阅读说明：本技术 频率跳变的宽带信道频率合成器及频率合成方法 (Frequency hopping broadband channel frequency synthesizer and frequency synthesis method ) 是由 王杨 杜金灿 孙增 薄淑华 于 2020-03-25 设计创作，主要内容包括：本发明提供了一种频率跳变的宽带信道频率合成器及频率合成方法,该频率合成器包括DDS及控制单元、S波段、X/Ku波段梳状谱及滤波单元、S波段混频单元、S波段、X/Ku波段开关滤波单元、宽带混频单元、宽带功分放大单元、参考分配单元和开关电源电路,S波段混频单元用于将窄带捷变频信号与第一本振信号混频以输出第一级中频信号,S波段开关滤波单元用于对第一级中频信号进行滤波；宽带混频单元用于将滤波后的第一级中频信号与第二本振信号混频以输出第二级中频信号；X/Ku波段开关滤波单元用于对第二级中频信号进行滤波。应用本发明的技术方案,以解决现有技术中频率合成器无法在保证宽带频率源输出的频谱纯度的基础上,缩短频率跳变时间的技术问题。(The invention provides a frequency hopping broadband channel frequency synthesizer and a frequency synthesis method, wherein the frequency synthesizer comprises a DDS (direct digital synthesizer), a control unit, an S waveband, an X/Ku waveband comb spectrum and filtering unit, an S waveband frequency mixing unit, an S waveband, an X/Ku waveband switching filtering unit, a broadband frequency mixing unit, a broadband power division amplifying unit, a reference distribution unit and a switching power supply circuit, wherein the S waveband frequency mixing unit is used for mixing a narrowband frequency agile signal with a first local oscillator signal to output a first-stage intermediate frequency signal, and the S waveband switching filtering unit is used for filtering the first-stage intermediate frequency signal; the broadband frequency mixing unit is used for mixing the filtered first-stage intermediate frequency signal with a second local oscillator signal to output a second-stage intermediate frequency signal; and the X/Ku waveband switch filtering unit is used for filtering the second-stage intermediate frequency signal. The technical scheme of the invention is applied to solve the technical problem that the frequency synthesizer in the prior art can not shorten the frequency hopping time on the basis of ensuring the spectral purity of the broadband frequency source output.)

1. A frequency hopped wideband channel frequency synthesizer, said frequency hopped wideband channel frequency synthesizer comprising:

the DDS and control unit (10), the DDS and control unit (10) is used for generating a narrow-band frequency agile signal;

the system comprises an S-band comb spectrum and filtering unit (20), wherein the S-band comb spectrum and filtering unit (20) is used for generating a first local oscillation signal;

the S-band mixing unit (30), the S-band mixing unit (30) is respectively connected with the DDS and control unit (10) and the S-band comb spectrum and filtering unit (20), and the S-band mixing unit (30) is used for mixing the narrowband frequency agile signal with the first local oscillation signal to output a first-stage intermediate frequency signal;

the S-band switch filtering unit (40), the S-band switch filtering unit (40) is connected with the S-band mixing unit (30), and the S-band switch filtering unit (40) is used for filtering the first-stage intermediate frequency signal;

the X/Ku waveband comb spectrum and filtering unit (50) is used for generating a second local oscillation signal;

the broadband frequency mixing unit (60), the broadband frequency mixing unit (60) is respectively connected with the S-band switch filtering unit (40) and the X/Ku-band comb spectrum and filtering unit (50), and the broadband frequency mixing unit (60) is configured to mix the filtered first-stage intermediate frequency signal with the second local oscillator signal to output a second-stage intermediate frequency signal;

the X/Ku waveband switch filtering unit (70), the X/Ku waveband switch filtering unit (70) is connected with the broadband mixing unit (60), and the X/Ku waveband switch filtering unit (70) is used for filtering the second-stage intermediate frequency signal;

the broadband power division amplifying unit (80), the broadband power division amplifying unit (80) is connected with the X/Ku waveband switch filtering unit (70), and the broadband power division amplifying unit (80) is used for performing power division amplification output on the filtered second-stage intermediate frequency signal;

a reference distribution unit (90), wherein the reference distribution unit (90) is respectively connected to the DDS and control unit (10), the S-band comb spectrum and filter unit (20), and the X/Ku-band comb spectrum and filter unit (50), and the reference distribution unit (90) is configured to provide a reference clock signal and a reference clock signal;

the digital synthesizer comprises a switch power supply circuit (100), wherein the switch power supply circuit (100) is respectively connected with the DDS and control unit (10), the S-band comb spectrum and filtering unit (20), the S-band switch filtering unit (40), the X/Ku-band comb spectrum and filtering unit (50) and the X/Ku-band switch filtering unit (70), and the switch power supply circuit (100) is used for supplying power to the DDS and control unit (10), the S-band comb spectrum and filtering unit (20), the S-band switch filtering unit (40), the X/Ku-band comb spectrum and filtering unit (50) and the X/Ku-band switch filtering unit (70) and realizing band control.

2. The frequency hopping wideband channel frequency synthesizer according to claim 1, wherein the reference distribution unit (90) generates a reference clock signal by using a 100MHz constant temperature crystal oscillator and provides a reference clock signal to the DDS and control unit (10), the reference distribution unit (90), the S-band comb spectrum and filter unit (20), and the X/Ku-band comb spectrum and filter unit (50) through a power division network according to the reference clock signal.

3. The frequency hopped wideband channel frequency synthesizer of claim 1, further comprising an external control interface coupled to the switching power supply circuit (100), the external control interface for inputting an external control signal to the switching power supply circuit (100).

4. The frequency hopping wideband channel frequency synthesizer according to claim 3, wherein the switching power supply circuit (100) uses an FPGA chip to realize switching control of the DDS and control unit (10), the S-band comb spectrum and filter unit (20), the S-band switch filter unit (40), the X/Ku-band comb spectrum and filter unit (50), and the X/Ku-band switch filter unit (70).

5. The frequency hopping wideband channel frequency synthesizer according to claim 4, wherein the switching power supply circuit (100) is configured to implement parallel timing control of the DDS and control unit (10), five-frequency-point control of the S-band comb spectrum and filter unit (20), five-frequency-point control of the X/Ku-band comb spectrum and filter unit (50), ten-segment filter selection control of the S-band switch filter unit (40), and ten-segment filter selection control of the X/Ku-band switch filter unit (70).

6. The frequency hopped wideband channel frequency synthesizer of any of claims 1-5, wherein the S-band comb spectrum and filter unit (20) comprises an S-band comb spectrum generator for generating an S-band wide spectrum signal and a first switched filter unit for filtering the S-band wide spectrum signal to generate a first local oscillator signal.

7. The frequency hopped wideband channel frequency synthesizer of claim 5, wherein the X/Ku band comb spectrum and filter unit (50) comprises an X/Ku band comb spectrum generator for generating an X/Ku band wide spectrum signal and a second switch filter unit for filtering the X/Ku band wide spectrum signal to generate a second local oscillator signal.

8. The frequency hopped wideband channel frequency synthesizer of claim 7, wherein the DDS and control unit (10) comprises a DDS signal generator and an FPGA chip, the DDS signal generator is connected with the FPGA chip, and the FPGA chip is configured to control the DDS signal generator to output a narrowband agile signal.

9. A wideband channel frequency synthesis method, characterized in that it uses the wideband channel frequency synthesizer according to any of claims 1 to 8 for frequency synthesis.

10. The wideband channel frequency synthesis method according to claim 9, wherein the wideband channel frequency synthesis method comprises:

a narrow-band frequency agile signal is output by using a DDS circuit of a DDS and control unit (10);

generating a first local oscillator signal by using an S-band comb spectrum and a filtering unit (20);

inputting the narrow-band frequency agility signal and the first local oscillator signal into an S-band mixing unit (30) for mixing to output a first-stage intermediate frequency signal;

filtering the first-stage intermediate frequency signal by using an S-band switch filtering unit (40);

generating a second local oscillator signal by using an X/Ku waveband comb spectrum and a filtering unit (50);

inputting the filtered first-stage intermediate frequency signal and the second local oscillator signal into a broadband frequency mixing unit (60) for frequency mixing so as to output a second-stage intermediate frequency signal;

filtering the second-stage intermediate frequency signal by using an X/Ku waveband switch filtering unit (70);

and a broadband power division amplifying unit (80) is used for carrying out power division amplification output on the filtered second-stage intermediate frequency signal so as to generate a microwave signal meeting the bandwidth requirement of a broadband frequency source.

Technical Field

The present invention relates to the field of communications systems, and in particular, to a frequency hopping wideband channel frequency synthesizer and a frequency synthesizing method.

Background

The frequency synthesizer is widely used in communication systems as a core component of the communication systems, plays a very critical role in modern communication and information processing systems, and the performance index of the frequency synthesizer plays a decisive role in the system performance index. At present, in wireless and mobile communication applications, with the increase of data transmission speed, the locking time of the local oscillator frequency synthesizer of the radio frequency transmitting and receiving machine becomes a key index of design more and more. The frequency switching time of the frequency synthesizer determines the channel switching speed of the communication system and the setup time of the system because the system is in a waiting state during the frequency conversion process and can receive and transmit data only after locking. The locking process is a waste of system power consumption and time, and if the locking time is short, more time is used for data processing, so that the system data processing speed is increased, and the waste of power consumption is reduced, so that the time should be as short as possible. In addition, in a frequency hopping spread spectrum communication system, the locking time is short, which is beneficial to improving the communication quality and reducing the error rate. In the secret frequency hopping communication, the faster the frequency hopping speed is, the more difficult the frequency hopping speed is to be tracked, which is beneficial to data security. Ultra-wideband, fast-lock, miniaturized, fully integrated frequency synthesizer designs continue to be a challenge for modern wireless communication systems.

Frequency synthesizers are classified by frequency synthesis technology, and mainly include two main categories, namely direct phase-locked loops and indirect phase-locked loops.

Direct frequency synthesis is to perform addition, subtraction, multiplication and division on one frequency or multiple frequencies by means of frequency division, frequency multiplication and frequency mixing to obtain output signals with different frequencies, and the frequency switching time is usually in the nanosecond level. However, due to the adoption of a large number of mixing and filtering circuits, clutter introduced by nonlinearity is difficult to suppress, and a good spurious suppression degree is difficult to achieve.

The frequency resolution and the frequency switching time of the indirect phase-locked loop frequency synthesis technology are a pair of contradictory quantities, and the higher the frequency resolution is, the longer the frequency switching time of the frequency synthesizer is, so that the frequency hopping time of the frequency synthesizer formed by the phase-locked loop is longer, and the indirect phase-locked loop frequency synthesis technology is not suitable for the field with high requirements on the frequency hopping time.

Therefore, it is necessary to select a new frequency synthesis method to solve the above problem.

Disclosure of Invention

The invention provides a frequency hopping broadband channel frequency synthesizer and a frequency synthesis method, which can solve the technical problem that the frequency synthesizer in the prior art cannot shorten the frequency hopping time on the basis of ensuring the spectral purity of broadband frequency source output.

According to an aspect of the present invention, there is provided a frequency hopped wideband channel frequency synthesizer, comprising: the DDS and control unit is used for generating a narrow-band frequency agile signal; the S-band comb spectrum and filtering unit is used for generating a first local oscillation signal; the S-band mixing unit is respectively connected with the DDS, the control unit and the S-band comb spectrum and filtering unit, and is used for mixing the narrow-band frequency agile signal with the first local oscillator signal to output a first-stage intermediate frequency signal; the S-band switch filtering unit is connected with the S-band mixing unit and is used for filtering the first-stage intermediate frequency signal; the X/Ku wave band comb spectrum and filtering unit is used for generating a second local oscillation signal; the broadband frequency mixing unit is respectively connected with the S-band switch filtering unit and the X/Ku-band comb spectrum and filtering unit, and is used for mixing the filtered first-stage intermediate frequency signal with a second local oscillator signal to output a second-stage intermediate frequency signal; the X/Ku waveband switch filtering unit is connected with the broadband mixing unit and is used for filtering the second-stage intermediate frequency signal; the broadband power division amplifying unit is connected with the X/Ku waveband switch filtering unit and is used for carrying out power division amplification output on the filtered second-stage intermediate-frequency signal; the reference distribution unit is respectively connected with the DDS and control unit, the S-band comb spectrum and filtering unit and the X/Ku-band comb spectrum and filtering unit and is used for providing a reference clock signal and a reference clock signal; the switching power supply circuit is respectively connected with the DDS and control unit, the S-band comb spectrum and filtering unit, the S-band switch filtering unit, the X/Ku-band comb spectrum and filtering unit and the X/Ku-band switch filtering unit, and is used for supplying power to the DDS and control unit, the S-band comb spectrum and filtering unit, the S-band switch filtering unit, the X/Ku-band comb spectrum and filtering unit and the X/Ku-band switch filtering unit and realizing band control.

Further, the reference distribution unit generates a reference clock signal by using a 100MHz constant temperature crystal oscillator and provides a reference clock signal for the DDS, the control unit, the reference distribution unit, the S-band comb spectrum and filter unit and the X/Ku-band comb spectrum and filter unit through a power distribution network according to the reference clock signal.

Furthermore, the wideband channel frequency synthesizer further comprises an external control interface, the external control interface is connected with the switching power supply circuit, and the external control interface is used for inputting an external control signal to the switching power supply circuit.

Furthermore, the switching power supply circuit adopts an FPGA chip to realize switching control of the DDS and control unit, the S-band comb spectrum and filtering unit, the S-band switch filtering unit, the X/Ku-band comb spectrum and filtering unit and the X/Ku-band switch filtering unit.

Further, the switching power supply circuit is used for realizing parallel time sequence control of the DDS and the control unit, five frequency point control of the S-band comb spectrum and filtering unit, five frequency point control of the X/Ku-band comb spectrum and filtering unit, ten-segment filter selection control of the S-band switch filtering unit and ten-segment filter selection control of the X/Ku-band switch filtering unit.

Furthermore, the S-band comb spectrum and filtering unit includes an S-band comb spectrum generator and a first switch filtering unit, the S-band comb spectrum generator is configured to generate an S-band wide spectrum signal, and the first switch filtering unit is configured to filter the S-band wide spectrum signal to generate a first local oscillation signal.

Furthermore, the X/Ku waveband comb spectrum and filtering unit comprises an X/Ku waveband comb spectrum generator and a second switch filtering unit, the X/Ku waveband comb spectrum generator is used for generating an X/Ku waveband wide spectrum signal, and the second switch filtering unit is used for filtering the X/Ku waveband wide spectrum signal to generate a second local oscillation signal.

Further, the DDS and control unit comprises a DDS signal generator and an FPGA chip, the DDS signal generator is connected with the FPGA chip, and the FPGA chip is used for controlling the DDS signal generator to output the narrowband frequency agile signal.

According to another aspect of the present invention, there is provided a wideband channel frequency synthesis method for frequency synthesis using a wideband channel frequency synthesizer as described above.

Further, the wideband channel frequency synthesis method comprises: a narrow-band frequency agile signal is output by utilizing a DDS circuit of a DDS and control unit; generating a first local oscillator signal by using an S-band comb spectrum and a filtering unit; inputting the narrow-band frequency agility signal and the first local oscillator signal into an S-band frequency mixing unit for frequency mixing so as to output a first-stage intermediate frequency signal; filtering the first-stage intermediate frequency signal by using an S-band switch filtering unit; generating a second local oscillator signal by using the X/Ku waveband comb spectrum and the filtering unit; inputting the filtered first-stage intermediate frequency signal and the second local oscillator signal into a broadband frequency mixing unit for frequency mixing so as to output a second-stage intermediate frequency signal; filtering the second-stage intermediate frequency signal by using an X/Ku waveband switch filtering unit; and performing power division amplification output on the filtered second-stage intermediate frequency signal by using a broadband power division amplification unit to generate a microwave signal meeting the bandwidth requirement of a broadband frequency source.

By applying the technical scheme of the invention, the frequency synthesizer of the frequency hopping broadband channel is provided, and the frequency synthesizer utilizes two-stage mixing and a plurality of groups of switch filtering units to realize the shifting and splicing of frequency bands, thereby meeting the requirements of realizing excellent stray indexes and 10MHz frequency hopping intervals in an ultra-wide frequency band range; a small-step agility signal is realized by adopting a DDS mode, agility performance is realized, and fast jump time is less than 1 us; the comb spectrum signal generation method is utilized to realize the generation of low-phase-noise multi-point frequency conversion local oscillation signals; in addition, the low-phase noise signal provided by the reference distribution unit passes through the comb spectrum and filtering unit, and the broadband local oscillator is provided by generating a harmonic signal, so that the volume is greatly reduced compared with the traditional multiple frequency mode. Therefore, compared with the prior art, the broadband channel frequency synthesizer provided by the invention can shorten the frequency hopping time, reduce the phase noise of the signal and reduce the volume on the basis of keeping the spurious-free dynamic range of the DDS output signal to the maximum extent and ensuring the spectral purity of the broadband frequency source output.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a block diagram illustrating a structure of a frequency hopping wideband channel frequency synthesizer according to an embodiment of the present invention;

fig. 2 is a flow chart illustrating a frequency hopping wideband channel frequency synthesis method according to an embodiment of the present invention;

fig. 3 is a block diagram illustrating an embodiment of a frequency hopped wideband channel frequency synthesizer according to an embodiment of the present invention.

Wherein the figures include the following reference numerals:

10. a DDS and a control unit; 20. an S-band comb spectrum and filtering unit; 30. an S-band mixing unit; 40. an S-band switch filtering unit; 50. an X/Ku wave band comb spectrum and filtering unit; 60. a broadband mixing unit; 70. an X/Ku waveband switch filtering unit; 80. a broadband power division amplifying unit; 90. a reference allocation unit; 100. a switching power supply circuit.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

As shown in fig. 1 to 3, according to an embodiment of the present invention, a frequency hopping wideband channel frequency synthesizer is provided, the frequency hopping wideband channel frequency synthesizer includes a DDS and control unit 10, an S-band comb spectrum and filter unit 20, an S-band mixer unit 30, an S-band switch filter unit 40, an X/Ku-band comb spectrum and filter unit 50, a wideband mixer unit 60, an X/Ku-band switch filter unit 70 (i.e., an X and Ku-band switch filter unit), a wideband power division amplifier unit 80, a reference distributor unit 90 and a switching power supply circuit 100, the DDS and control unit 10 is configured to generate a narrowband upconverted signal, the S-band comb spectrum and filter unit 20 is configured to generate a first local oscillator signal, the S-band mixer unit 30 is respectively connected to the DDS and control unit 10 and the S-band comb spectrum and filter unit 20, and the S-band mixer unit 30 is configured to mix the narrowband upconverted signal with the first local oscillator signal to output a first-stage intermediate frequency signal The signal, the S-band switch filtering unit 40 is connected to the S-band mixing unit 30, the S-band switch filtering unit 40 is configured to filter the first-stage intermediate frequency signal, the X/Ku-band comb spectrum and filtering unit 50 is configured to generate a second local oscillator signal, the wideband mixing unit 60 is respectively connected to the S-band switch filtering unit 40 and the X/Ku-band comb spectrum and filtering unit 50, the wideband mixing unit 60 is configured to mix the filtered first-stage intermediate frequency signal with the second local oscillator signal to output a second-stage intermediate frequency signal, the X/Ku-band switch filtering unit 70 is connected to the wideband mixing unit 60, the X/Ku-band switch filtering unit 70 is configured to filter the second-stage intermediate frequency signal, the wideband power division amplifying unit 80 is connected to the X/Ku-band switch filtering unit 70, the wideband power division amplifying unit 80 is configured to perform power division amplification on the filtered second-stage intermediate frequency signal to output, the reference distribution unit 90 is respectively connected to the DDS and control unit 10, the S-band comb spectrum and filter unit 20, and the X/Ku-band comb spectrum and filter unit 50, the reference distribution unit 90 is configured to provide a reference clock signal and a reference clock signal, the switching power supply circuit 100 is respectively connected to the DDS and control unit 10, the S-band comb spectrum and filter unit 20, the S-band switch filter unit 40, the X/Ku-band comb spectrum and filter unit 50, and the X/Ku-band switch filter unit 70, and the switching power supply circuit 100 is configured to supply power to the DDS and control unit 10, the S-band comb spectrum and filter unit 20, the S-band switch filter unit 40, the X/Ku-band comb spectrum and filter unit 50, and the X/Ku-band switch filter unit 70 and realize band control.

By applying the configuration mode, the frequency synthesizer of the frequency hopping broadband channel is provided, and the frequency synthesizer realizes the shifting and splicing of frequency bands by utilizing two-stage frequency mixing and a plurality of groups of switch filtering units, so that the relatively excellent stray indexes and 10MHz frequency hopping intervals in an ultra-wide frequency band range are realized; a small-step agile signal is realized by adopting a Direct Digital Synthesis (DDS) mode, agile frequency conversion performance is realized, and fast jump time is less than 1 us; the comb spectrum signal generation method is utilized to realize the generation of low-phase-noise multi-point frequency conversion local oscillation signals; in addition, the low-phase noise signal provided by the reference distribution unit passes through the comb spectrum and filtering unit, and the broadband local oscillator is provided by generating a harmonic signal, so that the volume is greatly reduced compared with the traditional multiple frequency mode. Therefore, compared with the prior art, the broadband channel frequency synthesizer provided by the invention can shorten the frequency hopping time, reduce the phase noise of the signal and reduce the volume on the basis of keeping the spurious-free dynamic range of the DDS output signal to the maximum extent and ensuring the spectral purity of the broadband frequency source output.

Specifically, in the invention, the frequency hopping time depends on the design mode of the frequency hopping circuit, and the frequency synthesizer provided by the invention adopts a DDS circuit real-time parallel control mode and a microwave switch switching mode to realize rapid frequency hopping. In addition, the broadband frequency source needs to analyze the input 10-bit frequency control word to obtain the parallel frequency control word of the DDS and the switch switching signal of each stage of the frequency conversion module. The frequency hopping time of the DDS circuit depends mainly on the highest clock controlled in parallel and the pipeline delay of the circuit itself. The highest frequency of the parallel control of the DDS circuit is 145MHz, the single setting time is less than 7ns, the pipeline delay is related to the system clock of the DDS, and when the system clock of the DDS is 3GHz, the pipeline delay is about 90 ns. The frequency switching time of the DDS circuit is less than 100 ns. The switching rate of a microwave switch depends primarily on the rate of the switch itself and the rate of the drive circuit, and the total switching time of this type of circuit may be less than 100 ns. Therefore, compared with the prior art, the frequency synthesizer provided by the invention can greatly reduce the frequency hopping time and realize rapid frequency hopping.

In addition, in terms of phase noise indexes, the phase noise of the frequency synthesizer provided by the invention is mainly generated from the output of the DDS circuit and the PLL circuit, and is specifically shown in FIG. 3. The phase noise of the output of the DDS is small, and at the frequency offset of 1KHz, the phase noise is less than or equal to-120 dBc/Hz and is far less than the output noise level of the traditional PLL circuit and the harmonic generation circuit. Therefore, the phase noise performance of the wideband frequency source is mainly determined by the S-band comb spectrum and the phase noise output by the filtering unit and the X/Ku-band comb spectrum and the phase noise output by the filtering unit.

In the invention, the worst frequency point of the phase noise of the local oscillation signal of the S-band comb spectrum and filter unit is 2700MHz, and the worst frequency point of the phase noise of the local oscillation signal of the X/Ku-band comb spectrum and filter unit is 15 GHz. The crystal oscillator phase noise of the selected reference distribution unit is about-155 dBc/Hz @1 kHz. According to a frequency multiplier phase noise deterioration formula: PN0+20 × logN +5dB, the worst phase noise of the local oscillation signal in the S-band comb spectrum and the filtering unit is about-121 dBc/Hz @1 kHz. The phase noise of the intermediate frequency signal generated by the DDS module is about-120 dBc/Hz @1 kHz. According to the basic principle of a mixer: the phase noise of the mixing output signal is mainly determined by one of the phase noise differences, so the worst phase noise of the S-band comb spectrum and the output signal of the filtering unit is about-117 dBc/Hz @1 kHz. The 15GHz phase noise is about-106 dBc/Hz @1kHz, and the worst phase noise of an output signal of an S wave band signal after passing through the broadband mixing module is about-106 dBc/Hz @1 kHz. Compared with the prior art, the frequency generator provided by the invention can greatly reduce the phase noise of the signal.

Further, in the present invention, in order to provide the reference clock signal and the reference clock signal, the reference distribution unit 90 may be configured to generate the reference clock signal by using a 100MHz constant temperature crystal oscillator, and provide the reference clock signal for the DDS and control unit 10, the reference distribution unit 90, the S-band comb spectrum and filter unit 20, and the X/Ku-band comb spectrum and filter unit 50 through a power distribution network according to the reference clock signal.

In addition, in the present invention, in order to implement the band control of the DDS and control unit 10, the S-band comb spectrum and filter unit 20, the S-band switch filter unit 40, the X/Ku-band comb spectrum and filter unit 50, and the X/Ku-band switch filter unit 70, the wideband channel frequency synthesizer may be configured to further include an external control interface, the external control interface is connected to the switching power supply circuit 100, and the external control interface is configured to input an external control signal to the switching power supply circuit 100.

In the present invention, the switching power supply circuit 100 uses an FPGA (Field Programmable Gate Array) chip to realize switching control of the DDS and control unit 10, the S-band comb spectrum and filter unit 20, the S-band switch filter unit 40, the X/Ku-band comb spectrum and filter unit 50, and the X/Ku-band switch filter unit 70.

As a specific embodiment of the present invention, the switching power supply circuit 100 uses an FPGA chip to implement switching control of each unit of the frequency synthesizer. The working clock adopts 100MHz, and the FPGA determines the current working frequency point according to the level states of external control signals FTW 0-FTW 10. The DDS and the control unit 10 are controlled in parallel time sequence through an internal logic circuit, and the current set frequency point is converted into a frequency control word corresponding to the DDS to be output through the parallel time sequence; the control of five frequency points of the S-band comb spectrum and filtering unit 20 and the control of five frequency points of the X/Ku-band comb spectrum and filtering unit 50 are realized; ten-stage filter selection control of the S-band switch filtering unit 40 and ten-stage filter selection control of the X/Ku-band switch filtering unit 70 are realized.

Further, in the present invention, in order to generate the first local oscillation signal, the S-band comb spectrum and filtering unit 20 may be configured to include an S-band comb spectrum generator and a first switch filtering unit, where the S-band comb spectrum generator is configured to generate an S-band wide spectrum signal, and the first switch filtering unit is configured to filter the S-band wide spectrum signal to generate the first local oscillation signal.

In addition, in order to generate the second local oscillation signal, the X/Ku band comb spectrum and filtering unit 50 may be configured to include an X/Ku band comb spectrum generator and a second switch filtering unit, where the X/Ku band comb spectrum generator is configured to generate an X/Ku band wide spectrum signal, and the second switch filtering unit is configured to filter the X/Ku band wide spectrum signal to generate the second local oscillation signal.

Further, in the present invention, in order to output the narrowband frequency agile signal, the DDS and control unit 10 may be configured to include a DDS signal generator and an FPGA chip, the DDS signal generator is connected to the FPGA chip, and the FPGA chip is configured to control the DDS signal generator to output the narrowband frequency agile signal.

According to another aspect of the present invention, as shown in fig. 2, there is provided a wideband channel frequency synthesis method for frequency synthesis using the wideband channel frequency synthesizer as described above. The broadband channel frequency synthesis method comprises the following steps: a narrow-band frequency agility signal is output by using a DDS circuit of the DDS and control unit 10; generating a first local oscillator signal by using the S-band comb spectrum and filtering unit 20; inputting the narrowband frequency agile signal and the first local oscillator signal into the S-band mixing unit 30 for mixing to output a first-stage intermediate frequency signal; filtering the first-stage intermediate frequency signal by using an S-band switch filtering unit 40; generating a second local oscillator signal by using the X/Ku waveband comb spectrum and the filtering unit 50; inputting the filtered first-stage intermediate frequency signal and the second local oscillator signal into a broadband frequency mixing unit 60 for frequency mixing to output a second-stage intermediate frequency signal; filtering the second-stage intermediate frequency signal by using an X/Ku band switch filtering unit 70; the broadband power division amplifying unit 80 is used to perform power division amplification on the filtered second-stage intermediate frequency signal to output so as to generate a microwave signal meeting the bandwidth requirement of the broadband frequency source.

By applying the configuration mode, a broadband channel frequency synthesis method is provided, the method utilizes a DDS circuit to output a small-step high-speed frequency hopping signal with a certain bandwidth, then utilizes an S-band comb spectrum, a first local oscillation signal output by a filter unit and an S-band switch filter unit to shift the frequency spectrum of the signal output by the DDS, and then utilizes the S-band switch filter unit to output in a time-sharing manner, thereby splicing to generate an intermediate frequency signal with a larger bandwidth. The frequency spectrum of the broadband intermediate-frequency signal is shifted by utilizing the X/Ku waveband comb spectrum, the second local oscillation signal output by the filtering unit and the broadband frequency mixing unit, and the broadband intermediate-frequency signal is output in a time-sharing mode through the X/Ku waveband switch filtering unit, so that the microwave signal meeting the bandwidth requirement of the broadband frequency source is spliced. The method can shorten the frequency jump time, reduce the phase noise of the signal and reduce the volume on the basis of ensuring the spectral purity of the broadband frequency source output.

For further understanding of the present invention, the frequency hopping wideband channel frequency synthesizer provided by the present invention is described in detail below with reference to fig. 1 to 3.

As shown in fig. 1 to 3, a frequency hopping wideband channel frequency synthesizer is provided according to an embodiment of the present invention. The frequency hopping broadband channel frequency synthesizer comprises a DDS and control unit 10, an S-band comb spectrum and filter unit 20, an S-band mixing unit 30, an S-band switch filter unit 40, an X/Ku-band comb spectrum and filter unit 50, a broadband mixing unit 60, an X/Ku-band switch filter unit 70, a broadband power division amplifying unit 80, a reference distribution unit 90 and a switching power supply circuit 100, wherein the DDS and control unit 10 is used for generating a narrowband frequency agile signal, the S-band comb spectrum and filter unit 20 is used for generating a first local oscillator signal, the S-band mixing unit 30 is respectively connected with the DDS and control unit 10 and the S-band comb spectrum and filter unit 20, the S-band mixing unit 30 is used for mixing the narrowband frequency agile signal with the first local oscillator signal to output a first-stage intermediate frequency signal, the S-band switch filter unit 40 is connected with the S-band mixing unit 30, the S-band switch filtering unit 40 is configured to filter the first-stage intermediate frequency signal, the X/Ku-band comb spectrum and filtering unit 50 is configured to generate a second local oscillator signal, the wideband frequency mixing unit 60 is connected to the S-band switch filtering unit 40 and the X/Ku-band comb spectrum and filtering unit 50, respectively, and the wideband frequency mixing unit 60 is configured to mix the filtered first-stage intermediate frequency signal with the second local oscillator signal to output a second-stage intermediate frequency signal.

An X/Ku band switch filtering unit 70 is connected with the broadband mixing unit 60, the X/Ku band switch filtering unit 70 is used for filtering the second-stage intermediate frequency signal, a broadband power division amplifying unit 80 is connected with the X/Ku band switch filtering unit 70, the broadband power division amplifying unit 80 is used for performing power division amplifying output on the filtered second-stage intermediate frequency signal, a reference distribution unit 90 is respectively connected with the DDS and control unit 10, the S-band comb spectrum and filtering unit 20 and the X/Ku-band comb spectrum and filtering unit 50, the reference distribution unit 90 is used for providing a reference clock signal and a reference clock signal, the switch power circuit 100 is respectively connected with the DDS and control unit 10, the S-band comb spectrum and filtering unit 20, the S-band switch filtering unit 40, the X/Ku-band comb spectrum and filtering unit 50 and the X/Ku band switch filtering unit 70, the switching power supply circuit 100 is configured to supply power to the DDS and control unit 10, the S-band comb spectrum and filter unit 20, the S-band switch filter unit 40, the X/Ku-band comb spectrum and filter unit 50, and the X/Ku-band switch filter unit 70, and to implement band control. The frequency synthesizer further includes an external control interface connected to the switching power supply circuit 100, and the external control interface is configured to input an external control signal to the switching power supply circuit 100.

In this embodiment, the DDS and control unit 10 generates a fine step intermediate frequency signal (F1) of 200MHz to 300MHz, the S-band comb spectrum and filtering unit 20 includes an S-band comb spectrum generator and a first switch filtering unit, the S-band comb spectrum generator is configured to generate an S-band wide spectrum signal, and the S-band wide spectrum signal passes through the S-band first switch filtering unit of five frequency points to generate a first local oscillation signal (F2) of 2.3GHz to 2.7GHz with an interval of 100 MHz. In the S-band mixing unit 30, five frequency points of the fine step intermediate frequency signal (F1) and the first local oscillation signal (F2) are mixed to generate a first-stage intermediate frequency signal of 2GHz to 3GHz, and after mixing, a second intermediate frequency signal of 10MHz step in the range of 2GHz to 3GHz is generated by the ten-stage S-band switch filtering unit 40 with an interval of 100MHz (F3).

The X/Ku band comb spectrum and filtering unit 50 includes an X/Ku band comb spectrum generator and a second switch filtering unit, the X/Ku band comb spectrum generator is used for generating an X/Ku band wide spectrum signal, and the X/Ku band wide spectrum signal passes through the X/Ku band second switch filtering unit with five frequency points to generate a second local oscillation signal (F4) with an interval of 1GHz between 11GHz and 15 GHz. In the broadband mixing unit 60, the two intermediate frequency signals (F3) are respectively mixed with five frequency points of the second local oscillator signal (F4) to generate a second-stage intermediate frequency signal of 8GHz to 18 GHz. After mixing, ten X/Ku band switch filter units 70 with 1GHz interval are used for generating broadband signals with any fine stepping of 8 GHz-18 GHz. The filtered broadband signal is amplified by the broadband power division amplifying unit 80, power is divided into three paths to be output, each path is driven and amplified to ensure the requirement of output power, and the requirement of higher isolation between the three paths can be ensured.

In the present embodiment, the high-stability reference clock signal is generated by a 100MHz constant-temperature crystal oscillator, and provides the reference clock signal for the DDS and control unit 10, the reference distribution unit 90, the S-band comb spectrum and filter unit 20, and the X/Ku-band comb spectrum and filter unit 50 through the power distribution network.

The switching power supply circuit 100 uses an FPGA to realize switching control of each unit of the frequency synthesizer. The working clock adopts 100MHz, and the FPGA determines the current working frequency point according to the level states of external control signals FTW 0-FTW 10. The following are realized by internal logic circuits:

a. the DDS and DDS control unit 10 controls the parallel timing sequence of the DDS circuit to convert the currently set frequency point into the frequency control word corresponding to the DDS and output the frequency control word through the parallel timing sequence.

b. The control of five frequency points of the S-band comb spectrum and filtering unit 20 and the control of five frequency points of the X/Ku-band comb spectrum and filtering unit 50. The frequency section selection control relationship is as follows: the S-band comb spectrum and filtering unit 20 is 0000-2.3 GHz; 0001-2.4 GHz; 0010-2.5 GHz; 0011-2.6 GHz; 0100-2.7 GHz. The X/Ku wave band comb spectrum and filtering unit 50 is 0000-11 GHz; 0001-12 GHz; 0010-13 GHz; 0011-14 GHz; 0100-15 GHz.

c. Ten-stage filter selection control of the S-band switch filtering unit 40 and ten-stage filter selection control of the X/Ku-band switch filtering unit 70. The frequency section selection control relationship is as follows: the S-band switch filtering unit 40 is 0000-2.0-2.1 GHz; 0001-2.1 to 2.2 GHz; 0010-2.2-2.3 GHz; 0011-2.3-2.4 GHz; 0100-2.4-2.5 GHz; 0101-2.5-2.6 GHz; 0110-2.6-2.7 GHz; 0111-2.7-2.8 GHz; 1000-2.8-2.9 GHz; 1001-2.9 to 3.0 GHz. The X/Ku band switch filtering unit 70 is 0000-8-9 GHz; 0001-9 to 10 GHz; 0010-10 to 11 GHz; 0011-11 to 12 GHz; 0100-12 to 13 GHz; 0101-13 to 14 GHz; 0110-14 ~ 15 GHz; 0111-15 ~ 16 GHz; 1000-16 to 17 GHz; 1001-17 to 18 GHz.

In addition, in the present invention, the electromagnetic compatibility design of the frequency hopping wideband channel frequency synthesizer mainly includes: 1) each unit in the module is designed by adopting an independent metal box body structure. The shielding shell adopts measures for preventing microwave leakage, such as adding a conductive gasket on a joint surface, coating conductive paint on a joint, shortening the space between fastening screws and the like, and has better shielding and isolating effects. 2) Analog ground and digital ground are reliably isolated from each other, and the isolation resistance is not less than 2M omega; 3) the connector is grounded by adopting multi-contact parallel connection, and the shield is grounded by a special lapping piece; 4) the shell of the switch filtering unit in the circuit is shielded, the shell is well grounded, and the input and output impedance of the filter is well matched with the front and rear-stage circuits.

In summary, the present invention provides a frequency hopping wideband channel frequency synthesizer, which can shorten the frequency hopping time, reduce the phase noise of the signal, and reduce the volume, while maintaining the spurious-free dynamic range of the DDS output signal to the maximum extent and ensuring the spectral purity of the wideband frequency source output, compared with the prior art.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.