Hierarchical filter circuit, filter and electronic equipment
By designing a hierarchical filtering circuit including switches and multiple filtering elements, the problem of difficult to meet complex and variable filtering needs in the prior art is solved, and the satisfaction of multiple filtering needs and cost reduction is achieved.
Patent Information
- Application Number
- CN202422056193.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-23
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2034-08-23
AI Technical Summary
Existing hierarchical filtering circuits are difficult to meet the complex and variable filtering needs, resulting in the need to set up multiple different circuits, which is costly and cumbersome.
A hierarchical filtering circuit is designed, including a first resistor, a first switch, a second switch, a first capacitor, a second capacitor, a first inductor, a second inductor and a signal amplification circuit. The combination of a variety of filtering circuits is realized through the control of the switch to meet the filtering requirements of different frequencies and levels.
This design can meet multiple filtering needs through a hierarchical filtering circuit, reduces setup costs, improves signal quality and accuracy, and solves the problem that the hierarchical filtering circuit is difficult to meet complex filtering needs.
Smart Images
Figure CN223024388U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of filtering, and particularly relates to a hierarchical filtering circuit, a filter and an electronic device. Background Art
[0002] A hierarchical filtering circuit refers to a circuit that utilizes the frequency selection function of a filtering circuit, that is, allows signals within a specific frequency range to pass through, blocks or attenuates other frequency components, so as to achieve the purpose of screening the signal frequency.
[0003] Currently, a hierarchical filtering circuit can only process an input signal into a signal output with a single characteristic. When there are different filtering requirements, different circuits need to be set separately to meet different filtering requirements, which is costly and cumbersome. Summary of the Utility Model
[0004] In view of this, the purpose of this application is to provide a hierarchical filtering circuit, a filter and an electronic device, which can meet different filtering requirements through a single hierarchical filtering circuit, and solves the problem that it is difficult for a hierarchical filtering circuit to meet complex and variable filtering requirements.
[0005] To achieve the above purpose, the following solutions are disclosed:
[0006] In a first aspect, this application provides a hierarchical filtering circuit, including: a first resistor, a first switch, a second switch, a first capacitor, a second capacitor, a first inductor, a second inductor, and a signal amplification circuit;
[0007] The first end of the first resistor serves as the input end of the hierarchical filtering circuit, and the second end of the first resistor is connected to the common end of the first switch;
[0008] The first end of the first switch is connected to the first end of the second switch, the second end of the first inductor, the first end of the second inductor, and the first end of the first capacitor;
[0009] The second end of the first switch is connected to the first end of the first inductor;
[0010] The second end of the second switch is connected to the second end of the second inductor and the first end of the second capacitor;
[0011] The second end of the first capacitor is connected to the second end of the second capacitor and grounded;
[0012] The common end of the second switch is connected to the first end of the signal amplification circuit, and the second end of the signal amplification circuit serves as the output end of the hierarchical filtering circuit.
[0013] Optionally, the signal amplification circuit includes: a second resistor, a third resistor, and an operational amplifier;
[0014] The common terminal of the second switch is connected to the first end of the signal amplification circuit, and the second end of the signal amplification circuit serves as the output end of the hierarchical filtering circuit, including: the common terminal of the second switch is connected to the non-inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier serves as the output end of the hierarchical filtering circuit;
[0015] The inverting input terminal of the operational amplifier is connected to the second end of the second resistor and the first end of the third resistor;
[0016] The output terminal of the operational amplifier is connected to the second end of the third resistor;
[0017] The first end of the second resistor is grounded.
[0018] Optionally, when the first switch connects the common terminal of the first switch to the first end of the first switch and the second switch connects the common terminal of the second switch to the first end of the second switch, the second inductor, the first capacitor, and the second capacitor form a first filtering circuit.
[0019] Optionally, when the first switch connects the common terminal of the first switch to the second end of the first switch and the second switch connects the common terminal of the second switch to the first end of the second switch, the first inductor, the second inductor, the first capacitor, and the second capacitor form a second filtering circuit.
[0020] Optionally, when the first switch connects the common terminal of the first switch to the first end of the first switch and the second switch connects the common terminal of the second switch to the second end of the second switch, the second inductor, the first capacitor, and the second capacitor form a third filtering circuit.
[0021] Optionally, when the first switch connects the common terminal of the first switch to the second end of the first switch and the second switch connects the common terminal of the second switch to the second end of the second switch, the first inductor, the second inductor, the first capacitor, and the second capacitor form a fourth filtering circuit.
[0022] Optionally, the amplification factor of the signal amplification circuit is the same as the ratio between the third resistor and the second resistor.
[0023] Optionally, the capacitance of the first capacitor is equal to the capacitance of the second capacitor.
[0024] In a second aspect, the present application further provides a filter, and the filter includes the filtering circuit provided in the first aspect.
[0025] In a third aspect, an electronic device provided by the present application includes a filter as provided in the second aspect.
[0026] A hierarchical filtering circuit, a filter, and an electronic device provided by the present utility model. The hierarchical filtering circuit includes: a first resistor, a first switch, a second switch, a first capacitor, a second capacitor, a first inductor, a second inductor, and a signal amplification circuit; a first end of the first resistor serves as an input end of the hierarchical filtering circuit, and a second end of the first resistor is connected to a common end of the first switch; the first end of the first switch is connected to the first end of the second switch, the second end of the first inductor, the first end of the second inductor, and the first end of the first capacitor; the second end of the first switch is connected to the first end of the first inductor; the second end of the second switch is connected to the second end of the second inductor and the first end of the second capacitor; the second end of the first capacitor is connected to the second end of the second capacitor and grounded; the common end of the second switch is connected to the first end of the signal amplification circuit, and the second end of the signal amplification circuit serves as an output end of the hierarchical filtering circuit. Through the above hierarchical filtering circuit, different filtering requirements can be met, and the problem that the hierarchical filtering circuit is difficult to meet the complex and changeable filtering requirements is solved. Description of the Drawings
[0027] Figure 1 is a schematic structural diagram of a hierarchical filtering circuit provided by an embodiment of the present application;
[0028] Figure 2 is a schematic structural diagram of another hierarchical filtering circuit provided by an embodiment of the present application;
[0029] Figure 3 is a schematic diagram of the connection and output of a hierarchical filtering circuit provided by an embodiment of the present application;
[0030] Figure 4 is a schematic diagram of the connection and output of another hierarchical filtering circuit provided by an embodiment of the present application
[0031] Figure 5 is a schematic diagram of the connection and output of yet another hierarchical filtering circuit provided by an embodiment of the present application;
[0032] Figure 6 is a schematic diagram of the connection and output of still another hierarchical filtering circuit provided by an embodiment of the present application. Detailed Embodiments
[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.
[0034] To facilitate the understanding of the technical solutions provided by the present utility model, a hierarchical filtering circuit provided by the present application will be described below in conjunction with the accompanying drawings. Refer to Figure 1 , which is a schematic structural diagram of a hierarchical filtering circuit provided by an embodiment of the present application. As Figure 1 shown, the hierarchical filtering circuit includes a first resistor R1, a first switch S1, a second switch S2, a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, and a signal amplification circuit 101.
[0035] In the embodiment of the present application, the first end of the first resistor R1 serves as the input end of the hierarchical filtering circuit, and the second end of the first resistor R1 is connected to the common end of the first switch S1.
[0036] It can be understood that in the present application, the signal to be filtered that needs to be filtered can be input from the first end of the first resistor R1. The present application does not limit the resistance value of the first resistor, and the resistance value of the first resistor can be determined according to the actual situation. It can be understood that one end of the first switch S1 is fixed to the common end, and the other end can be selected to connect to the first end or the second end of the first switch S1.
[0037] The first end of the first switch S1 is connected to the first end of the second switch S2, the second end of the first inductor L1, the first end of the second inductor L2, and the first end of the first capacitor C1.
[0038] In the embodiment of the present application, the first end of the first switch S1 is respectively connected to the first end of the second switch S2, the second end of the first inductor L1, the first end of the second inductor L2, and the first end of the first capacitor C1. This makes the first ends of the second switch S2, the first inductor L1, the second inductor L2, and the first capacitor C1 also connected to each other.
[0039] The second end of the first switch S1 is connected to the first end of the first inductor L1.
[0040] The present application does not limit the inductance value of the first inductor L1, and the inductance value of the first inductor L1 can be determined according to the actual situation.
[0041] The second terminal of the second switch S2 is connected to the second terminal of the second inductor L2 and the first terminal of the second capacitor C2.
[0042] In the embodiment of the present application, the second terminal of the second switch S2 is respectively connected to the second terminal of the second inductor LC and the second terminal of the second capacitor C2. It can be understood that the second terminal of the second inductor LC is also connected to the second terminal of the second capacitor C2.
[0043] The second terminal of the first capacitor C1 is connected to the second terminal of the second capacitor C2 and grounded.
[0044] In the embodiment of the present application, the second terminal of the first capacitor C1 and the second terminal of the second capacitor C2 are connected to each other and are both grounded.
[0045] The common terminal of the second switch S2 is connected to the first terminal of the signal amplification circuit 101, and the second terminal of the signal amplification circuit 101 serves as the output terminal of the hierarchical filtering circuit.
[0046] In the embodiment of the present application, one end of the second switch S2 is fixed to the common terminal of the second switch S2, and the other end can be selectively connected to the first terminal or the second terminal of the second switch S2. The signal amplification circuit is a circuit for amplifying an input signal to increase the amplitude or power of the signal. Through the signal amplification circuit in the present application, the requirements for the output amplitude or output power of the filtering circuit can be better met.
[0047] The above hierarchical filtering circuit is provided with a first switch S1 and a second switch S2. Through the filtering circuit controlled by two switches, the input signal to be filtered can respectively obtain corresponding frequency components according to the switch positions, and the amplitudes of waves with different frequencies are different, so as to meet the input requirements of different frequencies and levels, improve the quality and accuracy of the signal, enable the hierarchical filtering circuit to meet different filtering requirements, and solve the problem that it is difficult for the hierarchical filtering circuit to meet the complex and changeable filtering requirements. In addition, the number of filtering circuits provided can be reduced, and the setting cost can be reduced.
[0048] The present application does not limit the specific content of the signal amplification circuit. As a possible implementation, as Figure 2 shown, Figure 2 is a schematic structural diagram of another hierarchical filtering circuit provided by the embodiment of the present application. The signal amplification circuit includes: a second resistor R2, a third resistor R3, and an operational amplifier U1.
[0049] Figure 2 The structure other than the signal amplification circuit part in Figure 1 is the same, and will not be elaborated here.
[0050] The common terminal of the second switch is connected to the first end of the signal amplification circuit, and the second end of the signal amplification circuit serves as the output end of the hierarchical filtering circuit, including: the common terminal of the second switch is connected to the non-inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier serves as the output end of the hierarchical filtering circuit.
[0051] In the embodiment of the present application, the common terminal of the second switch S2 is connected to the non-inverting input terminal of the operational amplifier U1, and the output terminal of the operational amplifier U1 is used as the output end of the hierarchical filtering circuit. That is, the signal to be filtered after the final filtering is output from the output terminal of the operational amplifier U1.
[0052] The inverting input terminal of the operational amplifier U1 is connected to the second end of the second resistor R2 and the first end of the third resistor R3.
[0053] The output terminal of the operational amplifier U1 is connected to the second end of the third resistor R3.
[0054] The first end of the second resistor R2 is grounded.
[0055] In the embodiment of the present application, a signal amplification circuit can be constructed by the second resistor R2, the third resistor R3 and the operational amplifier U1, which can better meet the requirements of the output amplitude or output power of the filtering circuit.
[0056] As a possible implementation manner, the amplification factor of the signal amplification circuit is the same as the ratio between the third resistor R3 and the second resistor R2. It can be understood that the amplification factor of the signal amplification circuit can be determined according to the ratio between the third resistor R3 and the second resistor R2. Specifically, the amplification factor G1 of the signal amplification circuit = R3 / R2. For example, when R2 = 150 KΩ and R3 = 150 KΩ, the amplification factor G1 of the signal amplification circuit at this time = 1.
[0057] In the embodiment of the present application, by setting the second resistor and the third resistor with different resistance values, the amplification factor of the signal amplification circuit can be flexibly adjusted to meet the requirements of more filtering circuits.
[0058] The hierarchical filtering circuit provided by the present application can at least meet the filtering requirements of the following four output waveforms.
[0059] First, when the first switch connects the common terminal of the first switch S1 to the first end of the second switch S2, and the second switch S2 connects the common terminal of the second switch to the first end of the second switch S2, the second inductor L2, the first capacitor C1 and the second capacitor C2 form a first filtering circuit.
[0060] As Figure 3 shown, Figure 3 is a connection and output schematic diagram of a hierarchical filtering circuit provided by an embodiment of the present application.Figure 3 Among them, V1, V2, and V3 have an amplitude of 1V each, and frequencies of 100kHz, 10kHz, and 1kHz respectively. Thus, they are connected in series to simulate a signal to be filtered that requires filtering. In this application, the capacitance C1 of the first capacitor = the capacitance C2 of the second capacitor = 17nF, the inductance L2 of the second inductor = 5H, the inductance L1 of the first inductor = 1H, the frequencies of the signal to be filtered include 100kHz, 10kHz, 1kHz, and the input voltage U in = 3V, the second resistor R2 = 150KΩ, the third resistor R3 = 150KΩ. At this time, the amplification factor G1 of the signal amplification circuit = 1, that is, the amplification factor of the signal amplification circuit is 1 times. This will be used as an example for explanation, and the following embodiments will all be explained with this data. Figure 3 On Figure 2 this basis, it is also shown that the first end of the first resistor is connected to the oscilloscope image, which means that the signal to be filtered will be connected to the oscilloscope, and the output end of this hierarchical filtering circuit is also connected to the oscilloscope, thereby generating the oscilloscope image as shown in the figure.
[0061] It can be understood that when the first switch S1 connects the first end of the first switch S1 and the second switch S2 connects the first end of the second switch S2, the first filtering circuit formed by the second inductor L2, the first capacitor C1, and the second capacitor C2 is a CLC π - type filtering circuit. The input signal to be filtered undergoes a low - pass filtering once, removing part of the high - frequency part and outputting a certain frequency waveform. The cut - off frequency is:
[0062]
[0063] In the formula, C1 is the capacitance of the first capacitor, C2 is the capacitance of the second capacitor, L2 is the inductance of the second inductor, and f c1 is the cut - off frequency of the first filtering circuit. In the example of this application, taking C1 = C2 = 17nF and L2 = 5H as an example. Thus, the cut - off frequency f c1 of this filtering circuit is determined to be 1091Hz. It can be understood that the cut - off frequency represents the maximum frequency that the signal to be filtered can output.
[0064] The output voltage is: U O1 = G1U in ; U O1 represents the output voltage of the first filtering circuit. In the example of this application, the input voltage U in = 3V, and the amplification factor is G1 = 1. Thus, the amplitude of this filtering output is determined to be U O1 = 3V.
[0065] Second, when the first switch connects the common terminal of the first switch to the second terminal of the first switch, and the second switch connects the common terminal of the second switch to the first terminal of the second switch, the first inductor, the second inductor, the first capacitor, and the second capacitor form a second filter circuit.
[0066] As Figure 4 shown, Figure 4 is a connection and output schematic diagram of another hierarchical filter circuit provided by an embodiment of the present application. Figure 4 On Figure 2 this basis, it is also shown that the first end of the first resistor is connected to the oscillogram image, that is, it means that the signal to be filtered will be connected to the oscilloscope, and the output end of this hierarchical filter circuit is also connected to the oscilloscope, thereby generating the oscillogram image as shown in the figure.
[0067] When the first switch S1 connects the second terminal of the first switch S1, and the second switch S2 connects the first terminal of the second switch S2, the first inductor L1, the second inductor L2, the first capacitor C1, and the second capacitor C2 will form a second filter circuit. The signal to be filtered passes through the second filter circuit, first undergoes a low-pass filter to remove the high-frequency part, and then undergoes another low-pass filter to smooth and denoise the waveform, and outputs a frequency waveform. The cut-off frequency of the second filter circuit is:
[0068]
[0069] In the formula, f c2 represents the cut-off frequency of the second filter circuit. In this application example, taking C1 = C2 = 17 nF, L2 = 5 H, and L1 = 1 H as an example, the cut-off frequency f c2 of this filter circuit is determined to be 7023 Hz.
[0070] The output voltage of the second filter circuit is:
[0071]
[0072] In the formula, U O2 represents the output voltage of the second filter circuit. In this application example, f2 = 1 KHz, and the output voltage of the second filter circuit is determined to be U O2 = 1.6 V, and f2 represents the signal frequency that the signal to be filtered can pass through in the second filter circuit.
[0073] Third, when the first switch connects the common terminal of the first switch to the first terminal of the first switch, and the second switch connects the common terminal of the second switch to the second terminal of the second switch, the second inductor, the first capacitor, and the second capacitor form a third filter circuit.
[0074] As Figure 5 shown,Figure 5 Schematic diagram of the connection and output of yet another hierarchical filtering circuit provided by an embodiment of the present application. Similarly, Figure 5 In Figure 2 On this basis, it is also shown that the first end of the first resistor is connected to the oscillogram, which means that the signal to be filtered will be connected to the oscilloscope, and the output end of this hierarchical filtering circuit is also connected to the oscilloscope, thereby generating the oscillogram as shown in the figure.
[0075] When the first switch S1 connects the first end of the first switch S1 and the second switch S2 connects the second end of the second switch S2, the second inductor L2, the first capacitor C1, and the second capacitor C2 form a third filtering circuit, and this third filtering circuit is a CLC π-type filtering circuit. When the signal to be filtered passes through the third filtering circuit, it will undergo a low-pass filtering once to remove the high-frequency part, and then undergo another low-pass filtering to smooth and denoise the waveform, and output a frequency waveform. The cut-off frequency of the third filtering circuit is:
[0076]
[0077] In the formula, f c3 is the cut-off frequency of the third filtering circuit. In an example of the present application, taking C1 = C2 = 17 nF and L2 = 5 H as an example. Thus, the cut-off frequency f c3 of the third filtering circuit is determined to be 1091 Hz, and f3 represents the signal frequency that the signal to be filtered can pass through in the third filtering circuit.
[0078] The output voltage of the third filtering circuit is:
[0079]
[0080] In an example of the present application, f3 = 1 KHz, and thus the output voltage of the third filtering circuit is determined to be U O3 = 0.7 V.
[0081] Fourthly, when the first switch connects the common end of the first switch and the second end of the first switch, and the second switch connects the common end of the second switch and the second end of the second switch, the first inductor, the second inductor, the first capacitor, and the second capacitor form a fourth filtering circuit.
[0082] As Figure 6 shown, Figure 6 is the schematic diagram of the connection and output of yet another hierarchical filtering circuit provided by an embodiment of the present application. Similarly, Figure 6 In Figure 2 On this basis, it is also shown that the first end of the first resistor is connected to the oscillogram, which means that the signal to be filtered will be connected to the oscilloscope, and the output end of this hierarchical filtering circuit is also connected to the oscilloscope, thereby generating the oscillogram as shown in the figure.
[0083] When the first switch S1 is connected to the second end of the first switch S1 and the second switch S2 is connected to the second end of the second switch S2, the first inductor L1, the second inductor L2, the first capacitor C1, and the second capacitor C2 will form a fourth filter circuit. The signal to be filtered passes through the fourth filter circuit, first undergoes a low-pass filter to remove the high-frequency part, and then undergoes another low-pass filter to smooth and denoise the waveform, outputting a frequency waveform. The cut-off frequency of the fourth filter circuit is:
[0084]
[0085] In the formula, f c4 represents the cut-off frequency of the fourth filter circuit. In the example of this application, taking C1 = C2 = 17 nF, L2 = 5 H, and L1 = 1 H as an example, the cut-off frequency f c4 of this filter circuit is determined to be 7023 Hz.
[0086] The output voltage of the fourth filter circuit is:
[0087]
[0088] In the formula, U O4 represents the output voltage of the fourth filter circuit. In the example of this application, f4 = 1 KHz, and the output voltage of the fourth filter circuit is determined to be U O4 = 1.6 V. f4 represents the signal frequency that the signal to be filtered can pass through in the fourth filter circuit.
[0089] In this application, the specific circuit design and implementation method will vary according to application requirements and circuit characteristics. The values of the above various electronic components in this application can be set according to the frequency and amplitude requirements of the output signal in actual applications, and this application does not limit this.
[0090] This application does not limit the capacitance values of the first capacitor and the second capacitor. As a possible implementation method, the capacitance of the first capacitor in this application is equal to the capacitance of the second capacitor. It can be understood that setting the capacitance of the first capacitor in the filter circuit to be the same as the capacitance of the second capacitor in this application can simplify the calculation formulas for the output voltage and cut-off frequency of the hierarchical filter circuit, improve the calculation efficiency, and thus improve the output efficiency of the filter circuit.
[0091] This application embodiment also provides a filter, which can implement the steps provided in the above embodiment. It should be noted that the filter provided in this application embodiment has the technical effects of any one of the above embodiments, and this application embodiment will not elaborate on this here.
[0092] An embodiment of the present application further provides an electronic device, which includes the filter provided in the above embodiment. It should be noted that the electronic device provided in the embodiment of the present application has the technical effects of any one of the above embodiments, and the embodiments of the present application will not be elaborated herein.
[0093] In this article, specific examples are used to elaborate on the principles and implementation manners of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present utility model, several improvements and modifications can be made to the present utility model, and these improvements and modifications also fall within the protection scope of the claims of the present utility model.
Claims
1. A hierarchical filtering circuit, characterized in that: include: A first resistor, a first switch, a second switch, a first capacitor, a second capacitor, a first inductor, a second inductor, and a signal amplifying circuit; The first end of the first resistor serves as the input end of the hierarchical filtering circuit, and the second end of the first resistor is connected to the common end of the first switch; The first end of the first switch is connected to the first end of the second switch, the second end of the first inductor, the first end of the second inductor, and the first end of the first capacitor; The second end of the first switch is connected to the first end of the first inductor; The second end of the second switch is connected to the second end of the second inductor and the first end of the second capacitor; The second end of the first capacitor is connected to the second end of the second capacitor and is grounded; The common end of the second switch is connected to the first end of the signal amplifying circuit, and the second end of the signal amplifying circuit serves as the output end of the graded filtering circuit.
2. The circuit according to claim 1, characterized in that The signal amplifying circuit comprises: a second resistor, a third resistor and an operational amplifier; The common end of the second switch is connected to the first end of the signal amplifying circuit, and the second end of the signal amplifying circuit serves as the output end of the graded filtering circuit, including: the common end of the second switch is connected to the non-inverting input end of the operational amplifier, and the output end of the operational amplifier serves as the output end of the graded filtering circuit; The inverting input terminal of the operational amplifier is connected to the second end of the second resistor and the first end of the third resistor; The output end of the operational amplifier is connected to the second end of the third resistor; A first terminal of the second resistor is grounded.
3. The circuit according to claim 1 or 2, characterized in that: When the first switch connects the common end of the first switch and the first end of the first switch, and the second switch connects the common end of the second switch and the first end of the second switch, the second inductor, the first capacitor and the second capacitor form a first filtering circuit.
4. The circuit according to claim 1 or 2, characterized in that: When the first switch connects the common end of the first switch and the second end of the first switch, and the second switch connects the common end of the second switch and the first end of the second switch, the first inductor, the second inductor, the first capacitor and the second capacitor form a second filtering circuit.
5. The circuit according to claim 1 or 2, characterized in that: When the first switch connects the common end of the first switch and the first end of the first switch, and the second switch connects the common end of the second switch and the second end of the second switch, the second inductor, the first capacitor and the second capacitor form a third filtering circuit.
6. The circuit according to claim 1 or 2, characterized in that: When the first switch connects the common end of the first switch and the second end of the first switch, and the second switch connects the common end of the second switch and the second end of the second switch, the first inductor, the second inductor, the first capacitor and the second capacitor form a fourth filtering circuit.
7. The circuit according to claim 2, characterized in that The amplification factor of the signal amplifying circuit is the same as the ratio between the third resistor and the second resistor.
8. The circuit according to claim 1, characterized in that The capacity of the first capacitor is equal to the capacity of the second capacitor.
9. A filter, characterized in that: include: The filter circuit according to any one of claims 1 to 8.
10. An electronic device, characterized in that: Comprising the filter as claimed in claim 9.