Low noise amplifier and radio frequency front end module
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-25
- Publication Date
- 2026-08-11
Smart Images
Figure CN122553855A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of radio frequency technology, and in particular to a low-noise amplifier and radio frequency front-end module with adaptive gain control function. Background Technology
[0002] The Radio Frequency Front-End (RFFE) is a crucial component of the signal reception link in a wireless communication system. It is responsible for filtering, amplifying, and down-converting the weak radio frequency signals received by the antenna before sending them to the System on Chip (SOC) for demodulation and digitization. In the RFFE reception link, the Low Noise Amplifier (LNA), as the first-stage active amplifier circuit at the receiver, plays a critical role in amplifying small signals with low noise. Therefore, the noise figure (NF) and gain of the LNA directly determine the sensitivity and dynamic range of the entire receiving system, and its performance has a vital impact on the quality of wireless communication.
[0003] With the development of communication technology, the modern wireless communication environment is becoming increasingly complex, and the fluctuation range of the received signal strength of LNA has increased significantly. Therefore, how to balance the noise performance and linearity of LNA in a complex and ever-changing wireless communication environment, and adapt to the large fluctuations in the received signal strength, has become a technical problem in this field.
[0004] Application content
[0005] In view of the above problems, this application provides a low-noise amplifier and RF front-end module with adaptive gain control function. The specific solution is as follows:
[0006] A low-noise amplifier with adaptive gain control includes:
[0007] An input matching network and a transconductance amplifier stage are provided, wherein the input matching network includes an input matching element for receiving radio frequency signals, and the transconductance amplifier stage is used to amplify the radio frequency signals transmitted through the input matching network;
[0008] A signal acquisition element is used to couple the radio frequency signal transmitted in the input matching element;
[0009] A gain control circuit is used to control the gain of the low-noise amplifier based on the signal on the signal acquisition element, wherein the low-noise amplifier has a first gain when the signal on the signal acquisition element has a first strength, and the low-noise amplifier has a second gain when the signal on the signal acquisition element has a second strength, wherein the first strength is greater than the second strength, and the first gain is less than the second gain.
[0010] Optionally, the input matching network includes a first inductor and a first capacitor, and the input matching element is the first inductor or the first capacitor; the signal acquisition element is a conductor that is signal-coupled with the input matching element.
[0011] Optionally, the input matching element is the first inductor; the signal acquisition element includes a coupling coil, which is coupled to the first inductor to form a coupled transmission line structure.
[0012] Optionally, the gain control circuit includes:
[0013] The detection circuit is electrically connected to the signal acquisition element and is used to convert the radio frequency signal coupled by the signal acquisition element into a DC detection voltage. The magnitude of the DC detection voltage reflects the power intensity of the radio frequency signal input in the input matching network.
[0014] A comparison circuit, electrically connected to the detection circuit, is used to compare the DC detection voltage with at least one reference voltage and output the comparison result.
[0015] An attenuation control circuit, electrically connected to the comparison circuit, is used to adjust the gain of the low-noise amplifier based on the comparison result.
[0016] Optionally, the detection circuit includes at least one detection branch, which is used to convert the radio frequency signal coupled by the signal acquisition element into a DC detection voltage for output;
[0017] The comparison circuit includes at least one comparison branch, which corresponds one-to-one with the detection branch. It is used to output a comparison result based on the DC detection voltage output by the corresponding detection branch and its corresponding reference voltage. The reference voltages corresponding to different comparison branches are different.
[0018] Optionally, the detection circuit includes a second capacitor and at least one detection branch, wherein the second capacitor is connected to the output terminal of the signal acquisition element and is used to isolate the DC component in the coupled signal output by the signal acquisition element;
[0019] The detection branch includes a peak detection circuit connected to the output terminal of the second capacitor. It is used to rectify and maintain the peak value of the radio frequency signal output by the second capacitor, and output a DC detection voltage that reflects the power of the radio frequency signal transmitted in the input matching network.
[0020] Optionally, the peak detection circuit includes: a rectifier element, an energy storage capacitor, and a discharge resistor; wherein,
[0021] The rectifier element is connected to the second capacitor and is used to turn on when the signal voltage output by the second capacitor is higher than the voltage of the energy storage capacitor, and to turn off when the signal voltage output by the second capacitor is lower than the voltage of the energy storage capacitor.
[0022] The energy storage capacitor is connected to the rectifier element and is used to charge the rectifier element when it is turned on and to maintain the voltage when the rectifier element is turned off.
[0023] The discharge resistor is connected in parallel with the energy storage capacitor and is used to provide a discharge path for the energy storage capacitor when the rectifier element is turned off.
[0024] The charging time constant of the energy storage capacitor is less than that of the discharge resistor and the discharge time constant of the energy storage capacitor.
[0025] Optionally, the attenuation control circuit includes:
[0026] An input attenuation circuit is disposed between the input matching network and the transconductance amplification stage, and is used to control the gain of the low-noise amplifier based on the comparison result output by the comparison circuit;
[0027] And / or,
[0028] An output attenuation circuit, located at the output of the transconductance amplifier stage, is used to control the gain of the low-noise amplifier based on the comparison result output by the comparison circuit.
[0029] Optionally, the input attenuation circuit includes multiple sub-input attenuation circuits, each of which is connected to its corresponding comparison branch and controlled by the comparison result output by the comparison branch; each of the sub-input attenuation circuits is turned on when its corresponding comparison branch outputs a first level to access the signal path of the low-noise amplifier; and is turned off when its corresponding comparison branch outputs a second level to be bypassed outside the signal path.
[0030] The output attenuation circuit includes multiple sub-output attenuation circuits. Each sub-output attenuation circuit is connected to its corresponding comparison branch and is controlled by the comparison result output by the comparison branch. Each sub-output attenuation circuit is turned on when its corresponding comparison branch outputs a first level to access the signal path of the low-noise amplifier. It is turned off when its corresponding comparison branch outputs a second level to be bypassed outside the signal path.
[0031] A radio frequency front-end module includes a low-noise amplifier with adaptive gain control as described in any one of the claims.
[0032] The low-noise amplifier with adaptive gain control provided in this application includes an input matching network and a transconductance amplification stage, as well as a signal acquisition element and a gain control circuit. The input matching network includes an input matching element. The signal acquisition element obtains a coupling signal reflecting the strength of the RF signal input to the low-noise amplifier by coupling the RF signal transmitted through the input matching element. The gain control circuit controls the gain of the low-noise amplifier based on the coupling signal on the signal acquisition element, so that the low-noise amplifier has different gains when the input RF signal has different strengths. This allows the low-noise amplifier to maintain linearity in strong signal scenarios and maintain sensitivity in weak signal scenarios in application scenarios where the received signal strength fluctuates significantly, thus balancing the linearity and noise performance of the low-noise amplifier. Attached Figure Description
[0033] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.
[0034] Figure 1 This is a schematic diagram of the structure of a low-noise amplifier with adaptive gain control function provided in one embodiment of this application;
[0035] Figure 2 A schematic diagram of a low-noise amplifier with adaptive gain control function provided in another embodiment of this application;
[0036] Figure 3 A schematic diagram of a low-noise amplifier with adaptive gain control function provided in another embodiment of this application;
[0037] Figure 4 A schematic diagram of a low-noise amplifier with adaptive gain control function provided in another embodiment of this application;
[0038] Figure 5 A partial structural schematic diagram of a low-noise amplifier with adaptive gain control function provided in another embodiment of this application;
[0039] Figure 6 This is a schematic diagram showing the voltage range of the detection branch when the RF signal strength input to the RF input terminal of a low-noise amplifier with adaptive gain control provided in another embodiment of this application is different.
[0040] Figure 7 This is a schematic diagram showing the change of the DC detection voltage output by the detection branch over time when the RF signal strength input to the RF input terminal of the low-noise amplifier with adaptive gain control provided in another embodiment of this application is different. Detailed Implementation
[0041] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0042] Various modifications and variations can be made to this application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, this application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the implementation methods provided in the embodiments of this application can be combined with each other without contradiction.
[0043] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0044] As described in the background section, how to balance the noise performance and linearity of an LNA in a complex and ever-changing wireless communication environment, and adapt to large fluctuations in the received signal strength, has become a technical problem in this field.
[0045] It should be noted that when the signal strength received by the LNA fluctuates significantly, if the LNA gain is fixed, the following two technical problems will arise:
[0046] When the signal received by the LNA is too strong, the amplitude of the signal output after amplification by the LNA is too large, which will exceed the linear dynamic range of the subsequent circuits (such as mixers, analog-to-digital converters, filters, etc.), causing the aforementioned subsequent circuits to enter the saturation region or nonlinear region, resulting in nonlinear distortions such as harmonic distortion and intermodulation distortion, and even causing the receiving link to be completely blocked under the action of strong blocking signals.
[0047] When the signal received by the LNA is too weak, the amplitude of the output signal after amplification by the LNA cannot reach the normal operating level required by the subsequent circuit. At the same time, due to the low input signal-to-noise ratio of the weak signal, the signal-to-noise ratio of the output signal after amplification by the LNA is further deteriorated. The useful signal is submerged by the noise floor of the LNA, which reduces the LNA's receiving sensitivity and affects the demodulation reliability and overall communication quality of the communication system.
[0048] Therefore, there is an urgent need for a solution that can automatically adjust the LNA gain according to the received signal strength in order to balance the noise performance and linearity of the LNA.
[0049] In view of this, embodiments of this application provide a low-noise amplifier with adaptive gain control function, such as... Figure 1 As shown, the low-noise amplifier includes:
[0050] The system includes an input matching network 10 and a transconductance amplifier stage 20, wherein the input matching network 10 includes an input matching element for receiving radio frequency signals, and the transconductance amplifier stage 20 is used to amplify the radio frequency signals transmitted through the input matching network 10.
[0051] The signal acquisition element 30 is used to couple the radio frequency signal transmitted in the input matching element;
[0052] Gain control circuit 40 is used to control the gain of the low-noise amplifier based on the signal on the signal acquisition element 30.
[0053] It should be noted that, in this embodiment, when the signal on the signal acquisition element 30 has a first strength, the low-noise amplifier has a first gain; when the signal on the signal acquisition element 30 has a second strength, the low-noise amplifier has a second gain. The first strength is greater than the second strength, and the first gain is less than the second gain, so that the low-noise amplifier has different gains when its input radio frequency signal has different strengths. This allows the low-noise amplifier to maintain linearity in strong signal scenarios and maintain sensitivity in weak signal scenarios in application scenarios where the received signal strength fluctuates significantly, thus balancing the linearity and noise performance of the low-noise amplifier.
[0054] Specifically, in one embodiment of this application, the radio frequency signal input to the input terminal of the low noise amplifier is transmitted to the transconductance amplification stage 20 via the input matching network 10, and then amplified by the transconductance amplification stage 20 before being transmitted to the output terminal of the low noise amplifier for output.
[0055] Optionally, in one embodiment of this application, the input matching network 10 may include a first inductor Lg, a first capacitor Cin, or both the first inductor Lg and the first capacitor Cin. The first inductor Lg and the first capacitor Cin may be connected in series or in parallel. In other embodiments of this application, the input matching network 10 may also employ other forms of matching networks (such as Γ-type, T-type matching networks, etc.). This application does not limit the specific form of the matching network; it depends on the circumstances.
[0056] The following description uses the example of the input matching network 10 including a first inductor Lg and a first capacitor Cin connected in series to illustrate the low-noise amplifier provided in the embodiments of this application.
[0057] Continue as Figure 1 As shown, in one embodiment of this application, the input matching network 10 includes a first inductor Lg and a first capacitor Cin connected in series. One end of the first inductor Lg serves as the radio frequency signal input terminal, used to receive the externally input radio frequency signal RF_IN. The other end of the first inductor Lg is connected to one end of the first capacitor Cin, and the other end of the first capacitor Cin is electrically connected to the transconductance amplifier stage 20. In this embodiment, the input matching network 10 serves as impedance matching and frequency selective filtering, enabling maximum power transfer between the external 50Ω radio frequency signal source and the internal circuitry of the low-noise amplifier, while suppressing out-of-band interference signals.
[0058] Based on the above embodiments, in one embodiment of this application, the transconductance amplification stage 20 includes a common-source amplifier M1 and a cascode transistor M2. The gate of the common-source amplifier M1 is connected to the output terminal of the input matching network 10 (i.e., the connection node between the first capacitor Cin and the gate of the common-source amplifier M1), and is used to receive the radio frequency signal transmitted through the input matching network 10; the source of the common-source amplifier M1 is grounded; the drain of the common-source amplifier M1 is connected to the source of the cascode transistor M2; the gate of the cascode transistor M2 is connected to a DC voltage VDD, and its source is connected to the drain of the common-source amplifier M1. The drain serves as the radio frequency signal output terminal of the low-noise amplifier, and is used to output the amplified radio frequency signal RF_OUT.
[0059] Optionally, in one embodiment of this application, the transconductance amplifier stage 20 may further include a second inductor Ls (also called a source degradation inductor) disposed between the source of the common source amplifier tube M1 and ground, for adjusting the input matching of the low noise amplifier and improving the stability of the low noise amplifier.
[0060] Optionally, in one embodiment of this application, the transconductance amplifier stage 20 may further include a third inductor Ld disposed between the drain of the Cascode transistor M2 and the DC voltage VDD, and a third capacitor Cout disposed between the drain of the Cascode transistor M2 and the RF signal output terminal. The third inductor Ld is used to provide a bias current path for the Cascode transistor M2 on the DC path to determine the static operating point, while presenting high impedance at the RF frequency to prevent the RF signal at the drain of the Cascode transistor M2 from being bypassed by the DC voltage VDD. The third capacitor Cout is used to isolate the DC component in the signal output from the drain of the Cascode transistor M2 and couple the AC RF signal to the output terminal of the low noise amplifier.
[0061] It should be noted that, in this embodiment, the third inductor Ld and the third capacitor Cout can also assist other structures in the low-noise amplifier to make the low-noise amplifier present high impedance at the operating frequency, so that the Cascode tube M2 can obtain the maximum voltage gain at that frequency. However, this application does not limit this, and it depends on the specific situation.
[0062] Based on any of the above embodiments, in one embodiment of this application, the signal acquisition element 30 is used to couple the radio frequency signal transmitted in the input matching element to obtain a coupled signal reflecting the strength of the radio frequency input signal. It should be noted that, in this embodiment, there is a signal coupling relationship between the signal acquisition element 30 and the input matching element, and this coupling relationship can be in various forms such as magnetic coupling, capacitive coupling, or inductive coupling.
[0063] Optionally, in one embodiment of this application, the input matching element is a first inductor Lg, and the signal acquisition element 30 obtains a coupling signal reflecting the strength of the radio frequency signal input to the low-noise amplifier by coupling the radio frequency signal transmitted in the first inductor Lg. Specifically, in one implementation of this embodiment, as follows... Figure 2As shown, the input matching element is the first inductor Lg; the signal acquisition element 30 includes a coupling coil CPL, which is coupled to the first inductor Lg to form a coupled transmission line (CPL) structure. When the radio frequency signal input to the low-noise amplifier flows through the first inductor Lg, a coupled AC signal proportional to the power of the radio frequency signal transmitted in the first inductor Lg is induced in the coupling coil CPL through electromagnetic induction.
[0064] It should be noted that, in this embodiment, the coupling coefficient k between the coupling coil CPL and the first inductor Lg can be optimized by adjusting the number of turns of the coupling coil, the relative position of the coupling coil and the input matching element, and the material of the coupling coil, so as to obtain a suitable detection sensitivity and coupling efficiency. This application does not limit this, and it depends on the specific situation.
[0065] In another embodiment of this application, the input matching element is a first capacitor Cin, and the signal acquisition element 30 obtains a coupled signal reflecting the strength of the radio frequency signal input to the low-noise amplifier by coupling the radio frequency signal transmitted in the first capacitor Cin. Specifically, in one implementation of this embodiment, the signal acquisition element 30 is connected to the input matching element via capacitive coupling. For example, the signal acquisition element 30 can be a coil or a metal plate, disposed at the signal node between the first inductor Lg and the first capacitor Cin, and couples a portion of the signal energy from the path of the input matching network 10 as a coupled signal through capacitive voltage division.
[0066] In other embodiments of this application, the signal acquisition element 30 may also adopt other structures, as long as it is a conductor that has signal coupling with the input matching element and can couple the signal in the input matching element out.
[0067] Based on any of the above embodiments, in one embodiment of this application, the gain control circuit 40 is used to control the gain of the low noise amplifier based on the signal on the signal acquisition element 30, so that the low noise amplifier automatically switches to different gain levels when the signal on the signal acquisition element 30 has different intensities.
[0068] Optionally, in one embodiment of this application, such as Figure 3 As shown, the gain control circuit 40 includes a detection circuit 41, a comparison circuit 42, and an attenuation control circuit 43. Wherein,
[0069] The detection circuit 41 is electrically connected to the signal acquisition element 30 and is used to convert the radio frequency signal coupled by the signal acquisition element 30 into a DC detection voltage. The magnitude of the DC detection voltage reflects the power intensity of the radio frequency signal input in the input matching network 10.
[0070] Comparison circuit 42, electrically connected to detection circuit 41, is used to compare the DC detection voltage with at least one reference voltage and output the comparison result;
[0071] The attenuation control circuit 43 is electrically connected to the comparison circuit 42 and is used to adjust the gain of the low-noise amplifier according to the comparison result.
[0072] The following description uses the signal acquisition element 30 as an example to illustrate the low-noise amplifier provided in the embodiments of this application.
[0073] Specifically, in this embodiment, the detection circuit 41 is electrically connected to the signal acquisition element 30, and is used to convert the radio frequency AC signal coupled by the coupling coil CPL into a DC detection voltage Vdet. The magnitude of the DC detection voltage Vdet is directly proportional to the amplitude of the coupled signal (i.e., the power intensity of the input radio frequency signal). That is, the stronger the radio frequency signal input to the input matching network 10, the larger the amplitude of the coupled signal in the signal acquisition element 30, and the higher the DC detection voltage Vdet obtained after rectification; the weaker the radio frequency signal input to the input matching network 10, the smaller the amplitude of the coupled signal in the signal acquisition element 30, and the lower the DC detection voltage Vdet.
[0074] The comparison circuit 42 is electrically connected to the detection circuit 41 and is used to compare the DC detection voltage Vdet with at least one reference voltage Vref, and output the comparison result. The reference voltage Vref corresponds to a preset gain switching threshold. When the DC detection voltage Vdet exceeds the reference voltage Vref, it indicates that the RF signal input to the input matching network 10 has reached the corresponding strength and the gain level needs to be switched.
[0075] The attenuation control circuit 43 is electrically connected to the comparison circuit 42 and is used to adjust the gain of the low-noise amplifier according to the comparison result.
[0076] Based on the above embodiments, in one embodiment of this application, the detection circuit 41 includes at least one detection branch, which is used to convert the radio frequency signal coupled by the signal acquisition element 30 into a DC detection voltage for output;
[0077] The comparison circuit 42 includes at least one comparison branch, which corresponds one-to-one with the detection branch. It is used to output a comparison result based on the DC detection voltage output by the corresponding detection branch and its corresponding reference voltage. The reference voltages corresponding to different comparison branches are different.
[0078] Optionally, in a single threshold (two-level gain) implementation, the detection circuit 41 includes a single detection branch, and the comparison circuit 42 includes a single comparison branch, which compares the DC detection voltage Vdet output by the detection branch with a single reference voltage Vref and outputs a high-level or low-level control signal.
[0079] Optionally, in a multi-gain implementation, such as Figure 4 As shown, the detection circuit 41 includes multiple detection branches 411, and the comparison circuit 42 includes multiple comparison branches 421. Each detection branch 411 receives the coupling signal from the signal acquisition element 30 and outputs an independent DC detection voltage to meet the requirements of multi-threshold comparison. Each comparison branch 421 corresponds one-to-one with the corresponding detection branch 411. Each comparison branch 421 makes a judgment based on the DC detection voltage output by its corresponding detection branch 411 and the reference voltage corresponding to that comparison branch 421, thereby realizing automatic switching of multiple gain levels. It should be noted that the reference voltages corresponding to different comparison branches 421 are different. Specifically, the reference voltages corresponding to each comparison branch 421 can gradually increase, such as Vref1 > Vref2 > Vref3, or they can gradually decrease, or other rules can be used. This application does not limit this; it depends on the specific situation.
[0080] Optionally, in one embodiment of this application, the comparison branch 421 includes a comparator, but this application does not limit this and it depends on the specific circumstances.
[0081] Based on any of the above embodiments, in one embodiment of this application, the following continues... Figure 4 As shown, the detection circuit 41 includes a second capacitor C1 and at least one detection branch 411. The second capacitor C1 is connected to the output terminal of the signal acquisition element 30 and is used to isolate the DC component in the signal output by the signal acquisition element 30, allowing only the radio frequency AC signal to pass through. The detection branch 411 includes a peak detection circuit, which is connected to the output terminal of the second capacitor C1. This peak detection circuit rectifies and holds the peak value of the radio frequency AC signal output by the second capacitor C1, outputting a DC detection voltage Vdet that reflects the power of the radio frequency signal transmitted in the input matching network 10.
[0082] It should be noted that in the above embodiments, different detection branches 411 share the same second capacitor C1 to simplify the structure of the low noise amplifier. However, this application does not limit this. In other embodiments of this application, different detection branches 411 may also be provided with their respective second capacitors C1, depending on the specific circumstances.
[0083] Optionally, in one embodiment of this application, the peak detection circuit includes a rectifier element D1, an energy storage capacitor C2, and a discharge resistor R1. Wherein,
[0084] The rectifier element D1 is connected to the second capacitor C1 and is used to conduct when the signal voltage output by the second capacitor C1 is higher than the voltage of the energy storage capacitor C2, and to cut off when the signal voltage output by the second capacitor C1 is lower than the voltage of the energy storage capacitor C2. Specifically, the anode of the rectifier element D1 is connected to the output terminal of the second capacitor C1, and the cathode is connected to one end of the energy storage capacitor C2 and the common terminal of the discharge resistor R1. During the positive half-cycle of the radio frequency AC signal output by the second capacitor C1, when the voltage of the radio frequency AC signal output by the second capacitor C1 is higher than the voltage on the energy storage capacitor C2, the rectifier element D1 conducts to charge the energy storage capacitor C2; during the negative half-cycle of the radio frequency AC signal output by the second capacitor C1, or during the positive half-cycle of the radio frequency AC signal output by the second capacitor C1 but when the voltage of the radio frequency AC signal output by the second capacitor C1 is lower than the voltage of the energy storage capacitor C2, the rectifier element D1 is cut off. Optionally, the rectifier element D1 is a Schottky diode, which has a low forward voltage drop and fast switching speed, making it suitable for rectifying radio frequency signals. However, this application does not limit it in this regard, and it depends on the specific circumstances.
[0085] The energy storage capacitor C2 is connected to the rectifier element D1 and is used to charge when the rectifier element D1 is turned on and to maintain the voltage when the rectifier element D1 is turned off. Specifically, the energy storage capacitor C2 is connected to the cathode of the rectifier element D1 and is used to charge when the rectifier element D1 is turned on and to maintain the voltage when the rectifier element D1 is turned off, thereby storing the peak voltage of the radio frequency AC signal output by the second capacitor C1.
[0086] The discharge resistor R1 is connected in parallel with the energy storage capacitor C2 to provide a discharge path for the energy storage capacitor C2 when the rectifier element D1 is turned off, so that the voltage on the energy storage capacitor C2 can be dynamically adjusted according to the change of the input radio frequency signal power.
[0087] It should be noted that, in this embodiment, the charging time constant of the energy storage capacitor C2 (determined by the on-resistance of the rectifying element D1 and the capacitance value of the energy storage capacitor C2) is much smaller than the discharging time constant formed by the discharging resistor R1 and the energy storage capacitor C2, so that the detection circuit 41 can quickly rise following the rise of the RF signal power input in the input matching network 10, and slowly discharge through the discharging resistor R1 after the signal input in the input matching network 10 weakens, realizing the peak holding function.
[0088] Optionally, in an embodiment of the present application, the energy storage capacitor C2 is a small capacitor, and the discharging resistor R1 is a large resistor, so that the charging time constant RD*C of the energy storage capacitor C2 << R1*C, where R1*C is the discharging time constant. As Figure 5 shown, when the signal at the input end of the rectifying element D1 is greater than the voltage Vout of the energy storage capacitor C2, the rectifying element D1 conducts, and the energy storage capacitor C2 is quickly charged, and Vout rises. When the signal at the input end of the rectifying element D1 is less than the voltage Vout of the energy storage capacitor C2, the rectifying element D1 turns off, and the energy storage capacitor C2 slowly discharges, and the voltage Vout of the energy storage capacitor C2 (i.e., the output voltage of the peak detection circuit) almost remains unchanged.
[0089] It should be noted that, by selecting and setting the capacitance values of the second capacitor C1 and / or the energy storage capacitor C2, the low-noise amplifier provided by the embodiments of the present application can make the coupling coil CPL maintain a flat coupling characteristic within the target frequency band, and minimize the change of the coupling signal strength with frequency within the entire working frequency band, so as to ensure that the detection circuit 41 can effectively and stably detect the power of RF signals with different frequency components, and improve the detection accuracy and reliability.
[0090] It should also be noted that, in the above embodiment, the rectifying element D1 can also be replaced by other devices with unidirectional conductivity, such as a rectifying circuit composed of transistors, etc. The present application does not limit this, as long as it can achieve the rectifying function of the RF signal.
[0091] Based on any of the above embodiments, in an embodiment of the present application, continuing as Figure 4 shown, the attenuation control circuit 43 may include an input attenuation circuit 431 and / or an output attenuation circuit 432. That is, in this embodiment, the attenuation control circuit 43 may only include the input attenuation circuit 431, may only include the output attenuation circuit 432, or may include both the input attenuation circuit 431 and the output attenuation circuit 432, so as to use the output attenuation circuit 432 to cooperate with the input attenuation circuit 431 to achieve the adjustment of the gain step. The present application does not limit this, and it depends on the specific situation.
[0092] Specifically, the input attenuation circuit 431 is disposed between the input matching network 10 and the transconductance amplifier stage 20 (i.e., disposed on the signal path between the first capacitor Cin and the gate of the common-source amplifier M1), and is used to connect to the attenuation network when there is a strong signal to reduce the power of the RF signal input to the transconductance amplifier stage 20. The output attenuation circuit 432 is disposed at the output terminal of the transconductance amplifier stage 20 (i.e., between the drain of the Cascode transistor M2 and the RF output terminal), and is used to attenuate the output signal of the low-noise amplifier when there is a strong signal.
[0093] Optionally, in one embodiment of this application, the input attenuation circuit 431 includes at least one sub-input attenuation circuit 431a. When the input attenuation circuit 431 includes multiple sub-input attenuation circuits 431a, each sub-input attenuation circuit 431a corresponds one-to-one with the comparison branch 421, each sub-input attenuation circuit 431a is connected to its corresponding comparison branch 421 and controlled by the comparison result output by the comparison branch 421; each sub-input attenuation circuit 431a is turned on when its corresponding comparison branch 421 outputs a first level, so as to access the signal path of the low-noise amplifier, thereby reducing the gain of the low-noise amplifier, increasing the noise, and raising the 1dB gain compression point (P1dB); it is turned off when its corresponding comparison branch 421 outputs a second level, so as to be bypassed outside the signal path. Optionally, the first level is a high level and the second level is a low level, but this application is not limited to this. In other embodiments of this application, the first level may be a low level and the second level may be a high level, depending on the specific situation.
[0094] Specifically, in one embodiment of this application, the sub-input attenuation circuit 431a includes a series-connected switch SW1 and attenuation resistor R2. The control terminal of the switch SW1 is connected to the output terminal of its corresponding comparator branch 421. When its corresponding comparator branch 421 outputs a first level (e.g., a high level, indicating a strong signal is detected), the switch SW1 is turned on, and the attenuation resistor R2 is connected to the signal path to attenuate the input signal by voltage division. When its corresponding comparator branch 421 outputs a second level (e.g., a low level, indicating a weak signal is detected), the switch SW1 is turned off, and the attenuation resistor R2 is bypassed, without affecting the signal path.
[0095] It should be noted that in this embodiment, the resistance values of the attenuation resistor R2 in different sub-input attenuation circuits 431a are different, for example, R2_1 > R2_2 > R2_3, so that the gain of the low-noise amplifier is different when different sub-input attenuation circuits are connected to the signal path of the low-noise amplifier. Specifically, the larger the resistance value of the attenuation resistor R2 in the sub-input attenuation circuit 431a, the smaller the gain attenuation of the low-noise amplifier when the sub-input attenuation circuit 431a is connected to the signal path of the low-noise amplifier. This can be applied to scenarios where the signal strength input to the RF input terminal of the low-noise amplifier is relatively small. Conversely, the smaller the resistance value of the attenuation resistor R2 in the sub-input attenuation circuit 431a, the greater the gain attenuation of the low-noise amplifier when the sub-input attenuation circuit 431a is connected to the signal path of the low-noise amplifier. This can be applied to scenarios where the signal strength input to the RF input terminal of the low-noise amplifier is relatively large.
[0096] Optionally, in one embodiment of this application, the input attenuation circuit 431 further includes a fourth capacitor C3 disposed between each sub-input attenuation circuit and the common terminal of the input matching network and the transconductance amplifier stage, to block the DC component on the sub-input attenuation circuit side, while allowing the radio frequency signal to couple to the input terminal of the transconductance amplifier stage 20.
[0097] Based on any of the above embodiments, in one embodiment of this application, the output attenuation circuit 432 includes at least one sub-output attenuation circuit. When the comparison circuit 42 includes multiple comparison branches 421, the output attenuation circuit 432 includes multiple sub-output attenuation circuits. The sub-output attenuation circuits and comparison branches 421 correspond one-to-one. Each sub-output attenuation circuit is connected to its corresponding comparison branch 421 and is controlled by the comparison result output by the comparison branch 421. Each sub-output attenuation circuit is turned on when its corresponding comparison branch 421 outputs a first level to access the signal path of the low-noise amplifier. It is turned off when its corresponding comparison branch 421 outputs a second level to be bypassed outside the signal path.
[0098] Optionally, in one embodiment of this application, the output attenuation circuit 432 adopts a Π-type attenuation network structure. Specifically, as follows... Figure 4 As shown, the output attenuation circuit 432 includes:
[0099] A series resistor R3 is placed in the main signal path, with one end connected to the output terminal of the third capacitor Cout and the other end connected to the RF output terminal of the low noise amplifier.
[0100] Multiple parallel resistor branches are connected in parallel across the series resistor R3. Each parallel resistor branch includes a series switch SW2 and a parallel resistor R4. The control terminal of the switch SW2 is connected to the output terminal of its corresponding comparison branch 421 and is controlled by the comparison result output by its corresponding comparison branch 421.
[0101] Multiple first grounding resistor branches are electrically connected to the first end of each of the parallel resistor branches. Each first grounding resistor branch includes a series-connected switch SW3 and a grounding resistor R5, wherein the other end of the grounding resistor R5 is grounded. The control electrode of the switch SW3 is connected to the output terminal of its corresponding comparison branch 421 and receives the control of the comparison result output by its corresponding comparison branch 421.
[0102] Multiple second grounding resistor branches are electrically connected to the second end of each of the parallel resistor branches, the second end being opposite to the first end. Each second grounding resistor branch includes a series-connected switch SW4 and a grounding resistor R6, wherein the other end of the grounding resistor R6 is grounded. The control electrode of the switch SW4 is connected to the output terminal of its corresponding comparison branch 421 and receives control from the comparison result output by its corresponding comparison branch 421.
[0103] It should be noted that in the above embodiments, the resistance values of the parallel resistors R4 in different parallel resistor branches are different, for example, R4_1 > R4_2 > R4_3, so that the gain of the low-noise amplifier is different when different parallel resistor branches are connected to the signal path of the low-noise amplifier. Specifically, the larger the resistance value of the parallel resistor R4 in the parallel resistor branch, the smaller the gain attenuation of the low-noise amplifier when the parallel resistor branch is connected to the signal path of the low-noise amplifier. This can be applied to scenarios where the signal strength input to the RF input terminal of the low-noise amplifier is relatively small. Conversely, the smaller the resistance value of the parallel resistor R4 in the parallel resistor branch, the greater the gain attenuation of the low-noise amplifier when the parallel resistor branch is connected to the signal path of the low-noise amplifier. This can be applied to scenarios where the signal strength input to the RF input terminal of the low-noise amplifier is relatively large.
[0104] Similarly, the resistance values of the grounding resistor R5 in different first grounding resistor branches are different, for example, R5_1 > R5_2 > R5_3, so that the gain of the low noise amplifier is different when different first grounding resistor branches are connected to the signal path of the low noise amplifier; the resistance values of the grounding resistor R6 in different second grounding resistor branches are different, for example, R6_1 > R6_2 > R6_3, so that the gain of the low noise amplifier is different when different second grounding resistor branches are connected to the signal path of the low noise amplifier.
[0105] Optionally, in this embodiment, a sub-output attenuation circuit includes a parallel resistor branch, a first grounding resistor branch, and a second grounding resistor branch, all controlled by the comparison result output from the same comparison branch. However, this application does not limit this, and it depends on the specific circumstances. Optionally, in the same sub-output attenuation circuit, the resistance value of the grounding resistor in the first grounding resistor branch and the resistance value of the grounding resistor in the second grounding resistor branch can be the same. However, this application does not limit this, and it depends on the specific circumstances.
[0106] It should be noted that in other embodiments of this application, the output attenuation circuit may also adopt other attenuation network structures, such as a T-type attenuation network structure. This application does not limit this, and it depends on the specific situation.
[0107] The following description uses the example of an input attenuation circuit comprising three sub-input attenuation circuits and an output attenuation circuit comprising three sub-output attenuation circuits to illustrate the low-noise amplifier provided in the embodiments of this application.
[0108] As shown in Table 1 and Figure 4 As shown, when the signal strength of the RF signal RF_IN input to the RF signal input terminal of the low noise amplifier is in the range of -50dBm to -40dBm, comparator 1 outputs a high level of 1, and comparators 2 and 3 output a low level of 0. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 1 is located are connected to the signal path of the low noise amplifier. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 2 is located, as well as the sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 3 is located, are bypassed by the signal path of the low noise amplifier. The low noise amplifier has a gain A.
[0109] When the signal strength of the RF signal RF_IN input to the RF signal input terminal of the low noise amplifier is within the range of -40dBm to -30dBm, comparator 2 outputs a high level 1, and comparators 1 and 3 output a low level 0. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 2 is located are connected to the signal path of the low noise amplifier. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 1 is located, as well as the sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 3 is located, are bypassed by the signal path of the low noise amplifier. The low noise amplifier has a gain B.
[0110] When the signal strength of the RF signal RF_IN input to the RF signal input terminal of the low noise amplifier is in the range of -30dBm to -20dBm, comparator 3 outputs a high level 1, and comparators 1 and 2 output a low level 0. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 3 is located are connected to the signal path of the low noise amplifier. The sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 1 is located, as well as the sub-input attenuation circuit and sub-output attenuation circuit corresponding to the comparator branch where comparator 2 is located, are bypassed by the signal path of the low noise amplifier. The low noise amplifier has a gain C.
[0111] In this case, gain A ≠ gain B ≠ gain C.
[0112] Table 1:
[0113] RF_IN / dbm V1 V2 V3 -50~-40 1 0 0 -40~-30 0 1 0 -30~-20 0 0 1
[0114] It should be noted that in the above embodiments, the switching transistors SW1, SW2, SW3, and SW4 can be implemented using MOSFETs, pin diodes, or other controllable switching devices. This application does not limit this, and the specific implementation depends on the circumstances.
[0115] The low-noise amplifier provided in the embodiments of this application will be described below in conjunction with specific application scenarios.
[0116] In scenarios with strong signal input, when the power of the external input RF signal RF_IN is high (e.g., when the base station is close), the RF signal current flowing through the first inductor Lg is large, inducing a large-amplitude coupling signal in the coupling coil CPL through the coupling transmission line structure. After the DC component of this coupling signal is isolated by the second capacitor C1, an AC signal is output to the detection branch 411. The rectifier element D1 in the detection branch 411 rectifies the AC signal, and the energy storage capacitor C2 charges rapidly, causing the DC detection voltage Vdet output by the detection branch 411 to rise. When the DC detection voltage Vdet exceeds the reference voltage Vref of the comparison branch 421, the comparison branch 421 outputs a first-level control signal. This control signal drives the switching transistors in the input attenuation circuit 431 and / or the output attenuation circuit 432 to turn on, and the corresponding attenuation resistors are connected to the signal path, thereby reducing the input / output signal power of the transconductance amplifier stage 20, switching the low-noise amplifier to a low-gain mode, avoiding saturation of the subsequent circuits, and ensuring the linearity of the low-noise amplifier itself.
[0117] In weak signal input scenarios, when the power of the external input RF signal RF_IN is weak (e.g., when the base station is far away), the RF signal current flowing through the first inductor Lg is small, and the amplitude of the coupled signal induced in the coupling coil CPL is also small. The DC detection voltage Vdet output by the detection branch 411 is low, lower than the reference voltage Vref of the comparison branch, and the comparison branch 421 outputs a control signal at the second level. At this time, the switching transistors in the input attenuation circuit 431 and / or the output attenuation circuit 432 are turned off, the attenuation resistor is bypassed, and the low-noise amplifier switches to high-gain mode to obtain optimal noise performance and receiving sensitivity, ensuring that the weak signal can be effectively amplified and transmitted to the subsequent circuit.
[0118] like Figure 6 and Figure 7 As shown, Figure 6 and Figure 7 This diagram illustrates the results of transient response simulation analysis of the low-noise amplifier with adaptive gain control provided in this embodiment of the application. The simulation time range is 0~10μs. Specifically, Figure 6 The diagram shows the voltage range of the detection branch input when the RF signal strength at the RF input terminal of the low-noise amplifier is different. Figure 7 The diagram shows the variation curve of the DC detection voltage output by the detection branch over time when the RF signal strength input to the RF input terminal of the low-noise amplifier is different.
[0119] Combination Figure 6 and Figure 7 It can be seen that when the RF signal strength input to the RF input terminal of the low-noise amplifier corresponds to RF_IN pin=0, the voltage range of the input voltage of the detection branch is approximately -0.615mV to 0.615mV, and the steady-state voltage of the DC detection voltage output by the detection branch is -32mV; when the RF signal strength input to the RF input terminal of the low-noise amplifier corresponds to RF_IN pin=5, the voltage range of the input voltage of the detection branch is approximately -1.2295V to 1.2295V, and the steady-state voltage of the DC detection voltage output by the detection branch is 314mV; when the RF signal strength input to the RF input terminal of the low-noise amplifier corresponds to RF_IN pin=10, the voltage range of the input voltage of the detection branch is approximately -1.99857V to 1.99857V, and the steady-state voltage of the DC detection voltage output by the detection branch is 1.15V; the RF signal strength input to the RF input terminal of the low-noise amplifier corresponds to RF_IN... When pin=15, the voltage range of the input voltage of the detection branch is approximately -3.53961~1.99857V, and the steady-state voltage of the DC detection voltage output by the corresponding detection branch is 2.64V.
[0120] from Figure 7 It can be seen that the voltage output by each detection branch reaches a stable state within a few microseconds, and the voltages output by different detection branches have a clear voltage interval between them. Therefore, in the low-noise amplifier with adaptive gain control provided in this application embodiment, the detection circuit has a fast response speed, and each DC detection voltage output completes the establishment process within a few microseconds; and when different intensity radio frequency signals are input, there is a sufficient voltage interval between the output signals of each detection branch in the detection circuit, which can effectively avoid erroneous switching.
[0121] In addition, from Figure 7 It can also be seen that in the low-noise amplifier with adaptive gain control function provided in the embodiments of this application, the output voltage of each detection branch in the detection circuit does not have obvious oscillation or drift after steady state, indicating that the detection branch can provide a stable DC detection voltage as the input signal of the comparison branch in the comparison circuit, and compare it with the reference voltage set in the comparison branch.
[0122] In summary, the low-noise amplifier with adaptive gain control provided in this application embodiment can automatically switch the gain according to the strength of the radio frequency signal input to the radio frequency input terminal of the low-noise amplifier, so that the low-noise amplifier can adapt to application scenarios where the received signal strength fluctuates greatly, maintain linearity in strong signal scenarios, maintain sensitivity in weak signal scenarios, and balance the linearity and noise performance of the low-noise amplifier.
[0123] Moreover, the low-noise amplifier with adaptive gain control provided in this application embodiment is completed entirely by analog circuitry during the entire gain switching process. It does not require SOC register configuration or complex digital control logic. It can automatically switch the gain level according to the input RF signal power using only pure analog circuitry, resulting in fast response speed, low system overhead, and low power consumption.
[0124] Furthermore, this application also provides a radio frequency (RF) front-end module, which includes a low-noise amplifier with adaptive gain control provided in any of the above embodiments. Since the details of the low-noise amplifier with adaptive gain control have been described in detail in the above embodiments, they will not be repeated here.
[0125] The various embodiments in this specification are described in a progressive, parallel, or combined manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.
[0126] It should be noted that, in the description of this application, the accompanying drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments identify the same structures. It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in an article or device comprising the aforementioned element.
[0127] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A low noise amplifier having a self-adapting gain control function, characterized by include: An input matching network and a transconductance amplification stage are provided, wherein the input matching network includes an input matching element for receiving radio frequency signals, and the transconductance amplification stage is used to amplify the radio frequency signals transmitted through the input matching network; A signal acquisition element is used to couple the radio frequency signal transmitted in the input matching element; A gain control circuit is used to control the gain of the low-noise amplifier based on the signal on the signal acquisition element, wherein the low-noise amplifier has a first gain when the signal on the signal acquisition element has a first strength, and the low-noise amplifier has a second gain when the signal on the signal acquisition element has a second strength, wherein the first strength is greater than the second strength, and the first gain is less than the second gain.
2. The low noise amplifier of claim 1, wherein, The input matching network includes a first inductor and a first capacitor, and the input matching element is the first inductor or the first capacitor; the signal acquisition element is a conductor that is signal-coupled with the input matching element.
3. The low noise amplifier of claim 2, wherein, The input matching element is the first inductor; the signal acquisition element includes a coupling coil, which is coupled to the first inductor to form a coupled transmission line structure.
4. The low noise amplifier of claim 1, wherein, The gain control circuit includes: A detection circuit, electrically connected to the signal acquisition element, is used to convert the radio frequency signal coupled by the signal acquisition element into a DC detection voltage, the magnitude of which reflects the power intensity of the radio frequency signal input into the input matching network. A comparison circuit, electrically connected to the detection circuit, is used to compare the DC detection voltage with at least one reference voltage and output the comparison result. An attenuation control circuit, electrically connected to the comparison circuit, is used to adjust the gain of the low-noise amplifier based on the comparison result.
5. The low noise amplifier of claim 4, wherein, The detection circuit includes at least one detection branch, which is used to convert the radio frequency signal coupled by the signal acquisition element into a DC detection voltage for output. The comparison circuit includes at least one comparison branch, which corresponds one-to-one with the detection branch. It is used to output a comparison result based on the DC detection voltage output by the corresponding detection branch and its corresponding reference voltage. The reference voltages corresponding to different comparison branches are different.
6. The low noise amplifier of claim 5, wherein, The detection circuit includes a second capacitor and at least one detection branch, wherein the second capacitor is connected to the output terminal of the signal acquisition element and is used to isolate the DC component in the coupled signal output by the signal acquisition element; The detection branch includes a peak detection circuit connected to the output terminal of the second capacitor. It is used to rectify and maintain the peak value of the radio frequency signal output by the second capacitor, and output a DC detection voltage that reflects the power of the radio frequency signal transmitted in the input matching network.
7. The low noise amplifier of claim 6, wherein, The peak detection circuit includes: a rectifier element, an energy storage capacitor, and a discharge resistor; wherein... The rectifier element is connected to the second capacitor and is used to turn on when the signal voltage output by the second capacitor is higher than the voltage of the energy storage capacitor, and to turn off when the signal voltage output by the second capacitor is lower than the voltage of the energy storage capacitor. The energy storage capacitor is connected to the rectifier element and is used to charge the rectifier element when it is turned on and to maintain the voltage when the rectifier element is turned off. The discharge resistor is connected in parallel with the energy storage capacitor and is used to provide a discharge path for the energy storage capacitor when the rectifier element is turned off. The charging time constant of the energy storage capacitor is less than that of the discharge resistor and the discharge time constant of the energy storage capacitor.
8. The low noise amplifier of claim 5, wherein, The attenuation control circuit includes: An input attenuation circuit is disposed between the input matching network and the transconductance amplification stage, and is used to control the gain of the low-noise amplifier based on the comparison result output by the comparison circuit; And / or, An output attenuation circuit, located at the output of the transconductance amplifier stage, is used to control the gain of the low-noise amplifier based on the comparison result output by the comparison circuit.
9. The low noise amplifier of claim 8, wherein, The input attenuation circuit includes multiple sub-input attenuation circuits, each of which is connected to its corresponding comparison branch and controlled by the comparison result output by the comparison branch; each of the sub-input attenuation circuits is turned on when its corresponding comparison branch outputs a first level, so as to access the signal path of the low noise amplifier. When its corresponding comparison branch outputs a second level, it is turned off so as to be bypassed outside the signal path; The output attenuation circuit includes multiple sub-output attenuation circuits, each of which is connected to its corresponding comparison branch and controlled by the comparison result output by the comparison branch; each of the sub-output attenuation circuits is turned on when its corresponding comparison branch outputs a first level, so as to access the signal path of the low noise amplifier. It is turned off when its corresponding comparison branch outputs a second level, so as to be bypassed outside the signal path.
10. A radio frequency front end module, comprising: Including the low-noise amplifier with adaptive gain control function as described in any one of claims 1-9.