CN204304987U

CN204304987U - Passive type broadband millimeter-wave Frequency Synthesizer

Info

Publication number: CN204304987U
Application number: CN201520006351.3U
Authority: CN
Inventors: 石龙生; 姜文钰; 刘鑫
Original assignee: Wuxi Tianlu Technology Co Ltd
Current assignee: Wuxi Tianlu Technology Co Ltd
Priority date: 2015-01-06
Filing date: 2015-01-06
Publication date: 2015-04-29
Anticipated expiration: 2025-01-06

Abstract

The utility model discloses a kind of passive type broadband millimeter-wave Frequency Synthesizer, applies to magnetron mode of operation radar.The utility model comprises local oscillator generation circuit, millimeter wave mixting circuit and control circuit three part, adopt high stable crystal oscillator as a reference source of local oscillator generation circuit, combined by DDS and PLL circuit and millimeter wave PDRO and produce local oscillation signal, in millimeter wave mixting circuit, local oscillation signal and the beat that transmits are produced intermediate-freuqncy signal, intermediate-freuqncy signal enters the AFC analog circuit in control circuit, produces the control wave to DDS circuit through digital control circuit.Passive type broadband Frequency Synthesizer is extended to millimeter wave frequency band by X-band by the utility model, saves device, optimizes phase noise, decreases spuious, and is conducive to the frequency showing millimeter-wave transmitter.

Description

Passive type broadband millimeter-wave Frequency Synthesizer

Technical field

The utility model relates to broadband millimeter-wave magnetron radar, is specifically related to the Frequency Synthesizer applying to this type radar.

Background technology

Frequency Synthesizer is the abbreviation of frequency synthesizer, it is the important component part of contemporary electronic systems, be one of important indicator of systematic function, be widely used in many fields such as communication, radar, electronic countermeasure, navigation, radio and television, remote measuring and controlling, instrument and meter.In radar equipment, the modulator that it is emitter provides CF signal, also for the frequency mixer of receiver provides local oscillation signal.Along with the development of electronic science and technology, the requirement of all kinds of electronic system to Frequency Synthesizer is more and more higher, has higher requirement to the many indexes such as phase noise, frequency switching time, frequency resolution, relatively bandwidth of operation, volume and power consumption.When developing Frequency Synthesizer, and should require to select suitable scheme, to meet the requirement of system index according to embody rule.X-band magnetron radar is commonly used radio circuit and is done passive type Frequency Synthesizer.Broadband millimeter-wave magnetron radar is domestic comparatively rare, and regulate klystron frequency to do passive type Frequency Synthesizer with motor abroad, its stability is relatively poor.

Utility model content

For the problems referred to above, applicant carried out linguistic term, a kind of passive type broadband millimeter-wave Frequency Synthesizer that can meet the requirement of millimeter wave magnetron racon is provided.

The technical solution of the utility model is as follows:

A kind of passive type broadband millimeter-wave Frequency Synthesizer, comprises local oscillator generation circuit, millimeter wave mixting circuit and control circuit;

Local oscillator generation circuit comprises DDS circuit, prison circuitry phase, low pass filter, voltage controlled oscillator, two power dividers, millimeter wave PDRO, frequency multiplier circuit, wave filter and the first filter circuits; The output of DDS circuit connects an input of prison circuitry phase, and the output of prison circuitry phase is linked in sequence after low pass filter, voltage controlled oscillator, the first power splitter and is divided into two-way to output signal; Crystal oscillator input is divided into three-way output signal after the second power splitter, one tunnel output signal connects another input of prison circuitry phase, be connected the input of DDS circuit after one tunnel output signal outputs signal with a road of the first power splitter and synthesizes after frequency multiplier circuit through wave filter, a road output signal is connected millimeter wave mixting circuit through the first filter circuit after outputing signal with another road of the first power splitter after millimeter wave PDRO and synthesizing;

Millimeter wave mixting circuit comprises the 3rd power splitter and the second filter circuit; The input of the 3rd power splitter connects the output of local oscillator generation circuit, its output with transmit synthesize after through the second filter circuit connection control circuit;

Control circuit comprises AFC analog circuit and digital control circuit; The input of AFC analog circuit connects the output of millimeter wave mixting circuit, the input of its output linking number word control circuit; The input of digital control circuit connects the output of AFC analog circuit, and its output connects the control end of the aborning DDS circuit of local oscillator.

Advantageous Effects of the present utility model is:

Passive type broadband Frequency Synthesizer is extended to millimeter wave frequency band by X-band by the utility model, has filled up the blank of passive type broadband millimeter-wave Frequency Synthesizer, ensure that the reliably working of this type of radar.Introduce the mixing application mode that DDS, PLL circuit are special, save device, optimize phase noise, decrease spuious, be conducive to again the frequency showing millimeter-wave transmitter.

Accompanying drawing explanation

Fig. 1 is the system composition diagram of utility model.

Fig. 2 is search and plus-minus thresholding schematic diagram.

Fig. 3 is VCO voltage curve during search.

VCO voltage curve when Fig. 4 is for following the tracks of.

Detailed description of the invention

Below in conjunction with accompanying drawing, detailed description of the invention of the present utility model is described further.

As shown in Figure 1, in structure, the utility model mainly contains local oscillator generation circuit, millimeter wave mixting circuit and control circuit three part composition.

Local oscillator generation circuit, comprises DDS circuit, prison circuitry phase, low pass filter, voltage controlled oscillator, two power dividers, millimeter wave PDRO, frequency multiplier circuit, wave filter and the first filter circuits.The output of DDS circuit connects an input of prison circuitry phase, and the output of prison circuitry phase is linked in sequence after low pass filter, voltage controlled oscillator, the first power splitter and is divided into two-way to output signal.Crystal oscillator input is divided into three-way output signal after the second power splitter, one tunnel output signal connects another input of prison circuitry phase, be connected the input of DDS circuit after one tunnel output signal outputs signal with a road of the first power splitter and synthesizes after frequency multiplier circuit through wave filter, a road output signal is connected millimeter wave mixting circuit through the first filter circuit after outputing signal with another road of the first power splitter after millimeter wave PDRO and synthesizing.

Millimeter wave mixting circuit, comprises the 3rd power splitter and the second filter circuit.The input of the 3rd power splitter connects the output of local oscillator generation circuit, its output with transmit synthesize after through the second filter circuit connection control circuit.

Control circuit, comprises AFC analog circuit and digital control circuit.The input of AFC analog circuit connects the output of millimeter wave mixting circuit, the input of its output linking number word control circuit.The input of digital control circuit connects the output of AFC analog circuit, and its output connects the control end of the aborning DDS circuit of local oscillator.

Principle of the present utility model is below described in detail in detail:

The utility model adopts high stable crystal oscillator as a reference source of local oscillator generation circuit.Local oscillation signal main body is provided by millimeter wave PDRO, DDS circuit and the PLL circuit be made up of prison circuitry phase, low pass filter, voltage controlled oscillator (VCO) combine the part of analog signal as local oscillation signal for generation 800MHz bandwidth, the local oscillation signal main body that this bandwidth signal provides with millimeter wave PDRO is again synthesized, and is the required local oscillation signal produced.In the embodiment shown in fig. 1, DDS circuit is AD9510, and prison circuitry phase is PE3336.

Local oscillation signal and the f that transmits _tin millimeter wave mixting circuit, beat produces intermediate-freuqncy signal f _iF, send into control circuit.Intermediate-freuqncy signal f _iFenter the frequency discriminator in AFC analog circuit, f _iFwith frequency discriminator output voltage U in " S " curve, wherein abscissa initial point f ₀for the centre frequency of frequency discriminator.The DC voltage that the output signal of frequency discriminator obtains through peak value bar ripple compares with search thresholding " S ", obtains searching for control level.The signal entering " S " thresholding sends into "+" or "-" thresholding."+" or "-" threshold bandwidth is less times greater than the half of " S " thresholding, and " S " thresholding entangles "+", "-" thresholding.Search signal is from high to low search, and "-" signal is from high to low tracking, and "+" signal is followed the tracks of to height from low, and such IF-FRE is respectively to f ₀draw close.When search and tracking stop, intermediate frequency f signal falls into f ₀breach in, i.e. f < | f ₀± 100KHz|.As shown in Figure 2.

Digital control circuit adopts FPGA device, produces the control wave (comprising address and data) to DDS circuit, DDS circuit is produced and a stringly seems chirped analog signal (actual is a fixing 10MHz frequency signal).The input clock signal of DDS circuit is the 800MHz bandwidth linear frequency hopping analog frequency that PLL circuit exports.The chirp rate of voltage controlled oscillator (VCO) divides two kinds: search condition divides 80 frequencies, and plus-minus state is divided into 4000 frequencies.The former frequency accuracy is 10MHz, and the latter is 200KHz.When passive type Frequency Synthesizer captures transmitter frequency completely, error is at f ₀time within the scope of ± 100KHz, now "+", "-", " S " control signal are low level.For ensureing not miss emitter tranmitting frequency, passive type Frequency Synthesizer frequency should be abundant.In the utility model, frequency gets 4000 frequencies, by changing software, also can get 8000 frequencies.

The utility model introduces DDS circuit and the special mixing application mode of PLL circuit.Common application mode is: the parameters input f of PLL circuit phase detector PE3336 _rfor fixed frequency, another road input f _insignal is then the feedback signal of VCO, by changing R, A, M.Realize the change of frequency of PLL circuit.The incoming frequency of DDS circuit is a higher frequency signal, and output is a less linear FM signal, then PLL circuit is directly added with DDS circuit up-conversion.And the utility model application mode is: by the Pren bypass of phase detector PE3336, f _ininput crystal oscillator 100MHz signal, R, A, M are the address of phase detector PE3336, and R is parameter register, and R puts 1 here, when pren bypass, the content reset (i.e. A=0) of A.Because of reference frequency f _r=10MHz, time phase-locked, than phase frequency f _inalso should be 10MHz.Existing f _in=100MHz, frequency dividing ratio N=f _in/ f _r=100/10=10, due to N=M+1, therefore M=9 (i.e. M interior accommodating 9).During losing lock, PLL circuit produces wide-band linearity Frequency Hopping Signal after beat, inputs DDS circuit, and now DDS circuit is wide-band LFM clock, by changing control code, makes DDS export f _rfor 10MHz fixed frequency; If f _rbe not 10MHz, through than the frequency changing VCO after mutually, thus the clock of reverse change DDS circuit, make it export as 10MHz.This design essence be using DDS circuit as the element of in PLL ring, both retained the Low phase noise advantage of DDS circuit, avoided again the DDS circuit stray too much introduced because frequency.

Sweep speed is another key technology.Scan too fast, PLL circuit output frequency has little time to stablize, thus does not catch target; Slowly scanned, cannot the change of frequency of track transmitter.This just requires that sweep speed is suitably fast, and the utility model circuit arranges search and follows the tracks of two grades for this reason.During search, clock frequency is higher, and scanning frequency is few, and the scan period is short, sees Fig. 3.During tracking and add-subtract control state, clock frequency is lower, and Frequency point is more, and the scan period is long, and dotted line is expressed as and subtracts tracking mode, and solid line, for adding tracking mode, is shown in Fig. 4.

As can be seen from above-mentioned Fig. 3 and Fig. 4, because search time is short, Frequency Synthesizer can enter search thresholding very soon.Although the aircraft pursuit course time is longer, in search thresholding, frequency is few, thus can capture target very soon.

Conclusion: the utility model is applied to certain radar complete machine, no matter the start of emitter cold conditions causes tranmitting frequency drastic change, or manually automatically changes transmitter frequency, and this Frequency Synthesizer all can be followed the tracks of immediately.And product also improves a lot in index.The utility model actual measurement phase noise is-90dBc/Hz/1KHz, and spuious can guarantee is less than-55dBc, effectively meets the index request of millimetre-wave radar machine requirement.

Above-described is only preferred embodiment of the present utility model, and the utility model is not limited to above embodiment.Be appreciated that the oher improvements and changes that those skilled in the art directly derive or associate under the prerequisite not departing from spirit of the present utility model and design, all should think and be included within protection domain of the present utility model.

Claims

1. a passive type broadband millimeter-wave Frequency Synthesizer, is characterized in that: comprise local oscillator generation circuit, millimeter wave mixting circuit and control circuit;