CN210109311U

CN210109311U - X-waveband frequency-sweeping synthesizer for navigation radar

Info

Publication number: CN210109311U
Application number: CN201920833948.3U
Authority: CN
Inventors: 祁佳亮; 韩盈春
Original assignee: Wuxi Geyue Technology Co Ltd
Current assignee: Wuxi Geyue Technology Co Ltd
Priority date: 2019-06-04
Filing date: 2019-06-04
Publication date: 2020-02-21
Anticipated expiration: 2029-06-04

Abstract

The utility model provides a frequency is frequently combined is swept to X wave band for navigation radar, amplify filter circuit, DDS, mixing phase-locked loop and third including crystal oscillator, first amplification filter circuit, second, first amplification filter circuit's input with the second amplifies filter circuit's input and connects respectively the crystal oscillator, first amplification filter circuit's output is connected the input of DDS, the output of DDS is connected an input of mixing phase-locked loop, second amplification filter circuit's output is connected another input of mixing phase-locked loop, the output of mixing phase-locked loop is connected the input of third amplification filter circuit, the output that third amplification filter circuit's output was swept the frequency and is frequently combined as the X wave band. The X-band frequency-sweeping synthesizer for the navigation radar has the advantages of scientific design, strong practicability, simple structure, low cost, low noise and stability.

Description

X-waveband frequency-sweeping synthesizer for navigation radar

Technical Field

The utility model relates to a frequency is swept to X wave band for navigation radar is combined frequently.

Background

The frequency synthesizer, also called frequency synthesizer, frequency source, its main function is to generate various forms of frequency signals required by electronic system, such as signal forms required by various electronic systems, such as single frequency point continuous wave, frequency hopping signal, step frequency signal, linear frequency modulation signal, nonlinear frequency modulation signal, IQ modulation signal, etc., it is an important component of modern electronic system, and it has been widely used in many fields such as communication, radar, electronic countermeasure, remote control and remote measurement and instrument and meter. The X wave band is a radio wave band with the frequency of 8-12GHz, the existing X wave band frequency sweeping synthesis is generally realized by using an integrated chip capable of directly generating an X wave band signal, and the cost is high when the X wave band is used for a navigation radar.

In order to solve the above problems, people are always seeking an ideal technical solution.

Disclosure of Invention

The utility model aims at prior art not enough to a X wave band sweep frequency that is used for navigation radar that design science, practicality are strong, simple structure, with low costs, low noise are stable is synthesized frequently is provided.

In order to realize the purpose, the utility model discloses the technical scheme who adopts is: the utility model provides a frequency synthesis is swept to X wave band for navigation radar, includes crystal oscillator, first amplifier filter circuit, second amplifier filter circuit, DDS, mixing phase-locked loop and third amplifier filter circuit, first amplifier filter circuit's input with second amplifier filter circuit's input is connected respectively the crystal oscillator, first amplifier filter circuit's output is connected the input of DDS, the output of DDS is connected an input of mixing phase-locked loop, second amplifier filter circuit's output is connected another input of mixing phase-locked loop, mixing phase-locked loop's output is connected the input of third amplifier filter circuit, the output that third amplifier filter circuit's output was swept the frequency synthesis as the X wave band output.

Based on the above, the mixing phase-locked loop includes phase discriminator, voltage controlled oscillator and mixer, the phase discriminator the voltage controlled oscillator with the mixer concatenates in proper order, the phase discriminator still connects the output of first filtering circuit that amplifies, the mixer still connects the filtering circuit's that amplifies second output, voltage controlled oscillator's output is connected the filtering circuit's that amplifies third input.

The utility model discloses relative prior art has substantive characteristics and progress, specific theory, the utility model discloses utilize the third harmonic of 312.5 MHz's crystal oscillator as the frequency reference source of DDS, fourteen times harmonic is as the local oscillator input of mixer, and mode output central frequency through the mixing ring is 4.675GHz, and the frequency sweep bandwidth is 40 MHz's signal, and rethread amplification filtering obtains central frequency and is 9.35GHz, and the frequency sweep bandwidth is 80 MHz's signal, and it has design science, the practicality is strong, simple structure, with low costs, the stable advantage of low noise.

Drawings

Fig. 1 is a block diagram schematically illustrating the structure of the present invention.

Fig. 2 is a schematic diagram of the circuit structure of the low-noise amplifying circuit of the present invention.

Fig. 3 is a schematic circuit diagram of the bandpass filter circuit of the present invention.

Fig. 4 is a schematic circuit diagram of the pi decay circuit of the present invention.

Detailed Description

The technical solution of the present invention will be described in further detail through the following embodiments.

As shown in fig. 1, fig. 2, fig. 3 and fig. 4, an X wave band frequency-sweeping synthesizer for a navigation radar comprises a crystal oscillator, a first amplification filter circuit, a second amplification filter circuit, a DDS, a frequency mixing phase-locked loop and a third amplification filter circuit, wherein an input end of the first amplification filter circuit is connected with an input end of the second amplification filter circuit respectively, the crystal oscillator, an output end of the first amplification filter circuit is connected with an input end of the DDS, an output end of the DDS is connected with an input end of the frequency mixing phase-locked loop, an output end of the second amplification filter circuit is connected with another input end of the frequency mixing phase-locked loop, an output end of the frequency mixing phase-locked loop is connected with an input end of the third amplification filter circuit, and an output end of the third amplification filter circuit is used as an output end of the X wave band frequency-sweeping synthesizer.

In this embodiment, the mixing phase-locked loop includes phase discriminator, voltage controlled oscillator and mixer, the phase discriminator the voltage controlled oscillator with the mixer concatenates in proper order, the phase discriminator still connects first filtering circuit's that amplifies output, the mixer still connects second filtering circuit's that amplifies output, voltage controlled oscillator's output is connected the filtering circuit's that amplifies input of third.

The crystal oscillator power of 312.5MHz is divided into two paths, one path of the processed signal is amplified and filtered by a first amplification and filtering circuit to obtain a 937.5MHz third harmonic signal which is used as an external input clock of the DDS, and then a sweep frequency signal with the center frequency of 10MHz is obtained in a DRG mode of the DDS and enters the phase discriminator. And the other path of power of the crystal oscillator is subjected to amplification and filtering processing of the second amplification and filtering circuit to obtain a 4.375GHz dot frequency signal as a local oscillation signal to be input into the mixer, and the dot frequency signal is mixed with a VCO (voltage controlled oscillator), namely a radio frequency signal output by the voltage controlled oscillator to obtain an intermediate frequency signal which enters the phase discriminator and is compared with the phase discrimination frequency of the phase discriminator, so that a complete frequency mixing phase-locked loop output is formed. The signal output by the voltage-controlled oscillator is a C-band signal with the center frequency of 4.675GHz and the sweep frequency bandwidth of 40MHz, and the C-band signal is amplified and filtered to obtain a second harmonic signal with the center frequency of 9.35GHz and the sweep frequency bandwidth of 80MHz, namely the required X-band signal.

In this embodiment, the model of the DDS is AD9914, the model of the phase detector is HMC984, the model of the voltage-controlled oscillator is HMC358, and the model of the frequency mixer is LTC 5544. In this embodiment, the first amplification filter circuit, the second amplification filter circuit, and the third amplification filter circuit are respectively composed of a pi attenuation circuit, a low-noise amplification circuit, and a band-pass filter circuit, and the pi attenuation circuit is used for adjusting the signal size during debugging. In the first amplifying and filtering circuit, the output end of the crystal oscillator is connected with the input end of the low-noise amplifying circuit through the pi attenuation circuit, the output end of the low-noise amplifying circuit is connected with the input end of the band-pass filtering circuit, and the output end of the band-pass filtering circuit outputs 937.5MHz signals. Four low-noise amplifying circuits are adopted in the second amplifying and filtering circuit, and a pi attenuation circuit is connected between two adjacent low-noise amplifying circuits; the output end of the crystal oscillator is connected with the first low-noise amplifying circuit through a pi attenuation circuit, the output end of the last low-noise amplifying circuit is connected with the band-pass filter circuit, and the band-pass filter circuit outputs 4.675GHz signals. Three paths of low-noise amplifying circuits are adopted in the third amplifying and filtering circuit, and a pi attenuation circuit is connected between two adjacent paths of low-noise amplifying circuits; the output end of the voltage-controlled oscillator is connected with the first path of low-noise amplifying circuit, the output end of the last path of low-noise amplifying circuit is connected with the band-pass filter circuit, and the band-pass filter circuit outputs 9.35GHz signals.

In the embodiment, the harmonic wave of the crystal oscillator is used as the external reference clock for driving the DDS and the local oscillator input of the mixer, so that the cost is low, and simultaneously, the phase noise and the stability of the crystal oscillator can well avoid the introduction of noise. The frequency synthesizer is designed by utilizing a frequency mixing ring mode, noise introduced by frequency division can be greatly avoided by utilizing the frequency mixing ring, the output of the DDS is directly used as an external reference clock of the phase discriminator, the advantages of strong points and weak points can be obtained, the defects of low DDS output frequency and poor high-frequency signal quality are overcome, and meanwhile, the advantages of fast locking time and small frequency step are utilized, so that a VCO (voltage controlled oscillator) chip directly outputting an X waveband is not used, a scheme of outputting a C waveband and then filtering and amplifying to use a second harmonic wave is adopted, and the production cost can be greatly reduced on the premise of basically unchanging performance.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same; although the present invention has been described in detail with reference to preferred embodiments, it should be understood by those skilled in the art that: the invention can be modified or equivalent substituted for some technical features; without departing from the spirit of the present invention, it should be understood that the scope of the claims is intended to cover all such modifications and variations.

Claims

1. An X-band frequency-sweeping synthesizer for a navigation radar, comprising: including crystal oscillator, first amplifier filter circuit, second amplifier filter circuit, DDS, mixing phase-locked loop and third amplifier filter circuit, first amplifier filter circuit's input with the second amplifier filter circuit's input is connected respectively the crystal oscillator, first amplifier filter circuit's output is connected the input of DDS, the output of DDS is connected an input of mixing phase-locked loop, second amplifier filter circuit's output is connected another input of mixing phase-locked loop, mixing phase-locked loop's output is connected filter circuit's input is amplified to the third, third amplifier filter circuit's output is as the output that the X wave band swept frequency is synthesized.

2. The X-band swept frequency ensemble for a navigation radar of claim 1, wherein: the mixing phase-locked loop comprises a phase discriminator, a voltage-controlled oscillator and a frequency mixer, wherein the phase discriminator, the voltage-controlled oscillator and the frequency mixer are sequentially connected in series, the phase discriminator is further connected with the output end of the first amplification filter circuit, the frequency mixer is further connected with the output end of the second amplification filter circuit, and the output end of the voltage-controlled oscillator is connected with the input end of the third amplification filter circuit.