A kind of calibration frequency mixer calibrating method based on time-frequency dual domain
Technical field
The present invention relates to microwave and millimeter wave part characteristic parameter testing technical field, and in particular to one kind is double based on time-frequency
The calibration frequency mixer calibrating method in domain.
Background technology
As various advanced digital modulation techniques are widely used in such as broadband digital communication system, in order to reduce
The bit error rate of system, designer not only needs to be concerned about the amplitude versus frequency characte of whole radio-frequency system, while also requiring that to its phase
Frequency characteristic is measured.Vector network analyzer is a kind of general microwave and millimeter wave measuring instrument, for radio-frequency system
In widely used such as amplifier, wave filter, the so-called same frequency part of duplexer input and output frequency identical, it is possible to achieve it is right
The accurate measurement of its amplitude-frequency and phase frequency vectorial property.And in radio-frequency system widely used such as frequency mixer frequency converter
Part, because its input and output frequency is different, the measurement to its phase and group delay property is always a difficult point, because phase
Position measurement is that, based on common frequency measurement, two phases existed between frequency difference signal can change with the change of time of measuring, no
It is a definite value.
Carry out to be calibrated before accurate frequency mixer vectorial property is measured using vector network analyzer, one of those
Calibration steps needs to be connected between two calibration ports and calibrate frequency mixer known to a characteristic, and the radio frequency of this calibration frequency mixer is defeated
The matching properties of inbound port and medium frequency output end mouthful, forward and backward conversion loss characteristic must be completely known, all known
Characteristic information is Vector Message, i.e., include amplitude and phase information simultaneously.The known calibration frequency mixer of utilization level was being calibrated
Cheng Zhongke solves corresponding error term in whole machine error model, during the similar tradition S parameter full two-port calibration of its effect
Thru calibration.
When the calibration of vector frequency mixer is actually carried out, when first time frequency mixer is calibrated using certain, its characteristic present's number
According to typically unknown.Frequency mixer is determined for this vector network analyzer provides an extra frequency mixer sign function
Mark, extracts the vectorial property characterize data of calibration frequency mixer, and the result that will be extracted is stored in a calibration file, with
For using in a calibration process.Calibration frequency mixer is by a frequency mixer and a wave filter group into the function of its median filter is
Unwanted mixed product is filtered, is reflected known to filter output mouthful 3 characteristics of connection during calibration in calibration frequency mixer
Standard (usually open a way device, short-circuiting device and load machinery calibrating device or Electronic Calibration part), you can realize the mark of calibration frequency mixer
It is fixed.
In order to realize accurately calibrating frequency mixer calibration, it is necessary to do following limitation to calibration frequency mixer:
1) working frequency range can be covered need to calibrate frequency range;
2) frequency mixer must be reciprocity, i.e. prevention at radio-frequency port to intermediate frequency port, intermediate frequency port to prevention at radio-frequency port conversion loss
Magnitude-phase characteristics must be consistent;
3) frequency mixer rf inputs mouthful should have good port match, and its return loss should be better than 10dB;
4) conversion loss of frequency mixer forward and backward is sufficiently low, should be less than 10dB;
Requirement to frequency mixer reciprocity property ensures that most passive frequency mixer can meet by the implementation of frequency mixer
This requirement.But the matching performance of actually used general its prevention at radio-frequency port of calibration frequency mixer is not high, and reflection coefficient of port loss is more
Less than 10dB, when carrying out calibration frequency mixer calibration, the signal for reaching prevention at radio-frequency port through forward and backward double conversion floods completely
In the mismatch signal of prevention at radio-frequency port, calibration precision is caused to decline, the calibration accuracy and vector frequency mixer for directly affecting whole machine are surveyed
The precision of amount.Additionally, for the frequency mixer and harmonic mixer of many work to microwave and millimeter wave section, its unidirectional conversion loss allusion quotation
Type range value more be much larger than 10dB, cause calibration when vector network analyzer port receive comprising conversion loss width phase information
Signal less than whole machine residual directional error signal, more than the dynamic range of reflection measurement, now cannot be to frequency mixer
Calibrated.In addition traditional frequency mixer calibration process needs to carry out No. 3 frequency mixer measurement connections after completing single port calibration, whole
Individual process is comparatively laborious.
By above description it can be seen that:Because traditional calibration frequency mixer calibration process is to be carried out on frequency domain completely,
There are many limitations to the technical indicator of frequency mixer, it cannot be calibrated when calibrating mixer conversion loss and being excessive, calibrate
Low precision, process is cumbersome.
The content of the invention
It is mixed to calibration to reduce it is an object of the invention to provide a kind of calibration frequency mixer calibrating method based on time-frequency dual domain
The requirement of frequency device performance indications, extends the conversion loss scope of calibration calibration frequency mixer, improves the essence of calibration frequency mixer calibration
Degree, simplifies the calibration process of calibration frequency mixer.
It is that, up to above-mentioned purpose, the embodiment of the invention provides a kind of calibration frequency mixer calibrating method based on time-frequency dual domain,
Including:
Radio frequency incident frequencies, local frequency, the mixing number of times of calibration frequency mixer are set, IF-FRE is calculated;
RF input power, local oscillation power are set, the calibration frequency mixer is operated in correct linear condition, and make school
It is consistent when the input state of local oscillation power is calibrated with vector frequency mixer during quasi- frequency mixer;
Vector network analyzer does single port calibration in the range of the calibration frequency mixer radio frequency incoming frequency;
The calibration frequency mixer prevention at radio-frequency port is connected with the calibration port of vector network analyzer, local oscillation signal is connected,
And the intermediate-frequency filter output port in calibration frequency mixer connects high reflection standard known to a characteristic, the reflectance standard is in calibration
Known features value in mixer intermediate-frequency reference frequency output is ΓIF;
Setting single triggering makes vector network analyzer complete single pass and in hold mode, corresponding frequency domain measurement
It is S to be worth11;
By in the time domain measurement function of vector network analyzer, measurement pattern is set to band logical impulse pattern, and opening should
Time domain measurement function, obtains two pulses for separating on a timeline;Wherein, the first time domain impulse includes calibration frequency mixer
S11RFInformation, preceding reverse conversion loss T of second time domain impulse comprising calibration frequency mixer1、T2With reflectance standard characteristic information ΓIF;
The center of time domain door is placed in the crest of first time domain impulse, by the starting of time domain door and stop value point
The trough of the first time domain impulse left and right sides is not placed in, and the type for selecting the time domain door is band logical, opens the time domain
Door function, closes the time domain measurement function and returns to frequency domain, extracts the frequency domain information corresponding to the first time domain impulse, and its institute is right
The frequency-region signal answered is the S of the calibration frequency mixer11RF;
The time domain measurement function is reopened, and closes the time domain door function, the center of time domain door is placed in
The crest of second time domain impulse, the second time domain impulse both sides should be respectively placed in by the starting and termination of time domain door
Trough, the type for selecting time domain door is band logical, opens time domain door function, closes the time domain measurement pattern and returns to frequency domain,
The frequency domain information corresponding to the second time domain impulse is extracted, its corresponding frequency domain measurement value is S11T;
According to known features value Γ of the reflectance standard in calibration mixer intermediate-frequency reference frequency outputIF, second arteries and veins
Rush corresponding frequency domain measurement value S11TAnd equation 11T=T1T2ΓIF, it is known that,
S is calculated according to below equation22IF:
Wherein, the calibration frequency mixer is reciprocity;
The preceding anti-and reverse conversion loss T of the calibration frequency mixer1And T2Can be determined by following equation:
Further, according to equationThe two value amplitudes for obtaining are equal, and phase differs 180 °;
Wherein, real T1And T2Value there was only 1, by S11T/ΓIFCorresponding group delay duration determines.
Above-mentioned technical proposal has the advantages that:
The method extracts calibration frequency mixer using the metrical information in two domains of vector network analyzer time domain and frequency domain simultaneously
Property scale data;On a timeline comprising the signal and frequency mixer of calibration mixer conversion loss information under time domain measurement pattern
Port mismatch signal, the directional error of whole machine be completely separated, it is possible to use time domain door extracts become again respectively
Change to frequency domain;The method can reduce influencing each other between each signal, reduce the requirement to calibrating frequency mixer performance indications, solve
The mixer conversion loss excessive problem that can not be calibrated more than vector network analyzer reflection measurement dynamic range, improves
The precision that calibration frequency mixer is characterized;Calibration frequency mixer calibration process is simplified, measurement connection repeatability error is reduced.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description
Only some embodiments of the present invention, for those of ordinary skill in the art, are not paying the premise of creative work
Under, other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 is vector frequency mixer calibration error model;
Fig. 2 is calibration frequency mixer calibration model;
Fig. 3 is a kind of flow chart of the calibration frequency mixer calibrating method based on time-frequency dual domain of the embodiment of the present invention;
Fig. 4 is the structural representation of the calibration frequency mixer for being used that the embodiment of the present invention is used;
During Fig. 5 is the embodiment of the present invention, the oscillogram of time domain measurement.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
Modern Vector Network Analyzer can realize frequency mixer amplitude and phase characteristic by using unique technology scheme
Measurement.The vector network analyzer for being used is four port network analyzers, is internally integrated two independent signal sources and one
Parametric mixer is switched, and the RF excited and local oscillator that two sources are respectively used in frequency mixer measurement process drive.Can also use
Two-port vector network analyzer, now local oscillation signal is whole to survey by the independent signal source in outside one and power splitter offer
The corresponding error model of amount composition system is as shown in Figure 1.Whole vector frequency mixer calibration process includes source calibration, radio frequency and intermediate frequency
The frequency two-port tracking system that calibrates for error and transmit calibrates for error 3 stages.The characterisitic parameter of frequency mixer and source and local oscillator work(
Rate is directly related, and power meter combination two-port calibrates for error and is capable of achieving source and the local oscillation signal power electricity of removal system mismatch error
Flat calibration.Mechanically or electrically calibrating device calibrates for error for carrying out two-port, determines the directionality E in error modelDRF, source
Matching ESRF, skin tracking ERRFWith load matched ELIFTotally 4 kinds of systematic errors.When carrying out the calibration of vector frequency mixer and measurement, must also
A parametric mixer, parametric mixer must be used to be connected to the R of the front panel jumper wire device of port 1 always1Output and R1It is input into it
Between, wherein vector network analyzer R1Source exports reference signal when port match calibration and measurement is carried out by internal switch
It is directly inputted to R1Reference receiver, transmits action points E in error model is carried outTCalibration solution and mixer conversion loss
When vectorial property is measured, R1Source reference signal is switched to the input of parametric mixer by internal electronic switch, mixed with measurement
The mixed frequency signal produced after the mixing of frequency device identical local oscillator is input to internal R1Reference receiver, for the output for measuring frequency mixer is carried
For the reference signal of same frequency.Carry out frequency mixer transmission tracking system calibrate for error when, the connection performance between two calibration ports
Completely known calibration frequency mixer, the thru calibration of the similar tradition two-port calibration of process, in determining error model shown in Fig. 1
Transmission tracking error ET。
In whole 3 step calibration, preceding 2 step Technical comparing is ripe, and the calibration accuracy of the 3rd step depends primarily on calibration frequency mixer
Calibration data and actual characteristic matching degree.
Calibration frequency mixer calibrates used model as shown in Fig. 2 whole calibration process seeks to determine calibration frequency mixer
S11RF、S22IF、T1And T2Totally 4 values, comprise the following steps that:
1) vector network analyzer carries out single port calibration first, determines the directionality E in modelDRF, source matching ESRF, it is anti-
Penetrate tracking ERRFTotally 3 systematic errors of whole machine;
2) prevention at radio-frequency port of calibration calibration frequency mixer and the vector network analyzer end for having carried out single port calibration will be needed
Mouth connection, calibrates the local oscillator port connection local oscillation signal of frequency mixer, is to ensure calibration accuracy, calibrates local oscillator when frequency mixer is calibrated
Input state is completely the same when must be calibrated with vector frequency mixer;
3) for Fig. 2 institutes representation model, the S corresponding to calibration frequency mixer prevention at radio-frequency port11Measured value is as follows:
4) output port in calibration mixer filter connects reflectance standard known to 3 characteristics, 3 reflection marks respectively
Accurate characteristic value known on mixer intermediate-frequency output frequency is respectively Γ1IF、Γ2IFAnd Γ3IF, vector network analyzer correspondence
Calibration frequency mixer prevention at radio-frequency port single port S11Measured value is respectively M1RF、M2RFAnd M3RF, the error model according to Fig. 2 can
The property scale value for obtaining frequency mixer is as follows:
Equation (5) can obtain two values, and the two value amplitudes are equal, and phase differs 180 °, but actual value only has 1,
Correct T1And T2The selection of phase value is by T1T2Corresponding group delay duration determines, is exactly more than traditional calibration frequency mixer calibration
Method.
At present when the vector calibration of calibration frequency mixer is carried out, carried out on frequency domain completely, now vector network analysis
Instrument port receives the composite signal being made up of following signal:
1) the directional error signal of whole machine residual, determines the dynamic range of reflection measurement, can determine while also determining
The amplitude range of the quasi- mixer conversion loss of calibration;
2) through multiple reflections and the various mismatch signals of Multipath Transmission;
3) prevention at radio-frequency port is returned to through frequency conversion again by various other frequency mixer output components that intermediate-frequency filter reflects
Signal;
4) return to prevention at radio-frequency port through upper and lower double conversion and include sideband conversion loss width phase information needed for calibration frequency mixer
Signal.
Characteristic present's data S in calibration frequency mixer model shown in wherein Fig. 211RF、T1、T2And S22IFFor solving Fig. 1 institutes
Error term E in the vector frequency mixer calibration error model for showingT.Due to the letter of information being lost comprising calibration frequency mixer vector converter
Number need to be by upper and lower double conversion, and actually used itself prevention at radio-frequency port matching properties of calibration frequency mixer are generally poor, lead
Port mismatch signal of the signal far below calibration frequency mixer comprising calibration mixer conversion loss width phase information that cause is received
With some other useless mixed product frequency variation signal again, so when other significantly mismatch error signal magnitude-phase characteristics change drifts
During shifting, the T solved in frequency mixer calibration process can be caused1And T2There is larger error in value, directly affect vector frequency mixer below
The precision of calibration, and then the precision that impact vector frequency mixer is measured.When calibrating microwave and millimeter wave frequency range harmonic frequency mixer,
Because conversion loss is very big, it is whole that the amplitude comprising calibration mixer conversion loss information signal is even below vector network analyzer
The directional error signal of machine, more than the dynamic range of reflection measurement, cannot now calibrate calibration frequency mixer.Other school
The calibration process of quasi- frequency mixer needs to be connected by 3 measurements after completing single port calibration, and not only process is cumbersome, and excessive
Measurement connection procedure can introduce extra measurement connection repeatability error, reduce the precision of calibration frequency mixer calibration.
Because traditional calibration frequency mixer calibration process is to be carried out on frequency domain completely, the technical indicator to frequency mixer has very
Many limitations, cannot calibrate it when calibrating mixer conversion loss and being excessive, and calibration precision is poor, and process is cumbersome.For biography
The deficiency that system calibration frequency mixer calibration process is present, patent of the present invention proposes a kind of calibration frequency mixer based on time-frequency dual domain and determines
Mark method, mainly solves following both sides not enough:
1) requirement to calibrating frequency mixer performance indications is reduced, the conversion loss scope of calibration calibration frequency mixer is extended,
Improve the precision of calibration frequency mixer calibration.The calibration frequency mixer calibrating method based on time-frequency dual domain that the present invention is extracted is utilized simultaneously
Two metrical informations in domain of time domain and frequency domain carry out calibration frequency mixer calibration, under time domain measurement pattern, are mixed on a timeline
The mismatch reflected signal of device prevention at radio-frequency port, remaining directivity error signal have been with the signal with the two-way conversion loss information of carrying
It is complete separate, can respectively be extracted by the time domain of vector network analyzer door, then switch back to again between frequency domain, each signal
Will not influence each other, therefore reduce the requirement to indexs such as mixer ports matching and conversion loss, while solving mixing
The problem that cannot be calibrated during the excessive dynamic range more than reflection measurement of device conversion loss, and can enter compared with traditional method
One step improves the precision of calibration frequency mixer calibration;
2) calibration process of calibration frequency mixer is simplified.Traditional frequency mixer calibration process is also needed to after completing single port calibration
3 measurement connections are carried out, is respectively believed when the calibration frequency mixer calibrating method based on time-frequency dual domain that patent of the present invention is proposed is because of calibration
Number separated in time shaft, it is possible to use time domain door is extracted respectively, therefore only need to carry out 1 after completing single port calibration
Secondary measurement connection can complete calibration, simplify the calibration process of calibration frequency mixer.
Embodiment one
The calibration frequency mixer that the present embodiment is used is as shown in figure 4, by reverse conversion loss characteristic reciprocity of forward direction
Frequency mixer and a wave filter are constituted.Reverse characteristic reciprocity refers to positive from calibration frequency mixer radio frequency mouthful before so-called calibration frequency mixer
To intermediate-frequency filter output and reversely from intermediate-frequency filter delivery outlet to frequency mixer radio frequency during mouthful Up/Down Conversion conversion loss width
Degree is identical with phase characteristic.Intermediate-frequency filter is used for extracting the mixing sideband signals of needs, to other useless mixing point
Amount is presented reflection characteristic high, i.e., these garbage signals all can be reflected back the intermediate frequency port of frequency mixer by intermediate-frequency filter, and lead to
To cross be mixed again and return to radio frequency mouthful.The model that calibration frequency mixer property scale is used calibration frequency mixer is carried out as shown in Fig. 2 determine
Timestamp, the response signal b that vector network analyzer port receives1RFComprising 3 parts letter in addition to the directional error signal of residual
Number:Prevention at radio-frequency port mismatch signal, reflected and returned to through being mixed again the useless mixing sideband signals of prevention at radio-frequency port by intermediate-frequency filter,
The signal of sideband mixer conversion loss information needed for carrying.Preceding two parts of signals is not with the load termination situation of intermediate-frequency filter
Change, Part III changes with the termination of intermediate-frequency filter, and this is the principle of conventional calibration frequency mixer calibration.The present embodiment
The calibration frequency mixer calibrating method based on time-frequency dual domain for being proposed is as follows:
Fig. 3 is the flow chart of the calibration frequency mixer calibrating method based on time-frequency dual domain of the present embodiment, as shown in figure 3, bag
Include:
Step 301, sets radio frequency incident frequencies, local frequency, the mixing number of times of calibration frequency mixer, calculates IF-FRE;
Step 302, sets RF input power, local oscillation power, the calibration frequency mixer is operated in correct linear shape
State, and it is consistent when the input state of local oscillation power is calibrated with vector frequency mixer when making calibration frequency mixer;
Step 303, vector network analyzer does single port calibration in the range of the calibration frequency mixer radio frequency incoming frequency;
Step 304, the calibration frequency mixer prevention at radio-frequency port is connected with the calibration port of vector network analyzer, and connection is originally
Shake signal, and connects high reflection standard, the reflection mark known to a characteristic in the intermediate-frequency filter output port for calibrating frequency mixer
The accurate known features value in calibration mixer intermediate-frequency reference frequency output is ΓIF;
Step 305, setting single triggering makes vector network analyzer complete single pass and in hold mode, corresponding
Frequency domain measurement value is S11;
Step 306, by the time domain measurement function of vector network analyzer, measurement pattern is set to band logical impulse pattern,
And the time domain measurement function is opened, obtain two pulses for separating on a timeline;Wherein, the first time domain impulse includes calibration
The S of frequency mixer11RFInformation, preceding reverse conversion loss T of second time domain impulse comprising calibration frequency mixer1、T2With reflectance standard characteristic
Information ΓIF;
Now time domain measurement waveform is as shown in figure 5, be two pulses for separating on a timeline.
Step 307, the crest of first time domain impulse is placed in by the center of time domain door, by the starting of time domain door and
Stop value is respectively placed in the trough of the first time domain impulse left and right sides, and the type for selecting the time domain door is band logical, is opened
The time domain door function, closes the time domain measurement function and returns to frequency domain, extracts the frequency domain letter corresponding to the first time domain impulse
Breath, the frequency-region signal corresponding to it is the S of the calibration frequency mixer11RF;
Step 308, reopens the time domain measurement function, and closes the time domain door function, by time domain door
Center is placed in the crest of second time domain impulse, and the starting and termination of time domain door should be respectively placed in into the second time domain arteries and veins
The trough of both sides is rushed, the type for selecting time domain door is band logical, open time domain door function, closed the time domain measurement pattern and return
Frequency domain is returned, the frequency domain information corresponding to the second time domain impulse is extracted, its corresponding frequency domain measurement value is S11T;
The error model according to Fig. 2, S11TIt is worth and is:
S11T=T1T2ΓIF;
Step 309, according to known features value Γ of the reflectance standard in calibration mixer intermediate-frequency reference frequency outputIF, institute
State the corresponding frequency domain measurement value S of the second pulse11TAnd equation S11T=T1T2ΓIF, can obtain,
Because calibration frequency mixer is reciprocity, the preceding anti-and reverse conversion loss T of the calibration frequency mixer1And T2Can
It is calculated by following equation:
Further, two values can be obtained according to the equation, the two value amplitudes are equal, phase differs 180 °, but very
Real-valued only 1, real T1And T2Value is by S11T/ΓIFCorresponding group delay duration determines.
Step 310, S is calculated according to below equation22IF:
The equation is by equation (1)Obtain.
Above-mentioned technical proposal has the advantages that:
The method extracts calibration frequency mixer using the metrical information in two domains of vector network analyzer time domain and frequency domain simultaneously
Property scale data;On a timeline comprising the signal and frequency mixer of calibration mixer conversion loss information under time domain measurement pattern
Port mismatch signal, the directional error of whole machine be completely separated, it is possible to use time domain door extracts become again respectively
Change to frequency domain;The method can reduce influencing each other between each signal, reduce the requirement to calibrating frequency mixer performance indications, solve
The mixer conversion loss excessive problem that can not be calibrated more than vector network analyzer reflection measurement dynamic range, improves
The precision that calibration frequency mixer is characterized;Calibration frequency mixer calibration process is simplified, measurement connection repeatability error is reduced.
Those skilled in the art will also be appreciated that the various illustrative components, blocks that the embodiment of the present invention is listed
(illustrative logical block), unit, and step can be by the knot of electronic hardware, computer software, or both
Conjunction is realized.To clearly show that the replaceability (interchangeability) of hardware and software, above-mentioned various explanations
Property part (illustrative components), unit and step universally describe their function.Such work(
It can be the design requirement for realizing depending on specific application and whole system by hardware or software.Those skilled in the art
Can be for every kind of specific application, it is possible to use various methods realize described function, but this realization is understood not to
Beyond the scope of embodiment of the present invention protection.
Above-described specific embodiment, has been carried out further to the purpose of the present invention, technical scheme and beneficial effect
Describe in detail, should be understood that and the foregoing is only specific embodiment of the invention, be not intended to limit the present invention
Protection domain, all any modification, equivalent substitution and improvements within the spirit and principles in the present invention, done etc. all should include
Within protection scope of the present invention.