CN217904407U - Noise suppression circuit and radio frequency receiver - Google Patents
Noise suppression circuit and radio frequency receiver Download PDFInfo
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- CN217904407U CN217904407U CN202222424903.5U CN202222424903U CN217904407U CN 217904407 U CN217904407 U CN 217904407U CN 202222424903 U CN202222424903 U CN 202222424903U CN 217904407 U CN217904407 U CN 217904407U
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Abstract
The application provides a noise suppression circuit and a radio frequency receiver, and relates to the field of radio frequency. The noise suppression circuit includes: a first low noise amplifier having a signal input configured to electrically connect to a radio frequency antenna; a resistor, a first end of the resistor being connected to the signal output of the first low noise amplifier, a second end of the resistor being configured to be electrically connected to a radio frequency receiver. The first low noise amplifier can perform noise suppression on the radio frequency signal so as to improve the receiving sensitivity of the radio frequency receiver, and the resistor can attenuate the output of the first low noise amplifier, so that the signal output by the noise suppression circuit can be used by the radio frequency receiver. The resistor is small in size and easy to replace, so that the requirements of the radio frequency receiver on small size and convenience in replacement can be met.
Description
Technical Field
The present application relates to the field of radio frequency, and in particular, to a noise suppression circuit and a radio frequency receiver.
Background
The radio frequency receiver has the problem that the front end circuit has overlarge noise due to overlarge loss of each stage of the front end circuit, and the overlarge noise can reduce the receiving sensitivity of the radio frequency receiver on radio frequency signals and influence the receiving of the radio frequency signals. Therefore, an external Low Noise Amplifier (ehna) is added between the rf receiver and the antenna to suppress the influence of Noise on the reception of the rf signal, and then the rf signal passing through the ehna is sent to an LNA (Low Noise Amplifier) inside the rf receiver, thereby improving the receiving sensitivity of the receiver. However, the edna generates a gain for the output rf signal, and the rf signal is gained again by the LNA after being output by the LNA inside the rf receiver, at this time, when the rf signal is tested using the maximum input level, the rf signal is distorted due to the excessive rf signal, and then the problem of failed test of the maximum input level occurs in the rf receiver. The maximum input level refers to a maximum signal which can be input by the radio frequency receiver under the condition of no distortion, and the failure of the maximum input level test refers to the condition that when the maximum input level is used for testing the radio frequency signal input to the radio frequency receiver, the radio frequency signal is distorted and cannot be tested.
At present, for solving the problem that the maximum test level fails due to the eLNA, the eLNA meeting the gain condition is usually selected according to the gain of the LNA, but the eLNA is difficult to replace due to the subsequent problems. Some methods also connect an attenuation circuit between the eLNA and the LNA to attenuate the radio frequency signal output by the eLNA, but the attenuation circuit is composed of a plurality of devices, occupies a large volume, and cannot be used in a small-package radio frequency receiver. Therefore, the existing mode for solving the problem of failure of the maximum test level caused by the eLNA cannot meet the requirement of the radio frequency receiver on the structure.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present application aims to provide a noise suppression circuit and a radio frequency receiver, which can improve the sensitivity of the radio frequency receiver and solve the problem of failure in testing the maximum input level of an edna circuit with a smaller circuit structure that is convenient to adjust.
In a first aspect, an embodiment of the present application provides a noise suppression circuit, including: a first low noise amplifier having a signal input configured to electrically connect to a radio frequency antenna; a resistor, a first end of the resistor being connected to the signal output of the first low noise amplifier, a second end of the resistor being configured to be electrically connected to a radio frequency receiver.
In the embodiment of the application, the first low noise amplifier is connected with the radio frequency antenna, the first low noise amplifier is used as a first-stage circuit at the front end of the radio frequency receiver, and the first low noise amplifier has the characteristic of low noise coefficient, so that the noise of each stage of circuit behind the first low noise amplifier can be effectively inhibited, and the receiving sensitivity of the radio frequency receiver is improved. By setting the resistor, the signal output by the first low noise amplifier can be attenuated, so that the problem that the maximum input level test of the eLNA circuit fails is solved. Compared with the existing attenuator or attenuation circuit, the volume of the resistor is small, and the resistor is easy to replace, so that the volume of the noise suppression circuit and the convenience in replacement and adjustment can be effectively realized, and the requirements of a radio frequency receiver on small volume and convenience in replacement are met.
In one embodiment, the attenuation of the output signal of the first low noise amplifier by the resistor is larger than a difference between the first low noise amplifier and a preset target gain.
In the embodiment of the application, the preset target gain is the gain of a low noise amplifier built in the radio frequency receiver, and when the attenuation corresponding to the resistor is greater than the difference value between the first low noise amplifier and the preset target gain, the resistor can effectively attenuate the first low noise amplifier, so that the attenuated signal can be used for the maximum input level test of the radio frequency receiver, and the condition that the maximum input level test fails can be avoided.
In one embodiment, the number of the resistors is 1.
In the embodiment of the application, one resistor is used, so that the size of the noise suppression circuit can be effectively reduced compared with an attenuator or an attenuation circuit, the resistor is convenient to replace, and in addition, the cost of the noise suppression circuit can be effectively reduced.
In one embodiment, the noise suppression circuit further comprises: the first capacitor is electrically connected between the signal output end of the first low-noise amplifier and the first end of the resistor.
In this embodiment, the first capacitor may be used for blocking (i.e., isolating direct current), and the first capacitor is disposed between the first low noise amplifier and the resistor, so that it may be avoided that the output of the active device between the rf antenna and the resistor in the rf signal transmission link is charged, which may affect the subsequent circuit/device.
In one embodiment, the noise suppression circuit further comprises: a filter electrically connected to a signal input of the first low noise amplifier.
In the embodiment of the application, the filter is arranged in front of the signal input end of the first low noise amplifier, and the radio frequency signal received by the radio frequency antenna can be filtered to screen the signal of the required frequency band, so that the radio frequency receiver only processes the signal of the designated frequency band, and the processing efficiency is improved.
In one embodiment, the noise suppression circuit further comprises: and the first inductor is electrically connected with the signal input end of the first low-noise amplifier.
In the embodiment of the application, the first inductor is electrically connected with the signal input end of the first low noise amplifier, and the radio frequency signal at the position of the minimum noise coefficient in the noise source can be input into the first low noise amplifier through the first inductor, so that the noise of the radio frequency signal input into the first low noise amplifier is smaller, and the noise reduction effect of the noise suppression circuit is further improved.
In one embodiment, the noise suppression circuit further comprises: the second inductor is electrically connected with the second end of the resistor; the second inductor is configured to be connected with the radio frequency receiver.
In the embodiment of the application, the noise suppression circuit is connected with the radio frequency receiver through the second inductor, and the second inductor can input the radio frequency signal corresponding to the position of the minimum noise coefficient in the radio frequency signal output by the noise suppression circuit into the first noise amplifier, so that the noise reduction effect of the noise suppression circuit is further improved.
In one embodiment, the noise suppression circuit further includes: a ground circuit; the grounding circuit comprises a second capacitor and a third inductor; the third inductor is electrically connected with the second end of the resistor; one end of the second capacitor is grounded, and the other end of the second capacitor is electrically connected with the third inductor.
In the embodiment of the application, the third inductor and the second capacitor are grounded to block the noise suppression circuit, so that the influence of the output electrification of an active device in the radio frequency receiver on each device in the noise suppression circuit is avoided.
In a second aspect, an embodiment of the present application provides a radio frequency receiver, including: the radio frequency antenna is electrically connected with a signal input end of the first low noise amplifier in the noise suppression circuit; and the radio frequency receiver main body is connected with the second end of the resistor in the noise suppression circuit.
In one embodiment, a radio frequency receiver body comprises: a second low noise amplifier; and the receiving end of the second low-noise amplifier is electrically connected with the second end of the resistor.
Additional features and advantages of the disclosure will be set forth in the description which follows, or in part may be learned by the practice of the above-described techniques of the disclosure, or may be learned by practice of the disclosure.
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a block diagram of a noise suppression circuit according to an embodiment of the present disclosure;
fig. 2 is a circuit diagram of a noise suppression circuit according to an embodiment of the present disclosure;
fig. 3 is a block diagram of a radio frequency receiver according to an embodiment of the present disclosure;
fig. 4 is a circuit connection diagram of a radio frequency receiver according to an embodiment of the present application.
Icon: a noise suppression circuit 100; a first low noise amplifier 110; a resistor 120; a first capacitor 130; a filter 140; a first inductor 150; a second inductor 160; a third inductance 170; a second capacitor 180; a radio frequency receiver 200; a radio frequency antenna 210; a radio frequency receiver body 220; a second low noise amplifier 221.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further 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.
Referring to fig. 1, fig. 1 is a block diagram of a noise suppression circuit according to an embodiment of the present disclosure. The noise suppression circuit 100 includes a first low noise amplifier 110 and a resistor 120.
The first low noise amplifier 110 is a low noise amplifier, wherein the specific implementation structure of the low noise amplifier may refer to the prior art, which is not described herein again.
In this embodiment, the input terminal of the low noise amplifier may be configured to be electrically connected to a radio frequency antenna of the radio frequency receiver, so that a signal received by the radio frequency antenna may be amplified. Because the low-noise amplifier has a lower noise coefficient, the interference of the noise of the amplifier to the signal can be avoided when the signal is amplified.
When the radio frequency receiver receives a signal, the signal usually passes through a plurality of different circuits and then reaches a signal transmission section after being received by an antenna, and the noise cascade formula shows that the influence of a first-stage circuit on the noise coefficient of the whole radio frequency signal transmission link is the largest, and the noise of each subsequent-stage circuit is gradually reduced compared with the noise of the first-stage circuit, so that the low-noise amplifier is electrically connected with the radio frequency antenna, the low-noise amplifier can be used as the first-stage circuit of the radio frequency signal transmission link, the noise of each subsequent-stage circuit is suppressed based on the lower noise coefficient of the low-noise amplifier, and the noise in the radio frequency signal receiving process is suppressed. The prior art can be referred to for the principle that the noise cascade formula and the first-stage circuit have the greatest influence on the noise coefficient of the whole radio frequency signal transmission link.
In this embodiment, two ends of the resistor 120 are respectively used for electrically connecting with the first low noise amplifier 110 and the radio frequency receiver. Specifically, a first terminal of the resistor 120 is connected to the signal output terminal of the first low noise amplifier 110, and a second terminal of the resistor 120 is configured to be electrically connected to the radio frequency receiver. It is understood that the two ends of the resistor 120 are the same, and the first end and the second end are only used for distinguishing the position connected with the resistor 120, the first end and the second end do not affect the performance of the resistor 120, and the first end and the second end should not be limited in this application.
In this embodiment, the resistor 120 may be used to attenuate the signal output by the first low noise amplifier 110, so that the signal can be used by the radio frequency receiver without distortion, i.e. without the problem of test failure of the maximum input level. Compared with the prior art that an attenuator or an attenuation circuit (such as a pi or t type attenuation circuit) is used, the resistor 120 can also reduce the volume of the circuit occupied by the attenuation and facilitate replacement, thereby meeting the requirement of the radio frequency receiver on the structure.
In this embodiment, the resistor 120 has a set resistance value to attenuate the signal output from the first low noise amplifier 110 by a set attenuation amount. It is understood that the resistance value of the resistor 120 has a correlation with the attenuation of the output signal of the first low noise amplifier 110 by the resistor 120, and the attenuation of the output signal of the first low noise amplifier 110 can be controlled by controlling the resistance value of the resistor 120.
In this embodiment, the attenuation of the output signal of the first low noise amplifier 110 by the resistor 120 is greater than the difference between the first low noise amplifier 110 and the preset target gain.
In this embodiment, the preset target gain is a gain corresponding to the maximum power that a low noise amplifier inside the radio frequency receiver can bear. The signal output from the first low noise amplifier 110 is attenuated by the resistor 120, thereby enabling the internal use of the rf receiver for testing the maximum input level.
For example, in some embodiments, the amount of attenuation may satisfy a preset relationship:
A+G 1 +P 1 ＝G 2
wherein A is attenuation, G 1 Is the gain, P, of the first low noise amplifier 110 1 To test the power at maximum input level, G 2 Is a preset target gain. In some embodiments, G 2 ＝-20dBm，P 1 = -25.7dBm. It can be understood that there is a mutual conversion relationship between the power and the gain, and the specific conversion manner may refer to the prior art and is not described herein again.
Thus, a resistor having a resistance value according to the required attenuation amount can be used in the noise suppression circuit 100. Wherein. The resistance value of the resistor and the corresponding attenuation satisfy an attenuation formula, and the attenuation formula is as follows:
wherein A is attenuation, R 1 Is the resistance value of a resistor, R in Characteristic impedance of radio frequency microstrip line, i.e. R in =50 ohm. Illustratively, a 10 ohm resistance corresponds to an attenuation of about 3.4dB.
In one embodiment, the number of resistors 120 is 1.
In this embodiment, only one resistor 120 with a resistance value meeting the requirement may be used, so that the size of the device used for attenuation may be effectively reduced, and the size of the noise suppression circuit 100 may be further reduced. And because only one resistor is arranged, the resistor is convenient to replace.
In addition, the number of the resistors 120 in this embodiment may also be greater than 1, and at this time, the plurality of resistors 12 may be connected in series or in parallel to form a whole, so as to obtain a resistance value meeting the requirement.
Referring to fig. 2, fig. 2 is a circuit diagram of a noise suppression circuit 100 according to an embodiment of the present disclosure.
The noise suppression circuit 100 may further include a first capacitor 130, and the first capacitor 130 is connected between the signal output terminal of the first low noise amplifier 110 and the first terminal of the resistor 120.
In this embodiment, the capacitor has a dc blocking function, and therefore, the first capacitor 130 is disposed between the signal output end of the first low noise amplifier 110 and the resistor 120, so that it can be avoided that the output of the active device in the radio frequency signal transmission link carries dc power and affects the subsequent devices of the transmission link.
The noise suppression circuit 100 further comprises a filter 140, the filter 140 being electrically connected to the signal input of the first low noise amplifier 110. Wherein the filter 140 is configured to be electrically connected to the radio frequency antenna.
In this embodiment, the filter 140 may be used to filter the signal received by the rf antenna, so as to allow the signal in the designated frequency band to pass through, thereby avoiding interference of the rf signal in the invalid frequency band, and making the signal received by the rf receiver more accurate. The structure of the filter 140 may refer to the existing filter 140, and the filtering frequency band of the filter 140 may be set reasonably according to the requirement, which is described herein.
In one embodiment, the noise suppression circuit 100 may further include a first inductor 150, and the first inductor 150 is electrically connected to the signal input terminal of the first low noise amplifier 110. Wherein the first inductor 150 may be connected between the filter 140 and the first low noise amplifier 110.
In this embodiment, the rf signal input to the first low noise amplifier 110 is accompanied by noise, and the noise comes from a noise source, and by providing the first inductor 150, a position with the smallest noise coefficient in the noise source can be selected as a position to which the signal is input, so that the noise coefficient of the rf signal input to the first low noise amplifier 110 can be reduced, and the noise reduction effect of the noise suppression circuit 100 can be further reduced.
In one embodiment, the noise suppression circuit 100 may further include a second inductor 160. The second inductor 160 is electrically connected to the second terminal of the resistor 120. Wherein the second inductor 160 is configured to be connected to a radio frequency receiver.
In this embodiment, since the rf receiver incorporates a low noise amplifier, when the noise suppression circuit 100 is connected to the rf receiver, the resistor 120 can be connected to the low noise amplifier in the rf receiver through the second inductor 160, thereby further reducing noise of the rf signal output from the noise suppression circuit 100.
In one embodiment, the noise suppression circuit 100 may further include a ground circuit. The grounding circuit includes a second capacitor 180 and a third inductor 170; the third inductor 170 is electrically connected to the second end of the resistor 120; one end of the second capacitor 180 is grounded, and the other end of the second capacitor 180 is electrically connected to the third inductor 170.
In this embodiment, the second capacitor 180 and the third inductor 170 are grounded, so that the output of the active device in the rf receiver is prevented from being charged, which may affect the noise suppression circuit 100.
In the embodiment of the present application, the first low noise amplifier 110 is connected to the radio frequency antenna, the first low noise amplifier 110 is used as a first stage circuit at the front end of the radio frequency receiver, and the first low noise amplifier 110 has the characteristic of low noise coefficient, so that the noise of each stage circuit behind the first low noise amplifier 110 can be effectively suppressed, thereby improving the receiving sensitivity of the radio frequency receiver. By setting the resistor 120, the signal output by the first low noise amplifier 110 can be attenuated, thereby solving the problem that the maximum input level test of the eLNA circuit fails. Compared with the existing attenuator or attenuation circuit, the resistor 120 has a small volume and is easy to replace, so that the volume of the noise suppression circuit 100 and the convenience of replacement and adjustment can be effectively realized.
Referring to fig. 3, fig. 3 is a block diagram of an rf receiver 200 according to an embodiment of the present disclosure.
Based on the same inventive concept, the embodiment of the present application further provides a radio frequency receiver 200, which includes a reception noise suppression circuit 100, a radio frequency antenna 210, and a radio frequency receiver main body 220.
The rf antenna 210 is used for receiving rf signals.
Referring to fig. 4, fig. 4 is a circuit connection diagram of an rf receiver 200 according to an embodiment of the present disclosure.
In this embodiment, the signal input terminals of the first low noise amplifiers 110 in the noise suppression circuit 100 and are electrically connected to the rf antenna 210. Thereby, the noise suppression circuit 100 can be made to perform noise reduction on the radio frequency signal received by the radio frequency antenna 210.
And a radio frequency receiver main body 220 connected to the second terminal of the resistor 120 in the noise suppression circuit 100. Wherein the rf receiver 200 may be used to perform a maximum test level test.
In this embodiment, a second low noise amplifier 221 is disposed in the rf receiver main body 220, and a receiving end (or "input end") of the second low noise amplifier 221 is electrically connected to the second end of the resistor 120.
The noise of the rf signal transmitted from the rf antenna 210 to the rf receiver body 220 can be suppressed by the noise suppression circuit 100, so that the receiving sensitivity of the rf receiver 200 is improved, and the problem of failure of the maximum input level test can be avoided by the resistor 120 in the noise suppression circuit 100.
The above embodiments are merely examples of the present application and are not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A noise suppression circuit, comprising:
a first low noise amplifier having a signal input configured to electrically connect to a radio frequency antenna;
a resistor, a first end of the resistor being connected to the signal output of the first low noise amplifier, a second end of the resistor being configured to be electrically connected to a radio frequency receiver.
2. The muting circuit according to claim 1, characterized in that the resistance attenuates the output signal of the first low noise amplifier by an amount larger than the difference between the first low noise amplifier and a preset target gain.
3. The noise suppression circuit according to claim 1, wherein the number of the resistors is 1.
4. The noise suppression circuit according to claim 1, characterized in that the noise suppression circuit further comprises: the first capacitor is electrically connected between the signal output end of the first low-noise amplifier and the first end of the resistor.
5. The noise suppression circuit according to claim 1, characterized in that the noise suppression circuit further comprises: a filter electrically connected to a signal input of the first low noise amplifier.
6. The noise suppression circuit according to claim 1, characterized in that the noise suppression circuit further comprises: and the first inductor is electrically connected with the signal input end of the first low-noise amplifier.
7. The noise suppression circuit according to claim 1, characterized in that the noise suppression circuit further comprises: the second inductor is electrically connected with the second end of the resistor; the second inductor is configured to be connected with the radio frequency receiver.
8. The noise suppression circuit according to any one of claims 1 to 4, further comprising: a ground circuit; the grounding circuit comprises a second capacitor and a third inductor; the third inductor is electrically connected with the second end of the resistor; one end of the second capacitor is grounded, and the other end of the second capacitor is electrically connected with the third inductor.
9. A radio frequency receiver, comprising:
a noise suppression circuit as claimed in any one of claims 1 to 8;
the radio frequency antenna is electrically connected with a signal input end of the first low-noise amplifier in the noise suppression circuit;
and the radio frequency receiver main body is connected with the second end of the resistor in the noise suppression circuit.
10. The radio frequency receiver of claim 9, wherein the radio frequency receiver body comprises: a second low noise amplifier; and the receiving end of the second low noise amplifier is electrically connected with the second end of the resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222424903.5U CN217904407U (en) | 2022-09-13 | 2022-09-13 | Noise suppression circuit and radio frequency receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222424903.5U CN217904407U (en) | 2022-09-13 | 2022-09-13 | Noise suppression circuit and radio frequency receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN217904407U true CN217904407U (en) | 2022-11-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202222424903.5U Active CN217904407U (en) | 2022-09-13 | 2022-09-13 | Noise suppression circuit and radio frequency receiver |
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| CN (1) | CN217904407U (en) |
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- 2022-09-13 CN CN202222424903.5U patent/CN217904407U/en active Active
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