CN114584079A - Low-noise amplifying circuit - Google Patents
Low-noise amplifying circuit Download PDFInfo
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- CN114584079A CN114584079A CN202210148032.0A CN202210148032A CN114584079A CN 114584079 A CN114584079 A CN 114584079A CN 202210148032 A CN202210148032 A CN 202210148032A CN 114584079 A CN114584079 A CN 114584079A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/189—High frequency amplifiers, e.g. radio frequency amplifiers
- H03F3/19—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
- H03F3/193—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only with field-effect devices
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/294—Indexing scheme relating to amplifiers the amplifier being a low noise amplifier [LNA]
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier
Abstract
The invention discloses a low-noise amplifying circuit, which comprises a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit and a low-frequency filter circuit, wherein the signal input end is connected with the signal output end; the radio frequency amplification circuit is connected with the signal input end at one end and the signal output end at the other end, and is configured to receive a radio frequency input signal, amplify the radio frequency input signal and output a radio frequency amplified signal; the load circuit is connected with the output end of the radio frequency amplification circuit at one end and connected with a power supply end at the other end; and one end of the low-frequency filter circuit is connected with the power supply end, the other end of the low-frequency filter circuit is connected with the grounding end, and the low-frequency filter circuit is configured to filter low-frequency band signals outside the working frequency band of the low-noise amplification circuit. According to the technical scheme, the low-frequency band signals outside the working frequency band of the low-noise amplifying circuit can be filtered, and the low-frequency band signals are released to the ground, so that the gain of the low-noise amplifying circuit can meet the requirement under the condition that the low-noise amplifying circuit is stable.
Description
Technical Field
The invention relates to the technical field of radio frequency integrated circuits, in particular to a low-noise amplifying circuit.
Background
Receivers for transmitting or receiving radio frequency signals are typically included in radio frequency integrated circuits. The receiver includes a low noise amplifier. However, in the process of amplifying the radio frequency receiving signal, the conventional low noise amplifier usually needs to sacrifice the gain of the low noise amplifier circuit to ensure the stability of the low noise amplifier circuit. The low noise amplifier is used as a first-stage device on a receiving path and is directly connected with an antenna end so as to amplify the radio frequency receiving signal from the antenna. Since the antenna can receive all the radio frequency signals without selectivity, but since most of the received radio frequency signals in the frequency bands are in a mismatch state, and the radio frequency signals in the mismatch state affect the stability of the low noise amplifier, which further causes an unstable phenomenon in the whole radio frequency circuit, it is necessary to ensure that the low noise amplifier is in a stable state. Therefore, how to ensure the stability of the low noise amplifier circuit and simultaneously ensure that the gain of the low noise amplifier circuit is not affected is a problem to be solved at present.
Disclosure of Invention
The embodiment of the invention provides a low-noise amplifying circuit, which aims to solve the problem that the stability of the low-noise amplifying circuit cannot be ensured and the gain requirement cannot be met.
A low-noise amplifying circuit comprises a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit and a low-frequency filter circuit;
one end of the radio frequency amplifying circuit is connected with the signal input end, the other end of the radio frequency amplifying circuit is connected with the signal output end, and the radio frequency amplifying circuit is configured to receive a radio frequency input signal, amplify the radio frequency input signal and output a radio frequency amplified signal;
one end of the load circuit is connected with the output end of the radio frequency amplification circuit, and the other end of the load circuit is connected with a power supply end;
one end of the low-frequency filter circuit is connected with the power supply end, the other end of the low-frequency filter circuit is connected with the grounding end, and the low-frequency filter circuit is configured to filter low-frequency band signals outside the working frequency band of the low-noise amplification circuit.
Further, the low-frequency filter circuit comprises a first filter capacitor.
Further, the low-frequency filter circuit further includes a first filter resistor connected in series with the first filter capacitor, or a first filter inductor connected in series with the first filter capacitor.
Further, the low-frequency filter circuit further comprises a first filter resistor and a first filter inductor which are connected with the first filter capacitor in series.
Further, the capacitance reactance of the first filter capacitor is less than 10 ohms.
Further, the low-noise amplification circuit further comprises a high-frequency filter circuit configured to filter a high-frequency band signal outside an operating frequency band of the low-noise amplification circuit;
one end of the high-frequency filter circuit is connected with the output end of the radio-frequency amplifying circuit, and the other end of the high-frequency filter circuit is connected with the grounding end, or one end of the high-frequency filter circuit is connected with the input end of the radio-frequency amplifying circuit, and the other end of the high-frequency filter circuit is connected with the grounding end.
Further, the capacitive reactance of the high-frequency filter circuit is less than 10 ohms.
Further, the high frequency filter circuit comprises a second filter capacitor, wherein the capacitance value of the second filter capacitor is smaller than that of the first filter capacitor.
Further, the high frequency filter circuit includes a filter switch, wherein a capacitance value of a parasitic capacitance of the filter switch in a closed state is smaller than a capacitance value of the first filter capacitance.
Furthermore, the low-noise amplification circuit further comprises an in-band stabilizing circuit, one end of the in-band stabilizing circuit is connected with the output end of the radio-frequency amplification circuit, and the other end of the in-band stabilizing circuit is connected with the input end of the radio-frequency amplification circuit.
Further, the in-band stabilization circuit includes a first feedback capacitor and a first feedback resistor connected in series.
A low-noise amplifying circuit comprises a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit, a low-frequency filter circuit, a high-frequency filter circuit and an in-band stabilizing circuit; one end of the radio frequency amplifying circuit is connected with the signal input end, the other end of the radio frequency amplifying circuit is connected with the signal output end, and the radio frequency amplifying circuit is configured to receive a radio frequency input signal, amplify the radio frequency input signal and output a radio frequency amplified signal; one end of the load circuit is connected with the output end of the radio frequency amplification circuit, and the other end of the load circuit is connected with a power supply end;
one end of the low-frequency filter circuit is connected with the power supply end, the other end of the low-frequency filter circuit is connected with the grounding end, and the low-frequency filter circuit is configured to filter low-frequency band signals outside the working frequency band of the low-noise amplification circuit;
one end of the high-frequency filter circuit is connected with the output end of the radio-frequency amplification circuit, and the other end of the high-frequency filter circuit is connected with a grounding end, or one end of the high-frequency filter circuit is connected with the input end of the radio-frequency amplification circuit, and the other end of the high-frequency filter circuit is connected with the grounding end, and the high-frequency filter circuit is configured to filter high-frequency band signals outside the working frequency band of the low-noise amplification circuit;
one end of the in-band stabilizing circuit is connected with the output end of the radio frequency amplifying circuit, and the other end of the in-band stabilizing circuit is connected with the input end of the radio frequency amplifying circuit.
The low-noise amplifying circuit comprises a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit and a low-frequency filter circuit. The load circuit is configured to feed power to the radio-frequency amplification circuit in a manner of being matched with the power supply end and acquire a low-frequency-band signal at the output end of the radio-frequency amplification circuit; the low-frequency filter circuit is used for filtering the low-frequency band signal in the radio-frequency amplification signal and releasing the low-frequency band signal to the ground, the radio-frequency signal in the low-noise amplification circuit is divided into the radio-frequency amplification signal in the working frequency band and the low-frequency band signal outside the working frequency band, the low-frequency filter circuit is used for filtering the low-frequency band signal outside the working frequency band, the low-frequency filter circuit only filters the low-frequency band signal outside the working frequency band and has no influence on the radio-frequency amplification signal in the working frequency band, namely the low-frequency filter circuit does not influence the gain of the radio-frequency amplification signal in the working frequency band in the process of filtering the low-frequency band signal outside the working frequency band, so that the stability of the radio-frequency amplification signal in the working frequency band in the low-noise amplification circuit is ensured, and the gain requirement of the low-noise amplifying circuit can be met.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention 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 that other drawings can be obtained according to these drawings without inventive labor.
FIG. 1 is a circuit diagram of a low noise amplifier circuit according to an embodiment of the present invention;
FIG. 2 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 3 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 4 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 5 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 6 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 7 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 8 is another circuit diagram of the LNA in accordance with one embodiment of the present invention;
FIG. 9 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
FIG. 10 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the present invention;
fig. 11 is another circuit diagram of the low noise amplifier circuit according to an embodiment of the invention.
In the figure: 10. a signal input terminal; 20. a signal output terminal; 30. a radio frequency amplification circuit; 40. a load circuit; 50. a low frequency filter circuit; 60. a high-frequency filter circuit; 70. an in-band stabilization circuit; 80. a gain adjustment circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity to indicate like elements throughout.
It will be understood that when an element or layer is referred to as being "on …," "adjacent to …," "connected to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatial relational terms such as "under …," "under …," "below," "under …," "over …," "above," and the like may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.
The present embodiment provides a low-noise amplifier circuit, as shown in fig. 1, including a signal input terminal 10, a signal output terminal 20, a radio frequency amplifier circuit 30, a load circuit 40, and a low-frequency filter circuit 50; one end of the rf amplifying circuit 30 is connected to the signal input terminal 10, and the other end of the rf amplifying circuit 30 is connected to the signal output terminal 20, and is configured to receive an rf input signal, amplify the rf input signal, and output an rf amplified signal. One end of the load circuit 40 is connected to the output end of the rf amplifying circuit 30, and the other end of the load circuit 40 is connected to the power supply terminal VDD. One end of the low-frequency filter circuit 50 is connected to the power supply terminal VDD, and the other end of the low-frequency filter circuit 50 is connected to the ground terminal, and is configured to filter a low-frequency band signal outside the operating frequency band of the low-noise amplifier circuit.
The radio frequency input signal is a signal to be amplified. The rf amplification signal is a signal obtained by amplifying the rf input signal by the rf amplification circuit 30. The signal input 10 is a port for receiving a radio frequency input signal. The signal output terminal 20 is a port for outputting the rf amplified signal. The working frequency band of the low-noise amplifying circuit is a frequency band in which the low-noise amplifying circuit can amplify the radio frequency input signal without distortion. The operating frequency band of the low-noise amplifier circuit may also be referred to as the passband of the low-noise amplifier circuit. The low-frequency band signal is a signal smaller than the working frequency band of the low-noise amplification circuit.
For example, if the low-noise amplifier circuit can amplify the rf input signal with a frequency between 300KHZ and 3000KHZ without distortion, that is, the operating frequency range of the low-noise amplifier circuit is 300KHZ to 3000KHZ, the low-frequency band signal outside the operating frequency range of the low-noise amplifier circuit is a frequency band with a frequency less than 300 KHZ. It should be noted that the operating frequency bands corresponding to different low noise amplification circuits may be different.
As an example, the rf amplifying circuit 30 is disposed between the signal input terminal 10 and the signal output terminal 20, and configured to receive an rf input signal, amplify the rf input signal, and output an rf amplified signal. The rf amplifying circuit 30 may include one or more stages of power amplifying circuits; the rf amplifying circuit 30 may include a plurality of stages of power amplifying circuits to amplify the rf input signal in a plurality of stages. In this example, the rf amplifying circuit 30 is illustrated as including a first stage power amplifying circuit. Specifically, the radio frequency amplification circuit 30 includes a first stage power amplification circuit including a plurality of amplification transistors connected in series. Each amplification transistor may be a BJT transistor (e.g., HBT transistor) or a field effect transistor, among others. For example, the power amplifying circuit includes a first amplifying transistor M31 and a second amplifying transistor M32 connected in series.
In a specific embodiment, as shown in fig. 2, the rf amplifying circuit 30 may include a first stage power amplifying circuit including a first amplifying transistor M31 and a second amplifying transistor M32 connected in series, and a first dc blocking capacitor C31 disposed between the signal input terminal 10 and the input terminal of the first amplifying transistor M31. Wherein, the first dc blocking capacitor C31 is configured to block a dc signal in the rf input signal.
Specifically, the base (gate) of the first amplifying transistor M31 is connected to the first dc blocking capacitor C31, the collector (source) is connected to the emitter (drain) of the second amplifying transistor M32, and the emitter (drain) of the first amplifying transistor M31 is connected to the ground, and is configured to perform a first signal amplification on the rf input signal in the signal amplification mode; the base (gate) of the second amplifying transistor M32 is connected to the power supply terminal VDD, the collector (source) is connected to the signal output terminal 20, the second amplifying transistor M32 is configured to perform a second signal amplification on the rf input signal, and the rf input signal is amplified by the first amplifying transistor M31 and the second amplifying transistor M32 in the first stage power amplifying circuit and then output to the subsequent stage circuit.
In another embodiment, the rf amplifying circuit 30 may include a multi-stage power amplifying circuit, such as: the rf amplifier circuit 30 includes a first stage power amplifier circuit and a second stage power amplifier circuit, which are connected in series between the signal input terminal 10 and the signal output terminal 20 and configured to amplify the rf input signal in multiple stages, thereby increasing the gain of the low noise amplifier circuit.
In one embodiment, because some non-linear elements exist in the low noise amplifier circuit, the rf input signal may generate some signals outside the working frequency band after being amplified by the rf amplifier circuit 30 in the low noise amplifier circuit, such as: low band signals below the operating band and/or high band signals above the operating band; therefore, excessive useless signals are mixed in the radio frequency amplifying circuit 30, so that the radio frequency amplifying signals in the working frequency band are distorted, and the overall performance of the low-noise amplifying circuit is affected.
In this example, the output terminal of the rf amplifying circuit 30 is connected to a first terminal of a load circuit 40 and to the signal output terminal 20, and a second terminal of the load circuit 40 is connected to a power supply terminal. The power supply VDD feeds the rf amplifying circuit 30 through the load circuit 40. In one embodiment, the load circuit 40 includes a load inductor L41, i.e., the output terminal of the rf amplifying circuit 30 is connected to the power supply terminal through a load inductor L41. Because the load inductor L41 has the functions of blocking high frequency and passing low frequency, most of the low frequency band signals outside the working frequency band in the low noise amplifying circuit will flow to the power supply terminal VDD through the load inductor L41; most high-frequency signals outside the working frequency band in the low-noise amplification circuit are transmitted to the signal output end 20 due to the blocking effect of the load inductor L41.
Therefore, the present application accesses the low frequency filter circuit 50 on the path connecting the power supply terminal VDD and the load circuit 40; therefore, most of low-frequency band signals outside the working frequency band in the low-noise amplifying circuit are released to the ground, and the purpose of filtering the low-frequency band signals outside the working frequency band is achieved; therefore, the rf amplifying circuit 30 outputs the rf amplified signal of the middle frequency band with a good waveform, and then enters the post-stage signal processing system to process the rf amplified signal.
In the present embodiment, the output end of the rf amplifying circuit 30 is connected to the power supply end through the load circuit 40, most of the low-frequency signals outside the operating frequency band in the low-noise amplifying circuit flow to the power supply end VDD through the load circuit 40, and the low-frequency filter circuit 50 is connected to the power supply end VDD; therefore, most of low-frequency band signals outside the working frequency band in the low-noise amplifying circuit are released to the ground, the radio-frequency signals in the low-noise amplifying circuit are divided into radio-frequency amplifying signals inside the working frequency band and low-frequency band signals outside the working frequency band, the low-frequency band signals outside the working frequency band are filtered by the low-frequency filtering circuit 50, the low-frequency filtering circuit 50 only filters the low-frequency band signals outside the working frequency band and does not influence the radio-frequency amplifying signals inside the working frequency band, namely the gain of the radio-frequency amplifying signals inside the working frequency band is not influenced when the low-frequency filtering circuit 50 filters the low-frequency band signals outside the working frequency band, and therefore the gain requirement of the low-noise amplifying circuit can be met while the stability of the radio-frequency amplifying signals inside the working frequency band in the low-noise amplifying circuit is ensured.
In one embodiment, as shown in fig. 2, the low frequency filter circuit 50 includes a first filter capacitor C51.
In this embodiment, one end of the first filter capacitor C51 is connected to the power supply terminal VDD, and the other end is connected to the ground terminal, and is configured to introduce a low-frequency band signal outside the operating frequency band to the ground terminal, without affecting the rf amplification signal within the operating frequency band, so as to ensure the stability of the rf amplification signal within the operating frequency band in the low-noise amplification circuit, and at the same time, not affect the gain of the rf amplification signal within the operating frequency band, so as to meet the gain requirement of the low-noise amplification circuit.
In an embodiment, as shown in fig. 3 to 5, the low frequency filter circuit 50 further includes a first filter resistor R51 and/or a first filter inductor L51; the first filter resistor R51 is connected with the first filter capacitor C51 in series; alternatively, the first filter inductor L51 is connected in series with the first filter capacitor C51; alternatively, the first filter capacitor C51, the first filter resistor R51 and the first filter inductor L51 are connected in series.
As an example, as shown in fig. 3, in order to more effectively filter the low-band signal outside the operating band, the low-band filter circuit 50 may include a first filter capacitor C51 and a first filter resistor R51 connected in series. The first filter capacitor C51 is mainly used to introduce low-frequency signals outside the operating frequency band to the ground. The first filter resistor R51 is mainly used for reducing the influence of the voltage fluctuation of the power supply terminal VDD on the first filter capacitor C51, ensuring the stability of the low-frequency filter circuit 50, and improving the effect of filtering the low-frequency band signals outside the working frequency band.
It should be noted that, since the resistor consumes a certain amount of power, the resistance of the first filter resistor R51 cannot be too large to avoid excessive power loss caused by the first filter resistor R51. Preferably, the first filter resistor R51 has a resistance value of less than 10 ohms.
As another example, as shown in fig. 4, the low frequency filter circuit 50 further includes a first filter capacitor C51 and a first filter inductor L51 connected in series. In this example, the first filter capacitor C51 and the first filter inductor L51 may form a resonant circuit, and when a resonant frequency corresponding to the resonant circuit formed by the first filter capacitor C51 and the first filter inductor L51 is the same as a frequency of a corresponding low-frequency band signal, the resonant circuit formed by the first filter capacitor C51 and the first filter inductor L51 is resistive, and at this time, an impedance of the resonant circuit formed by the first filter capacitor C51 and the first filter capacitor C51 is minimum, so as to filter the low-frequency band signal. Specifically, according to the calculation formula of the resonance frequency:
wherein, foAt the resonant frequency, L is the inductance of the first filter inductor L51, and C is the capacitance of the first filter capacitor C51. From the above calculation formula of the resonance frequency, the resonance frequency foInversely proportional to the inductance L of the first filter inductor L51 and the capacitance C of the first filter capacitor C51. Because the signal to be filtered is a low-frequency-band signal, that is, the frequency of the low-frequency-band signal is small, in order to satisfy that the resonant frequency corresponding to the first filter capacitor C51 and the first filter inductor L51 is the same as the frequency of the low-frequency-band signal; the first filter capacitor C51 should be a capacitor with a larger capacitance, and the first filter inductor L51 should be an inductor with a larger inductance.
Further, in order to more efficiently filter signals with different frequencies in the low frequency band, the first filter capacitor C51 and the first filter inductor L51 can be set to be adjustable, and the signals with different frequencies in the low frequency band can be flexibly filtered by adjusting the capacitance of the first filter capacitor C51 and the inductance of the first filter inductor L51.
As another example, as shown in fig. 5, the low frequency filter circuit 50 may further include a first filter capacitor C51, a first filter resistor R51, and a first filter inductor L51 connected in series. In this example, the first filter capacitor C51, the first filter resistor R51, and the first filter inductor L51 may form a resonant circuit, and when a resonant frequency corresponding to the resonant circuit formed by the first filter capacitor C51, the first filter resistor R51, and the first filter inductor L51 is the same as a frequency of the low-frequency band signal, the resonant circuit formed by the first filter capacitor C51, the first filter resistor R51, and the first filter inductor L51 is resistive, and at this time, an impedance of the resonant circuit formed by the first filter capacitor C51, the first filter resistor R51, and the first filter inductor L51 is minimum, so that the low-frequency band signal is released to the ground, and stability of the low-noise amplification circuit is improved.
It should be noted that the first filter resistor R51 in the low-frequency filter circuit 50 does not generally affect the resonant frequency of the resonant circuit, but can reduce the amplitude of the current and the voltage corresponding to the band signal, control and adjust the resonance of the low-frequency filter circuit 50, improve the filtering effect of the low-frequency band signal, and improve the stability of the low-noise amplifier circuit.
In this embodiment, the low-frequency filter circuit 50 may select a corresponding component combination manner from the first filter capacitor C51, the first filter resistor R51, and the first filter inductor L51 according to an actual application scenario, that is, the low-frequency filter circuit 50 includes a first filter capacitor C51 and a first filter resistor R51 connected in series; alternatively, the low frequency filter circuit 50 includes a first filter capacitor C51 and a first filter inductor L51 connected in series; or, the low-frequency filter circuit 50 includes the first filter capacitor C51, the first filter resistor R51 and the first filter inductor L51 connected in series, and the above-mentioned component combination modes can all carry out filtering processing on the low-frequency band signal, so that most of the low-frequency band signals outside the working frequency band in the low-noise amplifier circuit are released to the ground, because the low-frequency filter circuit 50 only carries out filtering processing on the low-frequency band signals outside the working frequency band, and does not affect the radio-frequency amplified signals in the working frequency band, that is, the low-frequency filter circuit 50 does not affect the gain of the radio-frequency amplified signals in the working frequency band in the process of carrying out filtering processing on the low-frequency band signals outside the working frequency band, thereby realizing that the stability of the radio-frequency amplified signals in the working frequency band in the low-noise amplifier circuit is ensured, and simultaneously, the gain requirement of the low-noise amplifier circuit can be satisfied.
In one embodiment, the capacitance of the first filter capacitor C51 is less than 10 ohms.
As an example, to filter out low band signals outside the operating band of the low noise amplification circuit. In this example, the low frequency filter circuit 50 needs to satisfy the capacitive reactance Z of the first filter capacitor C51CIs small enough. In the present embodiment, the capacitive reactance of the first filtering capacitor C51 should be set to be less than 10 ohms so as to better filter the low-frequency band signal. Specifically, according to the calculation formula of the capacitive reactance:
wherein Z iscThe capacitance of the first filter capacitor C51, f is the operating frequency of the low noise amplifier circuit, and C is the capacitance of the capacitor. As can be seen from the above formula, in an actual application scenario of the low-noise amplifier circuit, the operating frequency f of the low-noise amplifier circuit is fixed, and meanwhile, in order to ensure the effect of filtering low-frequency band signals, the capacitive reactance Z of the first filter capacitor C51 iscShould be sufficiently small, i.e. satisfy the capacitive reactance small Z of the first filter capacitor C51cLess than 10 ohms, and therefore, the first filter capacitor C51 should be sufficiently large. In this embodiment, in order to release most of the low-frequency signals outside the operating frequency band in the low-noise amplifying circuit to the ground to perform the filtering processing on the low-frequency signals, the first filtering capacitor C51 should be a capacitor with a relatively large capacitance.
In the present embodiment, the capacitance value of the first filter capacitor C51 is set to be large enough so that the capacitive reactance Z of the first filter capacitor C51CLess than 10 ohms of the gas to be heated,therefore, the gain of the radio frequency amplification signal in the working frequency band is not influenced in the process of filtering the low frequency band signal outside the working frequency band by the low frequency filter circuit 50, so that the stability of the radio frequency amplification signal in the working frequency band in the low noise amplification circuit is ensured, and the gain requirement of the low noise amplification circuit can be met.
In one embodiment, as shown in fig. 6 and 7, the low noise amplifier circuit further includes a high frequency filter circuit 60, one end of the high frequency filter circuit 60 is connected to the output terminal of the rf amplifier circuit 30, and the other end of the high frequency filter circuit 60 is connected to the ground terminal. Or, one end of the high-frequency filter circuit 60 is connected to the input end of the radio-frequency amplifying circuit 30, and the other end of the high-frequency filter circuit 60 is connected to the ground end; is configured to filter the high-band signal outside the operating band of the low-noise amplification circuit.
As an example, as shown in fig. 6, one end of the high-frequency filter circuit 60 is connected to the output end of the radio frequency amplification circuit 30, and the other end is connected to the ground end, and is configured to filter a high-frequency band signal in the radio frequency amplified signal. In this example, because the load inductor L41 in the load circuit 40 has the functions of high frequency resistance and low frequency pass, most of the high frequency band signals outside the operating frequency band in the low noise amplifier circuit are transmitted to the signal output terminal 20 due to the blocking function of the load inductor L41, therefore, the application realizes that most of the high frequency band signals outside the operating frequency band in the output terminal of the low noise amplifier circuit are released to the ground through the high frequency filter circuit 60 by accessing the high frequency filter circuit 60 at the output terminal of the radio frequency amplifier circuit 30, so as to realize the effect of high frequency band signal filtering, and further improve the overall performance of the low noise amplifier circuit.
As another example, as shown in fig. 7, a high frequency band signal outside the operating frequency band may exist due to the input terminal of the low noise amplification circuit. Therefore, the present application may further include a high frequency filter circuit 60 at the input of the rf amplifying circuit 30. Specifically, one end of the high-frequency filter circuit 60 is connected to the input terminal of the radio frequency amplification circuit 30, and the other end is connected to the ground terminal. By connecting the high-frequency filter circuit 60 to the input end of the radio-frequency amplifying circuit 30, most high-frequency signals outside the working frequency range in the input end of the low-noise amplifying circuit are released to the ground, so that the effect of filtering the high-frequency signals is realized, and the overall performance of the low-noise amplifying circuit is improved.
In this embodiment, the present application divides the radio frequency signal in the low noise amplifier circuit into a radio frequency amplified signal within the working frequency band, a low frequency band signal outside the working frequency band, and a high frequency band signal outside the working frequency band, and filters the low frequency band signal outside the working frequency band by using the low frequency filter circuit 50, and filters the high frequency band signal outside the working frequency band by using the high frequency filter circuit 60; because the low-frequency filter circuit 50 only filters low-frequency band signals outside the working frequency band, the high-frequency filter circuit 60 only filters high-frequency band signals outside the working frequency band, and does not affect radio-frequency amplification signals inside the working frequency band, namely, the gain of the radio-frequency amplification signals inside the working frequency band is not affected by the low-frequency filter circuit 50 in the process of filtering the low-frequency band signals outside the working frequency band and the gain of the radio-frequency amplification signals inside the working frequency band of the high-frequency filter circuit 60 in the process of filtering the high-frequency band signals outside the working frequency band, thereby realizing the stability of the radio-frequency amplification signals inside the working frequency band in the low-noise amplification circuit and meeting the gain requirement of the low-noise amplification circuit.
By arranging the high-frequency filter circuit 60 at the input end and/or the output end of the radio-frequency amplification circuit 30, the filtering processing of the high-frequency band signals outside the working frequency band in the input end and/or the output end of the low-noise amplification circuit is realized, and the overall performance of the low-noise amplification circuit is improved.
In one embodiment, the high frequency filter circuit 60 has a capacitive reactance of less than 10 ohms.
As an example, to filter out high band signals outside the operating band of the low noise amplification circuit. In this example, the high-frequency filter circuit 60 needs to satisfy the adjustment that the capacitive reactance is small enough, and in this embodiment, the capacitive reactance of the high-frequency filter circuit 60 is set to be less than 10 ohms, so that the high-frequency band signal is filtered based on the low impedance of the high-frequency filter circuit 60.
In this embodiment, the capacitive reactance of the high-frequency filter circuit 60 is set to be less than 10 ohms so as to release most of the high-frequency band signals outside the working frequency band in the low-noise amplifier circuit to the ground, and since the high-frequency filter circuit 60 only filters the high-frequency band signals outside the working frequency band and has no influence on the radio-frequency amplified signals within the working frequency band, the stability of the radio-frequency amplified signals within the working frequency band in the low-noise amplifier circuit is ensured, and the gain of the radio-frequency amplified signals within the working frequency band is not influenced, so as to meet the gain requirement of the low-noise amplifier circuit.
In one embodiment, as shown in fig. 8, the high frequency filter circuit 60 includes a second filter capacitor C61, wherein the capacitance of the second filter capacitor C61 is smaller than the capacitance of the first filter capacitor C51.
As an example, the high frequency filter circuit 60 needs to satisfy that the capacitive reactance of the high frequency filter circuit 60 is less than 10 ohms in the process of filtering out the high frequency band signal outside the operating frequency band of the low noise amplifier circuit. Therefore, in the present embodiment, the capacitance of the second filter capacitor C61 in the high-frequency filter circuit 60 is set to be less than 10 ohms. Specifically, since the frequency of the high band signal is greater than the frequency of the operating band signal, according to the calculation formula of the capacitive reactance:
wherein Z iscoIs the capacitive reactance, f, of the second filter capacitor C61oIs the frequency of the high band signal, CoThe capacitance value of the second filter capacitor C61 is known. Capacitance value C of second filter capacitor C61oWhen the capacitance value C is smaller than the capacitance value C of the first filter capacitor C51, the high-band signal can be effectively filtered. It should be noted that, for filtering the high-frequency band signal, the capacitance value of the second filter capacitor C61 may be selected to be larger or smaller, and both the capacitance values can satisfy that the capacitance of the second filter capacitor C61 should be smaller than 10 ohms, so as to implement the operation of the working frequency band in the low-noise amplification circuitMost of the outer high band signals are released to ground. However, in practical applications, in consideration of the cost of the second filter capacitor C61 and the filtering effect of the high-frequency band signal, the capacitance of the second filter capacitor C61 is set to be smaller, that is, the capacitance of the second filter capacitor C61 is smaller than the capacitance of the first filter capacitor C51.
In this embodiment, in order to release most of the high-band signals outside the operating band in the low-noise amplifier circuit to the ground to improve the effect of filtering the high-band signals, the capacitance of the second filter capacitor C61 is smaller than that of the first filter capacitor C51, so that the cost of the second filter capacitor C61 is reduced while the high-band signals are filtered.
In one embodiment, as shown in fig. 9, the high frequency filter circuit 60 includes a filter switch S61, wherein the capacitance value of the parasitic capacitor of the filter switch in the closed state is smaller than the capacitance value of the first filter capacitor C51.
The filter switch S61 is a switch for filtering out high-frequency band signals. It should be noted that, due to the manufacturing process of the filter switch S61, the filter switch S61 has a parasitic capacitor with a small capacitance value in the closed state, so that when the filter switch S61 is closed, the high-band signal can be filtered through the parasitic capacitor, and the high-band signal is released to the ground. It should be noted that, the capacitance value of the parasitic capacitor of the filter switch in the closed state is smaller than the capacitance value of the first filter capacitor C51, and the derivation process of the magnitude relationship between the capacitance value of the parasitic capacitor of the filter switch in the closed state and the capacitance value of the first filter capacitor C51 is similar to the derivation process of the magnitude relationship between the capacitance value of the second filter capacitor C61 and the capacitance value of the first filter capacitor C51 in the foregoing embodiment, which is not repeated herein.
In this embodiment, in order to release most of the high-band signals outside the operating band in the low-noise amplifying circuit to the ground, so as to implement filtering processing on the high-band signals, the capacitance value of the parasitic capacitor of the filter switch in the closed state is smaller than the capacitance value of the first filter capacitor C51, so that while the filtering processing on the high-band signals is implemented, the cost of the filter switch is reduced, and the filtering effect of the high-band signals is improved.
In one embodiment, as shown in fig. 10, the low noise amplifier circuit further includes an in-band stabilizing circuit 70, one end of the in-band stabilizing circuit 70 is connected to the output terminal of the rf amplifier circuit 30, and the other end of the in-band stabilizing circuit 70 is connected to the input terminal of the rf amplifier circuit 30.
In the present embodiment, one end of the in-band stabilizing circuit 70 is connected to the output terminal of the rf amplifying circuit 30, and the other end is connected to the input terminal of the rf amplifying circuit 30, which is configured to further ensure the stability of the low noise amplifying circuit.
Optionally, as shown in fig. 10, the low noise amplification circuit further includes a second dc blocking capacitor C11 disposed on the output path. For example, a first terminal of a second dc blocking capacitor C11 is connected to the in-band stabilization circuit 70, and a second terminal of the second dc blocking capacitor is connected to the signal output terminal 20.
In one embodiment, as shown in fig. 11, the in-band stabilization circuit 70 includes a first feedback capacitor C71 and a first feedback resistor R71 connected in series.
In the present embodiment, the in-band stabilizing circuit 70 includes a first feedback capacitor C71 and a first feedback resistor R71 connected in series, and is configured to further ensure the stability of the low noise amplifier circuit.
Further, as shown in fig. 9, the low noise amplification circuit further includes a gain adjustment circuit 80; the gain adjustment circuit 80 has one end connected to the rf amplification circuit 30 and the other end connected to the ground, and is configured to perform gain adjustment on the rf amplification circuit 30.
As an example, the gain adjustment circuit 80 includes a gain adjustment inductor L81, a gain adjustment inductor L81, one end of which is connected to the rf amplification circuit 30, and the other end of which is connected to the ground terminal, and is configured to perform gain adjustment on the rf amplification circuit 30.
In the present embodiment, the gain adjustment circuit 80 performs gain adjustment on the radio frequency amplifier circuit 30 to increase the gain of the low noise amplifier circuit.
In another embodiment, the low noise amplifier circuit comprises a signal input terminal 10, a signal output terminal 20, a radio frequency amplifier circuit 30, a load circuit 40 and a high frequency filter circuit 60; a radio frequency amplifying circuit 30, one end of which is connected to the signal input terminal 10 and the other end of which is connected to the signal output terminal 20, configured to receive a radio frequency input signal, amplify the radio frequency input signal, and output a radio frequency amplified signal; the load circuit 40, one end of which is connected with the output end of the radio frequency amplifying circuit 30, and the other end is connected with the power supply end; one end of the high-frequency filter circuit 60 is connected to the output end of the rf amplifier circuit 30, and the other end is connected to the ground terminal, or one end of the high-frequency filter circuit 60 is connected to the input end of the rf amplifier circuit 30, and the other end is connected to the ground terminal. The high-frequency filter circuit 60 is configured to filter-process a high-frequency band signal outside the operating frequency band of the low-noise amplification circuit. The specific circuit structure of the high-frequency filter circuit 60 and the working principle of filtering the high-frequency band signal outside the working frequency band of the low-noise amplifier circuit are described in detail in the above embodiments, and redundant description is not repeated here.
Further, the low-noise amplification circuit in the present embodiment further includes a low-frequency filter circuit 50; the low-frequency filter circuit 50 has one end connected to the power supply terminal and the other end connected to the ground terminal, and is configured to filter a low-frequency band signal outside the operating frequency band of the low-noise amplifier circuit. The low-frequency filter circuit 50 includes a first filter capacitor and a first filter resistor connected in series; alternatively, the low-frequency filter circuit 50 includes a first filter capacitor and a first filter inductor connected in series; alternatively, the low frequency filter circuit 50 includes a first filter capacitor, a first filter resistor, and a first filter inductor connected in series. And the capacitive reactance of the first filter capacitor is less than 10 ohms. The working principle of the low-frequency filter circuit 50 for filtering the low-frequency band signal outside the working frequency band of the low-noise amplifier circuit is described in detail in the above embodiments, and redundant description is not repeated here.
Further, the low noise amplifier circuit in this embodiment further includes an in-band stabilizing circuit 70, where one end of the in-band stabilizing circuit 70 is connected to the output end of the rf amplifier circuit 30, and the other end is connected to the input end of the rf amplifier circuit 30. The in-band stabilizing circuit 70 includes a first feedback capacitor and a first feedback resistor connected in series, and is configured to further ensure the stability of the low noise amplification circuit. The working principle of the in-band stabilizing circuit 70 has been described in detail in the above embodiments, and redundant description is not repeated here.
The present embodiment provides a low noise amplifier circuit, which includes a signal input terminal 10, a signal output terminal 20, a radio frequency amplifier circuit 30, a load circuit 40, a low frequency filter circuit 50, a high frequency filter circuit 60, and an in-band stabilizing circuit 70. One end of the rf amplifying circuit 30 is connected to the signal input terminal 10, and the other end of the rf amplifying circuit 30 is connected to the signal output terminal 20, and is configured to receive an rf input signal, amplify the rf input signal, and output an rf amplified signal. One end of the load circuit 40 is connected to the output end of the rf amplifying circuit 30, and the other end of the load circuit 40 is connected to the power supply terminal. One end of the low-frequency filter circuit 50 is connected to a power supply terminal, and the other end of the low-frequency filter circuit 50 is connected to a ground terminal, and is configured to filter a low-frequency band signal outside the operating frequency band of the low-noise amplifier circuit. One end of the high-frequency filter circuit 60 is connected to the output end of the radio-frequency amplification circuit 30, and the other end of the high-frequency filter circuit 60 is connected to the ground, or one end of the high-frequency filter circuit 60 is connected to the input end of the radio-frequency amplification circuit 30, and the other end of the high-frequency filter circuit 60 is connected to the ground, and the high-frequency filter circuit 60 is configured to filter a high-frequency band signal outside the operating frequency band of the low-noise amplification circuit. One end of the in-band stabilizing circuit 70 is connected to the output end of the rf amplifying circuit 30, and the other end of the in-band stabilizing circuit 70 is connected to the input end of the rf amplifying circuit 30.
In one embodiment, the rf amplifying circuit 30, having one end connected to the signal input terminal 10 and the other end connected to the signal output terminal 20, is configured to receive an rf input signal, amplify the rf input signal, and output an rf amplified signal. In this embodiment, the rf amplifying circuit 30 may include a multi-stage power amplifying circuit, such as: the rf amplifier circuit 30 includes a first stage power amplifier circuit and a second stage power amplifier circuit, which are connected in series between the signal input terminal 10 and the signal output terminal 20 and configured to amplify the rf input signal in multiple stages, thereby increasing the gain of the low noise amplifier circuit.
In a specific embodiment, the output terminal of the rf amplifying circuit 30 is connected to a first terminal of the load circuit 40 and to the signal output terminal 20, and a second terminal of the load circuit 40 is connected to the power supply terminal. The power supply VDD feeds the rf amplifying circuit 30 through the load circuit 40. In one embodiment, the load circuit 40 includes a load inductor L41, i.e., the output terminal of the rf amplifying circuit 30 is connected to the power supply terminal through a load inductor L41. Because the load inductor L41 has the functions of blocking high frequency and passing low frequency, most of the low frequency band signals outside the working frequency band in the low noise amplifying circuit will flow to the power supply terminal VDD through the load inductor L41; most high-frequency signals outside the working frequency band in the low-noise amplification circuit are transmitted to the signal output end 20 due to the blocking effect of the load inductor L41.
In a specific embodiment, the output terminal of the rf amplifying circuit 30 is connected to the power supply terminal through the load circuit 40, and most of the low frequency band signals outside the operating frequency band in the low noise amplifying circuit flow to the power supply terminal VDD through the load circuit 40, and the low frequency filter circuit 50 is connected to the power supply terminal VDD; therefore, most of low-frequency band signals outside the working frequency band in the low-noise amplifying circuit are released to the ground, the radio-frequency signals in the low-noise amplifying circuit are divided into radio-frequency amplifying signals inside the working frequency band and low-frequency band signals outside the working frequency band, the low-frequency band signals outside the working frequency band are filtered by the low-frequency filtering circuit 50, the low-frequency filtering circuit 50 only filters the low-frequency band signals outside the working frequency band and does not influence the radio-frequency amplifying signals inside the working frequency band, namely the gain of the radio-frequency amplifying signals inside the working frequency band is not influenced when the low-frequency filtering circuit 50 filters the low-frequency band signals outside the working frequency band, and therefore the gain requirement of the low-noise amplifying circuit can be met while the stability of the radio-frequency amplifying signals inside the working frequency band in the low-noise amplifying circuit is ensured.
The low-noise amplifying circuit further comprises a high-frequency filter circuit 60, wherein one end of the high-frequency filter circuit 60 is connected with the output end of the radio-frequency amplifying circuit 30, and the other end of the high-frequency filter circuit 60 is connected with the ground end; or, one end of the high-frequency filter circuit 60 is connected to the input end of the radio-frequency amplifying circuit 30, and the other end is connected to the ground end; is configured to filter the high-band signal outside the operating band of the low-noise amplification circuit.
As an example, as shown in fig. 6, one end of the high-frequency filter circuit 60 is connected to the output end of the radio frequency amplification circuit 30, and the other end is connected to the ground end, and is configured to filter a high-frequency band signal in the radio frequency amplified signal. In this example, because the load inductor L41 in the load circuit 40 has the functions of high frequency resistance and low frequency pass, most of the high frequency band signals outside the operating frequency band in the low noise amplifier circuit are transmitted to the signal output terminal 20 due to the blocking function of the load inductor L41, therefore, the application realizes that most of the high frequency band signals outside the operating frequency band in the output terminal of the low noise amplifier circuit are released to the ground through the high frequency filter circuit 60 by accessing the high frequency filter circuit 60 at the output terminal of the radio frequency amplifier circuit 30, so as to realize the effect of high frequency band signal filtering, and further improve the overall performance of the low noise amplifier circuit.
As another example, as shown in fig. 7, a high frequency band signal outside the operating frequency band may exist due to the input terminal of the low noise amplification circuit. Therefore, the present application may further include a high frequency filter circuit 60 at the input of the rf amplifying circuit 30. Specifically, one end of the high-frequency filter circuit 60 is connected to the input terminal of the radio frequency amplification circuit 30, and the other end is connected to the ground terminal. By connecting the high-frequency filter circuit 60 to the input end of the radio-frequency amplifying circuit 30, most high-frequency signals outside the working frequency range in the input end of the low-noise amplifying circuit are released to the ground, so that the effect of filtering the high-frequency signals is realized, and the overall performance of the low-noise amplifying circuit is improved.
In this embodiment, the present application divides the radio frequency signal in the low noise amplifier circuit into a radio frequency amplified signal within the working frequency band, a low frequency band signal outside the working frequency band, and a high frequency band signal outside the working frequency band, and filters the low frequency band signal outside the working frequency band by using the low frequency filter circuit 50, and filters the high frequency band signal outside the working frequency band by using the high frequency filter circuit 60; because the low-frequency filter circuit 50 only filters the low-frequency band signals outside the working frequency band, the high-frequency filter circuit 60 only filters the high-frequency band signals outside the working frequency band, and has no influence on the radio-frequency amplified signals inside the working frequency band, that is, while the absolute stability of the radio-frequency amplified signals inside the working frequency band is ensured by the in-band stabilizing circuit 70, the low-frequency band signals outside the working frequency band are also filtered by the low-frequency filter circuit 50, and the high-frequency band signals outside the working frequency band are filtered by the high-frequency filter circuit 60, and the gain of the radio-frequency amplified signals inside the working frequency band is not influenced in the processes that the low-frequency band signals outside the working frequency band are filtered by the low-frequency filter circuit 50 and the high-frequency band signals outside the working frequency band are filtered by the high-frequency filter circuit 60, thereby realizing that under the combined action of the low-frequency filter circuit 50, the high-frequency filter circuit 60 and the in-band stabilizing circuit 70, the stability of the radio frequency amplification signal in the working frequency band in the low-noise amplification circuit can be guaranteed, and meanwhile the gain requirement of the low-noise amplification circuit can be met.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will 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 invention, and are intended to be included within the scope of the present invention.
Claims (12)
1. A low-noise amplifying circuit is characterized by comprising a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit and a low-frequency filter circuit;
one end of the radio frequency amplifying circuit is connected with the signal input end, and the other end of the radio frequency amplifying circuit is connected with the signal output end, and the radio frequency amplifying circuit is configured to receive a radio frequency input signal, amplify the radio frequency input signal and output a radio frequency amplified signal;
one end of the load circuit is connected with the output end of the radio frequency amplification circuit, and the other end of the load circuit is connected with a power supply end;
one end of the low-frequency filter circuit is connected with the power supply end, the other end of the low-frequency filter circuit is connected with the grounding end, and the low-frequency filter circuit is configured to filter low-frequency band signals outside the working frequency band of the low-noise amplification circuit.
2. The low-noise amplification circuit of claim 1, wherein the low-frequency filter circuit comprises a first filter capacitor.
3. The low-noise amplification circuit of claim 2, wherein the low-frequency filter circuit further comprises a first filter resistor connected in series with the first filter capacitor, or a first filter inductor connected in series with the first filter capacitor.
4. The low-noise amplification circuit of claim 2, wherein the low-frequency filter circuit further comprises a first filter resistor and a first filter inductor connected in series with the first filter capacitor.
5. The low noise amplification circuit of claim 2, wherein the capacitance of the first filter capacitor is less than 10 ohms.
6. The low-noise amplification circuit according to claim 2, further comprising a high-frequency filter circuit configured to filter a high-frequency band signal outside an operating frequency band of the low-noise amplification circuit;
one end of the high-frequency filter circuit is connected with the output end of the radio-frequency amplifying circuit, and the other end of the high-frequency filter circuit is connected with the grounding end, or one end of the high-frequency filter circuit is connected with the input end of the radio-frequency amplifying circuit, and the other end of the high-frequency filter circuit is connected with the grounding end.
7. The low-noise amplification circuit of claim 6, wherein the high-frequency filter circuit has a capacitive reactance of less than 10 ohms.
8. The low-noise amplification circuit of claim 7, wherein the high-frequency filter circuit comprises a second filter capacitor, wherein a capacitance value of the second filter capacitor is smaller than a capacitance value of the first filter capacitor.
9. The low-noise amplification circuit according to claim 7, wherein the high-frequency filter circuit includes a filter switch, and wherein a capacitance value of a parasitic capacitance of the filter switch in a closed state is smaller than a capacitance value of the first filter capacitance.
10. The low noise amplification circuit of any one of claims 1 to 9, further comprising an in-band stabilizing circuit, one end of the in-band stabilizing circuit being connected to the output of the rf amplification circuit, the other end of the in-band stabilizing circuit being connected to the input of the rf amplification circuit.
11. The low noise amplification circuit of claim 10, wherein the in-band stabilization circuit comprises a first feedback capacitor and a first feedback resistor connected in series.
12. A low-noise amplifying circuit is characterized by comprising a signal input end, a signal output end, a radio frequency amplifying circuit, a load circuit, a low-frequency filter circuit, a high-frequency filter circuit and an in-band stabilizing circuit; one end of the radio frequency amplifying circuit is connected with the signal input end, and the other end of the radio frequency amplifying circuit is connected with the signal output end, and the radio frequency amplifying circuit is configured to receive a radio frequency input signal, amplify the radio frequency input signal and output a radio frequency amplified signal; one end of the load circuit is connected with the output end of the radio frequency amplification circuit, and the other end of the load circuit is connected with a power supply end;
one end of the low-frequency filter circuit is connected with the power supply end, the other end of the low-frequency filter circuit is connected with the grounding end, and the low-frequency filter circuit is configured to filter low-frequency band signals outside the working frequency band of the low-noise amplification circuit;
one end of the high-frequency filter circuit is connected with the output end of the radio-frequency amplification circuit, and the other end of the high-frequency filter circuit is connected with a grounding end, or one end of the high-frequency filter circuit is connected with the input end of the radio-frequency amplification circuit, and the other end of the high-frequency filter circuit is connected with the grounding end, and the high-frequency filter circuit is configured to filter high-frequency band signals outside the working frequency band of the low-noise amplification circuit;
one end of the in-band stabilizing circuit is connected with the output end of the radio frequency amplifying circuit, and the other end of the in-band stabilizing circuit is connected with the input end of the radio frequency amplifying circuit.
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