阅读说明：本技术 一种s波段低相噪低杂散细步进频率源组件及使用方法 (S-band low-phase-noise low-spurious fine-stepping frequency source component and using method ) 是由 朱红辉 杜珂 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种S波段低相噪低杂散细步进频率源组件及使用方法,所述频率源组件包括依次相连的恒温晶振、梳状谱电路、第一滤波器、功分器、混频器、第二滤波器、分频器、以及锁相环电路,所述功分器的一个输出端与混频器的本振输入端相连,所述功分器的另一个输出端经DDS电路与混频器的中频输入端相连,所述锁相环电路包括顺次环状相连的鉴相器、环路滤波器和压控振荡器。本发明中采用直接模拟合成、直接数字合成以及间接数字锁相合成相结合在一起的混合频率合成方式,整体结构简单,设计合理,同时有效地实现了低相位噪声、低杂散和超小跳频步进指标。(The invention discloses an S-band low-phase-noise low-spurious fine stepping frequency source component and a using method thereof. The invention adopts a mixed frequency synthesis mode combining direct analog synthesis, direct digital synthesis and indirect digital phase-locked synthesis, has simple integral structure and reasonable design, and effectively realizes low phase noise, low stray and ultra-small frequency hopping step index.)

1. The utility model provides a S wave band low phase noise hangs down fine step-by-step frequency source subassembly, includes phase-locked loop circuit, its characterized in that still includes consecutive constant temperature crystal oscillator, comb spectrum circuit, first wave filter, merit and divides ware, mixer, second wave filter and frequency divider, an output of merit branch ware links to each other with the local oscillator input of mixer, another output of merit branch ware links to each other with the intermediate frequency input of mixer through the DDS circuit, the output of frequency divider links to each other with phase-locked loop circuit, phase-locked loop circuit is including cyclic annular phase discriminator, loop filter and the voltage controlled oscillator that links to each other in order.

2. The source assembly according to claim 1, wherein an output terminal of the oven controlled crystal oscillator is connected to an input terminal of a comb spectrum circuit, an output terminal of the comb spectrum circuit is connected to an input terminal of a first filter, and an output terminal of the first filter is connected to an input terminal of the power divider.

3. An S-band low-phase-noise low-spurious fine stepped frequency source module according to claim 2, wherein an output terminal of said mixer is connected to an input terminal of a second filter, and an output terminal of said second filter is connected to an input terminal of a frequency divider.

4. The source assembly of claim 3, wherein the output of the frequency divider is connected to an input of a phase detector, another input of the phase detector is connected to an output of a voltage controlled oscillator, and another output of the voltage controlled oscillator is a signal output of the S-band frequency source.

5. The source assembly of claim 4, wherein an output of the phase detector is coupled to an input of a loop filter, and an output of the loop filter is coupled to an input of a voltage controlled oscillator.

6. The method for using an S-band low-phase-noise low-spurious fine-step frequency source assembly according to any one of claims 1 to 5, comprising the following steps:

1) oscillating a constant-temperature crystal oscillator to generate a first reference signal, sending the first reference signal into a comb spectrum circuit, and generating a comb spectrum signal to output;

2) after the comb spectrum signal is filtered, stray and expanded by a first filter, a second signal is generated and is divided into two paths to be output by a power divider, one path of the comb spectrum signal is provided for a DDS circuit to serve as a reference clock and generate an intermediate frequency signal, and the other path of the comb spectrum signal is provided for a mixer to serve as a local oscillation signal;

3) mixing the intermediate frequency signal and the local oscillator signal through a mixer, filtering stray by a second filter, and generating an L-band reference signal after the stray is amplified;

4) sending the L-waveband reference signal to a frequency divider for frequency division to generate a third signal used as a reference signal for phase discrimination;

5) and feeding back the radio frequency signal of the voltage-controlled oscillator to the phase discriminator, performing phase discrimination comparison on the radio frequency signal and the low-frequency signal of the frequency divider, outputting a low-frequency error signal to the loop filter, filtering the low-frequency error signal by the loop filter, and outputting a low-frequency direct current signal to tune the voltage-controlled oscillator to form a loop and complete phase locking.

7. The use method of an S-band low-phase-noise low-spur fine-step frequency source assembly according to claim 6, wherein the comb spectrum signal is at the same frequency as the first reference signal.

8. The method of claim 7, wherein the second signal is frequency doubled with respect to the comb spectrum signal.

Technical Field

The invention relates to the technical field of radio frequency microwaves, in particular to an S-band low-phase-noise low-stray fine-stepping frequency source component and a using method thereof.

Background

In the field of radio frequency microwave, a frequency synthesis technology is an important technology in the design of internal electronic systems of radar reconnaissance, aerospace measurement and control, wireless communication and the like; among other things, the need for low phase noise, low spurs, and ultra-small frequency hopping steps for frequency source components that implement frequency synthesis is increasing.

At present, there are many design schemes for the frequency source component, but these schemes cannot simultaneously achieve low phase noise, low spurs and ultra-small frequency hopping steps. For example, a single method adopting direct analog synthesis is easier to obtain a low-phase noise index, but an ultra-small frequency hopping step and a high spurious suppression index are not easy to make; the single method of direct digital synthesis is adopted, so that low-phase noise indexes and superfine small stepping signals can be easily obtained, but the signal frequency is low and the bandwidth is narrow; the single indirect phase-locked frequency synthesis is adopted, and the ultra-small frequency hopping stepping and high spurious suppression indexes are difficult to meet at the same time.

Chinese granted patent publication No. CN209105149U, publication No. 2019, 7/12/h, discloses a small-sized ultra-fine stepped low-phase-noise ultra-high spurious suppression frequency source, and it is proposed that "the crystal oscillator module is connected to a first mixer filter through a DDS and a direct synthesis high-stability reference, respectively, the first mixer filter is connected to a built-in R frequency divider through a frequency dividing filter, the built-in R frequency divider is connected to a main phase-locked loop, the main phase-locked loop is connected to a voltage-controlled oscillator through a loop filter and a second mixer filter, respectively, and the second mixer filter is connected to a frequency mixing reference module". The structure is complicated among this prior art, and frequency stability is general, and the crystal oscillator module directly passes through DDS and directly synthesizes high steady reference ware and connect first mixing filter simultaneously, and its subsequent low phase noise that corresponds, low spurious and the stepped index's of super little frequency hopping realization effect is also general.

Disclosure of Invention

The invention aims to provide an S-band low-phase-noise low-spurious fine stepping frequency source component and a using method thereof, and aims to solve the technical problems that the existing frequency source component proposed in the background technology is complex in structure, general in frequency stability and incapable of achieving low-phase-noise low-spurious and ultra-small frequency hopping stepping indexes at the same time.

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a S wave band low phase noise hangs down fine step frequency source subassembly, includes consecutive constant temperature crystal oscillator, comb spectrum circuit, first wave filter, merit branch ware, mixer, second wave filter, frequency divider and phase-locked loop circuit, phase-locked loop circuit includes cyclic annular phase discriminator, loop filter and the voltage controlled oscillator that links to each other in order.

Wherein, the output end of the constant temperature crystal oscillator is connected with the input end of a comb spectrum circuit, the output end of the comb spectrum circuit is connected with the input end of a first filter, the output end of the first filter is connected with the input end of a power divider, one output end of the power divider is connected with the local oscillator input end of a frequency mixer, the other output end of the power divider is connected with the intermediate frequency input end of the frequency mixer through a DDS circuit, the output end of the frequency mixer is connected with the input end of a second filter, the output end of the second filter is connected with the input end of the frequency divider, the output end of the frequency divider is connected with one input end of a phase discriminator, the other input end of the phase discriminator is connected with one output end of a voltage-controlled oscillator, the other output end of the voltage-controlled oscillator is the signal output end of an S-band frequency source, and the output end of the phase discriminator is connected with the input end of a loop filter, and the output end of the loop filter is connected with the input end of the voltage-controlled oscillator.

The invention also provides a use method of the S-band low-phase-noise low-spurious fine step frequency source component, which comprises the following specific operation steps:

1) oscillating a constant-temperature crystal oscillator to generate a first reference signal, sending the first reference signal into a comb spectrum circuit, and generating a comb spectrum signal with the same frequency as the first reference signal to output;

2) after the comb spectrum signal is filtered, stray and expanded by the first filter, a second signal which is the comb spectrum signal and is multiplied by ten is generated, the second signal is divided into two paths to be output by the power divider, one path of the second signal is provided for the DDS circuit to serve as a reference clock and generate an intermediate frequency signal, and the other path of the second signal is provided for the mixer to serve as a local oscillation signal;

3) mixing the intermediate frequency signal and the local oscillator signal through a mixer, filtering stray by a second filter, and generating an L-band reference signal after the stray is amplified;

4) sending the L-waveband reference signal to a frequency divider for frequency division to generate a low-frequency signal which is used as a reference signal for phase discrimination;

5) and feeding back the radio frequency signal of the voltage-controlled oscillator to the phase discriminator, performing phase discrimination comparison on the radio frequency signal and the low-frequency signal of the frequency divider, outputting a low-frequency error signal to the loop filter, filtering the low-frequency error signal by the loop filter, and outputting a low-frequency direct current signal to tune the voltage-controlled oscillator to form a loop and complete phase locking.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, a mixed frequency synthesis mode combining direct analog synthesis, direct digital synthesis and indirect digital phase-locked synthesis is adopted, an L-waveband reference signal is generated through the direct analog synthesis and direct digital synthesis modes, and a final S-waveband frequency source is generated through the indirect digital phase-locked synthesis mode after the frequency division of the L-waveband reference signal;

2. according to the invention, a first reference signal generated by constant-temperature crystal oscillator oscillation is divided into two paths to be output through a comb spectrum circuit, a first filter and a power divider in sequence, a local oscillation signal and a DSS clock are both derived from the comb spectrum circuit, the comb spectrum generator circuit can generate relatively flat and stable comb spectrum signals, meanwhile, filtering and expanding processing is uniformly carried out in advance before power division output, the integral processing effect in the early stage of frequency mixing is good, the realization of low phase noise, low stray and ultra-small frequency hopping stepping indexes is further ensured, and the frequency stability of an S-band frequency source finally output is improved;

3. the constant-temperature crystal oscillator is adopted to generate the first reference signal, so that the frequency stability of the generated first reference signal is greatly improved.

Drawings

FIG. 1 is a block diagram of the modules of the present invention.

Detailed Description

The preferred embodiments of the present invention are described below with reference to the accompanying drawings:

as shown in fig. 1, an S-band low-phase-noise low-spurious fine stepped frequency source assembly includes a constant temperature crystal oscillator, a comb spectrum circuit, a first filter, a power divider, a mixer, a second filter, a frequency divider, a phase discriminator, a loop filter and a voltage controlled oscillator, an output end of the constant temperature crystal oscillator is connected to an input end of the comb spectrum circuit, an output end of the comb spectrum circuit is connected to an input end of the first filter, an output end of the first filter is connected to an input end of the power divider, the power divider is divided into two paths of output, one output end of the power divider is connected to a local oscillator input end of the mixer, another output end of the power divider is connected to an intermediate frequency input end of the mixer through a DDS circuit, an output end of the mixer is connected to an input end of the second filter, an output end of the second filter is connected to an input end of the frequency divider, an output end of the frequency divider is connected to an input end of the phase discriminator, the output end of the phase discriminator is connected with the input end of the loop filter, the output end of the loop filter is connected with the input end of the voltage-controlled oscillator, the other input end of the phase discriminator is connected with one output end of the voltage-controlled oscillator, and the other output end of the voltage-controlled oscillator is the signal output end of the S-band frequency source.

The use method of the wave band low-phase-noise low-spurious fine-step frequency source component comprises the following specific operation steps:

firstly, an external constant-temperature crystal oscillator oscillates to generate a 100MHz reference signal, the reference signal is sent to a comb spectrum circuit, after the 100MHz comb spectrum signal is generated, a first filter filters stray and expands the signal, and a 1200MHz signal with high stray rejection degree is generated; then, the 1200MHz signal is divided into two paths to be output by the power divider, one path is provided for the DDS circuit to be used as a reference clock, and the other path is provided for the frequency mixer to be used as a local oscillation signal; meanwhile, the DDS circuit generates a section of narrow-range fine-step intermediate frequency signal, the frequency range of the intermediate frequency signal is 129-plus 159MHz, the intermediate frequency signal is subjected to frequency mixing through a frequency mixer and a local oscillator signal, and after the spurious is filtered and amplified through a second filter, an L-band reference signal of 1041-plus 1071MHz with high spurious suppression degree is generated; then, the L-waveband reference signal is sent to a frequency divider for frequency division to generate 260.25-267.75 MHz low-frequency signals which are used as reference signals for phase discrimination; and finally, feeding back the radio frequency signal of the voltage-controlled oscillator to the phase discriminator, performing phase discrimination comparison on the radio frequency signal and the low-frequency signal of the frequency divider, outputting a low-frequency error signal to the loop filter, filtering the low-frequency error signal by the loop filter, and further outputting a low-frequency direct current signal to tune the voltage-controlled oscillator to form a loop, thereby completing the phase locking function and synthesizing the 1800-plus-2400 MHz S-band frequency source.

The L-waveband reference signal is generated by mixing a local oscillation signal and a DDS intermediate frequency signal, the local oscillation signal and a DDS clock are both from a comb spectrum circuit, the phase noise of the L-waveband reference signal is low, and the phase noise of the L-waveband reference signal and the phase noise of a crystal oscillation signal meet the relationship of 20 lgN; the L-band reference signal is subjected to frequency division and then generates a final S-band frequency source in an indirect digital phase-locked synthesis mode, the phase-locked mode is an integer mode, the noise floor of the phase discriminator is very low, the noise contribution of the L-band reference signal is lower than that of a subsequent 8-phase discriminator, so that the phase noise of the finally output S-band frequency source directly depends on the noise floor of the phase discriminator, and the low-noise phase discriminator is selected to meet the low-phase-noise requirement of the S-band frequency source.

The frequency hopping of the intermediate frequency signal output by the DDS circuit is stepped, the mu Hz level is met, and the near-end stray index is high; in summary, since the L-band reference signal is generated by mixing the local oscillator signal and the DDS intermediate frequency signal, the near-end spurious signal of the L-band reference signal mainly depends on the near-end spurious of the intermediate frequency signal output by the DDS circuit, which is better than 85 dBc; and the frequency hopping step of the L-band reference signal also depends on the frequency hopping step of the intermediate frequency signal output by the DDS circuit, and the level of mu Hz is satisfied. The L-band reference signal and the S-band frequency source which is finally output meet the relation of 20 lgN; therefore, the S-band frequency source near-end spurs depend only on the L-band reference signal, degrading 6dB to 79 dBc; and the frequency modulation step of the S-band frequency source depends on the L-band reference signal, and the level of mu Hz is satisfied.

Finally, typical phase noise of S-band frequency sources: less than-115 dBc @ 10K-300 KHz; stray: < -75 dBc; frequency hopping and stepping: < 0.1Hz, the frequency source signal has low phase noise, low spurs and fine steps.