Frequency source and radar system
By combining a multi-stage power divider, a comb spectrum circuit, and a mixer, the design of this frequency source solves the problem that traditional frequency sources cannot achieve multiple frequency points and arbitrarily adjustable bandwidth. It achieves high-quality multi-frequency signal output and low phase noise signal, making it suitable for radar systems.
Patent Information
- Application Number
- CN202423248395.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-27
AI Technical Summary
Traditional frequency sources cannot meet the requirements of radar systems for multiple frequency points and arbitrary bandwidth adjustment, and cannot output high-frequency signals with low phase noise.
The design combines a multi-stage power divider, a comb spectrum circuit, and a mixer. Using a reference clock as a reference, and incorporating a phase-locked loop and a filter, it achieves multi-frequency signal output and arbitrarily adjustable bandwidth. The comb spectrum circuit and mixing loop reduce phase noise, and the insulator cavity filter improves signal quality.
It achieves multi-frequency signal output and arbitrarily adjustable bandwidth, ensures full signal coherence, reduces size and improves signal quality, with RF signal phase noise ≤-115dBc/Hz@1KHz, high spurious suppression level, and is suitable for radar systems.
Smart Images
Figure CN223625854U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of frequency generation technology, and in particular relates to a frequency source and radar system with multi-channel ultra-low phase noise and high spurious suppression output. Background Technology
[0002] Frequency sources are core components of electronic equipment such as communication, radar, and electronic jamming and countermeasures systems, and their performance directly determines the overall performance of the entire electronic device. Frequency sources typically employ three design methods: direct frequency synthesis, direct digital frequency synthesis, and indirect frequency synthesis. Direct frequency synthesis offers the best signal quality but is relatively large in size. While direct digital and indirect frequency synthesis can achieve smaller sizes, their phase noise performance deteriorates significantly at high frequencies.
[0003] Radar systems have high requirements for frequency sources. If direct frequency synthesis technology is used, it is impossible to meet the radar system's requirements for multiple frequency points and arbitrarily adjustable bandwidth; if direct digital frequency synthesis technology or indirect frequency synthesis technology is used, it is impossible to output high-frequency signals with low phase noise. Utility Model Content
[0004] The purpose of this invention is to provide a frequency source and radar system to solve at least one of the problems of traditional frequency sources being unable to meet the requirements of radar systems for multiple frequency points and arbitrary bandwidth adjustment, and being unable to output high-frequency signals with low phase noise.
[0005] This utility model solves the above-mentioned technical problems through the following technical solution: a frequency source, including a reference clock, a first power divider, a second power divider, a third power divider, a fourth power divider, a comb spectrum circuit, a first mixer, a second mixer, and a mixing loop;
[0006] The output of the reference clock is connected to the input of the first power divider; the first output of the first power divider is connected to the input of the comb spectrum circuit, the output of the comb spectrum circuit is connected to the input of the second power divider, and the first output of the second power divider, the first mixer, the second mixer, and the third power divider are connected in sequence; the second output of the first power divider, the mixing loop, and the fourth power divider are connected in sequence; the second output of the second power divider is connected to the mixing loop, and the first output of the fourth power divider is connected to the input of the second mixer; the first mixer is also connected to an external clock.
[0007] Furthermore, the reference clock is a temperature-controlled crystal oscillator.
[0008] Furthermore, the mixing loop includes a phase-locked loop (PLL) and a third mixer. The input terminal of the PLL is connected to the second output terminal of the first power divider, the output terminal of the PLL is connected to the first input terminal of the third mixer, the second input terminal of the third mixer is connected to the second output terminal of the second power divider, and the output terminal of the third mixer is connected to the fourth power divider.
[0009] Furthermore, a first filter is provided between the second power divider and the first mixer, and a second filter and a first amplifier are provided between the first mixer and the second mixer, with the output terminal of the second filter connected to the input terminal of the first amplifier.
[0010] Furthermore, a third filter and a second amplifier are provided between the second power divider and the mixer loop, and the output terminal of the third filter is connected to the input terminal of the second amplifier.
[0011] Furthermore, the third filter is an insulator cavity filter.
[0012] Furthermore, the insulator cavity filter includes a filter body and a cover plate disposed on the filter body. Grooves are provided at both ends of the cover plate, and pressure plates are provided on both sides of the glass bead insulator of the filter body.
[0013] Furthermore, the second power divider is a broadband power divider.
[0014] Furthermore, the second, third, and fourth power dividers are all switching power dividers.
[0015] Based on the same concept, this utility model also provides a radar system, which includes the frequency source described above.
[0016] Beneficial effects
[0017] Compared with the prior art, the advantages of this utility model are:
[0018] The frequency source of this utility model achieves the requirements of multi-frequency signal output and arbitrary bandwidth adjustment by combining a multi-stage power divider, a comb spectrum circuit and a mixer. Furthermore, since all output signals use the same reference clock as a reference, it ensures that all signals are fully coherent.
[0019] This invention combines a comb spectrum circuit, a second power divider, and a mixer loop to save space while outputting multiple signals, and at the same time ensures that the output signals have low near-end phase noise and high spurious suppression, thus improving signal quality. Compared with the step adjustment limitations of direct frequency synthesis, this invention can achieve step adjustment at the kHz level. Attached Figure Description
[0020] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a structural block diagram of the frequency source in an embodiment of this utility model;
[0022] Figure 2 This is a schematic diagram of the structure of the insulator cavity filter in an embodiment of this utility model;
[0023] Figure 3 This is the phase noise curve of the radio frequency signal output by the frequency source in this embodiment of the present invention;
[0024] Figure 4 This is a waveform diagram of the radio frequency signal output by the frequency source in an embodiment of this utility model;
[0025] Figure 5 This is the phase noise curve of the local oscillator signal output by the frequency source in this embodiment of the present invention;
[0026] Figure 6 This is a schematic diagram of a 5300MHz to 5700MHz filter in an embodiment of this utility model.
[0027] Explanation of reference numerals in the attached drawings: 1-cover plate, 2-filter body, 11-groove, 21-pressure plate, 22-glass bead insulator. Detailed Implementation
[0028] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0029] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0030] like Figure 1As shown in the figure, a frequency source provided by this utility model embodiment includes a reference clock, a first power divider, a second power divider, a third power divider, a fourth power divider, a comb spectrum circuit, a first mixer, a second mixer, and a mixing loop; the output terminal of the reference clock is connected to the input terminal of the first power divider; the first output terminal of the first power divider is connected to the input terminal of the comb spectrum circuit, the output terminal of the comb spectrum circuit is connected to the input terminal of the second power divider, the first output terminal of the second power divider, the first mixer, the second mixer, and the third power divider are connected in sequence; the second output terminal of the first power divider, the mixing loop, and the fourth power divider are connected in sequence; the second output terminal of the second power divider is connected to the mixing loop, and the first output terminal of the fourth power divider is connected to the input terminal of the second mixer; the first mixer is also connected to an external clock.
[0031] In a specific embodiment of this utility model, the reference clock is a temperature-controlled crystal oscillator.
[0032] In a specific embodiment of this invention, the mixing loop includes a phase-locked loop (PLL) and a third mixer. The input terminal of the PLL is connected to the second output terminal of the first power divider, the output terminal of the PLL is connected to the first input terminal of the third mixer, the second input terminal of the third mixer is connected to the second output terminal of the second power divider, and the output terminal of the third mixer is connected to a fourth power divider. The mixing loop reduces the feedback frequency through down-conversion, bringing the near-end phase noise of the output close to the performance level of a direct conversion method.
[0033] In a specific embodiment of this utility model, a first filter is provided between the second power divider and the first mixer, and a second filter and a first amplifier are provided between the first mixer and the second mixer. The output terminal of the second filter is connected to the input terminal of the first amplifier. The first filter removes the harmonic components of the output signal at the first output terminal of the second power divider, and the output signal of the first mixer is filtered and amplified by the second filter and the first amplifier before being mixed with the output signal of the fourth power divider.
[0034] In a specific embodiment of this invention, a third filter and a second amplifier are provided between the second power divider and the mixer loop, with the output terminal of the third filter connected to the input terminal of the second amplifier. The output signal from the second output terminal of the second power divider is filtered and amplified by the third filter and the second amplifier, and then used as the local oscillator signal of the mixer loop.
[0035] In a specific embodiment of this utility model, the third filter is an insulator cavity filter. For example... Figure 2 As shown, the insulator cavity filter includes a filter body 2 and a cover plate 1 disposed on the filter body 2. Grooves 11 are also provided at both ends of the cover plate 1, and pressure plates 21 are provided on both sides of the glass bead insulator 22 of the filter body 2.
[0036] In the high-frequency section, an insulator cavity filter is used. This filter abandons the traditional method of welding the two ends of the cover plate 1 to the component structure. Instead, pressure plates 21 are added to both ends of the glass bead insulator 22 of the filter body 2 to connect and lock with the PCB. Grooves 11 are added to both ends of the cover plate 1 to connect and lock with the PCB cover structure. This ensures the continuity of ground and does not affect the relevant indicators. While ensuring out-of-band suppression and in-band standing wave, it improves the convenience of disassembly, replacement and maintenance.
[0037] In a specific embodiment of this utility model, the second power divider is selected as a broadband power divider.
[0038] In a specific embodiment of this utility model, the second power divider, the third power divider, and the fourth power divider are all switching power dividers.
[0039] For example, a reference clock outputs a 100MHz signal, which is divided into four paths by a first power divider. Two of these paths output 100MHz signals: one is input to a comb spectrum circuit and serves as its reference, and the other is input to a mixer loop and serves as its reference. The comb spectrum circuit generates rich harmonic components based on the 100MHz fundamental frequency. These harmonic components are then divided by a second power divider, outputting 1500MHz and 6500MHz signals. The remaining harmonic components of these two signals are filtered by a first filter and a third filter, respectively. The first and third filters can be narrowband filters. The 6500MHz signal output from the second power divider is filtered and amplified by the third filter and the second amplifier, and then used as the local oscillator signal for the mixing loop. The mixing loop reduces the feedback frequency through down-conversion, bringing the near-end phase noise of the output close to the performance level of direct conversion. The mixing loop outputs a 6840MHz to 7240MHz signal, which is divided by the fourth power divider and output in two paths as local oscillator signals, while one path is input to the second mixer and used as the local oscillator signal for internal RF conversion. The second power divider outputs a 1500MHz signal, which is mixed with an externally input 40MHz signal to output a 1540MHz signal. This 1540MHz signal is then filtered and amplified by the second filter and the first amplifier, and then converted to 5300MHz to 5700MHz by the 6840MHz to 7240MHz signal output from the fourth power divider. Finally, it is divided by the third power divider and output.
[0040] Therefore, it can be seen that the frequency source outputs two radio frequency signals of 5300MHz to 5700MHz, two local oscillator signals of 1500MHz and 6840MHz to 7240MHz, and two clock signals of 100MHz. All signals are based on the same reference clock, ensuring that all signals are fully coherent and the step can reach the KHz level. The phase noise of the radio frequency signal and the local oscillator signal is ≤-115dBc / Hz@1KHz.
[0041] Figure 3 The diagram shows the phase noise curve of the RF signal output from the frequency source, where the vertical axis represents the phase noise value and the horizontal axis represents the frequency offset during signal measurement. Mark 1 indicates that the measured phase noise value at a deviation of 1 kHz from the carrier frequency is -117.57 dBc / Hz. Figure 3 It can be seen that the phase noise level of the radio frequency signal reaches -117.57dBc / Hz@1KHz, and it is synchronously correlated with the output local oscillator signal, with a step size that can reach the KHz level between 5300MHz and 5700MHz. The frequency source of this invention can greatly improve the sensitivity, limit improvement factor and other indicators of the radar system, and facilitate the selectivity of frequency points when selecting radar sites.
[0042] Figure 4 The waveform of the radio frequency signal output from the frequency source is shown, where the vertical axis represents the signal power value and the horizontal axis represents the signal frequency value. Mark 1 indicates that the signal power value at 5.5 GHz is 19.268 dBm, and the signal noise floor is approximately -70 dBm. Figure 4 It can be seen that the spectrum of the radio frequency signal is very clean, and the spurious suppression level can reach 90dBc within the 2GHz bandwidth of the test frequency point, providing a very clean radio frequency signal for the radar system and greatly reducing the work of correlation filtering and anti-interference.
[0043] Figure 5 The diagram shows the phase noise curve of the local oscillator signal output from the frequency source, where the vertical axis represents the phase noise value, the horizontal axis represents the frequency offset during signal measurement, and the numbers in the upper right corner represent the phase noise value of the signal at points deviating from the carrier frequency, for example...
[0044] 1.000kHz, -136.61dBc / Hz indicates that the phase noise of the signal at a frequency 1kHz away from the carrier frequency is -136.61dBc / Hz. Figure 5 It can be seen that the local oscillator signal output by the comb spectrum circuit has a phase noise level of -136.61dBc / Hz@1KHz, which is comparable to the theoretical phase noise degradation level of direct frequency doubling of the reference source, with virtually no additional degradation value. The comb spectrum circuit is also simpler and more efficient than other direct frequency doubling methods.
[0045] Figure 6 A filter for the 5300MHz–5700MHz range is shown, where the vertical axis represents the signal power value and the horizontal axis represents the signal frequency value. Figure 6It can be seen that the insertion loss at 5.5 GHz is 1.6062 dB, and the return losses at the two ports are -22.626 dB and -26.664 dB, respectively, indicating that the filter has good in-band insertion loss and VSWR. This improved insulator cavity filter, while ensuring ease of maintenance, maintains in-band VSWR and in-band loss values close to the normal design simulation values, without being affected by performance degradation caused by ground discontinuities.
[0046] For multi-output, compared to other frequency multiplication links with stage-by-stage frequency multiplication and filtering amplification, this invention uses a comb spectrum circuit, which only requires one fundamental frequency input to output the fundamental frequency harmonics up to approximately 8GHz. The output is filtered for the required frequency points through a second power divider (wideband power divider) + filter, which greatly saves the volume of the frequency source, while ensuring high frequency multiplication efficiency and low phase noise degradation.
[0047] This invention combines a comb spectrum, a broadband power divider, and a mixer loop to save space while outputting multiple signals. At the same time, it ensures low near-end phase noise and high spurious suppression, thus improving signal quality. Compared with the step adjustment limitations of direct frequency synthesis, this invention can achieve step adjustment at the kHz level.
[0048] The above description only discloses specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.
Claims
1. A frequency source, characterized in that: The frequency source includes a reference clock, a first power divider, a second power divider, a third power divider, a fourth power divider, a comb spectrum circuit, a first mixer, a second mixer, and a mixing loop; The output of the reference clock is connected to the input of the first power divider; the first output of the first power divider is connected to the input of the comb spectrum circuit, the output of the comb spectrum circuit is connected to the input of the second power divider, and the first output of the second power divider, the first mixer, the second mixer, and the third power divider are connected in sequence; the second output of the first power divider, the mixing loop, and the fourth power divider are connected in sequence; the second output of the second power divider is connected to the mixing loop, and the first output of the fourth power divider is connected to the input of the second mixer; the first mixer is also connected to an external clock.
2. The frequency source according to claim 1, characterized in that: The reference clock is a temperature-controlled crystal oscillator.
3. The frequency source according to claim 1, characterized in that: The mixing loop includes a phase-locked loop (PLL) and a third mixer. The input terminal of the PLL is connected to the second output terminal of the first power divider, the output terminal of the PLL is connected to the first input terminal of the third mixer, the second input terminal of the third mixer is connected to the second output terminal of the second power divider, and the output terminal of the third mixer is connected to the fourth power divider.
4. The frequency source according to claim 1, characterized in that: A first filter is provided between the second power divider and the first mixer, and a second filter and a first amplifier are provided between the first mixer and the second mixer. The output terminal of the second filter is connected to the input terminal of the first amplifier.
5. The frequency source according to claim 1, characterized in that: A third filter and a second amplifier are provided between the second power divider and the mixer loop, and the output of the third filter is connected to the input of the second amplifier.
6. The frequency source according to claim 5, characterized in that: The third filter is an insulator cavity filter.
7. The frequency source according to claim 6, characterized in that: The insulator cavity filter includes a filter body and a cover plate disposed on the filter body. Grooves are provided at both ends of the cover plate, and pressure plates are provided on both sides of the glass bead insulator of the filter body.
8. The frequency source according to claim 1, characterized in that: The second power divider is a broadband power divider.
9. The frequency source according to any one of claims 1 to 8, characterized in that: The second, third, and fourth power dividers are all switching power dividers.
10. A radar system, characterized in that: The radar system includes a frequency source as described in any one of claims 1 to 9.