CN102332914A

CN102332914A - C-waveband frequency comprehensive generator with low phase noise

Info

Publication number: CN102332914A
Application number: CN201110230666A
Authority: CN
Inventors: 高阳
Original assignee: TIANWEI ELECTRONIC SYSTEM ENGINEERING Co Ltd XI'AN
Current assignee: TIANWEI ELECTRONIC SYSTEM ENGINEERING Co Ltd XI'AN
Priority date: 2011-08-12
Filing date: 2011-08-12
Publication date: 2012-01-25
Anticipated expiration: 2031-08-12
Also published as: CN102332914B

Abstract

The invention discloses a C-waveband frequency comprehensive generator with low phase noise and wide frequency agility. The generator comprises a 100 MHz of constant-temperature crystal oscillator, a power divider, a frequency tripler, a P-waveband phase locked loop, a C-waveband sampling phase locked medium oscillator, a mixer, a filter, a programmable logic device, a digital frequency direct synthesizer and a frequency divider. The generator disclosed by the invention has the characteristics that: the digital frequency synthesizer (DDS) is rationally utilized; the radar emission waveform is easy to generate; the digital phase locked circuit is simple; the frequency change is convenient; the remote end of the sampling phase locked medium oscillator has excellent phase noise; the shortcomings are mutually made up; the circuit structure is simple; the phase noise is good; the radar waveform is convenient to change; furthermore, the frequency agility is rapid to carry out.

Description

A kind of C-band low phase noise comprehensive frequency generator

Technical field

The present invention relates to the low phase noise comprehensive frequency generator, particularly a kind of C-band low phase noise comprehensive frequency generator.

Background technology

Comprehensive frequency generator is the core component of radar, and it produces the required various radio-frequency components of radar, and the index of comprehensive frequency generator also is the critical index of radar.The phase noise of comprehensive frequency generator directly has influence on the detection sensitivity of radar; Short-term stability directly influences the improvement factor of radar.Because radar electric antagonism function needs changeable frequency; Just require transmitting of comprehensive frequency generator output in bandwidth, to work than broad; Should guarantee the low phase noise that transmits to carry out frequency agility again within the specific limits, both take into account is a very thing of difficulty.

Summary of the invention

The objective of the invention is to, provide a kind of C-band low phase noise broadband the prompt comprehensive frequency generator that becomes, its existing good phase noise characteristic can carry out frequency agility again in than the bandwidth of broad.

In order to realize above-mentioned task, the present invention takes following technical solution:

The prompt comprehensive frequency generator that becomes of a kind of C-band low phase noise broadband; It is characterized in that, comprise 100MHz constant-temperature crystal oscillator, power splitter, frequency tripler, pattern-band phase-locked loop, C-band sampling phase lock dielectric oscillator, frequency mixer, filter, programmable logic device, numerical frequency direct synthesizer and frequency divider;

The 100MHz constant-temperature crystal oscillator is used to provide reference clock; Be divided into 5 road 100MHz signals through power splitter; One the tunnel directly exports the 100MHz coherent signal supplies other part of radar to use; One the tunnel provides clock to programmable logic device, and one the tunnel sends into frequency tripler, and two-way is respectively the pattern-band phase-locked loop in addition and C-band sampling phase lock dielectric oscillator provides reference clock; Programmable logic device plays the register configuration address of SECO and pattern-band phase-locked loop and digital frequency synthesizer, the effect that control frequency changes;

The 100MHz signal is divided into three road signals through power splitter again through frequency tripler output 300MHz signal, is respectively signal f2, signal f2 ' and 300MHz signal f2 ";

Signal f2 ' provides clock for the numerical frequency direct synthesizer; The basic waveform signal f1 of numerical frequency direct synthesizer output radar; Basic waveform signal f1 and signal f2 are after mixing, filtering; The frequency signal f4 mixing that the frequency signal f3 that then produces with the pattern-band phase-locked loop produces with C-band sampling phase lock dielectric oscillator after mixing, filtering again, through power splitter obtain transmitting f and f ', f=f1+f2+f3+f4 promptly transmits behind filter;

300MHz signal f2 " produce frequency f 5 through frequency divider, frequency f 5 behind filter, in frequency mixer with transmit f ' mixing, obtain local oscillation signal f _LO, i.e. f _LO=f '+f5.

The characteristics of the prompt comprehensive frequency generator that becomes of C-band low phase noise broadband of the present invention are: promptly rationally utilized digital frequency synthesizer (DDS) to be easy to generate radar emission waveform, convenient, the sampling phase lock dielectric oscillator far-end phase noise mark excellent characteristics of the simple frequency change of digital PLL circuit, remedied weak point separately again mutually.Circuit structure is simple, phase noise is outstanding, both can easily change radar waveform, can carry out frequency agility fast again.

Description of drawings

Fig. 1 is a C-band low phase noise comprehensive frequency generator theory diagram;

Fig. 2 is the theory diagram of digital phase-locked loop.

Fig. 3 is the theory diagram of the prompt comprehensive frequency generator that becomes of C-band low phase noise broadband.

Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed description.

Embodiment

Referring to Fig. 3; Present embodiment provides the realization example of the prompt comprehensive frequency generator that becomes of a kind of C-band low phase noise broadband, comprises compositions such as 100MHz constant-temperature crystal oscillator, power splitter, frequency tripler, pattern-band phase-locked loop, C-band sampling phase lock dielectric oscillator, frequency mixer, filter, programmable logic device, digital frequency synthesizer (DDS), frequency divider.

The 100MHz constant-temperature crystal oscillator is used to provide reference clock signal; Be divided into five road 100MHz signals through power splitter; The first via is directly exported 100MHz coherent reference signal and is supplied other part of radar to use; The second the tunnel provides clock to programmable logic device, and Third Road is sent into frequency tripler, and the four the road and the five the tunnel provides pattern-band phase-locked loop and C-band sampling phase lock dielectric oscillator clock as a reference respectively;

Programmable logic device is used for the output timing control signal, and the register in pattern-band phase-locked loop and the digital frequency synthesizer is carried out address configuration, and control frequency changes;

The f production process that transmits is following:

The 100MHz signal is divided into three road signals through power splitter again through frequency tripler output 300MHz signal, is respectively f2, f2 ' and f2 "; Wherein, f2 ' is that digital frequency synthesizer (DDS) provides clock.The basic waveform f1 of digital frequency synthesizer (DDS) output radar emission signal; F1 and f2 carry out up-conversion through mixing and filtering; The signal f3 that then produces with the pattern-band phase-locked loop is through the mixing and filtering up-conversion; The signal f4 that produces with C-band sampling phase lock dielectric oscillator again is through the mixing and filtering up-conversion, at last through power splitter obtain transmitting f and f '.f＝f1+f2+f3+f4。

Local oscillation signal f _LOProduction process is following:

300MHz signal f2 " produce signal f5 through the frequency divider filter, f5 obtains local oscillation signal f with the f ' uppermixing that transmits _LO, i.e. f _LO=f '+f5.

All clock signals of comprehensive frequency generator are all come the constant-temperature crystal oscillator to 100MHz, the equal coherent of the signal of output.The radar basic waveform frequency f 1 of digital frequency synthesizer (DDS) output is controlled in f2 * 20%, has effectively reduced spurious signal, has guaranteed good phase noise.Pattern-band phase-locked loop frequency scope is controlled between 100MHz * 8～11 times, has guaranteed that promptly phase noise satisfies the system index requirement, can frequency changed fast through programmable logic device control phase-locked loop again.

The basic principle of the prompt comprehensive frequency generator that becomes of C-band low phase noise broadband of the present invention please refer to Fig. 1, is the radar waveform fundamental frequency f that utilizes direct frequency synthesis (DDS) generation of numeral to need ₁, with 300MHz clock signal f ₂Up-conversion, the frequency f that then can the prompt pattern-band digital phase-locked loop that becomes produces with frequency ₃Uppermixing, the frequency f that sampling phase lock dielectric oscillator last and C-band produces ₄Uppermixing finally obtains the frequency f that radar emission needs.

The microwave signal that traditional frequency multiplier chain mode produces, advantage are that the near-end phase noise is better; Shortcoming is the requirement that the phase noise index of far-end is difficult to reach system index, must use the switch filter group if carry out frequency agility, and complicated circuit, structural volume are huge.

Directly produce microwave signal with digital phase-locked loop, advantage is that circuit is simple; Shortcoming is along with the rising phase noise deterioration of frequency is serious.The phase-locked loop block diagram please refer to Fig. 2.Because phase-locked loop is based on digital circuit, the noise objective of phase detector is poor, has relational expression 20log N according to frequency multiplication times N and phase noise deterioration, and along with the change of N is big, output signal frequency increases, and phase noise worsens serious more; If control the number of times of N well, the phase noise index that can guarantee to export signal within the acceptable range.

Sampling phase lock dielectric oscillator advantage is that output frequency has good phase noise characteristic, and particularly far-end phase noise index is excellent; Shortcoming is to carry out frequency change, can only export single-frequency.

Numeral directly frequency synthesis (DDS) can design radar waveform easily, and the phase noise index is outstanding, but can not produce than higher frequency.

Claims

1. the prompt comprehensive frequency generator that becomes of a C-band low phase noise broadband; It is characterized in that, include 100MHz constant-temperature crystal oscillator, power splitter, frequency tripler, pattern-band phase-locked loop, C-band sampling phase lock dielectric oscillator, frequency mixer, filter, programmable logic device, numerical frequency direct synthesizer and frequency divider;

The 100MHz constant-temperature crystal oscillator is used to provide reference clock; Be divided into 5 road 100MHz signals through power splitter; One the tunnel directly exports the 100MHz coherent signal supplies other part of radar to use; One the tunnel provides clock to programmable logic device, and one the tunnel sends into frequency tripler, and two-way is respectively the pattern-band phase-locked loop in addition and C-band sampling phase lock dielectric oscillator provides reference clock;

Programmable logic device is used for the register configuration address of SECO and pattern-band phase-locked loop and digital frequency synthesizer, and control frequency changes;

Signal f2 ' provides clock for the numerical frequency direct synthesizer; The basic waveform signal f1 of digital frequency synthesizer output radar; Basic waveform signal f1 and signal f2 are after mixing, filtering; The signal f4 mixing that the signal f3 that then produces with the pattern-band phase-locked loop produces with C-band sampling phase lock dielectric oscillator after mixing, filtering again, through power splitter obtain transmitting f and f ', f=f1+f2+f3+f4 promptly transmits behind filter;

300MHz signal f2 " produce signal f5 through frequency divider, f5 behind filter, in frequency mixer with transmit f ' mixing, obtain local oscillation signal f _LO, i.e. f _LO=f '+f5.