Phase noise and stray level adjustable microwave signal source and adjusting method

Abstract

The invention discloses a microwave signal source with adjustable and controllable phase noise and stray level and an adjusting and controlling method, the microwave signal source comprises a power divider, a phase noise adjusting and controlling circuit, a main phase-locked loop circuit, a coupler and a low-pass filter 2 which are sequentially connected from a constant-temperature crystal oscillator to the output end of the microwave signal source, and the microwave signal source further comprises a stray level adjusting and controlling circuit; the power divider comprises two branches, one branch is connected to the phase noise regulation and control circuit, the other branch is connected to the reference input end of the stray level regulation and control circuit, and the output end of the stray level regulation and control circuit is connected to the coupling port of the coupler. According to the scheme, the problem that the phase noise index of the microwave signal source is accurate and controllable is solved, the phase noise index of the microwave signal source is regulated and controlled in a large range, and the phase noise regulation and control precision and the numerical control attenuator regulation and control precision are at the same level.

Description

Technical Field

[0001] This invention relates to the field of microwave system testing and evaluation technology for communications, radar, electronic countermeasures, etc., and particularly to a microwave signal source and control method with adjustable phase noise and spurious levels. Background Technology

[0002] Microwave signal sources are core units in microwave systems such as microwave communication, radar systems, and electronic countermeasures, playing a crucial role in determining the performance of these systems. Phase noise and spurious levels are key indicators of microwave signal sources, directly affecting technical and tactical indicators such as microwave communication bit error rate, radar clutter visibility, radar false alarm rate, and target or threat detection success rate. Therefore, quantitatively assessing the impact of microwave signal source phase noise and spurious levels on microwave systems is of great significance. On the one hand, it allows for accurate evaluation of system performance under different levels of phase noise and spurious levels, clarifying the associated system parameters, and thus providing threshold indicators for each microwave subsystem based on measured data. On the other hand, it allows for the improvement and optimization of signal processing algorithms under different levels of phase noise and spurious levels, enhancing overall system performance and accurately evaluating the degree of performance improvement. Therefore, precise controllability of microwave signal source phase noise and spurious levels is fundamental to achieving the above objectives.

[0003] Phase noise is a frequency domain parameter representing the degree of random phase jitter in a sinusoidal wave. Typically, crystal oscillators with different phase noise levels are used as reference signals for frequency synthesizers to generate microwave signal sources with varying phase noise levels. However, due to the significant differences in phase noise parameters among various crystal oscillators, it is impossible to achieve high-resolution control of phase noise, rendering it meaningless for precise quantitative assessment. Furthermore, signal sources based on crystal oscillators with multiple phase noise levels suffer from disadvantages in terms of size, power consumption, and cost. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a microwave signal source and control method with adjustable phase noise and spurious levels. Based on a crystal oscillator, a phase noise control circuit links the adjustment of phase noise to the control of the attenuation of a reference signal, ensuring that the control accuracy and range of the microwave signal source's phase noise are at the same level as the attenuation accuracy and range of a digitally controlled attenuator. This design not only simplifies the circuit architecture but also significantly improves the resolution of phase noise control, making quantitative assessment based on phase noise feasible.

[0005] This invention is achieved using the following technical solution: In a first aspect, a microwave signal source with adjustable phase noise and spurious level includes a power divider, a phase noise control circuit, a main phase-locked loop circuit, a coupler, and a low-pass filter 2 connected sequentially from a temperature-controlled crystal oscillator to the output terminal of the microwave signal source, and also includes a spurious level control circuit.

[0006] Specifically, the power divider includes two branches, one of which is connected to the phase noise control circuit, and the other is connected to the reference input terminal of the spurious level control circuit. The output terminal of the spurious level control circuit is connected to the coupling port of the coupler.

[0007] Specifically, the phase noise control circuit includes a symmetrically arranged single-pole double-throw switch 1 and a single-pole double-throw switch 2. Each of the single-pole double-throw switches 1 and 2 includes two branches. Branch 1 of the single-pole double-throw switch 1 is connected to branch 2 of the single-pole double-throw switch 2 to form channel one, and branch 2 of the single-pole double-throw switch 1 is connected to branch 1 of the single-pole double-throw switch 2 to form channel two.

[0008] Specifically, the second channel is also connected in sequence to a digitally controlled attenuator 1, a digitally controlled attenuator 2, a low-noise amplifier, and a variable gain amplifier.

[0009] Specifically, the spurious level control circuit includes a spurious generation phase-locked loop, a digitally controlled attenuator 3, a digitally controlled attenuator 4, and a low-pass filter 1 connected in sequence; the output terminal of the low-pass filter 1 is connected to the coupling port of the coupler.

[0010] On the other hand, a method for controlling a microwave signal source with adjustable phase noise and spurious levels, based on the aforementioned microwave signal source with adjustable phase noise and spurious levels, includes phase noise control and spurious level control, wherein the phase noise control specifically includes: When the microwave signal source phase noise is at its optimal setting, switch single-pole double-throw switch 1 and single-pole double-throw switch 2 to channel one for direct connection; When adjusting the phase noise value, switch single-pole double-throw switch 1 and single-pole double-throw switch 2 to channel two, and control the attenuation IL1 of digitally controlled attenuator 1 to be close to the gain G1 of the low noise amplifier; at the same time, control the attenuation IL2 of digitally controlled attenuator 2 to be close to the gain G2 of the variable gain amplifier, so that IL2 and G2 are equivalent; at this time, the increase in phase noise corresponds to the increase in IL2 and G2. By changing IL2 and the corresponding G2 value, the phase noise value can be precisely controlled.

[0011] Specifically, the attenuation range of the numerically controlled attenuator 1 is set to 31.5dB, and the attenuation step is set to 0.5dB; the attenuation range of the numerically controlled attenuator 2 is set to 31.5dB, and the attenuation step is set to 0.5dB; the gain of the low-noise amplifier is set to 25dB; and the gain range of the variable gain amplifier is set to 0dB~31.5dB, and the gain step is set to 0.5dB.

[0012] Specifically, the spurious level modulation includes: The stray generation phase-locked loop generates a microwave signal with a frequency deviation from the main phase-locked loop. The frequency deviation value can be precisely set according to the application requirements. By controlling the attenuation of digitally controlled attenuators 3 and 4, precise control of the output stray level can be achieved.

[0013] Specifically, the attenuation range of the numerically controlled attenuator 3 is set to 31.5dB, and the attenuation step is set to 0.5dB; the attenuation range of the numerically controlled attenuator 4 is set to 31.5dB, and the attenuation step is set to 0.5dB.

[0014] The beneficial effects of this invention are as follows: This invention generates a frequency-controllable signal source through a phase-locked loop circuit and controls the output power of the signal source through a digitally controlled attenuator. This signal source is coupled to a carrier signal via a coupler to form a spurious signal whose frequency and power can be flexibly controlled to adapt to various application scenarios. The phase-compensated microstrip power divider in this invention can perform phase compensation at the phase-sensitive local oscillator signal, thereby achieving the phase consistency of the channel. This method requires no additional component overhead; the compensation circuit and power divider network are designed on a printed circuit board, resulting in a simple structure that introduces almost no additional differential loss. The phase compensation amount can be accurately compensated based on test results, eliminating the need for complex phase compensation algorithms.

[0015] The technical solution of this invention solves the problem of precise and controllable phase noise index of microwave signal source. The phase noise control accuracy is at the same level as that of digitally controlled attenuator, with a typical value of 0.5dB. It also solves the problem of wide-range control of phase noise index of microwave signal source, with a phase noise control range of 31.5dB. Furthermore, it solves the problem of controllable frequency deviation of microwave signal source spurious signals, with a frequency resolution of <1Hz. Finally, it solves the problem of controllable spurious signal level of microwave signal source, with a spurious level control range of 63dB and a spurious level control step of 0.5dB. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a circuit diagram of a microwave signal source with adjustable phase noise and spurious levels, as shown in an embodiment of the present invention. Detailed Implementation

[0018] 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.

[0019] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0020] The following is in conjunction with the appendix Figure 1 The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] This invention proposes a microwave signal source with adjustable phase noise and spurious levels. In a preferred embodiment, such as... Figure 1 As shown, the microwave signal source consists of a temperature-controlled crystal oscillator, a power divider, a phase noise control circuit, a spurious level control circuit, a main phase-locked loop circuit, a coupler, and a low-pass filter 2. The phase noise control circuit comprises a single-pole double-throw switch 1, a single-pole double-throw switch 2, a digitally controlled attenuator 1, a digitally controlled attenuator 2, a low-noise amplifier, and a variable gain amplifier. The spurious level control circuit comprises a spurious generation phase-locked loop, a digitally controlled attenuator 3, a digitally controlled attenuator 4, and a low-pass filter 2.

[0022] In this embodiment, the low phase noise reference signal output from the temperature-controlled crystal oscillator is divided into two paths by a power divider. One path is output to the phase noise control circuit, and the other path is output to the reference input of the spurious level generation phase-locked loop (PLL) circuit. The phase noise control circuit outputs to the reference port of the main PLL, which generates the required microwave signal source, which is then output via a coupler and a low-pass filter. The spurious level control circuit outputs to the coupling port of the coupler.

[0023] The phase noise control circuit is configured as follows: the signal input from the two power dividers is fed to the common port of single-pole double-throw switch 1, and one branch 1 of single-pole double-throw switch 1 is directly connected to branch 2 of single-pole double-throw switch 2. Branch 2 of single-pole double-throw switch 1 is connected to branch 1 of single-pole double-throw switch 2 after passing through digitally controlled attenuator 1, digitally controlled attenuator 2, low-noise amplifier, and variable gain amplifier.

[0024] The spurious level control circuit is configured as follows: the RF output terminal of the spurious generation phase-locked loop is connected to the input terminal of the digitally controlled attenuator 3; the output terminal of the digitally controlled attenuator 3 is connected to the input terminal of the digitally controlled attenuator 4; the output terminal of the digitally controlled attenuator 4 is connected to the input terminal of the low-pass filter 1; and the output terminal of the low-pass filter is connected to the coupling port of the coupler.

[0025] The following is a detailed explanation of the control mechanism of this microwave signal source with adjustable phase noise and spurious levels: (1) Phase noise modulation mechanism: When the microwave signal source is in its optimal phase noise setting, the single-pole double-throw switch is switched to the direct-on position, i.e., channel one. When it is necessary to adjust the phase noise value, the single-pole double-throw switch is switched to channel two, controlling the attenuation IL1 of the digitally controlled attenuator 1 to be close to the gain G1 of the low-noise amplifier. Simultaneously, the attenuation IL2 of the digitally controlled attenuator 2 is controlled to be approximately equal to the gain G2 of the variable-gain amplifier. At this point, the increase in phase noise corresponds to the increase in IL2 and G2. Therefore, by simply changing IL2 and the corresponding G2 value, the phase noise value can be precisely adjusted.

[0026] Among them, the attenuation range of the numerically controlled attenuator 1 is 31.5dB, with an attenuation step of 0.5dB; the attenuation range of the numerically controlled attenuator 2 is 31.5dB, with an attenuation step of 0.5dB; the gain of the low-noise amplifier is 25dB; the gain range of the variable gain amplifier is 0dB~31.5dB, with a gain step of 0.5dB.

[0027] (2) Spurious level control mechanism: The stray signal generation phase-locked loop generates a microwave signal that deviates from the main phase-locked loop at a certain frequency. The frequency offset value can be precisely set according to the application requirements. By controlling the attenuation of digitally controlled attenuators 3 and 4, the output stray signal level can be precisely controlled. This achieves precise control over the stray frequency offset and the magnitude of the stray signal level.

[0028] Among them, the attenuation range of the CNC attenuator 3 is 31.5dB, and the attenuation step is 0.5dB; the attenuation range of the CNC attenuator 4 is 31.5dB, and the attenuation step is 0.5dB.

[0029] This invention, based on a crystal oscillator, uses a phase noise modulation circuit to correlate phase noise control with the control of reference signal attenuation. This ensures that the control accuracy and modulation range of the microwave signal source's phase noise are at the same level as the attenuation accuracy and range of a digitally controlled attenuator. This design not only simplifies the circuit architecture but also significantly improves the resolution of phase noise control, making quantitative assessment based on phase noise feasible.

[0030] This invention generates a frequency-controllable signal source through a phase-locked loop circuit and controls the output power of the signal source through a digitally controlled attenuator. This signal source is then coupled to a carrier signal via a coupler to form a spurious signal whose frequency and power can be flexibly controlled, adapting to the needs of various application scenarios.

[0031] For the foregoing embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to this application.

[0032] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Modifications and variations made by those skilled in the art without departing from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. A microwave signal source with adjustable phase noise and spurious level, characterized in that, It includes a power divider, a phase noise control circuit, a main phase-locked loop circuit, a coupler, and a low-pass filter 2, which are connected in sequence from the temperature-controlled crystal oscillator to the output of the microwave signal source. It also includes a spurious level control circuit.

2. A microwave signal source with adjustable phase noise and spurious levels as described in claim 1, characterized in that, The power divider includes two branches, one of which is connected to the phase noise control circuit, and the other is connected to the reference input terminal of the spurious level control circuit. The output terminal of the spurious level control circuit is connected to the coupling port of the coupler.

3. A microwave signal source with adjustable phase noise and spurious levels as described in claim 1, characterized in that, The phase noise control circuit includes a symmetrically arranged single-pole double-throw switch 1 and a single-pole double-throw switch 2. Each single-pole double-throw switch 1 and single-pole double-throw switch 2 includes two branches. Branch 1 of single-pole double-throw switch 1 is connected to branch 2 of single-pole double-throw switch 2 to form channel one, and branch 2 of single-pole double-throw switch 1 is connected to branch 1 of single-pole double-throw switch 2 to form channel two.

4. A microwave signal source with adjustable phase noise and spurious levels as described in claim 3, characterized in that, Channel 2 is also connected in sequence to digitally controlled attenuator 1, digitally controlled attenuator 2, low-noise amplifier and gain variable amplifier.

5. A microwave signal source with adjustable phase noise and spurious levels as described in claim 1, characterized in that, The spurious level control circuit includes a spurious generation phase-locked loop, a digitally controlled attenuator 3, a digitally controlled attenuator 4, and a low-pass filter 1 connected in sequence; the output terminal of the low-pass filter 1 is connected to the coupling port of the coupler.

6. A method for controlling a microwave signal source with adjustable phase noise and spurious levels, implemented based on a microwave signal source with adjustable phase noise and spurious levels as described in any one of claims 1 to 5, characterized in that, This includes phase noise modulation and spurious level modulation, wherein the phase noise modulation specifically includes: When the microwave signal source phase noise is at its optimal setting, switch single-pole double-throw switch 1 and single-pole double-throw switch 2 to channel one for direct connection; When adjusting the phase noise value, switch single-pole double-throw switch 1 and single-pole double-throw switch 2 to channel two, and control the attenuation IL1 of digitally controlled attenuator 1 to be close to the gain G1 of the low noise amplifier; at the same time, control the attenuation IL2 of digitally controlled attenuator 2 to be close to the gain G2 of the variable gain amplifier, so that IL2 and G2 are equivalent; at this time, the increase in phase noise corresponds to the increase in IL2 and G2. By changing IL2 and the corresponding G2 value, the phase noise value can be precisely controlled.

7. The method for controlling a microwave signal source with adjustable phase noise and spurious levels as described in claim 6, characterized in that, The attenuation range of the numerically controlled attenuator 1 is set to 31.5dB, and the attenuation step is set to 0.5dB; the attenuation range of the numerically controlled attenuator 2 is set to 31.5dB, and the attenuation step is set to 0.5dB; the gain of the low-noise amplifier is set to 25dB; and the gain range of the variable-gain amplifier is set to 0dB~31.5dB, and the gain step is set to 0.5dB.

8. The method for controlling a microwave signal source with adjustable phase noise and spurious levels as described in claim 6, characterized in that, The spurious level control specifically includes: The stray generation phase-locked loop generates a microwave signal with a frequency deviation from the main phase-locked loop. The frequency deviation value can be precisely set according to the application requirements. By controlling the attenuation of digitally controlled attenuators 3 and 4, precise control of the output stray level can be achieved.

9. The method for controlling a microwave signal source with adjustable phase noise and spurious levels as described in claim 8, characterized in that, The attenuation range of the numerically controlled attenuator 3 is set to 31.5dB, and the attenuation step is set to 0.5dB; the attenuation range of the numerically controlled attenuator 4 is set to 31.5dB, and the attenuation step is set to 0.5dB.

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