CN215452899U - EMI suppression circuit and EMI suppressor - Google Patents
EMI suppression circuit and EMI suppressor Download PDFInfo
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- CN215452899U CN215452899U CN202120803266.5U CN202120803266U CN215452899U CN 215452899 U CN215452899 U CN 215452899U CN 202120803266 U CN202120803266 U CN 202120803266U CN 215452899 U CN215452899 U CN 215452899U
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Abstract
An EMI suppression circuit and an EMI suppressor, wherein when receiving a first electric signal, a trap circuit traps the first electric signal to output a second electric signal; wherein the notch frequency range comprises double frequency of the preset frequency; the low-pass filter circuit performs low-pass filtering on the second electric signal to output a third electric signal; wherein the upper cut-off frequency of the low-pass filtering is between the preset frequency and twice the preset frequency; because the EMI radiated energy is concentrated in the frequency doubling frequency band of the preset frequency, and the frequency doubling frequency band of the preset frequency is concentrated in the main EMI radiated energy, the notch frequency range is set to include double frequency of the preset frequency to carry out notch, and the upper cut-off frequency of the low-pass filter is set to be positioned between the preset frequency and the frequency doubling frequency of the preset frequency to carry out low-pass filtering, an enhancement filter is not needed, the EMI suppression effect is ensured, and meanwhile, the cost is reduced.
Description
Technical Field
The application belongs to the field of wireless communication, and particularly relates to an EMI (electro-magnetic interference) suppression circuit and an EMI suppressor.
Background
The conventional electromagnetic Interference (EMI) suppression circuit adopts a low-pass filter, and when a common low-pass filter is used, although the cost is low, the EMI suppression effect is poor; when the enhanced low-pass filter is used, although the EMI suppression effect is good, the cost is high.
Therefore, the conventional EMI suppression circuit cannot reduce the cost while ensuring the EMI suppression effect.
SUMMERY OF THE UTILITY MODEL
The present application aims to provide an EMI suppression circuit and an EMI suppressor, and aims to solve the problem that the cost is reduced while the EMI suppression effect is ensured in the conventional EMI suppression circuit.
The embodiment of the application provides an EMI suppression circuit, including:
a notch circuit configured to notch a first electrical signal to output a second electrical signal when the first electrical signal is received; wherein the notch frequency range comprises double frequency of the preset frequency;
a low-pass filter circuit connected to the trap circuit and configured to low-pass filter the second electrical signal to output a third electrical signal; wherein the upper cut-off frequency of the low-pass filtering is located between the preset frequency and twice the preset frequency.
In one embodiment, the trap circuit includes a first inductance and a first capacitance;
a first end of the first inductor is connected to a first electrical signal input of the trap circuit and a second electrical signal output of the trap circuit; the second end of the first inductor is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the power ground.
In one embodiment, the low-pass filter circuit comprises a second inductor and a second capacitor;
the first end of the second inductor is connected to the second electric signal input end of the low-pass filter circuit; the second end of the second inductor and the first end of the second capacitor are connected to a third electric signal output end of the low-pass filter circuit together, and the second end of the second capacitor is connected with a power ground.
In one embodiment, the trap circuit further comprises a third inductor and a third capacitor;
a first end of the third inductor is connected to a first electrical signal input end of the trap circuit and a second electrical signal output end of the trap circuit; and the second end of the third inductor is connected with the first end of the third capacitor, and the second end of the third capacitor is connected with the power ground.
In one embodiment, the low-pass filter circuit further comprises a fourth inductor and a fourth capacitor;
the first end of the fourth inductor is connected to the second electric signal input end of the low-pass filter circuit; the second end of the fourth inductor and the first end of the fourth capacitor are connected to the third electrical signal output end of the low-pass filter circuit together, and the second end of the fourth capacitor is connected with the power ground.
The embodiment of the application also provides an EMI suppressor, and the EMI suppressor comprises the EMI suppression circuit.
The embodiment of the present application further provides a wireless transmission device, where the wireless transmission device includes a transmitting circuit, a first antenna, and the EMI suppression circuit as described above;
the transmitting circuit is connected with the trap circuit and the low-pass filter circuit and is configured to output the first electric signal from a line;
the first antenna is connected with the low-pass filter circuit and is configured to convert the third electric signal into a first wireless communication signal and transmit the first wireless communication signal from a wireless link.
The embodiment of the present application further provides a wireless receiving device, where the wireless receiving device includes a receiving circuit, a second antenna, and the EMI suppression circuit as described above;
the second antenna, coupled to the notch circuit and the low pass filter circuit, configured to receive a second wireless communication signal from a wireless link and convert the second wireless communication signal to the first electrical signal;
the receiving circuit is connected with the low-pass filtering circuit and is configured to receive the third electric signal from a line.
Compared with the prior art, the embodiment of the utility model has the following beneficial effects: because the EMI radiated energy is concentrated in the frequency doubling frequency band of the preset frequency, and the frequency doubling frequency band of the preset frequency is concentrated in the main EMI radiated energy, the notch frequency range is set to include double frequency of the preset frequency to carry out notch, and the upper cut-off frequency of the low-pass filter is set to be positioned between the preset frequency and the frequency doubling frequency of the preset frequency to carry out low-pass filtering, an enhancement filter is not needed, the EMI suppression effect is ensured, and meanwhile, the cost is reduced.
Drawings
In order to more clearly illustrate the technical utility model in the embodiment of the present invention, the drawings used in the description of the embodiment will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic diagram of an EMI suppression circuit according to an embodiment of the present disclosure;
FIG. 2 is an exemplary circuit schematic of an EMI suppression circuit provided in accordance with an embodiment of the present application;
FIG. 3 is another exemplary circuit schematic of an EMI suppression circuit provided in accordance with an embodiment of the present application;
fig. 4 is a schematic structural diagram of a wireless transmitting device according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of a wireless receiving device according to an embodiment of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
Fig. 1 shows a schematic structural diagram of an EMI suppression circuit according to a preferred embodiment of the present application, and for convenience of description, only the portions related to the embodiment are shown, and detailed descriptions are as follows:
the EMI suppression circuit comprises a trap circuit and a low-pass filter circuit.
A notch circuit 11 configured to notch the first electrical signal to output a second electrical signal when receiving the first electrical signal; wherein the notch frequency range comprises double frequency of the preset frequency;
a low-pass filter circuit 12 connected to the trap circuit 11 and configured to low-pass filter the second electrical signal to output a third electrical signal; wherein the upper cut-off frequency of the low-pass filtering is between the preset frequency and twice the preset frequency.
When the EMI suppression circuit is applied to the device, the preset frequency may be an operating frequency of the device.
Fig. 2 shows an exemplary circuit structure of an EMI suppression circuit provided in an embodiment of the present invention, and for convenience of description, only the portions related to the embodiment of the present invention are shown, and detailed descriptions are as follows:
the trap circuit 11 includes a first inductor L1 and a first capacitor C1;
a first terminal of the first inductor L1 is connected to a first electrical signal input terminal of the trap circuit 11 and a second electrical signal output terminal of the trap circuit 11; the second terminal of the first inductor L1 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to ground.
The trap circuit 11 is realized by adopting a capacitance-inductance circuit, and the circuit is simple and reliable.
In a specific implementation, the method for calculating the suppressed center frequency point of the notch circuit 11 includes:
wherein f is1A center frequency point for suppression by the trap circuit 11; l is1Is the inductance of the first inductor L1; c1Is the capacitance value of the first capacitor C1. For example, when the operating frequency of a product to which the EMI suppression circuit is applied is 850MHz to 900MHz, the frequency point of suppression of the notch circuit 11 is between 1.6GHZ to 1.8GHZ, so that the first inductance L1 of 3.7nH and the first capacitance C1 of 2.4pF can be selected, and thus the notch circuit 11 with the suppressed center frequency point of 1.689GHZ is obtained, and the notch requirement of the product with the operating frequency of 850MHz to 900MHz is met.
The low-pass filter circuit 12 comprises a second inductor L2 and a second capacitor C2;
a first end of the second inductor L2 is connected to a second electrical signal input end of the low-pass filter circuit 12; the second terminal of the second inductor L2 and the first terminal of the second capacitor C2 are commonly connected to the third electrical signal output terminal of the low-pass filter circuit 12, and the second terminal of the second capacitor C2 is connected to the power ground.
The low-pass filter circuit 12 is realized by adopting a capacitance-inductance circuit, and the circuit is simple and reliable.
In a specific implementation, the method for calculating the upper cutoff frequency of the low-pass filter circuit 12 includes:
wherein f is2The upper cut-off frequency of the low-pass filter circuit 12; l is2Is the inductance of the second inductor L2; c2Is the capacitance value of the second capacitor C2. For example, if the operating frequency of the product to which the EMI suppression circuit is applied is 850MHz to 900MHz, the upper cutoff frequency of the low-pass filter circuit 12 may be 950MHz, so that the second inductor L2 with 7.5nH and the second capacitor C2 with 3.6pF may be selected, and thus the low-pass filter circuit 12 with the upper cutoff frequency of 968.5MHz is obtained, which meets the requirement of low-pass filtering of the product with the operating frequency of 850MHz to 900 MHz.
Fig. 3 shows an exemplary circuit structure of an EMI suppression circuit provided in an embodiment of the present invention, and for convenience of description, only the portions related to the embodiment of the present invention are shown, and detailed descriptions are as follows:
in addition to the notch circuit 11 shown in FIG. 2, the notch circuit 11 further includes a third inductor L3 and a third capacitor C3.
A first terminal of the third inductor L3 is connected to the first electrical signal input terminal of the trap circuit 11 and the second electrical signal output terminal of the trap circuit 11; the second terminal of the third inductor L3 is connected to the first terminal of the third capacitor C3, and the second terminal of the third capacitor C3 is connected to ground.
By connecting the third inductor L3 and the third capacitor C3 in parallel on the basis of the trap circuit 11 shown in fig. 2, the attenuation amplitude of the trap wave is enhanced.
On the basis of the low-pass filter circuit 12 shown in fig. 2, the low-pass filter circuit 12 further includes a fourth inductor L4 and a fourth capacitor C4.
A first end of the fourth inductor L4 is connected to a second electrical signal input end of the low-pass filter circuit 12; a second terminal of the fourth inductor L4 and a first terminal of the fourth capacitor C4 are commonly connected to the third electrical signal output terminal of the low-pass filter circuit 12, and a second terminal of the fourth capacitor C4 is connected to the power ground.
By connecting the fourth inductor L4 and the fourth capacitor C4 in parallel on the basis of the low-pass filter circuit 12 shown in fig. 2, the attenuation of the low-pass filtered filter frequency is enhanced.
The following further description of fig. 2 and 3 is made in conjunction with the working principle:
in fig. 2, when receiving the first electrical signal, the first inductor L1 and the first capacitor C1 notch the first electrical signal to output a second electrical signal; wherein the notch frequency range comprises double frequency of the preset frequency; the second inductor L2 and the second capacitor C2 low-pass filter the second electrical signal to output a third electrical signal; wherein the upper cut-off frequency of the low-pass filtering is between the preset frequency and twice the preset frequency.
In fig. 3, when receiving the first electrical signal, the first inductor L1, the first capacitor C1, the third inductor L3, and the third capacitor C3 notch the first electrical signal to output a second electrical signal; wherein the notch frequency range comprises double frequency of the preset frequency; the second inductor L2, the second capacitor C2, the fourth inductor L4 and the fourth capacitor C4 low-pass filter the second electrical signal to output a third electrical signal; wherein the upper cut-off frequency of the low-pass filtering is between the preset frequency and twice the preset frequency.
The embodiment of the utility model also provides an EMI suppressor, which comprises the EMI suppression circuit.
An embodiment of the present invention further provides a wireless transmitting apparatus, as shown in fig. 4, the wireless transmitting apparatus includes a transmitting circuit 21, a first antenna 22, and the EMI suppression circuit 10.
A transmission circuit 21 connected to the trap circuit 11 and the low-pass filter circuit 12, and configured to output a first electric signal from a line;
the first antenna 22 is connected to the low pass filter circuit 12 and configured to convert the third electrical signal into a first wireless communication signal and transmit the first wireless communication signal from the wireless link.
An embodiment of the present invention further provides a wireless receiving device, as shown in fig. 5, the wireless receiving device includes a receiving circuit 24, a second antenna 23, and the EMI suppression circuit 10.
A second antenna 23 connected to the trap circuit 11 and the low-pass filter circuit 12, and configured to receive a second wireless communication signal from the wireless link and convert the second wireless communication signal into a first electrical signal;
and a receiving circuit 24 connected to the low-pass filter circuit 12 and configured to receive the third electrical signal from the line.
In the embodiment of the utility model, when the trap circuit receives the first electric signal, the trap circuit traps the first electric signal to output the second electric signal; wherein the notch frequency range comprises double frequency of the preset frequency; the low-pass filter circuit performs low-pass filtering on the second electric signal to output a third electric signal; wherein the upper cut-off frequency of the low-pass filtering is between the preset frequency and twice the preset frequency; because the EMI radiated energy is concentrated in the frequency doubling frequency band of the preset frequency, and the frequency doubling frequency band of the preset frequency is concentrated in the main EMI radiated energy, the notch frequency range is set to include double frequency of the preset frequency to carry out notch, and the upper cut-off frequency of the low-pass filter is set to be positioned between the preset frequency and the frequency doubling frequency of the preset frequency to carry out low-pass filtering, an enhancement filter is not needed, the EMI suppression effect is ensured, and meanwhile, the cost is reduced.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (8)
1. An EMI suppression circuit, comprising:
a notch circuit configured to notch a first electrical signal to output a second electrical signal when the first electrical signal is received; wherein the notch frequency range comprises double frequency of the preset frequency;
a low-pass filter circuit connected to the trap circuit and configured to low-pass filter the second electrical signal to output a third electrical signal; wherein the upper cut-off frequency of the low-pass filtering is located between the preset frequency and twice the preset frequency.
2. The EMI suppression circuit of claim 1 wherein the notch circuit comprises a first inductance and a first capacitance;
a first end of the first inductor is connected to a first electrical signal input of the trap circuit and a second electrical signal output of the trap circuit; the second end of the first inductor is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the power ground.
3. The EMI suppression circuit of claim 1 wherein the low pass filter circuit comprises a second inductor and a second capacitor;
the first end of the second inductor is connected to the second electric signal input end of the low-pass filter circuit; the second end of the second inductor and the first end of the second capacitor are connected to a third electric signal output end of the low-pass filter circuit together, and the second end of the second capacitor is connected with a power ground.
4. The EMI suppression circuit of claim 2 wherein the notch circuit further comprises a third inductance and a third capacitance;
a first end of the third inductor is connected to a first electrical signal input end of the trap circuit and a second electrical signal output end of the trap circuit; and the second end of the third inductor is connected with the first end of the third capacitor, and the second end of the third capacitor is connected with the power ground.
5. The EMI suppression circuit of claim 3 wherein the low pass filter circuit further comprises a fourth inductor and a fourth capacitor;
the first end of the fourth inductor is connected to the second electric signal input end of the low-pass filter circuit; the second end of the fourth inductor and the first end of the fourth capacitor are connected to the third electrical signal output end of the low-pass filter circuit together, and the second end of the fourth capacitor is connected with the power ground.
6. An EMI suppressor comprising the EMI suppression circuit of any one of claims 1 to 5.
7. A wireless transmitting device, comprising a transmitting circuit, a first antenna, and the EMI suppression circuit of any one of claims 1 to 5;
the transmitting circuit is connected with the trap circuit and the low-pass filter circuit and is configured to output the first electric signal from a line;
the first antenna is connected with the low-pass filter circuit and is configured to convert the third electric signal into a first wireless communication signal and transmit the first wireless communication signal from a wireless link.
8. A wireless receiving device comprising a receiving circuit, a second antenna, and the EMI suppression circuit of any one of claims 1 to 5;
the second antenna, coupled to the notch circuit and the low pass filter circuit, configured to receive a second wireless communication signal from a wireless link and convert the second wireless communication signal to the first electrical signal;
the receiving circuit is connected with the low-pass filtering circuit and is configured to receive the third electric signal from a line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120803266.5U CN215452899U (en) | 2021-04-19 | 2021-04-19 | EMI suppression circuit and EMI suppressor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120803266.5U CN215452899U (en) | 2021-04-19 | 2021-04-19 | EMI suppression circuit and EMI suppressor |
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| Publication Number | Publication Date |
|---|---|
| CN215452899U true CN215452899U (en) | 2022-01-07 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120803266.5U Active CN215452899U (en) | 2021-04-19 | 2021-04-19 | EMI suppression circuit and EMI suppressor |
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| CN (1) | CN215452899U (en) |
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- 2021-04-19 CN CN202120803266.5U patent/CN215452899U/en active Active
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