CN109802673A - A kind of frequency-locked loop with frequency displacement - Google Patents
A kind of frequency-locked loop with frequency displacement Download PDFInfo
- Publication number
- CN109802673A CN109802673A CN201711135033.7A CN201711135033A CN109802673A CN 109802673 A CN109802673 A CN 109802673A CN 201711135033 A CN201711135033 A CN 201711135033A CN 109802673 A CN109802673 A CN 109802673A
- Authority
- CN
- China
- Prior art keywords
- frequency
- locking ring
- voltage
- frequency locking
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Landscapes
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Abstract
A kind of frequency-locked loop with frequency displacement or abbreviation frequency locking ring are a control system or circuit, and output signal frequency can follow frequency input signal, and the difference of keep frequency is constant.Basic band frequency displacement frequency locking ring is made of frequency mixer, frequency-voltage amplitude transform component, wave detector, adjustment amplifier and voltage controlled oscillator.Appropriately designed circuit, so that frequency-voltage amplitude transform component intermediate zone frequency-voltage amplitude decline (rising) and the voltage-frequency rising (decline) of voltage controlled oscillator reach balance on some frequency-electrical voltage point in frequency locking ring, that is, realize the locking in circuit.Actual frequency locking ring has raising frequency formula and two kinds of frequency-reducing type, their output signal frequency is respectively above or below frequency input signal.It can be directly used as the frequency locking receiver that frequency shifter, two-frequency signal generator, tool automatically track locking ability with frequency displacement frequency locking ring, provide new concept and mechanism for the design of the systems such as radar, communication.The present invention can constitute frequency locking ring special chip in whole or in part.
Description
Technical field
The present invention relates to electronic information fields, propose a kind of frequency-locked loop (Frequency Locked with frequency displacement
Loop, FLL).
Background technique
Phaselocked loop (Phase Locked Loop, PLL) technology is to be widely used in electronic information field and mature
Technology.But phaselocked loop can not meet application demand in the application.Common experience is that the realization cost of phaselocked loop is higher,
The catching range of phase or frequency is relatively narrow, designs and adjusts and is more troublesome.The problem of there are also some more depth.Such as radar,
In communication and electronic instrument design, it is often necessary to referring to some Setting signal frequency F1Generate another signal frequency F2, they it
Between frequency difference Δ F=F1-F2Very little.Such as to millimeter wave, Terahertz, until in the weak signal reception conversion process of optical frequency, letter
Number very high frequency, it is desirable to be converted in some lower frequency and handle, the frequency that people need is difference frequency Δ F.At this moment opposite
Frequency shift amount | Δ F/F1| very little, such as to 10-6Or it is smaller, and frequency shift amount Δ F numerical stability is required, this is not just one and simply asks
Topic.Designer is, it can be seen that this cost using phaselocked loop of processing can be very high, it is not easy to be in industrial applications and be received.
In the application, frequency F1Signal S1It can be reception signal, F1Numerical value may drift about at any time.Therefore to have one with
Track mechanism generates F2, just can guarantee Δ F numerical stability.In addition, the phaselocked loop in all uses a large amount of pulse digit electricity
Road causes the noise floor of output frequency high, is unfavorable for the reception conversion process of weak signal；When phaselocked loop is for generating transmitting letter
Number when, noise floor will affect transmitting signal quality.
The frequency locking ring with frequency displacement proposed in the present invention is a control system or circuit, it receives an input signal
And an output signal is generated, the frequency of the output signal and the difference of frequency input signal are a fixed values；Work as input signal
Frequency variation, output frequency will be with changing everywhere, and the difference of their frequencies remains unchanged.
Frequency locking ring with frequency displacement is properly termed as tracking mode frequency shifter.It is usually reached using a kind of frequency shifter in Audiotechnica
To a kind of special auditory effect.This Audio-Frequency Frequency Shift device is usually realized with amplitude modulation and sideband extracting method and of the invention
Working mechanism is entirely different.When frequency reaches GHz or more and relative phase shift very little, the realization cost of sideband extracting method can be got over
Come higher.
A variety of frequency locking ring without frequency displacement, also referred to as frequency tracker are reported in communication and control field, document,
Function and mechanism are different from the present invention.These frequency locking ring are served in specified application demand, such as recovery input signal
Synchronization fundamental frequency；Or the sensor as frequency variation, measurement receive the error of frequency and assigned frequency, for feeding back control
System, keep frequency are stablized.The technical goal of frequency locking ring and phaselocked loop without frequency displacement is close, and only frequency locking ring is hopeful to reach more
Wide frequency acquisition range.It in these techniques, include estimation link to frequency input signal even Digital Signal Processing
Demand, this technology are basically limited to dedicated.There is a kind of frequency locking ring of frequency of use-voltage conversion unit, frequency is locked
Accuracy limited by analog component characteristic coherency and temperature stability.In particular, it is not suitable for coming in fact referring to weak signal
Existing Frequency Locking.
Band frequency displacement frequency locking ring proposed by the present invention is both a kind of frequency shift signal generator, can also be received as a kind of frequency locking
Machine.This frequency locking receiver has the form of superhet, and the local frequency of conventional superheterodyne receiver is without this hair
The Frequency tracking mechanisms of bright proposition.Therefore frequency locking ring of the invention can be directly used for transmitter, can be used for receiving and detecting micro-
The signal that weak and band is made an uproar.When tracking signal synchronizing frequency with being used to band frequency displacement, just mentioned for extraction frequency modulation, amplitude modulation, phase modulation information
The new mechanism of the frequency tracker different from no frequency displacement is supplied.It means that frequency locking loop technique proposed by the present invention is a kind of base
This technology, may be directly applied to various electronics and optical transmitting and receiving system and measuring system, and the design that will affect these systems is general
Thought and method, derive new application development.
Summary of the invention
Basic band frequency displacement frequency-locked loop, hereinafter referred to as frequency locking ring (FLL), by frequency mixer (1), frequency-voltage amplitude
Transform component (2), wave detector (3), adjustment amplifier (4) and voltage controlled oscillator (5) composition, as shown in Figure 1.
In frequency locking ring basic circuit scheme shown in Fig. 1, the input signal or reference signal frequency f of frequency locking ringrWith it is defeated
Signal frequency f outcAfter frequency mixer 1, difference frequency F is obtainedi=fr-fc(or Fi=fc-fr, it is decided by the specific design and tune of circuit
It is whole).Difference frequency FiIt is added on frequency-voltage amplitude transform component 2.The frequency-voltage amplitude transform component typical example is one
A low-pass filter, however, it is also possible to use a band logical, the intermediate zone with resistance or high-pass filter, but use low pass filtered
The design of wave device is easiest to, and is easy to reach wide pullin banwidth.It is most basic in the present invention, difference frequency FiIt needs to fall in
In the intermediate zone of filter, the intermediate zone characteristic of filter is exactly the frequency-voltage amplitude Transformation Properties needed in frequency locking ring.When
Difference frequency FiWhen changing in intermediate zone, converter (filter) output amplitude changes, and 3 output voltage of wave detector changes therewith.It is false
The output frequency for determining voltage controlled oscillator 5 increases with input voltage and is increased.Appropriately designed adjustment amplifier, can make frequency locking ring
The voltage-frequency of middle frequency-voltage amplitude converter output frequency-voltage amplitude decline (rising) and voltage controlled oscillator rises
(decline) reaches balance on some frequency-electrical voltage point, that is, realizes the locking in circuit.
Fig. 2 is a specific implementation example of frequency locking ring.Frequency-voltage amplitude transform component in this example is one
Low-pass filter, adjustment amplifier constitute non-inverting amplifier on the whole, have accessory circuit to be used in the input terminal of amplifier
The original state of initialization circuit.
The frequency locking ring course of work shown in Fig. 2 is explained as follows.Design and setting circuit, so that switch connects in short-term when starting
It is disconnected after logical.When a switch is on, v is forcedAIn high potential, vcHeight, so that fcMuch higher than fr, mixer output frequency fc-
fr=FiOther than pass band.Switch disconnects immediately, and the capacitor on amplifier input terminal can temporarily keep vANo
Become, thus vcIt is temporarily constant.Due to FiOutside passband, wave detector output is low, is not able to maintain vAHigh potential, vA↓, → vc↓, → fc
↓.This process can continue, until frequency FiInto the passband of filter.Due to circuit closed loop, the output signal of voltage controlled oscillator
Frequency fcThe fixed point that balance is converged under the conditions of following two must be met at the same time:
(1) the voltage-frequency characteristic of VCO, is expressed as with mathematical model
F=Hc(v), (1)
(2) do not include VCO, frequency locking ring whole remaining circuits frequency-voltage amplitude characteristic, be expressed as
V=HL1(f), (2)
Wherein
HL1(f)=VrKmKdKoKL(f) (3)
Wherein Vr--- reference signal virtual value；
Km--- mixer gain value, it is assumed that the local oscillation signal amplitude that VCO is provided is fixed；
Kd--- wave detector gain (ratio of output DC voltage and input signal virtual value)；
Ko--- the gain exported from wave detector output voltage to operational amplifier；
KL(f) --- gain of the low-pass filter in frequency locking ring.
On equalization point, when the voltage that frequency locking ring is supplied to voltage controlled oscillator meets v=vcWhen, voltage controlled oscillator output frequency
Rate f=fc。
Static Analysis Method can be used and be balanced point analysis, i.e., do not consider the mistake of each component units in frequency locking ring first
Cross course.About KL(f) must give to explain.It is certainly that the frequency-amplitude characteristic of low-pass filter, which is generally written into Frequency,
The form K of variableL(F).Notice mixer input frequency f=frFrequency F=F is inputted corresponding to low-pass filteri=0.With change
Amount replacement F=f-frIt obtains
KL(F)=KL(f-fr), f >=fr (4)
Above formula is mathematically simply, however, it is to be understood that KL(F) and KL(f-fr) it is physically that two frequencies are sat
The function put on.Since frAs reference frequency, it can be considered fixed.It therefore can be by KL(f-fr) simply write as KL(f)=KL
(f-fr).Here it is K in (3) formulaL(f) meaning.Fig. 3 shows the meaning of (4) formula.As it can be seen that for steady-state analysis, frequency locking
Loop back path frequency-amplitude characteristic is decided by the intermediate zone characteristic of low-pass filter.
It needs formula (1) and (2) being placed on the same coordinate system, be just convenient for determining while meeting the two non trivial solutions.By
In the nonlinearity of problem, it is convenient for being illustrated with graphic technique.It can be assumed function f=Hc(v) and v=HL1(f)
It is all monotonic function in frequency-voltage amplitude working region.It then can be by v=HL1(f) it is expressed, is write with inverse function form
At
F=HL1_mv(v) (5)
Depict two function f=H involved in frequency locking ring simultaneously on Fig. 4c(v) and f=HL1_mv(v) typical case is bent
Line.Due in f >=frRegion upper curve has monotonicity, and two curves have been only possible to an intersection point p, that is, have converged to frequency locker
Fixed equalization point.On this aspect, reach v=vcAnd f=fc。
It is easy explanation, in f >=frRegion on, from any one initial state of circuit, circuit state can all be received
Hold back equalization point p.According to the explanation to Fig. 2, if circuit is originated according to switch connection-disconnection mode, state must converge to p
Point.Now consider a kind of different situations.It is assumed that switch is to disconnect, but v when circuit originatesAIn compared with low potential.Therefore vcIt is low, electricity
Line state is in f >=frThe near border in region, i.e. fc≈fr, mixer output frequency fc-fr=FiIn pass band
Near middle maximum gain, wave detector output is high, and inherently the frequency of occurrences adjusts process: vA↑, → vc↑, → fc↑.This process meeting
Continue, until frequency fcConverge to equalization point p.
For the frequency locking ring of Fig. 2, in f >=frRegion on, from any one initial state of circuit, circuit state
A frequency f will be converged toc> frPlace.Therefore, Fig. 2 shows frequency locking ring be known as raising frequency frequency locking ring.
Fig. 5 is slightly different frequency locking loop circuit, and wherein frequency-voltage transformation component is a low-pass filter, and is adjusted
Whole amplifier is a differential amplifier.
Differential amplifier in Fig. 5, output input relationship can be write as
The state closed the switch in Fig. 5, for the original state of initialization circuit.At this moment vB=0, vc≤ 0, VCO dead-beat,
The output of frequency mixer no signal, vA=0.Design and adjustment FLL include differential amplifier, so that when forcing vA=0 and switch disconnect when
VCO output frequency is close to fr.Then, it is just disconnected after allowing switch to be closed in short-term, the initial oscillation of VCO is close to fr.At this moment it is mixed
Device output frequency is in low-pass filter band, vARapid increase, FLL enter closed-loop working state.NoteIt is put for operation
Big gain of the device to differential input.Frequency-the voltage amplitude characteristic for not including VCO, frequency locking ring whole remaining circuits can be with
It is expressed as
V=HL2(f)=VrKmKdKop(1-KL(f)) (7)
Wherein Vr--- reference signal virtual value；
Km--- mixer gain value, it is assumed that the local oscillation signal amplitude that VCO is provided is fixed；
Kd--- wave detector gain (ratio of output DC voltage and input signal virtual value)；
KL(f) --- gain of the low-pass filter in frequency locking ring, peak are set as 1.
For the frequency locking ring containing differential amplifier, low-pass filter characteristic is transferred to the relationship on radio frequency and is
KL(F)=KL(fr- f), f≤fr (8)
Fig. 6 shows KL(F) and (1-KL(F)) example.It is similar with the explanation about formula (4), K in formula (8)L(F)
And KL(fr- f), f≤frIt is the function on two different frequency coordinates, and by KL(fr- f), f≤frIt is abbreviated as KL(f).By HL2
(f) inverse function of function is denoted as HL2_mv(v), it and by inverse function with VCO Frequency Stability is drawn on same Fig. 7, it can be easily
Explain the convergence of frequency locking ring.
Consider the frequency locking ring of Fig. 5.When a switch is on, VCO dead-beat.It is that capacitor charging in circuit makes first after disconnection
Obtain vBRapid increase, vcRapid increase makes fcQuickly towards frIt is mobile, mixer output frequency fr-fc=FiInto low-pass filtering
Device passband, so that vA↑, FLL enters closed-loop working state.vA↑ v can be offsetedBRising, and two function curves shown in Fig. 7
Intersection point on reach balance, that is, realize the locking in circuit.
For the frequency locking ring of Fig. 5, in f≤frRegion on, from any one initial state of circuit, circuit state
A frequency f will be converged toc< frPlace.Therefore, the frequency locking ring shown in Fig. 5 is known as frequency reducing frequency locking ring.
According to above principle analysis it can be concluded that the design and Adjustment principle of frequency locking ring.After one rationally designs and adjusts
Frequency locking ring, need to guarantee wherein VCO voltage-frequency characteristic and frequency locking ring remaining circuit formed frequency-voltage amplitude characteristic
There is solution in a case where, and have unique solution: active and passive device characteristic deviation；Device property is in operating temperature model
Enclose interior variation；Characteristic variations caused by power supply.Under this hypothesis, according to the initialization side shown in schematic diagram 2 and Fig. 5
Method, frequency locking ring can defer to the working principle of Fig. 4 and Fig. 7 signal, guarantee output frequency fcAn equalization point is converged to, into lock
Frequency state.
It is assumed that a frequency locking ring is suitably designed and adjusts, into frequency-locked state.As input frequency frDrifting type occurs
When slowly varying, the output frequency f of frequency locking ring is consideredcHow to change.By taking raising frequency frequency locking ring shown in Fig. 2 as an example.Work as frIt increases
When, circuit will appear following adjustment process: frF after ↑ → mixingc-fr=Fi↓ → filter frequencies are to passband offset → vA↑→vc↑
→fc↑, output frequency fcF can be followedrIt is adjusted to direction is increased, and prevents FiDecline.Work as frWhen reduction, circuit will appear not
Same adjustment process: frF after ↓ → mixingc-fr=Fi↑ → filter frequencies are to stopband offset → vA↓→vc↓→fc↓, output frequency
Rate fcF can be followedrIt is adjusted to descent direction, and prevents FiRising.The feedback effect of frequency locking ring is intended to maintain difference frequency as a result,
FiIt is constant.For frequency reducing frequency locking ring shown in fig. 5 when inputting frequency variation, output frequency can track variation, be intended to maintain difference frequency
fr-fc=FiIt is constant, raising frequency frequency locking ring can be imitated to carry out analytic explanation.
The frequency locking ring working principle explanation illustrated from Fig. 4 and Fig. 7 is it is understood that no matter which kind of reason causes frequency locking ring to export
Frequency variation, as long as the feedback control mechanism of frequency locking ring works, difference frequency fc-fr=Fi(to raising frequency frequency locking ring) or fr-fc=Fi
(to frequency reducing frequency locking ring) must be fallen in the intermediate zone of low-pass filter.
It is example with frequency reducing frequency locking ring, illustrates state change of the frequency locking ring in temperature change.Fig. 8 illustrates voltage-controlled vibration
Swing control voltage-frequency characteristic curve of the device under three representative temperatures.When to fixed working voltage and control voltage, industry is answered
The frequency of oscillation amount of varying with temperature of VCO chip is very big.Such as the 24GHz of Hittite company production is commonly used in the market
VCO chip HMC533LP4, temperature drift rate reach 2.3MHz/ DEG C.It means that if VCO operating temperature range is -40 DEG C
~+85 DEG C, to fixed operating voltage and control voltage, frequency drift total amount caused by temperature change be can achieve
287.5MHz.When VCO is in frequency locking ring, situation becomes different.It is assumed that design and adjustment frequency locking ring, so that at normal temperature, lock
On the midpoint of the low-pass filter intermediate zone of frequency ring locking.The point of the frequency locking ring locking under A0 point signal room temperature in fig. 8.Such as
Fruit temperature increases, and VCO characteristic curve is mobile towards+85 DEG C of characteristic curves.Then fc↓→ fr-fc=Fi↑→FiIt is hindered to filter
Band offset → vA↓→vc↑→fc↑, it is meant that frequency-locked loop feedback can make to control voltage vcIncrease, heating is prevented to lead to fcDecline.
In this way, the feedback mechanism of frequency locking ring will limit fcVariation so that difference frequency is in always on low-pass filter sideband；Equivalently,
Limit fcA in fig. 80To BHCurve on change.If temperature reduces, similar deduction be can be determined that, fcTo A in fig. 80It arrives
BLCurve on change.Notice that the width of transition zone of low-pass filter may be lower than the temperature offset amount of microwave frequency multiple
The order of magnitude, it is meant that even if microwave oscillator has biggish temperature drift, the output signal frequency f of frequency locking ringcIt will not occur
Big drift, and fcDrift value be limited in the corresponding working condition variation range of low-pass filter intermediate zone.
It is described analysis shows, if it is desired to different frequency stabilisation, it is important that the stable and steeper low pass filtered of selection intermediate zone
Wave device.This property is extremely important.There is following facts highly beneficial to the implementation and application of frequency locking ring: (1) passive filter
Frequency-the voltage amplitude characteristic of (such as LC filter of extensive application) has low sensitivity to device tolerance and temperature change；
(2) good RC active filter is designed, frequency-voltage amplitude characteristic also has muting sensitive sense to device tolerance and temperature change
Degree；(3) frequency location of intermediate zone is decided by external switch clock frequency in frequency-voltage amplitude characteristic of switch capacitor filter
Rate, such as use crystal oscillator as external switch clock, it can guarantee that frequency-voltage amplitude of filter intermediate zone is special
Property stablize.Frequency sensitivity mentioned here or frequency stabilization refer to stabilization of the frequency-voltage amplitude characteristic about temperature change
Property, this is directly linked the temperature stability of difference frequency in frequency locking ring.Due to the closed loop adjust automatically ability of FLL, make microwave frequency
Influence of the drift to difference frequency be limited in the intermediate zone of low-pass filter.Pay attention to the intermediate zone characteristic of low-pass filter with temperature
Degree variation and the frequency drift of VCO be not completely in an order of magnitude, by difference frequency FiIt is limited in intermediate zone, can to export micro-
Wave frequency rate declines with becoming into the order of magnitude relative to drift.
No matter frequency locking ring in practical application is used as transmitting unit or receiving unit, may all need to basic frequency locking ring
Circuit makees simple variation, these variations do not change the Frequency Locking mechanism in frequency locking ring, therefore should not be considered as different skills
Art should not be considered as different with the present invention naturally.Several examples simply changed have:
(1) addition amplifier before or after any part in basic frequency locking loop back path, attenuator, shunt circuit,
Switching circuit etc., when frequency locking ring circuit closed, the frequency locking mechanism of the output frequency tracking input frequency in the circuit does not change
Become.
(2) input reference signal can be the reception signal entered by receiving antenna；It is primary to be also possible to local one
The oscillator signal that oscillator coupling comes.In the later case, it needs to add power splitter or coupler naturally in circuit, and it is primary
The major part of oscillator output can be launched again by transmitting antenna.
(3) major part of the voltage controlled oscillator output in frequency locking ring can be launched outward by antenna, and pass through coupling
The frequency mixer of device or power splitter into frequency locking ring provides the working mechanism that sub-fraction power is just able to maintain frequency locking ring.
Following example illustrates industrial applicibility of the invention.
The direct application of frequency locking ring of the present invention is as frequency shifter, however, it would be possible to be applied to all frequencies and wide scope can
The frequency shift amount of choosing.At this moment, major part is used as frequently by voltage controlled oscillator output signal using power splitter or coupler in frequency locking ring
The output of device is moved, and fraction oscillator signal gives frequency mixer to guarantee the work of frequency locking ring.The frequency shift amount of described frequency shifter
Size is mainly decided by the frequency location of low-pass filter intermediate zone, and can be by adjusting adjusting amplifier in frequency locking ring
Gain to frequency shift amount carry out fine adjustment.This frequency shifter has the simplicity of strong versatility and implementation, can be design thunder
New concept and basic module are provided up to transceiver communication system.
Fig. 9 shows a kind of application form with frequency displacement frequency locking ring: two-frequency signal generator, wherein 101 be the first oscillation
Device；102 be power splitter or signal coupler, and the output of the first oscillator is largely sent to output end 1 by it, and fraction power
It is sent to frequency mixer 103.It is basic frequency locking ring in the box of Fig. 9, wherein 105 be voltage controlled oscillator, power splitter is passed through in its output
Or signal coupler 104 will largely be sent to output end 2, and fraction power is sent to frequency mixer 103；106 be low-pass filtering
Device, 107 be wave detector, and 108 be adjustment amplifier.It is decided by adjust the design of amplifier and accessory circuit, frequency locking ring can be
Raising frequency formula, it is also possible to frequency-reducing type.Two-frequency signal generator in the present invention is used as microwave dual frequency doppler radar
Transmitting unit is easy to keep the numerical stability of the difference of double frequency, and this dual frequency doppler radar is capable of providing more accurate target range
Measured value.The typical case of microwave dual frequency doppler radar is before can be used as automobile to Anticollision Radar.
Figure 10 is another application form with frequency displacement frequency locking ring, i.e. frequency locking receiver, it can be used as radio or logical
Believe the main part of receiver.Frequency locking ring in the receiver by frequency mixer 203, signal amplifier 205, low-pass filter 206,
Wave detector 207, adjustment amplifier 208 and voltage controlled oscillator 204 are constituted.201 be receiving antenna, and 202 be low-noise amplifier.
Available reception signal (209,210) of different nature before and after from low-pass filter, and the signal drawn from 209 is to receive
Signal shifting frequency is suitable for signal detection and application to the version of low frequency.Frequency locking ring in this design can be raising frequency,
It is also possible to frequency reducing.When receiving multiple channel signals using frequency locking receiver, it is desirable to which which channel receiver, which captures, to lead to
Change initial frequencies are crossed to give.By taking raising frequency formula frequency locking receiver as an example, if inputting channel frequency is f1< f2< ... <
fN, in order to capture frequency fi(i=1,2 ..., N) can input an initialization voltage in short-term in adjustment amplifier in
(211), so that voltage controlled oscillator output frequency is in fiAbove and in fi+1Below.After initialization voltage shutdown, frequency locking
Ring can lock fcTo higher than fiA frequency values on.Design engineer will be appreciated that this channel setting mechanism is received than locking phase
Machine is much simpler.Meanwhile containing in phase-locked receive there are many digital circuit, no small noise floor can be generated to receiver；And
Frequency locking receiver is essentially to simulate entirely, available very low noise floor, is easy to reach higher reception spirit in other words
Sensitivity.
Whole circuits as involved in frequency locking ring of the present invention, including frequency mixer, preamplifier, low-pass filter, inspection
Wave device, adjustment amplifier and VCO have had mature chip design and market product, by these in semiconductor devices industry
Design is combined in whole or in part, is constituted frequency locking ring specialized simulation chip, can be guided new design concept and method, significantly
Simplify and accelerate the development process of a big electronic product, and reduces the price of many radars, communication products.Whole frequency locking ring core
Piece is described by claim the 1 to the 7th article complete at being grouped as, and has specified specificity；And general frequency locking ring chip
Only comprising a part being fully composed in ingredient, such as only comprising low-pass filter, wave detector and adjustment amplifier；It is described
Low-pass filter can be fixed-bandwidth, and it is settable to be also possible to bandwidth；Described adjustment amplifier and its attached initializing circuit
It can be designed to be suitble to raising frequency formula or frequency-reducing type frequency locking ring or both of which optional.
Summary of drawings
Fig. 1 basic frequency-locked loop constitutes block diagram, by frequency mixer, frequency-voltage amplitude transform component, wave detector, tune
Whole amplifier and voltage controlled oscillator composition.
A kind of principle of compositionality figure of raising frequency type frequency locking ring of Fig. 2, adjustment amplifier therein is noninverting on the whole；It puts
Initializing circuit is contained in big device input circuit.
Fig. 3 low-pass filter characteristic relationship under different frequency coordinate.
Fig. 4 raising frequency type frequency locking ring frequency locking principle illustrates.
A kind of frequency reducing type frequency locking ring of Fig. 5, adjustment amplifier therein is differential amplifier；Include in amplifier input circuit
Initializing circuit.
Characteristic conversion of Fig. 6 low-pass filter in frequency reducing ring.
Fig. 7 frequency reducing type frequency locking ring frequency locking principle illustrates.
Control voltage-frequency characteristic curve of Fig. 8 voltage controlled oscillator under three representative temperatures；And when VCO is in lock
In frequency ring, when the temperature is changed, VCO frequency of oscillation changes the schematic diagram limited by low-pass filter intermediate zone.
The two-frequency signal generator that Fig. 9 is constructed with frequency displacement frequency locking ring, can be used as the transmitting unit of dual frequency doppler radar.
Figure 10 basic frequency locking receiver, can be used as the main part of radio or communication control processor.
Embodiments of the present invention
It is said in principle, the design and implementation technology of frequency locking ring sums up are as follows: guarantees with equation (1) and (2) and (1) and (7)
The mathematical model of description has solution on specified frequency field and has unique solution.
Frequency-voltage amplitude inverting element plays an important role in frequency locking ring.Frequency locking ring in practice has two quasi-representatives
Application target.First kind application is that the output signal of one with input frequency different frequency are generated with frequency locking ring, it is desirable to output frequency
Rate and the difference for inputting frequency are a stable low frequencies；In the application of second class, the input of frequency locking ring is a modulated signal
(frequency modulation, amplitude modulation, phase modulation), there are also sideband spectral lines in addition to carrier frequency, it is desirable that frequency locking ring tracking input carrier frequency generates the sheet of single-frequency
Ground oscillator signal.Second class is using similar to existing superhet, and only conventional superhet does not have frequency locking
That the automatic frequency tracking mechanism just having in ring.Above two class apply to the requirement of frequency-voltage amplitude inverting element some
Different.Frequency locking ring towards single-frequency input is suitable for the frequency for selecting intermediate zone very precipitous-voltage amplitude transformation member
Part；And the frequency locking ring towards modulated signal input, the width of frequency-voltage amplitude inverting element intermediate zone are preferably able to cover
The width that lid spectrum modulation signal occupies.Implementation technology in the present invention for ease of description assumes the input of frequency locking ring below
It is single-frequency signals, and frequency-voltage amplitude inverting element is a low-pass filter, the intermediate zone with a routine
Characteristic.
First illustrate the implementation technology of raising frequency frequency locking ring, implements referring to circuit diagram 2.
The first step selects the VCO device needed, its voltage-according to the requirement of input frequency, output frequency or difference frequency
Frequency characteristic need to cover the possible mobility scale of output signal frequency.Low-pass filter is selected, allows frequency characteristic of filter transition
Band midpoint (such as by filter passband while and average frequency value when stop-band be considered as intermediate zone midpoint frequency) at the filter that calculates
Wave device bandwidth is equal to frequency locking ring and wishes the difference frequency value reached.Routinely circuit design requirements carry out for the selection of other component.
Second step, estimation and decision following values: Vr--- reference signal virtual value；Km--- mixer gain value, it is assumed that
The local oscillation signal amplitude that VCO is provided is fixed；Kd--- wave detector gain (ratio of output DC voltage and input signal virtual value)；
Ko--- the gain exported from wave detector output voltage to operational amplifier；KL(f) --- increasing of the low-pass filter in frequency locking ring
Benefit.The estimation method of this tittle can obtain in conventional circuit design theory and technology；Wherein KLIt (f) is low-pass filter KL
(F) frequency displacement is to f=frIt obtains, and specified passband maximum gain is 1.
The VCO of frequency locking ring is inputted and is disconnected, is added to VCO input terminal using an external voltage by third step, allows signal source
Output frequency is equal to desired output frequency value.Op-amp gain is adjusted simultaneously, so that VCO input terminal gap is amplifying
Frequency locking ring loop, is then closed by (open loop) control voltage that device side measures voltage value additional slightly larger than VCO input terminal.
4th step designs initializing circuit, reaches following target: when switch connection in Fig. 2, making vAIn higher electricity
Position guarantees VCO output frequency fcMuch higher than fr, mixer output frequency fc-fr=FiOther than pass band；And works as and open
When shutdown is opened, if A point is forced zero setting, v can be obtainedCIt is very low, VCO output frequency fcIt is near or below fr；It needs to design simultaneously
Circuit, so that v when the switches are openedALocating the transient occurred can terminate within the appropriate short time, guarantee frequency locking ring energy
Enough rapidly enter lock state.
The implementation technology and raising frequency frequency locking ring of frequency reducing frequency locking ring implement technology without essential distinction.Frequency reducing frequency locking ring implements reference
Fig. 5 is carried out.Specific step is as follows.
The first step, selects the VCO device needed, its voltage-frequency characteristic need to cover the possible variation model of output signal
It encloses.Select low-pass filter, allow frequency characteristic of filter intermediate zone midpoint (such as by filter passband while and it is flat when stop-band
Equal frequency values are considered as intermediate zone midpoint frequency) at the filter bandwidht that calculates be equal to frequency locking ring and wish the difference frequency value reached.Other
Routinely circuit design requirements carry out for the selection of component.
Second step, estimation and decision following values: Vr--- reference signal virtual value；Km--- mixer gain value, it is assumed that
The local oscillation signal amplitude that VCO is provided is fixed；Kd--- wave detector gain (ratio of output DC voltage and input signal virtual value)；--- the gain of operational amplifier output；KL(f) --- gain of the low-pass filter in frequency locking ring.This tittle is estimated
Meter method can obtain in conventional circuit design theory and technology；Wherein KLIt (f) is low-pass filter KL(F) frequency displacement is to f=
frIt obtains, and specified passband maximum gain is 1.
The VCO of frequency locking ring is inputted and is disconnected, is added to VCO input terminal using a voltage by third step, so that VCO output frequency
Rate reaches fr, record the input voltage v of VCO at this timerNumerical value.By vAIt is grounded to 0, designs vBDC voltage generation circuit,
Make to adjust amplifier output voltage greater than vr.Then, by vAIt is disconnected from ground, allows frequency locking ring to input out in VCO and open a way, and with previous
The v of recordrVoltage value is added to VCO input.Under this condition, design and adjust differential amplifer gain and attached initialization electricity
Road reaches vB=vA；Guarantee the following conditions simultaneously: under frequency locking ring closure situation, if switch connection makes vB=0, thus vCVery
It is low, reach that VCO output frequency is very low, the difference frequency after mixing is fallen on other than filter passband.
4th step designs initializing circuit, reaches target as defined in third step, carry out test verification with this condition: when
When switch is gone off by connection, vBLocating the transient occurred can terminate within the appropriate short time, guarantee frequency locking ring energy
Enough rapidly enter lock state.
Claims (8)
1. a kind of frequency-locked loop (FLL) with frequency displacement or abbreviation frequency locking ring are a control system or circuit, it is characterised in that
Output signal frequency can follow frequency input signal, and the difference of keep frequency is constant；
Described frequency locking ring is by frequency mixer, frequency-voltage amplitude transform component, wave detector, adjustment amplifier and voltage controlled oscillator group
At；
Described frequency mixer receives input reference signal and carrys out the local signal realization mixing of voltage controlled oscillator；
Described frequency-voltage amplitude transform component is typically a low-pass filter, intermediate zone characteristic working frequency-voltage
The difference frequency signal of amplitude conversion characteristics, frequency mixer output will be fallen into described intermediate zone；
The difference frequency signal detection that frequency-voltage transformation component exports is become DC voltage by described wave detector；
Described adjustment amplifier is used to that the direct current that wave detector exports is amplified and adjusted, and the input circuit of amplifier includes
To the setting circuit of voltage controlled oscillator initial oscillation；
Described voltage controlled oscillator generates output signal, and frequency of oscillation receives the control of adjustment amplifier output voltage；
Feedback effect can occur when frequency locking ring closure, so that loop state converges to a fixed point, only in this fixed point,
The output generated by voltage controlled oscillator output frequency-frequency mixer-voltage to frequency amplitude transform component-wave detector-adjustment amplifier
Voltage is exactly equal to the input voltage of voltage controlled oscillator output frequency needs, i.e. realization Frequency Locking；In the state of Frequency Locking
On, the difference frequency of frequency mixer output must be in frequency-voltage amplitude converter intermediate zone.
2. belonging to the band frequency displacement frequency locking ring of claim 1, a kind of physical circuit is raising frequency formula frequency locking ring, it is characterised in that: described
Adjustment amplifier be a positive amplifier on the whole；In the convergent fixed point of frequency locking ring status, voltage controlled oscillator output frequency
Rate is higher than frequency locking ring and inputs frequency；When carrying out Initialize installation by adjusting amplifier input circuit, voltage controlled oscillator initialization
Frequency need to be higher than frequency locking ring and input frequency.
3. belonging to the band frequency displacement frequency locking ring of claim 1, a kind of physical circuit is frequency-reducing type frequency locking ring, is characterized in that: described
Adjusting amplifier is a differential amplifier；In the convergent fixed point of frequency locking ring status, voltage controlled oscillator output frequency is lower than lock
Frequency ring inputs frequency；When carrying out Initialize installation by adjusting amplifier input circuit, voltage controlled oscillator initial frequencies need low
Frequency is inputted in frequency locking ring.
4. belonging to the band frequency displacement frequency locking ring of claim 1, it is characterized in that, in the frequency locking that 1, the 2nd, the 3rd article of claim the is advocated
On the basis of ring constituent, increase following component and do not change the working mechanism of frequency locking ring, thus also belongs to scope of the claims:
Amplifier, attenuator, shunt circuit, switching circuit etc. are added before or after any part in basic frequency locking loop back path, when
When frequency locking ring circuit closed, the frequency locking mechanism of the output frequency tracking input frequency in the circuit is had not been changed；Typically, mixed
Increase before frequency device and receives signal low-noise amplifier；Increase intermediate frequency amplifier after frequency mixer, the bandwidth of the amplifier need to include
The intermediate zone of low-pass filter；Power splitter or coupler are set in voltage controlled oscillator output end, using most of power as frequency locking
The output of ring, and fraction power gives frequency mixer, to guarantee the work of frequency locking ring.
5. belong to a kind of band frequency displacement frequency locking ring of claim 1, a kind of direct application form is as frequency shifter, and feature exists
In: output of the voltage controlled oscillator output signal using power splitter or coupler by major part as frequency shifter in frequency locking ring, and
Fraction oscillator signal gives frequency mixer to guarantee the work of frequency locking ring.The size of the frequency shift amount of described frequency shifter mainly determines
In the frequency location of low-pass filter intermediate zone, and can by adjusting in frequency locking ring adjust amplifier gain to frequency shift amount
Carry out fine adjustment.
6. belong to a kind of band frequency displacement frequency locking ring of claim 1, a kind of application form is two-frequency signal generator, and feature exists
In: the frequency input signal of frequency locking ring is known as first frequency, is generated by a separate oscillators；Voltage controlled oscillator produces in frequency locking ring
Raw signal frequency is second frequency；Two frequency signals that two oscillators generate, major power can be respectively independent defeated
Out, fraction power is separated using power splitter or coupler to keep the working mechanism of frequency locking ring.
7. belong to a kind of band frequency displacement frequency locking ring of claim 1, a kind of application form is frequency locking receiver, is characterized in that: lock
The input signal of frequency ring is the reception signal sent via antenna, low-noise amplifier；In frequency locking ring after the output end of frequency mixer
A signal amplifier may be added, band is wider than subsequent frequencies-voltage amplitude transformation low-pass filter bandwidth；Frequency locking
The output signal of receiver can be derived from before or after low-pass filter；Frequency locking ring can be raising frequency formula or frequency-reducing type；If
Using raising frequency formula frequency locking ring, the initial frequencies of voltage controlled oscillator need to be higher than the frequency input signal for wishing to capture；If used
The initial frequencies of frequency-reducing type frequency locking ring, voltage controlled oscillator need to be lower than the frequency input signal for wishing to capture.
8. belonging to a kind of band frequency displacement frequency locking ring of claim 1, circuit is suitable for integrated special chip, feature in whole or in part
Be: whole frequency locking ring chip is described by claim the 1 to the 7th article complete at being grouped as, and has specified specificity；And
General frequency locking ring chip only includes a part being fully composed in ingredient, for example, only comprising low-pass filter, wave detector and
Adjust amplifier；Described low-pass filter can be designed to fixed-bandwidth or the settable two kinds of forms of bandwidth；Described adjustment amplification
Device and its attached initializing circuit can be designed to be suitble to raising frequency formula or frequency-reducing type frequency locking ring or both of which optional.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711135033.7A CN109802673A (en) | 2017-11-16 | 2017-11-16 | A kind of frequency-locked loop with frequency displacement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711135033.7A CN109802673A (en) | 2017-11-16 | 2017-11-16 | A kind of frequency-locked loop with frequency displacement |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109802673A true CN109802673A (en) | 2019-05-24 |
Family
ID=66555341
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711135033.7A Withdrawn CN109802673A (en) | 2017-11-16 | 2017-11-16 | A kind of frequency-locked loop with frequency displacement |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109802673A (en) |
-
2017
- 2017-11-16 CN CN201711135033.7A patent/CN109802673A/en not_active Withdrawn
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Wu et al. | A 56.4-to-63.4 GHz multi-rate all-digital fractional-N PLL for FMCW radar applications in 65 nm CMOS | |
| Jia et al. | A 77 GHz frequency doubling two-path phased-array FMCW transceiver for automotive radar | |
| US9660655B2 (en) | Ultra low phase noise frequency synthesizer | |
| US4205272A (en) | Phase-locked loop circuit for use in synthesizer tuner and synthesizer tuner incorporating same | |
| EP3280061B1 (en) | Method and system for high resolution tuning of the phase for active load modulation in a nfc system | |
| US9893716B2 (en) | Resonant circuit calibration | |
| CN105790730B (en) | A kind of automatic frequency control apparatus | |
| JPS6013341B2 (en) | Frequency stabilized single oscillator transceiver | |
| CN109150109A (en) | Radio signal processing apparatus, semiconductor device and frequency of oscillation change correction method | |
| Akhmetov et al. | 2.4-2.5 GHz fractional-n frequency synthesizer with integrated VCO in 0.18 um CMOS for RFID Systems | |
| Hao et al. | A CMOS phase noise filter with passive delay line and PD/CP-based frequency discriminator | |
| CN106533437A (en) | Broadband and small-step frequency source circuit | |
| CN101567689B (en) | Phase-locked loop based on equivalent phase demodulation frequency | |
| CN109728808B (en) | Method for reducing injection pulling effect and related signal system | |
| CN109802673A (en) | A kind of frequency-locked loop with frequency displacement | |
| WO2020024570A1 (en) | Phase adjustment device and system for extracting terahertz signals | |
| Mann et al. | A high-sensitivity radar system featuring low weight and power consumption | |
| KR102477864B1 (en) | A frequency hopping spread spectrum frequency synthesizer | |
| CN110995259B (en) | Frequency synthesizer for handheld ultrashort wave frequency hopping radio station | |
| Choi et al. | Improved Tx-to-Rx isolation of radar transceivers using integrated full duplexer with PLL | |
| CN108169697B (en) | High-stability frequency automatic controller based on RF-SQUID application | |
| CN103490770B (en) | A kind of fast lockign apparatus based on C-band continuous wave answering machine | |
| CN100459433C (en) | Digital logic phase-locked loop realizing apparatus | |
| WO1991007016A1 (en) | A phase locked loop for producing a reference carrier for a coherent detector | |
| CN204481795U (en) | A kind of Low phase noise Microwave Frequency Source phase lock circuitry and equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| WW01 | Invention patent application withdrawn after publication | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20190524 |
|
| DD01 | Delivery of document by public notice | ||
| DD01 | Delivery of document by public notice |
Addressee: BEIJING HUATONG MICROWAVE TECHNOLOGY Co.,Ltd. Document name: Notification of Passing Examination on Formalities |