feedback control sub-circuit. The error feedback control sub-circuit is used to receive the DC component and the DC bias voltage, and to obtain the current sampling signal based on the DC component, so as to perform error calculation on the current sampling signal and the DC bias voltage to obtain the first voltage control signal and transmit it to the ripple cancellation sub-circuit. The ripple cancellation sub-circuit is used to receive the first voltage control signal and adjust the AC ripple absorption degree according to the first voltage control signal, so as to perform high-frequency ripple filtering on the AC ripple component based on the AC ripple absorption degree.

[0006] In the above scheme, the external mixed current is separated in the frequency domain by the first inductor, which separates the DC component from the AC ripple component in the frequency domain, and only filters out the high-frequency ripple of the AC ripple component. Next, the error feedback control sub-circuit performs error calculation between the current sampling signal obtained based on the DC component and the acquired DC bias voltage to generate a first voltage control signal, which provides a basis for subsequent high-frequency ripple cancellation. Then, the ripple cancellation sub-circuit receives the first voltage control signal and adjusts the AC ripple absorption degree according to the first voltage control signal, which can filter out the high-frequency ripple of the AC ripple component based on the AC ripple absorption degree, thereby maintaining the high efficiency of the switching power supply while filtering out high-frequency ripple noise.

[0007] Furthermore, the load sub-circuit includes a first load and a first capacitor, specifically: One end of the first load is electrically connected to the first input terminal of the ripple cancellation sub-circuit as the input terminal of the load sub-circuit, one end of the first load is electrically connected to one end of the first inductor, one end of the first load is electrically connected to one end of the first capacitor, and the other end of the first load is electrically connected to the first input terminal of the error feedback control sub-circuit as the output terminal of the load sub-circuit. The other end of the first capacitor is grounded.

[0008] In the above scheme, filtering the DC component separated from the first inductor using the first capacitor can reduce instantaneous fluctuations to help stabilize the output voltage, thus improving the high-frequency ripple filtering effect in conjunction with the ripple cancellation sub-circuit. Then, through the first load, the DC component can be converted into a current sampling signal that can be processed by the error feedback control sub-circuit for subsequent error calculation.

[0009] Furthermore, the error feedback control sub-circuit includes a first operational amplifier, a first resistor, a second capacitor, and a first sampling resistor, specifically: The output terminal of the first operational amplifier is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier is electrically connected to one end of the first resistor. The inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor is electrically connected to one end of the second capacitor, and the other end of the first resistor is grounded; The other end of the second capacitor is electrically connected to one end of the first sampling resistor; One end of the first sampling resistor is electrically connected to the other end of the first load as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor is grounded.

[0010] In the above scheme, the DC component flowing through the first load is converted into a voltage sampling signal by the first sampling resistor and transmitted to the second capacitor, providing the original signal for subsequent error calculation with the DC bias voltage. Next, a high-pass filter structure is formed by the second capacitor and the first resistor, which isolates the DC component from the voltage sampling signal and separates the residual AC component, sending the residual AC component to the first operational amplifier. Then, the DC bias voltage is received at the inverting input terminal and the residual AC component signal is received at the non-inverting input terminal of the first operational amplifier. Error calculation is performed between the AC component signal and the DC bias voltage to obtain a first voltage control signal, which is then sent to the ripple cancellation sub-circuit, providing the control basis for the ripple cancellation sub-circuit.

[0011] Furthermore, the ripple cancellation sub-circuit includes a second operational amplifier, a second resistor, a second sampling resistor, and a first transistor, specifically: The positive input terminal of the second operational amplifier is electrically connected to the output terminal of the first operational amplifier as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the emitter of the first transistor. The output terminal of the second operational amplifier is electrically connected to one end of the second resistor. The other end of the second resistor is electrically connected to the base of the first transistor; The emitter of the first transistor is electrically connected to one end of the second sampling resistor, and the collector of the first transistor is electrically connected to one end of the first inductor as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor is grounded.

[0012] In the above scheme, the first voltage control signal output by the first operational amplifier is received at the non-inverting input of the second operational amplifier, and the current sampling voltage fed back by the second sampling resistor is received at the inverting input of the second operational amplifier. This allows for calculation of the two input voltages, outputting a drive voltage to the second resistor. The second resistor limits the current, protecting the base of the first transistor from overcurrent damage. Simultaneously, the conduction level of the first transistor is adjusted by the drive voltage to match the AC ripple component to be absorbed. Next, the AC ripple component output by the first inductor is received at the collector of the first transistor, and the conduction level is adjusted according to the base drive voltage to regulate the AC ripple absorption level. Simultaneously, the emitter of the first transistor outputs a compensation ripple current, which is converted into a voltage sampling signal by the second sampling resistor and sent to the inverting input of the second operational amplifier. This provides real-time feedback on the magnitude of the compensation ripple current, stabilizing the output amplitude of the compensation current.

[0013] Furthermore, the DC bias sub-circuit includes a third operational amplifier, a third resistor, and a reference voltage source, specifically: The output terminal of the third operational amplifier is electrically connected to the inverting input terminal of the first operational amplifier as the output terminal of the DC bias sub-circuit. The output terminal of the third operational amplifier is electrically connected to the inverting input terminal of the third operational amplifier. The non-inverting input terminal of the third operational amplifier is electrically connected to the emitter of the first transistor as the input terminal of the DC bias sub-circuit. The inverting input terminal of the third operational amplifier is electrically connected to one end of the third resistor. The other end of the third resistor is electrically connected to the positive terminal of the reference voltage source; The negative terminal of the reference voltage source is grounded.

[0014] In the above scheme, a stable DC voltage is output through a reference voltage source, and the DC voltage is divided and regulated by a third resistor to provide an initial reference voltage for the third operational amplifier. Then, the voltage sampling signal output from the emitter of the first transistor is received at the non-inverting input of the third operational amplifier, and the initial reference voltage transmitted by the third resistor is received at the inverting input of the third operational amplifier. The voltage sampling signal and the initial reference voltage are processed, and the generated DC bias voltage is transmitted to the inverting input of the first operational amplifier to provide a DC bias voltage for the error feedback control sub-circuit, ensuring that the first transistor can continuously operate in the linear range.

[0015] Furthermore, the DC bias sub-circuit also includes a fourth resistor, a third capacitor, and a fourth capacitor, specifically: One end of the third capacitor is electrically connected to the output terminal of the third operational amplifier, and the other end of the third capacitor is electrically connected to the inverting input terminal of the third operational amplifier. One end of the fourth resistor is electrically connected to the positive input terminal of the third operational amplifier, one end of the fourth resistor is electrically connected to one end of the fourth capacitor, and the other end of the fourth resistor is electrically connected to the emitter of the first transistor. The other end of the fourth capacitor is grounded.

[0016] In the above scheme, by passing the voltage sampling signal output from the emitter of the first transistor through a filter structure composed of a fourth resistor and a fourth capacitor, high-frequency noise can be filtered out before it is transmitted to the positive input terminal of the third operational amplifier. Then, by connecting the third capacitor across the output terminal and the inverting input terminal of the third operational amplifier, the third operational amplifier can provide a stable and oscillating DC bias voltage to the error feedback control sub-circuit.

[0017] This invention provides a high-frequency ripple filtering device, comprising a housing, wherein a high-frequency ripple filtering circuit as described in any one of claims 1 to 6 is disposed within the housing; the housing includes a first input interface and a first output interface; wherein: The first input terminal of the ripple cancellation sub-circuit is electrically connected to the first input interface, and the other end of the first load is electrically connected to the first output interface.

[0018] The high-frequency ripple filtering device provided by this invention is simple. In practical applications, it only needs to be connected to the first input terminal of the ripple cancellation sub-circuit through the first input interface and the other end of the first load through the first output interface. Thus, the high-frequency ripple filtering device can separate the external mixed current in the frequency domain, separate the DC component and the AC ripple component in the frequency domain, and filter the AC ripple component at high frequency, so as to maintain the high efficiency of the switching power supply while filtering out high-frequency ripple noise.

[0019] Furthermore, the load sub-circuit includes a first load and a first capacitor, specifically: One end of the first load is electrically connected to the first input terminal of the ripple cancellation sub-circuit as the input terminal of the load sub-circuit, one end of the first load is electrically connected to one end of the first inductor, one end of the first load is electrically connected to one end of the first capacitor, and the other end of the first load is electrically connected to the first input terminal of the error feedback control sub-circuit as the output terminal of the load sub-circuit. The other end of the first capacitor is grounded.

[0020] In the above scheme, filtering the DC component separated from the first inductor using the first capacitor can reduce instantaneous fluctuations to help stabilize the output voltage, thus improving the high-frequency ripple filtering effect in conjunction with the ripple cancellation sub-circuit. Then, through the first load, the DC component can be converted into a current sampling signal that can be processed by the error feedback control sub-circuit for subsequent error calculation.

[0021] Furthermore, the error feedback control sub-circuit includes a first operational amplifier, a first resistor, a second capacitor, and a first sampling resistor, specifically: The output terminal of the first operational amplifier is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier is electrically connected to one end of the first resistor. The inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor is electrically connected to one end of the second capacitor, and the other end of the first resistor is grounded; The other end of the second capacitor is electrically connected to one end of the first sampling resistor; One end of the first sampling resistor is electrically connected to the other end of the first load as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor is grounded.

[0022] In the above scheme, the DC component flowing through the first load is converted into a voltage sampling signal by the first sampling resistor and transmitted to the second capacitor, providing the original signal for subsequent error calculation with the DC bias voltage. Next, a high-pass filter structure is formed by the second capacitor and the first resistor, which isolates the DC component from the voltage sampling signal and separates the residual AC component, sending the residual AC component to the first operational amplifier. Then, the DC bias voltage is received at the inverting input terminal and the residual AC component signal is received at the non-inverting input terminal of the first operational amplifier. Error calculation is performed between the AC component signal and the DC bias voltage to obtain a first voltage control signal, which is then sent to the ripple cancellation sub-circuit, providing the control basis for the ripple cancellation sub-circuit.

[0023] Furthermore, the ripple cancellation sub-circuit includes a second operational amplifier, a second resistor, a second sampling resistor, and a first transistor, specifically: The positive input terminal of the second operational amplifier is electrically connected to the output terminal of the first operational amplifier as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the emitter of the first transistor. The output terminal of the second operational amplifier is electrically connected to one end of the second resistor. The other end of the second resistor is electrically connected to the base of the first transistor; The emitter of the first transistor is electrically connected to one end of the second sampling resistor, and the collector of the first transistor is electrically connected to one end of the first inductor as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor is grounded.

[0024] In the above scheme, the first voltage control signal output by the first operational amplifier is received at the non-inverting input of the second operational amplifier, and the current sampling voltage fed back by the second sampling resistor is received at the inverting input of the second operational amplifier. This allows for calculation of the two input voltages, outputting a drive voltage to the second resistor. The second resistor limits the current, protecting the base of the first transistor from overcurrent damage. Simultaneously, the conduction level of the first transistor is adjusted by the drive voltage to match the AC ripple component to be absorbed. Next, the AC ripple component output by the first inductor is received at the collector of the first transistor, and the conduction level is adjusted according to the base drive voltage to regulate the AC ripple absorption level. Simultaneously, the emitter of the first transistor outputs a compensation ripple current, which is converted into a voltage sampling signal by the second sampling resistor and sent to the inverting input of the second operational amplifier. This provides real-time feedback on the magnitude of the compensation ripple current, stabilizing the output amplitude of the compensation current. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a high-frequency ripple filtering circuit provided in an embodiment of the present invention; Figure 2 A circuit structure diagram of a high-frequency ripple filtering circuit provided in an embodiment of the present invention; Figure 3 This is a simulation comparison diagram of a conventional switching power supply and a switching power supply containing a high-frequency ripple filtering circuit provided in this embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This embodiment provides a high-frequency ripple filtering circuit, the architecture of which can be found in [reference needed]. Figure 1 It includes a first inductor L1, an error feedback control subcircuit, a DC bias subcircuit, a ripple cancellation subcircuit, and a load subcircuit, wherein: The first inductor L1 is used to receive external mixed current and perform frequency domain separation on the received external mixed current to obtain AC ripple component and DC component; The load sub-circuit is used to transmit the DC component to the error feedback control sub-circuit; The DC bias sub-circuit is used to generate a DC bias voltage and transmit it to the error feedback control sub-circuit. The error feedback control sub-circuit is used to receive the DC component and the DC bias voltage, and to obtain the current sampling signal based on the DC component, so as to perform error calculation on the current sampling signal and the DC bias voltage to obtain the first voltage control signal and transmit it to the ripple cancellation sub-circuit. The ripple cancellation sub-circuit is used to receive the first voltage control signal and adjust the AC ripple absorption degree according to the first voltage control signal, so as to perform high-frequency ripple filtering on the AC ripple component based on the AC ripple absorption degree.

[0028] In this embodiment, since the first inductor L1 has a very small impedance to DC current but a high impedance to high-frequency AC ripple current, it will prevent the current from flowing to the load. Therefore, by using the first inductor L1 to separate the external mixed current in the frequency domain, the DC component and the AC ripple component can be separated in the frequency domain, achieving physical isolation in the frequency domain. This allows the DC component to flow to the load sub-circuit, while guiding the AC ripple component to the ripple cancellation sub-circuit. Only the AC ripple component is filtered for high-frequency ripple, resulting in extremely low power consumption and fundamentally solving the problem of low efficiency of the switching power supply. Next, the error feedback control sub-circuit performs error calculation on the current sampling signal obtained based on the DC component and the acquired DC bias voltage to generate the first voltage control signal, which can provide a basis for subsequent high-frequency ripple cancellation. Then, the first voltage control signal is received through the ripple cancellation sub-circuit and the degree of AC ripple absorption is adjusted according to the first voltage control signal. A compensation current with the opposite phase and equal amplitude to the detected AC ripple component is generated according to the degree of AC ripple absorption, so that most of the AC ripple component is filtered out, thereby maintaining the high efficiency of the switching power supply while filtering out high-frequency ripple noise.

[0029] Furthermore, the load sub-circuit includes a first load Rload and a first capacitor Cout, specifically: One end of the first load Rload is electrically connected to the first input terminal of the load sub-circuit and the first input terminal of the ripple cancellation sub-circuit. One end of the first load Rload is electrically connected to one end of the first inductor L1. One end of the first load Rload is electrically connected to one end of the first capacitor Cout. The other end of the first load Rload is electrically connected to the first input terminal of the error feedback control sub-circuit and the output terminal of the load sub-circuit. The other end of the first capacitor Cout is grounded.

[0030] In this embodiment, the DC component separated from the first inductor L1 is filtered by the first capacitor Cout, which weakens instantaneous fluctuations to help stabilize the output voltage. This, combined with the ripple cancellation sub-circuit, enhances the high-frequency ripple filtering effect, ultimately reducing the voltage ripple across the first load Rload to an extremely low level. Then, the DC component is converted into a current sampling signal that can be processed by the error feedback control sub-circuit for subsequent error calculation. The first load Rload and the first inductor L1 constitute the main power path; the first inductor L1, the error feedback control sub-circuit, the DC bias sub-circuit, and the ripple cancellation sub-circuit constitute a parallel active ripple compensation path, avoiding mutual interference between complex loops.

[0031] Further, please see Figure 2 The error feedback control sub-circuit includes a first operational amplifier op1, a first resistor R1, a second capacitor C2, and a first sampling resistor Rs1, specifically: The output terminal of the first operational amplifier op1 is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier op1 is electrically connected to one end of the first resistor R1. The inverting input terminal of the first operational amplifier op1 is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor R1 is electrically connected to one end of the second capacitor C2, and the other end of the first resistor R1 is grounded. The other end of the second capacitor C2 is electrically connected to one end of the first sampling resistor Rs1; One end of the first sampling resistor Rs1 is electrically connected to the other end of the first load Rload as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor Rs1 is grounded.

[0032] In this embodiment, the DC component flowing through the first load Rload is converted into a voltage sampling signal by the first sampling resistor Rs1 and transmitted to the second capacitor C2, providing the original signal for subsequent error calculation with the DC bias voltage. Next, the second capacitor C2 and the first resistor R1 form a high-pass filter structure, which isolates the DC component from the voltage sampling signal and separates the residual AC component signal, sending the residual AC component to the first operational amplifier op1. Then, the DC bias voltage is received at the inverting input terminal and the residual AC component signal is received at the non-inverting input terminal of the first operational amplifier op1. Error calculation is performed between the AC component signal and the DC bias voltage to obtain a first voltage control signal, which is then sent to the ripple cancellation sub-circuit, providing control basis for the ripple cancellation sub-circuit. The first operational amplifier op1 can be a proportional (P) controller, a proportional-integral (PI) controller, or a proportional-integral-derivative (PID) controller.

[0033] Furthermore, the ripple cancellation sub-circuit includes a second operational amplifier op2, a second resistor R2, a second sampling resistor Rs2, and a first transistor Q1, specifically: The positive input terminal of the second operational amplifier op2 is electrically connected to the output terminal of the first operational amplifier op1 as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier op2 is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier op2 is electrically connected to the emitter of the first transistor Q1. The output terminal of the second operational amplifier op2 is electrically connected to one end of the second resistor R2. The other end of the second resistor R2 is electrically connected to the base of the first transistor Q1; The emitter of the first transistor Q1 is electrically connected to one end of the second sampling resistor Rs2, and the collector of the first transistor Q1 is electrically connected to one end of the first inductor L1 as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor Rs2 is grounded.

[0034] In this embodiment, the first voltage control signal output by the first operational amplifier op1 is received at the non-inverting input terminal of the second operational amplifier op2, and the current sampling voltage fed back by the second sampling resistor Rs2 is received at the inverting input terminal of the second operational amplifier op2. This allows for calculation of the two input voltages, outputting a drive voltage to the second resistor R2. The second resistor R2 limits the current, protecting the base of the first transistor Q1 from overcurrent damage. Simultaneously, the conduction level of the first transistor Q1 is adjusted by the drive voltage to match the AC ripple component to be absorbed. Next, the AC ripple component output by the first inductor L1 is received at the collector of the first transistor Q1, and its conduction level is adjusted according to the base drive voltage to regulate the AC ripple absorption level. Simultaneously, the emitter of the first transistor Q1 outputs a compensation ripple current, which is converted into a voltage sampling signal by the second sampling resistor Rs2 and sent to the inverting input terminal of the second operational amplifier op2. This provides real-time feedback on the magnitude of the compensation ripple current, stabilizing the output amplitude of the compensation current. Where Vo1 is the output ripple of the switching power supply, Iripple is the current of the parallel active ripple compensation path (equivalent to the AC ripple component), and Vo is the output ripple voltage.

[0035] Furthermore, the DC bias sub-circuit includes a third operational amplifier op3, a third resistor R3, and a reference voltage source DC, specifically as follows: The output terminal of the third operational amplifier op3 is electrically connected to the inverting input terminal of the first operational amplifier op1 as the output terminal of the DC bias sub-circuit. The output terminal of the third operational amplifier op3 is electrically connected to the inverting input terminal of the third operational amplifier op3. The non-inverting input terminal of the third operational amplifier op3 is electrically connected to the emitter of the first transistor Q1 as the input terminal of the DC bias sub-circuit. The inverting input terminal of the third operational amplifier op3 is electrically connected to one end of the third resistor R3. The other end of the third resistor R3 is electrically connected to the positive terminal of the reference voltage source DC. The DC negative terminal of the reference voltage source is grounded.

[0036] In this embodiment, a stable DC voltage is output from a reference voltage source, and the DC voltage is divided and regulated by a third resistor R3 to provide an initial reference voltage for the third operational amplifier op3. Next, the voltage sampling signal output from the emitter of the first transistor Q1 is received at the positive input terminal of the third operational amplifier op3, and the initial reference voltage transmitted by the third resistor R3 is received at the inverting input terminal of the third operational amplifier op3. The voltage sampling signal and the initial reference voltage are processed, and the generated DC bias voltage is transmitted to the inverting input terminal of the first operational amplifier op1 to provide a DC bias voltage for the error feedback control sub-circuit, ensuring that the first transistor Q1 can continuously operate in the linear range. Furthermore, due to the use of active negative feedback compensation, stable filtering and fast response of AC ripple components are ensured, and the ripple suppression effect is independent of the size of passive components.

[0037] Furthermore, the DC bias sub-circuit also includes a fourth resistor R4, a third capacitor C3, and a fourth capacitor C4, specifically: One end of the third capacitor C3 is electrically connected to the output terminal of the third operational amplifier op3, and the other end of the third capacitor C3 is electrically connected to the inverting input terminal of the third operational amplifier op3. One end of the fourth resistor R4 is electrically connected to the positive input terminal of the third operational amplifier op3, one end of the fourth resistor R4 is electrically connected to one end of the fourth capacitor C4, and the other end of the fourth resistor R4 is electrically connected to the emitter of the first transistor Q1. The other end of the fourth capacitor C4 is grounded.

[0038] In this embodiment, by passing the voltage sampling signal output from the emitter of the first transistor Q1 through a filter structure composed of the fourth resistor R4 and the fourth capacitor C4, high-frequency noise can be filtered out before it is transmitted to the positive input terminal of the third operational amplifier op3. Then, by connecting the third capacitor C3 across the output terminal and the inverting input terminal of the third operational amplifier op3, the third operational amplifier op3 can provide a stable and oscillating DC bias voltage to the error feedback control sub-circuit.

[0039] The first inductor L1 and each capacitor required in this embodiment can be smaller than those required by large-volume LC filters or multi-phase schemes, which is beneficial for miniaturization and low cost of switching power supplies.

[0040] This embodiment provides a high-frequency ripple filtering device, including a housing, wherein a high-frequency ripple filtering circuit as described in any one of claims 1 to 6 is disposed within the housing; the housing includes a first input interface and a first output interface; wherein: The first input terminal of the ripple cancellation sub-circuit is electrically connected to the first input interface, and the other end of the first load Rload is electrically connected to the first output interface.

[0041] The high-frequency ripple filtering device provided in this embodiment is simple. In practical applications, it only needs to be connected to the first input terminal of the ripple cancellation sub-circuit through the first input interface and the other end of the first load Rload through the first output interface. Thus, the high-frequency ripple filtering device can separate the external mixed current in the frequency domain, separate the DC component and the AC ripple component in the frequency domain, and filter the AC ripple component at high frequency, so as to maintain the high efficiency of the switching power supply while filtering out high-frequency ripple noise.

[0042] Furthermore, the load sub-circuit includes a first load Rload and a first capacitor Cout, specifically: One end of the first load Rload is electrically connected to the first input terminal of the load sub-circuit and the first input terminal of the ripple cancellation sub-circuit. One end of the first load Rload is electrically connected to one end of the first inductor L1. One end of the first load Rload is electrically connected to one end of the first capacitor Cout. The other end of the first load Rload is electrically connected to the first input terminal of the error feedback control sub-circuit and the output terminal of the load sub-circuit. The other end of the first capacitor Cout is grounded.

[0043] In this embodiment, the DC component separated from the first inductor L1 is filtered by the first capacitor Cout, which can weaken instantaneous fluctuations to help stabilize the output voltage, thus improving the high-frequency ripple filtering effect in conjunction with the ripple cancellation sub-circuit. Then, the DC component can be converted into a current sampling signal that can be processed by the error feedback control sub-circuit for subsequent error calculation.

[0044] Furthermore, the error feedback control sub-circuit includes a first operational amplifier op1, a first resistor R1, a second capacitor C2, and a first sampling resistor Rs1, specifically as follows: The output terminal of the first operational amplifier op1 is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier op1 is electrically connected to one end of the first resistor R1. The inverting input terminal of the first operational amplifier op1 is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor R1 is electrically connected to one end of the second capacitor C2, and the other end of the first resistor R1 is grounded. The other end of the second capacitor C2 is electrically connected to one end of the first sampling resistor Rs1; One end of the first sampling resistor Rs1 is electrically connected to the other end of the first load Rload as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor Rs1 is grounded.

[0045] In this embodiment, the DC component flowing through the first load Rload is converted into a voltage sampling signal by the first sampling resistor Rs1 and transmitted to the second capacitor C2, providing the original signal for subsequent error calculation with the DC bias voltage. Next, the second capacitor C2 and the first resistor R1 form a high-pass filter structure, which isolates the DC component from the voltage sampling signal and separates the residual AC component signal, sending the residual AC component to the first operational amplifier op1. Then, the DC bias voltage is received at the inverting input terminal and the residual AC component signal is received at the non-inverting input terminal of the first operational amplifier op1. Error calculation is performed between the AC component signal and the DC bias voltage to obtain a first voltage control signal, which is then sent to the ripple cancellation sub-circuit, providing control basis for the ripple cancellation sub-circuit.

[0046] Furthermore, the ripple cancellation sub-circuit includes a second operational amplifier op2, a second resistor R2, a second sampling resistor Rs2, and a first transistor Q1, specifically: The positive input terminal of the second operational amplifier op2 is electrically connected to the output terminal of the first operational amplifier op1 as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier op2 is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier op2 is electrically connected to the emitter of the first transistor Q1. The output terminal of the second operational amplifier op2 is electrically connected to one end of the second resistor R2. The other end of the second resistor R2 is electrically connected to the base of the first transistor Q1; The emitter of the first transistor Q1 is electrically connected to one end of the second sampling resistor Rs2, and the collector of the first transistor Q1 is electrically connected to one end of the first inductor L1 as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor Rs2 is grounded.

[0047] In this embodiment, the first voltage control signal output by the first operational amplifier op1 is received at the non-inverting input terminal of the second operational amplifier op2, and the current sampling voltage fed back by the second sampling resistor Rs2 is received at the inverting input terminal of the second operational amplifier op2. This allows for calculation of the two input voltages, outputting a drive voltage to the second resistor R2. The second resistor R2 limits the current, protecting the base of the first transistor Q1 from overcurrent damage. Simultaneously, the conduction level of the first transistor Q1 is adjusted by the drive voltage to match the AC ripple component to be absorbed. Next, the AC ripple component output by the first inductor L1 is received at the collector of the first transistor Q1, and its conduction level is adjusted according to the base drive voltage to regulate the AC ripple absorption level. Simultaneously, the emitter of the first transistor Q1 outputs a compensation ripple current, which is converted into a voltage sampling signal by the second sampling resistor Rs2 and sent to the inverting input terminal of the second operational amplifier op2. This provides real-time feedback on the magnitude of the compensation ripple current, stabilizing the output amplitude of the compensation current.

[0048] To demonstrate that the high-frequency ripple filtering circuit provided in this embodiment can deeply filter out high-frequency ripple noise while maintaining the high efficiency of the switching power supply, the following embodiment is provided for illustration: Simulations of traditional switching power supplies and switching power supplies containing the high-frequency ripple filtering circuit provided in this embodiment yield the following results: Figure 3 The waveform comparison diagrams shown, from top to bottom, represent the switching power supply output ripple Vo1, the parallel active ripple compensation path current Iripple, and the output ripple voltage Vo. Figure 3 (a) shows the simulation results for a traditional switching power supply. Figure 3 (b) shows the simulation results of a switching power supply containing a high-frequency ripple filtering circuit provided in this embodiment. It can be seen that the average current of the parallel active ripple compensation path is about 0.4A, and the output voltage ripple is close to zero volts, thus achieving deep filtering of high-frequency ripple.

[0049] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A high-frequency ripple filtering circuit, characterized in that, It includes a first inductor, an error feedback control subcircuit, a DC bias subcircuit, a ripple cancellation subcircuit, and a load subcircuit, wherein: The first inductor is used to receive external mixed current and perform frequency domain separation on the received external mixed current to obtain AC ripple component and DC component; The load sub-circuit is used to transmit the DC component to the error feedback control sub-circuit; The DC bias sub-circuit is used to generate a DC bias voltage and transmit it to the error feedback control sub-circuit. The error feedback control sub-circuit is used to receive the DC component and the DC bias voltage, and to obtain the current sampling signal based on the DC component, so as to perform error calculation on the current sampling signal and the DC bias voltage to obtain the first voltage control signal and transmit it to the ripple cancellation sub-circuit. The ripple cancellation sub-circuit is used to receive the first voltage control signal and adjust the AC ripple absorption degree according to the first voltage control signal, so as to perform high-frequency ripple filtering on the AC ripple component based on the AC ripple absorption degree.

2. The high-frequency ripple filtering circuit according to claim 1, characterized in that, The load sub-circuit includes a first load and a first capacitor, specifically: One end of the first load is electrically connected to the first input terminal of the ripple cancellation sub-circuit as the input terminal of the load sub-circuit, one end of the first load is electrically connected to one end of the first inductor, one end of the first load is electrically connected to one end of the first capacitor, and the other end of the first load is electrically connected to the first input terminal of the error feedback control sub-circuit as the output terminal of the load sub-circuit. The other end of the first capacitor is grounded.

3. The high-frequency ripple filtering circuit according to claim 2, characterized in that, The error feedback control sub-circuit includes a first operational amplifier, a first resistor, a second capacitor, and a first sampling resistor, specifically: The output terminal of the first operational amplifier is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier is electrically connected to one end of the first resistor. The inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor is electrically connected to one end of the second capacitor, and the other end of the first resistor is grounded; The other end of the second capacitor is electrically connected to one end of the first sampling resistor; One end of the first sampling resistor is electrically connected to the other end of the first load as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor is grounded.

4. The high-frequency ripple filtering circuit according to claim 3, characterized in that, The ripple cancellation sub-circuit includes a second operational amplifier, a second resistor, a second sampling resistor, and a first transistor, specifically: The positive input terminal of the second operational amplifier is electrically connected to the output terminal of the first operational amplifier as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the emitter of the first transistor. The output terminal of the second operational amplifier is electrically connected to one end of the second resistor. The other end of the second resistor is electrically connected to the base of the first transistor; The emitter of the first transistor is electrically connected to one end of the second sampling resistor, and the collector of the first transistor is electrically connected to one end of the first inductor as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor is grounded.

5. The high-frequency ripple filtering circuit according to claim 4, characterized in that, The DC bias sub-circuit includes a third operational amplifier, a third resistor, and a reference voltage source, specifically: The output terminal of the third operational amplifier is electrically connected to the inverting input terminal of the first operational amplifier as the output terminal of the DC bias sub-circuit. The output terminal of the third operational amplifier is electrically connected to the inverting input terminal of the third operational amplifier. The non-inverting input terminal of the third operational amplifier is electrically connected to the emitter of the first transistor as the input terminal of the DC bias sub-circuit. The inverting input terminal of the third operational amplifier is electrically connected to one end of the third resistor. The other end of the third resistor is electrically connected to the positive terminal of the reference voltage source; The negative terminal of the reference voltage source is grounded.

6. The high-frequency ripple filtering circuit according to claim 5, characterized in that, The DC bias sub-circuit also includes a fourth resistor, a third capacitor, and a fourth capacitor, specifically: One end of the third capacitor is electrically connected to the output terminal of the third operational amplifier, and the other end of the third capacitor is electrically connected to the inverting input terminal of the third operational amplifier. One end of the fourth resistor is electrically connected to the positive input terminal of the third operational amplifier, one end of the fourth resistor is electrically connected to one end of the fourth capacitor, and the other end of the fourth resistor is electrically connected to the emitter of the first transistor. The other end of the fourth capacitor is grounded.

7. A high-frequency ripple filtering device, characterized in that, The device includes a housing, within which a high-frequency ripple filtering circuit as described in any one of claims 1 to 6 is disposed; the housing includes a first input interface and a first output interface; wherein: The first input terminal of the ripple cancellation sub-circuit is electrically connected to the first input interface, and the other end of the first load is electrically connected to the first output interface.

8. The high-frequency ripple filtering device according to claim 7, characterized in that, The load sub-circuit includes a first load and a first capacitor, specifically: One end of the first load is electrically connected to the first input terminal of the ripple cancellation sub-circuit as the input terminal of the load sub-circuit, one end of the first load is electrically connected to one end of the first inductor, one end of the first load is electrically connected to one end of the first capacitor, and the other end of the first load is electrically connected to the first input terminal of the error feedback control sub-circuit as the output terminal of the load sub-circuit. The other end of the first capacitor is grounded.

9. A high-frequency ripple filtering device according to claim 8, characterized in that, The error feedback control sub-circuit includes a first operational amplifier, a first resistor, a second capacitor, and a first sampling resistor, specifically: The output terminal of the first operational amplifier is electrically connected to the second input terminal of the ripple cancellation sub-circuit as the output terminal of the error feedback control sub-circuit. The non-inverting input terminal of the first operational amplifier is electrically connected to one end of the first resistor. The inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the DC bias sub-circuit as the second input terminal of the error feedback control sub-circuit. One end of the first resistor is electrically connected to one end of the second capacitor, and the other end of the first resistor is grounded; The other end of the second capacitor is electrically connected to one end of the first sampling resistor; One end of the first sampling resistor is electrically connected to the other end of the first load as the first input terminal of the error feedback control sub-circuit, and the other end of the first sampling resistor is grounded.

10. A high-frequency ripple filtering device according to claim 9, characterized in that, The ripple cancellation sub-circuit includes a second operational amplifier, a second resistor, a second sampling resistor, and a first transistor, specifically: The positive input terminal of the second operational amplifier is electrically connected to the output terminal of the first operational amplifier as the second input terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the input terminal of the DC bias sub-circuit as the first output terminal of the ripple cancellation sub-circuit. The negative input terminal of the second operational amplifier is electrically connected to the emitter of the first transistor. The output terminal of the second operational amplifier is electrically connected to one end of the second resistor. The other end of the second resistor is electrically connected to the base of the first transistor; The emitter of the first transistor is electrically connected to one end of the second sampling resistor, and the collector of the first transistor is electrically connected to one end of the first inductor as the first input terminal of the ripple cancellation sub-circuit. The other end of the second sampling resistor is grounded.

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