An adaptive AGC control circuit and method for wideband radio frequency front end

Abstract

This invention provides an adaptive AGC control circuit and method for broadband RF front-ends. The circuit includes: a gain tuning circuit connected to the RF link of the broadband RF front-end; and a signal detection circuit connected to the gain tuning circuit. The signal detection circuit is used to sample the RF signal in the RF link of the broadband RF front-end through an ADC, and to perform signal processing and gain control on the sampled RF signal based on an FPGA, thereby controlling the gain tuning circuit. This invention uses an FPGA+ADC hardware solution to achieve real-time detection and closed-loop fast control to realize adaptive AGC control of the broadband RF front-end, which has the following characteristics: 1. Simple circuit structure, clear logic, and easy implementation; 2. Real-time signal acquisition and processing with low state control delay; 3. High accuracy of dual-threshold signal detection and discrimination; 4. Flexible and controllable gain, and wide applicability.

Description

Technical Field

[0001] This invention relates to the field of control technology for radio frequency front-end products, and more specifically, to an adaptive AGC control circuit and method for broadband radio frequency front-ends. Background Technology

[0002] In electronic warfare applications, RF front-ends typically employ wide-bandwidth reception, such as 2–18 GHz. This approach is primarily based on the goal of receiving signals over a large bandwidth, but it also has significant drawbacks, especially in complex electromagnetic environments where its detection capability for specific or large signals is very limited. Furthermore, to ensure distortion-free reception of the RF channel signal, the gain of the entire broadband RF front-end link must not be oversaturated, placing high demands on the gain allocation of the broadband RF front-end signal link. Therefore, the signal sensitivity and dynamic range of the broadband RF front-end are key design considerations.

[0003] Existing broadband RF front-ends typically employ fixed gain configurations to simplify signal link design complexity. Gain flatness is maintained through equalizers and temperature compensation, but this approach severely limits channel sensitivity and dynamic range, hindering the acquisition and processing of broadband RF signals. In such applications, adding adaptive AGC (Automatic Gain Control) to the broadband RF front-end link plays a crucial role in improving channel sensitivity and dynamic range, and achieving distortion-free acquisition of broadband RF signals. Summary of the Invention

[0004] This invention aims to provide an adaptive AGC control circuit and method for broadband radio frequency front-ends, which is designed to improve the dynamic range of the radio frequency channel when the dynamic range is limited and it is impossible to achieve distortion-free reception of specific or large signals under wide open and large dynamic reception conditions.

[0005] This invention provides an adaptive AGC control circuit for broadband radio frequency front-ends, comprising:

[0006] Gain tuning circuit in broadband RF front-end RF link;

[0007] And a signal detection circuit connected to the gain tuning circuit;

[0008] The signal detection circuit is used to sample the radio frequency signal in the broadband radio frequency front-end radio frequency link through the ADC, and to perform signal processing and gain control on the sampled radio frequency signal based on the FPGA, thereby controlling the gain tuning circuit.

[0009] Furthermore, the gain tuning circuit includes a gain compensation circuit, a digitally controlled attenuation circuit, a single-pole double-throw switch SPDT1, and a single-pole double-throw switch SPDT2 connected to the signal detection circuit.

[0010] The two output terminals of the single-pole double-throw switch SPDT1 are connected to the two input terminals of the single-pole double-throw switch SPDT2 via a gain compensation circuit and a digitally controlled attenuation circuit, respectively.

[0011] Furthermore, the signal detection circuit includes a broadband coupled logarithmic detector, a signal conditioning circuit, and a signal detection and processing control circuit connected in sequence.

[0012] The broadband coupled logarithmic detector is used to acquire radio frequency signals in the broadband radio frequency front-end radio frequency link.

[0013] The signal detection and processing control circuit is connected to the gain tuning circuit.

[0014] Furthermore, the signal conditioning circuit is a signal differential conditioning circuit.

[0015] This invention also provides an adaptive AGC control method for broadband radio frequency front-ends, comprising the following steps:

[0016] S1, connect the above-mentioned adaptive AGC control circuit for broadband RF front-end to the broadband RF front-end RF link; wherein the broadband RF front-end RF link includes a broadband filter, a limiter and a low noise amplifier; the broadband filter is connected in sequence to the limiter, the gain tuning circuit and the low noise amplifier.

[0017] S2, the signal detection circuit samples the RF signal in the broadband RF front-end RF link from the output of the limiter, and uses a dual-threshold signal amplitude detection method to control the gain tuning circuit based on the sampled RF signal in the broadband RF front-end RF link.

[0018] Furthermore, step S2 includes:

[0019] S21, the broadband coupled logarithmic detector samples the radio frequency signal in the broadband radio frequency front-end radio frequency link and performs nonlinear fitting of the amplitude and voltage curves to calculate the amplitude value corresponding to the radio frequency signal voltage.

[0020] S22 compares the calculated amplitude value of the RF signal voltage with the preset dual-threshold amplitude threshold, and controls the gain tuning circuit based on the comparison result.

[0021] Furthermore, A H A is a preset high threshold for signal detection. L Assuming a preset low threshold for signal detection and an engineering margin of ΔA, and that the calculated amplitude value corresponding to the RF signal voltage is A, then step S22 includes:

[0022] (1)A H +ΔA and A>A L ​-ΔA indicates that the calculated amplitude value of the RF signal voltage is within the preset dual-threshold amplitude threshold. The single-pole double-throw switch SPDT1 and single-pole double-throw switch SPDT2 in the control gain tuning circuit connect the digitally controlled attenuator to the broadband RF front-end RF link and the digitally controlled attenuation is 0.

[0023] (2) A>A H ±ΔA indicates that the calculated amplitude of the RF signal voltage exceeds the preset high threshold for signal detection. This controls the single-pole double-throw switches SPDT1 and SPDT2 in the gain tuning circuit, connecting the digitally controlled attenuator to the broadband RF front-end RF link with a digitally controlled attenuation of AA. H ;

[0024] (3)A L ±ΔA indicates that the calculated amplitude value of the RF signal voltage is within the preset low threshold for signal detection. This controls the single-pole double-throw switches SPDT1 and SPDT2 in the gain tuning circuit, connecting the gain compensation circuit to the broadband RF front-end RF link.

[0025] In summary, this invention utilizes an FPGA+ADC hardware solution to achieve real-time detection and closed-loop fast control, thereby realizing adaptive AGC control of the broadband RF front-end. It has the following characteristics:

[0026] 1. The circuit structure is simple, the logic is clear, and it is easy to implement;

[0027] 2. Real-time signal acquisition and processing, with minimal delay in status control;

[0028] 3. High accuracy in dual-threshold signal detection and discrimination;

[0029] 4. The gain is flexible and controllable, and it has a wide range of applications. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of an adaptive AGC control circuit for a broadband radio frequency front end in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the gain tuning circuit in an embodiment of the present invention.

[0033] Figure 3 ​This is a schematic diagram of the signal detection circuit in an embodiment of the present invention.

[0034] Figure 4 This is a flowchart of an adaptive AGC control method for broadband radio frequency front-ends in an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of dual-threshold signal amplitude detection and discrimination in an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] Example

[0039] This embodiment uses an FPGA+ADC hardware solution to implement real-time detection and closed-loop fast control, achieving adaptive AGC control of the broadband RF front-end, such as... Figure 1 As shown, this embodiment proposes an adaptive AGC control circuit for broadband radio frequency front-ends, including:

[0040] Gain tuning circuit in broadband RF front-end RF link, and signal detection circuit connected to gain tuning circuit;

[0041] The signal detection circuit is used to sample the radio frequency signal in the broadband radio frequency front-end radio frequency link through the ADC, and to perform signal processing and gain control on the sampled radio frequency signal based on the FPGA, thereby controlling the gain tuning circuit.

[0042] like Figure 2As shown, the gain tuning circuit includes a gain compensation circuit, a digitally controlled attenuation circuit, a single-pole double-throw (SPDT1) switch, and a single-pole double-throw (SPDT2) switch connected to the signal detection circuit. The two output terminals of the single-pole double-throw (SPDT1) switch are connected to the two input terminals of the single-pole double-throw (SPDT2) switch via the gain compensation circuit and the digitally controlled attenuation circuit, respectively. By controlling the single-pole double-throw (SPDT1) switch and the single-pole double-throw (SPDT2) switch through the signal detection circuit, the gain tuning circuit can select an appropriate path, i.e., the gain compensation circuit or the digitally controlled attenuation circuit, to connect to the broadband RF front-end RF link. Furthermore, the attenuation amount of the digitally controlled attenuation circuit can be controlled to achieve dynamic gain adjustment, thereby expanding the signal detection dynamic range of the broadband RF front-end.

[0043] like Figure 3 As shown, the signal detection circuit includes a broadband coupled logarithmic detector, a signal conditioning circuit, and a signal detection and processing control circuit connected in sequence.

[0044] The broadband coupled logarithmic detector is used to acquire radio frequency signals in the broadband radio frequency front-end radio frequency link.

[0045] The signal conditioning circuit is a differential signal conditioning circuit;

[0046] The signal detection and processing control circuit adopts FPGA+ADC and is connected to the gain tuning circuit.

[0047] Therefore, this embodiment can also implement an adaptive AGC control method for broadband radio frequency front-ends, such as... Figure 4 As shown, it includes the following steps:

[0048] S1, connect the above-mentioned adaptive AGC control circuit for broadband RF front-end to the broadband RF front-end RF link; wherein the broadband RF front-end RF link includes a broadband filter, a limiter and a low noise amplifier; the broadband filter is connected in sequence to the limiter, the gain tuning circuit and the low noise amplifier.

[0049] S2, the signal detection circuit samples the RF signal in the broadband RF front-end RF link from the output of the limiter, and controls the gain tuning circuit using a dual-threshold signal amplitude detection method based on the sampled RF signal in the broadband RF front-end RF link. Specifically, it includes the following sub-steps:

[0050] S21, the broadband coupled logarithmic detector samples the radio frequency signal in the broadband radio frequency front-end radio frequency link and performs nonlinear fitting of the amplitude and voltage curves to calculate the amplitude value corresponding to the radio frequency signal voltage.

[0051] S22 compares the calculated amplitude value of the RF signal voltage with a preset dual-threshold amplitude threshold (i.e., preset according to the dynamic range), and controls the gain tuning circuit based on the comparison result. A HA is a preset high threshold for signal detection. L Assuming a preset low threshold for signal detection, with an engineering margin of ΔA, and assuming the calculated amplitude of the RF signal voltage is A, for example... Figure 5 As shown, step S22 is as follows:

[0052] (1)A H +ΔA and A>A L -ΔA indicates that the calculated amplitude value of the RF signal voltage is within the preset dual-threshold amplitude threshold. The single-pole double-throw switch SPDT1 and single-pole double-throw switch SPDT2 in the control gain tuning circuit connect the digitally controlled attenuator to the broadband RF front-end RF link and the digitally controlled attenuation is 0.

[0053] (2) A>A H ±ΔA indicates that the calculated amplitude of the RF signal voltage exceeds the preset high threshold for signal detection. This controls the single-pole double-throw switches SPDT1 and SPDT2 in the gain tuning circuit, connecting the digitally controlled attenuator to the broadband RF front-end RF link with a digitally controlled attenuation of AA. H ;

[0054] (3)A L ±ΔA indicates that the calculated amplitude value of the RF signal voltage is within the preset low threshold for signal detection. This controls the single-pole double-throw switches SPDT1 and SPDT2 in the gain tuning circuit, connecting the gain compensation circuit to the broadband RF front-end RF link.

[0055] In a sample product development project, a broadband RF front-end module was developed using the method of this invention, achieving 20dB dynamic expansion and low-latency switching of AGC within 100ns, thus well meeting the needs of engineering applications. Therefore, this invention uses an FPGA+ADC hardware solution to achieve real-time detection and closed-loop fast control to realize adaptive AGC control of the broadband RF front-end, which has the following characteristics:

[0056] 1. The circuit structure is simple, the logic is clear, and it is easy to implement;

[0057] 2. Real-time signal acquisition and processing, with minimal delay in status control;

[0058] 3. High accuracy in dual-threshold signal detection and discrimination;

[0059] 4. The gain is flexible and controllable, and it has a wide range of applications.

[0060] ​​The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive AGC control circuit for broadband radio frequency front-ends, characterized in that, include: Gain tuning circuit in broadband RF front-end RF link; And a signal detection circuit connected to the gain tuning circuit; The signal detection circuit is used to sample the radio frequency signal in the broadband radio frequency front-end radio frequency link through the ADC, and to perform signal processing and gain control on the sampled radio frequency signal based on the FPGA, thereby controlling the gain tuning circuit. The gain tuning circuit includes a gain compensation circuit, a digitally controlled attenuation circuit, a single-pole double-throw switch SPDT1 and a single-pole double-throw switch SPDT2 connected to the signal detection circuit; the two output terminals of the single-pole double-throw switch SPDT1 are connected to the two input terminals of the single-pole double-throw switch SPDT2 via the gain compensation circuit and the digitally controlled attenuation circuit, respectively. The signal detection circuit includes a broadband coupled logarithmic detector, a signal conditioning circuit, and a signal detection and processing control circuit connected in sequence. The broadband coupled logarithmic detector is used to acquire the radio frequency signal in the broadband radio frequency front-end radio frequency link, and to perform nonlinear fitting of the amplitude and voltage curves to calculate the amplitude value corresponding to the radio frequency signal voltage. The calculated amplitude value corresponding to the radio frequency signal voltage is compared with a preset dual-threshold amplitude threshold, and the gain tuning circuit is controlled according to the comparison result. The signal detection and processing control circuit is connected to the gain tuning circuit. The signal conditioning circuit is a signal differential conditioning circuit.

2. An adaptive AGC control method for broadband radio frequency front-ends, characterized in that, Includes the following steps: S1, the adaptive AGC control circuit for broadband RF front-end as described in claim 1 is connected to the broadband RF front-end RF link; wherein the broadband RF front-end RF link includes a broadband filter, a limiter and a low-noise amplifier; the broadband filter is connected in sequence to the limiter, the gain tuning circuit and the low-noise amplifier. S2, the signal detection circuit samples the RF signal in the broadband RF front-end RF link from the output of the limiter, and uses a dual-threshold signal amplitude detection method to control the gain tuning circuit based on the sampled RF signal in the broadband RF front-end RF link.

3. The adaptive AGC control method for broadband radio frequency front-ends according to claim 2, characterized in that, Step S2 includes: S21, the broadband coupled logarithmic detector samples the radio frequency signal in the broadband radio frequency front-end radio frequency link and performs nonlinear fitting of the amplitude and voltage curves to calculate the amplitude value corresponding to the radio frequency signal voltage. S22 compares the calculated amplitude value of the RF signal voltage with the preset dual-threshold amplitude threshold, and controls the gain tuning circuit based on the comparison result.

4. The adaptive AGC control method for broadband radio frequency front-ends according to claim 3, characterized in that, This is a preset high threshold for signal detection. The preset low threshold for signal detection. Engineering margin, assuming the calculated amplitude value of the RF signal voltage is A, then step S22 includes: (1) and This means that the calculated amplitude value of the RF signal voltage is within the preset double threshold amplitude threshold. The single-pole double-throw switch SPDT1 and single-pole double-throw switch SPDT2 in the gain tuning circuit are controlled to connect the digitally controlled attenuator to the broadband RF front-end RF link and the digitally controlled attenuation is 0. (2) This indicates that the calculated amplitude value of the RF signal voltage exceeds the preset high threshold for signal detection. The single-pole double-throw switches SPDT1 and SPDT2 in the control gain tuning circuit are then used to connect the digitally controlled attenuator to the broadband RF front-end RF link, with the digitally controlled attenuation being A-. ; (3) This indicates that the calculated amplitude value of the RF signal voltage is within the preset low threshold for signal detection. The single-pole double-throw switch SPDT1 and single-pole double-throw switch SPDT2 in the gain tuning circuit are controlled to connect the gain compensation circuit to the broadband RF front-end RF link.

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