CN118137808A - Filter circuit, filter and switching power supply - Google Patents
Filter circuit, filter and switching power supply Download PDFInfo
- Publication number
- CN118137808A CN118137808A CN202211537069.9A CN202211537069A CN118137808A CN 118137808 A CN118137808 A CN 118137808A CN 202211537069 A CN202211537069 A CN 202211537069A CN 118137808 A CN118137808 A CN 118137808A
- Authority
- CN
- China
- Prior art keywords
- resistor
- transconductance amplifier
- output
- operational amplifier
- filter circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 21
- 239000002131 composite material Substances 0.000 claims description 6
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 238000001914 filtration Methods 0.000 abstract description 25
- 230000000694 effects Effects 0.000 abstract description 14
- 238000005070 sampling Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 8
- 230000003321 amplification Effects 0.000 description 5
- 238000003199 nucleic acid amplification method Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 230000001629 suppression Effects 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Landscapes
- Networks Using Active Elements (AREA)
Abstract
The invention discloses a filter circuit, a filter and a switching power supply, wherein the filter circuit comprises an inductor L1, a capacitor C2, a resistor R2 and a transconductance amplifier, one end of the inductor L1 is an input end, the other end of the inductor L1, one end of the capacitor C2 and a first output end of the transconductance amplifier are connected to form an output end, the other end of the capacitor C2 is connected with one end of the resistor R2 and the first input end of the transconductance amplifier, and the other end of the resistor R2, a second input end of the transconductance amplifier and a second output end of the transconductance amplifier are connected to form a grounding end; when differential mode current flows from the input terminal into the inductor L1, the transconductance amplifier converts the differential voltage across the resistor R2 into a current flowing from the first output terminal of the transconductance amplifier to the second output terminal thereof. Compared with the traditional voltage sampling current feedback filtering scheme, the filtering effect of the invention is better; compared with the traditional passive filtering scheme, the invention has better filtering effect on the differential mode noise under the condition of the same differential mode inductance; compared with the existing mixed filtering scheme, the method has smaller loss.
Description
Technical Field
The present invention relates to the field of EMI filtering technologies, and in particular, to a filtering circuit, a filter, and a switching power supply.
Background
In recent years, switching power supplies and other power electronic devices are being developed toward higher frequencies, miniaturization and higher power densities, and with the popularization and application of unmanned technologies, electric vehicles and other precision electronic products, there is a trend to make higher demands on EMI filters in order to ensure the reliability of these technologies and products. The limitation of the volume and the weight of the passive filter circuit is not suitable for the current development trend. The hybrid filter circuit has the advantages of small volume, convenient integration and good dynamic characteristics due to the adoption of an active cancellation technology, and is widely paid attention to.
The traditional voltage sampling current feedback filtering scheme is limited by smaller internal resistance of a differential mode noise source and smaller output current of an operational amplifier, and has poor filtering effect on the differential mode noise.
MichaelBriere in patent No. US006898092B2, EMIFILTERCIRCUIT, a schematic circuit diagram for suppressing differential mode noise is provided as shown in fig. 1. Wherein terminals 228, 229 are connected to the power use terminal, and terminals 227, 228 are connected to the power supply terminal, from which differential mode current flows to the power use terminal.
The working principle of the patent EMIFILTERCIRCUIT for suppressing differential mode noise is to suppress differential mode current by increasing (decreasing) the on-resistance Rds of the switching tube X1, i.e. increasing (decreasing) the differential mode loop impedance, when the differential mode current increases (decreases). The hybrid filtering scheme of the patent, however, has a switching tube on-resistance Rds in series in the power loop, which will lead to increased filter losses.
Disclosure of Invention
In view of the above, the invention and the technical problem solved by the invention are to provide a filter circuit, a filter and a switching power supply, which can reduce the differential mode interference caused by a power utilization end to a power supply end and have lower loss.
As a first aspect of the present invention, an embodiment of a filter circuit is provided as follows:
The filter circuit is used for suppressing differential mode noise and comprises an inductor L1, a capacitor C2, a resistor R2, a transconductance amplifier, an input end, an output end and a grounding end, wherein one end of the inductor L1 is the input end and is used for being connected with one end of a power utilization end, the other end of the inductor L1, one end of the capacitor C2 and a first output end of the transconductance amplifier are connected together and then are used for being connected with one end of a power supply end, the other end of the capacitor C2 is simultaneously connected with one end of the resistor R2 and the first input end of the transconductance amplifier, and the other end of the resistor R2, a second input end of the transconductance amplifier and a second output end of the transconductance amplifier are connected together and then are used for being connected with the other end of the power supply end and the other end of the power utilization end; the transconductance amplifier is configured to convert a differential voltage across the resistor R2 into a current flowing from the first output terminal of the transconductance amplifier to the second output terminal of the transconductance amplifier when a differential mode current flows from the input terminal into the inductor L1.
Further, the current magnitude is equal to the differential mode current magnitude.
As a specific embodiment of the transconductance amplifier, it includes: resistor R1, resistor R7, resistor R5, resistor R10, operational amplifier X1, triode Q1, resistor R3 and resistor R4; the first input end of the transconductance amplifier is arranged at one end of the resistor R1, the other end of the resistor R1 is simultaneously connected with one end of the resistor R7 and the in-phase input end of the operational amplifier X1, the other end of the resistor R7 is used for inputting a power supply voltage, one end of the resistor R5 is simultaneously connected with one end of the resistor R10 and the opposite-phase input end of the operational amplifier X1, the other end of the resistor R5 is the second input end of the transconductance amplifier, the output end of the operational amplifier X1 is connected with the base electrode of the triode Q1, the collector electrode of the triode Q1 is connected with one end of the resistor R4, the other end of the resistor R4 is the first output end of the transconductance amplifier, the emitter electrode of the triode Q1 is simultaneously connected with the other end of the resistor R10 and one end of the resistor R3, and the other end of the resistor R3 is the second output end of the transconductance amplifier.
Further, the triode Q1 is a composite NPN triode composed of two NPN triodes or a composite NPN triode composed of an NPN triode and a PNP triode.
Further, the transconductance amplifier further comprises a resistor R8, a resistor 10 and an operational amplifier X2, the output end of the operational amplifier X1 is connected with the in-phase input end of the operational amplifier X2, one end of the resistor R8 is simultaneously connected with one end of the resistor R10 and the inverting input end of the operational amplifier X2, the other end of the resistor R8 is connected with the second input end of the transconductance amplifier, the other end of the resistor R10 is connected with the emitter of the triode Q1, and the output end of the operational amplifier X2 is connected with the base of the triode Q1.
As another specific embodiment of the transconductance amplifier, the method includes: resistor R1, resistor R7, resistor R5, resistor R10, operational amplifier X1 and resistor R4; the one end of resistance R1 is the second input of transconductance amplifier, the resistance R1 other end is connected simultaneously resistance R7 one end with operational amplifier X1's homophase input, the resistance R7 other end is used for the input power supply voltage, resistance R5 one end is connected simultaneously resistance R10 one end with operational amplifier X1's inverting input, the resistance R5 other end is transconductance amplifier's first input, operational amplifier X1's output the resistance R10 other end is connected resistance R4 one end, resistance R4 other end coupling is the first output of transconductance amplifier, operational amplifier X1's power supply ground is transconductance amplifier's second output.
Further, the transconductance amplifier further includes: the output end of the transconductance amplifier is connected with the capacitor C1, one end of the resistor R4 is connected with the second output end of the transconductance amplifier after passing through the resistor R3, and the other end of the resistor R4 is connected with the first output end of the transconductance amplifier after passing through the capacitor C1.
Further, the transconductance amplifier further includes: the output end of the operational amplifier X1 is connected with the non-inverting input end of the operational amplifier X2, one end of the resistor R6 is simultaneously connected with one end of the resistor R13 and the inverting input end of the operational amplifier X2, the other end of the resistor R6 is connected with the second input end of the transconductance amplifier, and the other end of the resistor R13 and the output end of the operational amplifier X2 are simultaneously connected with one end of the resistor R4.
As a second aspect of the present invention, an embodiment of a filter is provided as follows:
A filter comprising an embodiment of the filter circuit as claimed in any one of the above first aspects.
As a third aspect of the present invention, an embodiment of a switching power supply is provided as follows:
The embodiment of the filter circuit provided in the first aspect is further included in the switching power supply, wherein an output end of the output circuit is connected to an output end of the filter circuit, an input end of the filter circuit is an output end of the switching power supply, and a ground end of the output circuit and a ground end of the filter circuit are connected together and then are output grounds of the switching power supply.
The beneficial effects of the invention are as follows:
1. Compared with the scheme that the traditional passive filter only adopts a passive device to filter the differential mode noise, the filtering effect of the invention on the differential mode noise is better under the condition that the differential mode inductance is the same; under the condition of the same filtering effect, the differential mode inductance is smaller in volume;
2. For Gao Pincha mode noise, even if the differential mode inductance is reduced, the filter circuit of the embodiment of the invention has a strong inhibition effect on the differential mode noise, and compared with the scheme that the traditional passive filter only adopts a passive device to filter the differential mode noise, the filter circuit of the embodiment of the invention has a better inhibition effect on high-frequency differential mode noise under the condition that the differential mode inductance is the same as the frequency characteristic;
3. For the case of smaller differential mode noise source impedance, the filter circuit of the embodiment of the invention increases the differential mode noise source impedance through inductance equivalence, and compared with the scheme that the traditional voltage sampling current feedback filter scheme is limited by smaller differential mode noise source impedance, the filter effect of the invention is better;
4. for the case of larger differential mode noise, the filter circuit amplifies feedback current through the triode, and compared with the scheme that the traditional voltage sampling current feedback filter scheme is limited by the maximum output current of the operational amplifier, the filter circuit has wider suppression range of the differential mode noise and better filter effect;
5. According to the filter circuit provided by the embodiment of the invention, differential mode noise is suppressed by injecting feedback current which counteracts differential mode current, and compared with the scheme that the existing mixed filter scheme is changed by connecting resistors in series on a power loop, the filter circuit is smaller in loss.
Drawings
FIG. 1 is a schematic circuit diagram of a prior art hybrid filter scheme;
FIG. 2 is a schematic diagram of a filter circuit according to a first embodiment of the present invention;
FIG. 3 provides a schematic diagram of a transconductance amplifier circuit constructed from a single stage amplifier based on FIG. 2;
FIG. 4 is a schematic diagram of a transconductance amplifier circuit constructed from two stages of amplifiers provided in accordance with FIG. 2;
FIG. 5 is a schematic diagram of an equivalent alternative to the circuit of FIG. 3;
Fig. 6 is a schematic diagram of a transconductance amplifier circuit formed from two stages of amplifiers provided in accordance with fig. 5.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present application can be understood in detail, a more particular description of the application, briefly summarized below, may be had by reference to embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "comprising" and "having," and any variations thereof, as described in the specification and claims of the present application are intended to cover a non-exclusive inclusion, for example, comprising a series of elements or unit circuits that are not necessarily limited to those elements or unit circuits explicitly listed, but may include elements or unit circuits that are not explicitly listed or inherent to such circuits.
In addition, the embodiments of the present application and the features in the embodiments may be combined with each other without collision.
It should be understood that, in the description and in the claims, when an element is described as being "connected/coupled" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.
First embodiment
Referring to fig. 1, the filter circuit 101 is a hybrid filter circuit, and includes an LCR passive filter circuit formed by serially connecting a differential-mode inductor L1, a capacitor C2 and a resistor R2, and a transconductance amplifier G1.
The filter circuit 101 includes three ports, i.e., an input terminal, an output terminal, and a ground terminal, the input terminal and the ground terminal being connected to the power consumption terminal U1, and the output terminal and the ground terminal being connected to the power supply terminal U2.
The input end of the filter circuit 101 is connected with one end of a differential mode inductor L1, the other end of the differential mode inductor L1 is connected with one end of a capacitor C2, the output end of the filter circuit 101 and a first output end C of a transconductance amplifier G1, the other end of the capacitor C2 is connected with one end of a resistor R2 and a first input end a of the transconductance amplifier G1, and the other end of the resistor R2 is connected with the grounding end of the filter circuit 101, a second input end b of the transconductance amplifier G1 and a second output end d of the transconductance amplifier G1.
The filter circuit 101 in fig. 2 operates as follows:
When differential mode current I DM flows through the loop of differential mode inductance L1, capacitor C2 and resistor R2, differential voltage uab is generated at two ends of sampling resistor R2, and after the differential voltage uab is converted into current I by the transconductance amplifier, the current I flows from the first output end of the transconductance amplifier to the second output end, i.e. is injected back to the other end of differential mode inductance L1, the current I and differential mode current I DM cancel each other, so that the differential mode current is prevented from flowing into the output end of filter circuit 101, i.e. the influence of differential mode noise on the power supply end through the power utilization end is prevented.
The filtering circuit of fig. 2 adopts an active device transconductance amplifier, so that most of differential mode noise can be filtered, and compared with the scheme that the traditional passive filter only adopts a passive device to filter the differential mode noise, the filtering effect of the filtering circuit of fig. 2 on the differential mode noise is better under the condition that the differential mode inductance is the same; under the condition of the same filtering effect, the differential mode inductance of the filtering circuit of the figure 2 is smaller; for high-frequency differential mode noise, even if the differential mode inductance is reduced, the filter circuit of fig. 2 has a strong suppression effect on the differential mode noise, and compared with the scheme that the traditional passive filter only adopts a passive device to filter the differential mode noise, the filter circuit of fig. 2 has a better suppression effect on Gao Pincha mode noise under the condition that the differential mode inductance is the same as the frequency characteristic; in addition, for the case of smaller differential mode noise source impedance, the filtering circuit of fig. 2 increases the differential mode noise source impedance through inductance equivalent, and compared with the traditional voltage sampling current feedback filtering scheme limited by the smaller differential mode noise source impedance, the filtering effect of the invention is better. Finally, the filter circuit of fig. 2, in which differential mode noise is suppressed by injecting feedback currents that cancel the differential mode currents, has less loss than prior hybrid filter schemes by varying the series resistance across the power loop.
Further, through parameter design, when the current I is equal to the differential mode current I DM, the best effect of suppressing differential mode noise can be obtained.
The voltage gain from the input to the output of the filter circuit 101 is-20 lgl 1+j2pi fLG, where lg represents a logarithmic function, f represents the voltage frequency of the input u1, L represents the inductance of the differential-mode inductor L1, and G represents the amplification factor of the transconductance amplifier G1. As can be seen from the voltage gain expression from the input end to the output end of the filter circuit 101, the filter circuit 101 is a low-pass filter, the turning frequency is 1/2 pi LG, and when the voltage frequency of the input end of the filter circuit 101 is smaller than the turning frequency, the filter circuit 101 does not attenuate the voltage of the input end; when the voltage frequency of the input end of the filter circuit 101 is larger than the turning frequency, the voltage change speed of the filter circuit 101 to the input end is-20 dB/dec.
Wherein the transconductance amplifier G1 functions to convert a differential voltage uab between its first input a and its second input b into a current flowing from its first output c to its second output d. There are various implementations of the transconductance amplifier G1.
Fig. 3 provides a schematic diagram of a transconductance amplifier circuit formed by a single-stage amplifier based on fig. 2, please refer to fig. 3, in which the transconductance amplifier G1 includes a transconductance amplifier circuit 102. The transconductance amplifier circuit 102 includes a dc power supply VCC, a dc bias circuit, an operational amplifier circuit, and a common collector triode amplifier circuit. The direct current bias circuit comprises a resistor R1 and a resistor R7, wherein the resistor R1 is connected in series with the resistor R7 and is used for providing a proper static working point for an operational amplifier X1 in the operational amplifier circuit; the operational amplifier circuit comprises an operational amplifier X1, a feedback resistor R10 and a feedback resistor R5; the common collector triode amplifying circuit comprises a triode Q1, a resistor R3 and a resistor R4.
One end of the resistor R1 is a first input end a of the transconductance amplifier, the other end of the resistor R1 is simultaneously connected with one end of the resistor R7 and the in-phase input end of the operational amplifier X1, the other end of the resistor R7 is used for inputting a power supply voltage VCC, one end of the resistor R5 is simultaneously connected with one end of the resistor R10 and the opposite-phase input end of the operational amplifier X1, the other end of the resistor R5 is a second input end b of the transconductance amplifier, the output end of the operational amplifier X1 is connected with the base electrode of the triode Q1, the collector electrode of the triode Q1 is connected with one end of the resistor R4, the other end of the resistor R4 is a first output end c of the transconductance amplifier, the emitter electrode of the triode Q1 is simultaneously connected with the other end of the resistor R10 and one end of the resistor R3, and the other end of the resistor R3 is a second output end d of the transconductance amplifier.
The transconductance amplifier circuit 102 of fig. 3 operates as follows:
The direct current power supply VCC, the resistor R1 and the resistor R7 form a direct current bias circuit to provide proper static working points for the operational amplifier X1 and the triode Q1, the static working voltage of the non-inverting input end of the operational amplifier X1 is VCC R1/(R1+R7), and the static working voltage of the output end of the operational amplifier X1 is VCC (1+R10/R5)/(R1+R7); the triode Q1, the resistor R3 and the resistor R4 form a triode amplifying circuit, and for high-frequency signals, the amplifying factor is (1+beta) R3/((1+beta) R3+ rbe) approximately equal to 1, wherein the codes of the resistors represent the resistance values of the corresponding resistors, rbe represents the equivalent resistance between the base electrode and the emitter electrode in the triode small signal amplifying circuit, and beta represents the amplifying factor of the triode; the operational amplifier X1, the resistor R10 and the resistor R5 form an in-phase proportional operational amplifier circuit, and the voltage amplification factor is 1+R5/R10; from this, the amplification factor G of the transconductance amplifier G1 is (r10+r5)/(r3×r10).
Further, the triode Q1 is a composite NPN triode composed of two NPN triodes or a composite NPN triode composed of the NPN triode and the PNP triode, so that the current amplifying capability of the triode Q1 is enhanced.
For the case of large differential mode noise, the feedback current is amplified by the filter circuit in the figure 3 through the triode, and compared with the scheme that the traditional voltage sampling current feedback filter scheme is limited by the maximum output current of the operational amplifier, the differential mode noise suppression range is wider, and the filter effect is better.
In order to reduce the bandwidth requirement of the operational amplifier X1 by the transconductance amplifier circuit 102, the transconductance amplifier in fig. 3 may further use two stages of operational amplifiers to form the transconductance amplifier circuit 103, at this time, the transconductance amplifier circuit 103 further includes a resistor R8, a resistor 10 and an operational amplifier X2 on the basis of the transconductance amplifier circuit 102 in fig. 3, the output end of the operational amplifier X1 is connected to the in-phase input end of the operational amplifier X2, one end of the resistor R8 is simultaneously connected to one end of the resistor R10 and the inverting input end of the operational amplifier X2, the other end of the resistor R8 is connected to the second input end of the transconductance amplifier, the other end of the resistor R10 is connected to the emitter of the triode Q1, and the output end of the operational amplifier X2 is connected to the base of the triode Q1.
The transconductance amplifying circuit 103 formed by two-stage operational amplifiers is based on a transconductance amplifying circuit formed by single-stage operational amplifiers, the single-stage operational amplifier X1 is decomposed into two operational amplifiers which are connected in series, and under the condition that the amplification factor of the transconductance amplifier G1 is unchanged, the amplification factor of a single operational amplifier is reduced, so that the bandwidth of the single operational amplifier is increased.
For the circuit of fig. 3, an equivalent alternative circuit is provided fig. 3 please refer to fig. 5, wherein the transconductance amplifier comprises: resistor R1, resistor R7, resistor R5, resistor R10, operational amplifier X1 and resistor R4; one end of the resistor R1 is a second input end of the transconductance amplifier, the other end of the resistor R1 is simultaneously connected with one end of the resistor R7 and the in-phase input end of the operational amplifier X1, the other end of the resistor R7 is used for inputting power supply voltage, one end of the resistor R5 is simultaneously connected with one end of the resistor R10 and the anti-phase input end of the operational amplifier X1, the other end of the resistor R5 is a first input end of the transconductance amplifier, the other end of the resistor R10 is connected with one end of the resistor R4, the other end of the resistor R4 is coupled with the first output end of the transconductance amplifier, and the power supply ground end of the operational amplifier X1 is a second output end of the transconductance amplifier.
Further, the transconductance amplifier further comprises a capacitor C1 and a resistor R3, one end of the resistor R4 is connected with the second output end d of the transconductance amplifier after passing through the resistor R3, and the other end of the resistor R4 is connected with the first output end C of the transconductance amplifier after passing through the capacitor C1.
In fig. 5, the capacitor C1 and the resistor R3 are optional components, the capacitor C1 is used for isolating direct current, reducing the power consumption of the filter, and the resistor R3 is used for accelerating the response speed of the filter to noise.
The circuit of fig. 5 can be similarly modified to use two-stage op-amp to form the transconductance amplifier circuit 103, and please refer to fig. 6 at this time, the transconductance amplifier further includes a resistor R6, a resistor R13, and an op-amp X2, the output end of the op-amp X1 is connected to the in-phase input end of the op-amp X2, one end of the resistor R6 is simultaneously connected to one end of the resistor R13 and the inverting input end of the op-amp X2, the other end of the resistor R6 is connected to the second input end of the transconductance amplifier, and the other end of the resistor R13 and the output end of the op-amp X2 are simultaneously connected to one end of the resistor R4.
Second embodiment
The present embodiment provides a filter, including an embodiment of any one of the filtering circuits provided in the first embodiment.
Third embodiment
The embodiment provides a switching power supply, which comprises an output circuit, and further comprises any one of the embodiments of the filtering circuit provided by the first embodiment, wherein an output end of the output circuit is connected with an output end of the filtering circuit, an input end of the filtering circuit is an output end of the switching power supply, and a grounding end of the output circuit and a grounding end of the filtering circuit are connected together to form an output ground of the switching power supply.
The above embodiments are only for aiding in understanding the inventive concept and are not intended to limit the invention, and any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. A filter circuit for suppressing differential mode noise, characterized by: the filter circuit comprises an inductor L1, a capacitor C2, a resistor R2, a transconductance amplifier, an input end, an output end and a grounding end, wherein one end of the inductor L1 is the input end and is used for being connected with one end of a power utilization end, the other end of the inductor L1, one end of the capacitor C2 and the first output end of the transconductance amplifier are connected together and then are the output end and are used for being connected with one end of a power supply end, the other end of the capacitor C2 is simultaneously connected with one end of the resistor R2 and the first input end of the transconductance amplifier, and the other end of the resistor R2, the second input end of the transconductance amplifier and the second output end of the transconductance amplifier are connected together and then are the grounding end and are used for being simultaneously connected with the other end of the power supply end and the other end of the power utilization end; the transconductance amplifier is configured to convert a differential voltage across the resistor R2 into a current flowing from the first output terminal of the transconductance amplifier to the second output terminal of the transconductance amplifier when a differential mode current flows from the input terminal into the inductor L1.
2. The filter circuit of claim 1, wherein: the current magnitude is equal to the differential mode current magnitude.
3. The filter circuit of claim 1, wherein the transconductance amplifier comprises: resistor R1, resistor R7, resistor R5, resistor R10, operational amplifier X1, triode Q1, resistor R3 and resistor R4; the first input end of the transconductance amplifier is arranged at one end of the resistor R1, the other end of the resistor R1 is simultaneously connected with one end of the resistor R7 and the in-phase input end of the operational amplifier X1, the other end of the resistor R7 is used for inputting a power supply voltage, one end of the resistor R5 is simultaneously connected with one end of the resistor R10 and the opposite-phase input end of the operational amplifier X1, the other end of the resistor R5 is the second input end of the transconductance amplifier, the output end of the operational amplifier X1 is connected with the base electrode of the triode Q1, the collector electrode of the triode Q1 is connected with one end of the resistor R4, the other end of the resistor R4 is the first output end of the transconductance amplifier, the emitter electrode of the triode Q1 is simultaneously connected with the other end of the resistor R10 and one end of the resistor R3, and the other end of the resistor R3 is the second output end of the transconductance amplifier.
4. A filter circuit according to claim 3, wherein: the triode Q1 is a composite NPN triode composed of two NPN triodes or a composite NPN triode composed of an NPN triode and a PNP triode.
5. The filter circuit of claim 3 or 4, wherein the transconductance amplifier further comprises a resistor R8, a resistor R10 and an operational amplifier X2, wherein an output end of the operational amplifier X1 is connected to a non-inverting input end of the operational amplifier X2, one end of the resistor R8 is simultaneously connected to one end of the resistor R10 and an inverting input end of the operational amplifier X2, the other end of the resistor R8 is connected to a second input end of the transconductance amplifier, the other end of the resistor R10 is connected to an emitter of the triode Q1, and an output end of the operational amplifier X2 is connected to a base of the triode Q1.
6. The filter circuit of claim 1, wherein the transconductance amplifier comprises: resistor R1, resistor R7, resistor R5, resistor R10, operational amplifier X1 and resistor R4; the one end of resistance R1 is the second input of transconductance amplifier, the resistance R1 other end is connected simultaneously resistance R7 one end with operational amplifier X1's homophase input, the resistance R7 other end is used for the input power supply voltage, resistance R5 one end is connected simultaneously resistance R10 one end with operational amplifier X1's inverting input, the resistance R5 other end is transconductance amplifier's first input, operational amplifier X1's output the resistance R10 other end is connected resistance R4 one end, resistance R4 other end coupling is the first output of transconductance amplifier, operational amplifier X1's power supply ground is transconductance amplifier's second output.
7. The filter circuit of claim 6, wherein the transconductance amplifier further comprises: the output end of the transconductance amplifier is connected with the capacitor C1, one end of the resistor R4 is connected with the second output end of the transconductance amplifier after passing through the resistor R3, and the other end of the resistor R4 is connected with the first output end of the transconductance amplifier after passing through the capacitor C1.
8. The filter circuit of claim 6 or 7, wherein the transconductance amplifier further comprises: the output end of the operational amplifier X1 is connected with the non-inverting input end of the operational amplifier X2, one end of the resistor R6 is simultaneously connected with one end of the resistor R13 and the inverting input end of the operational amplifier X2, the other end of the resistor R6 is connected with the second input end of the transconductance amplifier, and the other end of the resistor R13 and the output end of the operational amplifier X2 are simultaneously connected with one end of the resistor R4.
9. A filter, characterized by: comprising a filter circuit according to any of claims 1 to 8.
10. A switching power supply comprising an output circuit, characterized in that: the filter circuit of any one of claims 1 to 8, wherein the output end of the output circuit is connected with the output end of the filter circuit, the input end of the filter circuit is the output end of the switching power supply, and the grounding end of the output circuit and the grounding end of the filter circuit are connected together to be the output ground of the switching power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211537069.9A CN118137808A (en) | 2022-12-01 | 2022-12-01 | Filter circuit, filter and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211537069.9A CN118137808A (en) | 2022-12-01 | 2022-12-01 | Filter circuit, filter and switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118137808A true CN118137808A (en) | 2024-06-04 |
Family
ID=91238273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211537069.9A Pending CN118137808A (en) | 2022-12-01 | 2022-12-01 | Filter circuit, filter and switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118137808A (en) |
-
2022
- 2022-12-01 CN CN202211537069.9A patent/CN118137808A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11984859B2 (en) | Chopper amplifying circuit employing negative impedance compensation technique | |
| US6472925B1 (en) | Mixer circuit with negative feedback filtering | |
| CN101978600B (en) | Capacitance multiplier circuit | |
| US6515542B1 (en) | Differential intermediate frequency (IF) amplifier with narrow band noise dithering for driving high speed analog-to-digital conversion and communication applications | |
| CN104662795B (en) | Microwave amplifier | |
| US8803595B2 (en) | Common mode noise cancellation circuit for unbalanced signals | |
| US7880536B2 (en) | Simplified sallen-key low-pass filter circuit | |
| EP0595561A1 (en) | Amplifiers | |
| CN116232241A (en) | Instrument amplifying circuit and current monitor | |
| CN118137808A (en) | Filter circuit, filter and switching power supply | |
| US6208205B1 (en) | Amplifier circuit and method for reducing noise therein | |
| JPH07307625A (en) | Unbalance/balance conversion circuit | |
| CN112165311A (en) | Active EMI filter and system connected to ground loop of power electronic converter system | |
| CN218850735U (en) | Integrated amplifying circuit of audio signal and terminal equipment | |
| CN110662128A (en) | Microphone signal amplification system for active noise reduction | |
| CN111162742A (en) | Signal processing system for inhibiting signal interference of motor vehicle detection device | |
| CN217335565U (en) | Power supply filter circuit for voltage-controlled oscillator and communication equipment | |
| CN113572436B (en) | Bias circuit for power amplifier and power amplifier | |
| CN215581070U (en) | Bias circuit board | |
| CN114944830B (en) | Filter circuit | |
| EP1176711A2 (en) | Apparatus and method for electrical signal amplification | |
| GB2272812A (en) | Active filter capable of effectively eliminating common mode noise component | |
| CN218162406U (en) | High-performance operational amplifier replacement circuit for audio | |
| JP3300301B2 (en) | Low pass filter | |
| JP3485452B2 (en) | Filtering amplifier |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication |