CN109450445A - A kind of variable loop bandwidth frequency synthesizer, system and method - Google Patents
A kind of variable loop bandwidth frequency synthesizer, system and method Download PDFInfo
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- H—ELECTRICITY
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- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/16—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop
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Abstract
The present invention discloses a kind of variable loop bandwidth frequency synthesizer, system and method, the device includes VCO signal selecting unit, VCO signal is coupled into two paths of signals, signal is sent into fundamental signal frequency unit and fundamental signal multiplier unit as fundamental signal all the way, and another way signal feedback after VCO signal frequency unit frequency dividing arrives the coupler of phase discriminator；Phase discriminator, receives input reference signal and VCO signal carries out phase demodulation after VCO signal frequency unit frequency dividing, generates two signals with identical frequency, the phase of two same frequency signals is compared, according to phase difference Linear Control charge pump output current；By the fundamental signal frequency unit of the fundamental signal frequency dividing of coupler output；By the fundamental signal multiplier unit of the fundamental signal frequency multiplication of coupler output；Programmable attenuator.The present invention can generate the frequency sweep local vibration source of high stable, and the synthesizer integrated level is high, and stability is strong, and debugging is convenient.
Description
Technical field
This disclosure relates to a kind of apparatus for frequency synthesizing, and in particular to a kind of variable loop wide frequency of broadband low phase noise
Rate synthesizer, system and method.
Background technique
Modular instrument is developed rapidly towards the direction of small size high target, due to its small size, the advantages that low-power consumption, and mould
Block instrument using more and more extensive, people propose increasingly higher demands to the performance indicator of modular instrument, and determine
A key technology of modular instrument performance indicator be exactly to minimize the design of frequency synthesizer circuit, therefore people are designing
The volume of upper continuous compression frequency combiner circuit, improves the performance of frequency synthesizer circuit, thus frequency synthesizer have frequency range it is wide,
The features such as high and low phase of frequency is made an uproar.
Frequency synthesis technique is varied at present, but it is a phase-locked loop circuit that it is constituted all substantially, and phase-locked loop circuit is
The automatic control system of one phase negative-feedback can track phase, realize that output signal is synchronous with input signal.It is existing
The shortcomings that core of frequency synthesis technique is Mixing PLL circuit, the circuit includes following 3 aspects:
(1) circuit is made of multiple phaselocked loops and switching circuit, including reference signal frequency multiplier circuit, reference signal locking phase
Loop, broadband signal locking phase major loop and filter amplification circuit, complex circuit designs power consumptions is high, and circuit volume it is big need compared with
Large scale PCB realizes that debugging work load increases therewith.
(2) circuit is made of multiple phase-locked loop circuits, and the larger signal of the different direct power of loop is easy to be crosstalked into it
In his circuit, so needing to paste various absorbing materials when debugging and covering shielding box, there is debugging index difficulty, debugging process needs
Repeated disassembled and assembled shielding box is wanted, debugging efficiency is reduced, increases cost of labor.
(3) loop bandwidth of the phaselocked loop of the circuit is fixed, and the keys such as frequency jitter, phase noise and locking time refer to
It marks changeless, relationship between phase noise and locking time can not be optimized, application scenarios are limited.
In conclusion how to design a kind of high performance monocycle frequency sweep local vibration source, spelled by optimization circuit, multiband VCO
Connect, the methods of variable loop bandwidth realizes a small size, wide-band, high-frequency, the apparatus for frequency synthesizing of Low phase noise, be still to
The technical solution of solution.
Summary of the invention
In order to overcome the above-mentioned deficiencies of the prior art, present disclose provides a kind of variable loop bands of broadband low phase noise
Broadband synthesizer, system and frequency combining method, using monocycle locking phase, integrated level is high, and stability is strong, and debugging is convenient, accounts for
It is small with area.
Technical solution used by the disclosure is:
A kind of variable loop bandwidth frequency synthesizer of broadband low phase noise, the device include:
Select the VCO signal selecting unit of VCO signal corresponding with output signal frequency value；
The VCO signal that VCO signal selecting unit exports is coupled into two paths of signals, signal is sent into as fundamental signal all the way
Fundamental signal frequency unit and fundamental signal multiplier unit, another way signal feedback after VCO signal frequency unit frequency dividing arrive mirror
The coupler of phase device；
Phase discriminator, receives input reference signal and VCO signal carries out phase demodulation after VCO signal frequency unit frequency dividing, generates
Two signals with identical frequency, the phase of two same frequency signals are compared, according to phase difference Linear Control charge
Pump output electric current；
The fundamental signal that coupler exports is divided into the fundamental signal for the signal that frequency range is 62.5MHz~250MHz
Frequency unit；
By the fundamental signal frequency multiplication of coupler output at frequency range up to the fundamental signal multiplier unit of 12GHz；With,
Programmable attenuator, the power of the signal for adjusting fundamental signal frequency unit or the output of fundamental signal multiplier unit
Level.
Further, the VCO signal selecting unit include switching circuit I, switching circuit II and be connected to switch electricity
Three voltage controlled oscillators in parallel between road I, switching circuit II control three pressures by switching circuit I and switching circuit II
The tuning voltage of oscillator is controlled, and selects VCO signal corresponding with output signal frequency value to carry out frequency synthesis.
Further, the VCO signal frequency unit includes sequentially connected amplifier I, switching circuit III, switching circuit
IV and frequency divider II, frequency divider I, the coupled signal of coupler output are also connected between switching circuit III and switching circuit IV
After amplifier I amplifies, through path and pre- frequency dividing access are selected by switching circuit III and switching circuit IV, when
When selecting through path, amplified signal carries out phase demodulation after II fractional frequency division of frequency divider, into phase discriminator；When selection is pre-
When dividing access, amplified signal successively by frequency divider I in advance frequency dividing, after II fractional frequency division of frequency divider, into phase discriminator into
Row phase demodulation.
It further, further include programmable loop bandwidth filter, the input terminal of the programmable loop bandwidth filter
It is connect with phase discriminator, output end is connect with VCO signal selecting unit, and the charge pump current that phase discriminator generates is by programmable loop
Bandwidth filter is converted to tuning voltage and is sent into VCO signal selecting unit.
Further, the fundamental signal multiplier unit includes sequentially connected switching circuit V, amplifier II, frequency multiplier
1, bandpass filter and switching circuit VIII enter the fundamental signal of frequency multiplication chain by switching circuit V, successively pass through amplifier
After II amplification, 1 frequency multiplication of frequency multiplier and band-pass filter, exported by switching circuit VIII.
Further, the fundamental signal frequency unit includes sequentially connected switching circuit V, amplifier III, may be programmed
Frequency divider, switching circuit VI, switching circuit VII and switching circuit VIII are connected with three between switching circuit VII and switching circuit VIII
A low-pass filter being connected in parallel a, wherein low-pass filter is in series with frequency divider III；
Enter the fundamental signal of frequency-shared channel by switching circuit V, successively by the amplification of amplifier III, frequency programmable dividing
After device frequency dividing, 3 filter channels and through path are selected by switching circuit VI and switching circuit VII；When selection put-through channel
When, the fractional frequency signal that programmable frequency divider generates directly passes through switching circuit VIII and exports；It, can when selecting first filter channel
The fractional frequency signal that programming frequency division device generates successively after the frequency dividing of frequency divider III, low-pass filter filtering, passes through switching circuit VIII
Output；When selecting second filter channel or third filter channel, the fractional frequency signal that programmable frequency divider generates is through too low
After bandpass filter filtering, exported by switching circuit VIII.
A kind of frequency synthesis of the variable loop bandwidth frequency synthesizer based on broadband low phase noise as described above
Method, method includes the following steps:
The VCO signal corresponding with output signal frequency value that coupler selects VCO signal selecting unit is divided into two-way letter
Number, main path signal is sent into fundamental signal frequency unit and fundamental signal multiplier unit, another way coupling as fundamental signal all the way
Signal is successively divided, II fractional frequency division of frequency divider in advance by frequency divider I, is reflected into phase discriminator after the amplification of amplifier I
Phase；
The charge pump current that phase discriminator generates is converted to tuning voltage by programmable loop bandwidth filter and is sent into VCO letter
Number selecting unit locks the fundamental signal of 2~6GHz；
The fundamental signal of 2~6GHz is opened up frequency range by fundamental signal multiplier unit and fundamental signal frequency unit
Open up 62.5MHz~12GHz.
A kind of variable loop bandwidth frequency synthesis system of broadband low phase noise, the system include as described above variable
Loop bandwidth apparatus for frequency synthesizing, control unit and power supply unit；
Described control unit is configured as control variable loop bandwidth frequency synthesizer, according to the frequency values meter of setting
Calculate the frequency dividing ratio of the output signal frequency value needed, frequency dividing ratio and input reference signal；
The power supply unit, the electricity being configured as needed for being provided to variable loop bandwidth frequency synthesizer and control unit
Source.
Compared with prior art, the beneficial effect of the disclosure is:
(1) disclosure is effectively improved by improving phase demodulation frequency and selecting the phase discriminator mode of low phase noise, low spurious
Signal mutually make an uproar than with it is spuious；Using monocycle locking phase, integrated level is high, and stability is strong, and debugging is convenient, and it is small to occupy PCB surface product；
(2) VCO that the disclosure has selected three frequencies that can be connected by four selects a switch to select different VCO and join
Add frequency synthesis, then pass through the frequency programmable dividing and frequency multiplier circuit of rear class, greatly widens the output local oscillator letter of frequency synthesis
Number range, frequency range can reach 62.5MHz-12GHz；
(3) phase discriminator of the disclosure uses 24 decimal modulators, can generate sufficiently small stepping-in amount, minimum frequency
Stepping is less than 1Hz；
(4) the programmable loop bandwidth filter of the disclosure is made of operational amplifier combination Low ESR multiplexer
Feedback network composition forms 8 grades of highest different loop bandwidth filters, adjusts different usage scenario lower frequency locking times and phase
Position noise objective.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is the structure chart of the existing conventional phase locked loops based on VCO；
Fig. 2 is the structure chart of the existing Mixing PLL based on VCO；
Fig. 3 is the structure chart of the variable loop bandwidth frequency synthesizer of the disclosure；
Fig. 4 is the structure chart of the variable loop bandwidth frequency synthesis system of the disclosure.
Specific embodiment
The invention will be further described with embodiment with reference to the accompanying drawing.
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
It is a phase-locked loop circuit that existing frequency synthesis technique is constituted all substantially.As shown in Figure 1, existing be based on VCO
Conventional phase locked loops be made of frequency divider, phase discriminator, loop filter, four part of voltage controlled oscillator.Its basic functional principle is:
Voltage controlled oscillator (VCO) function is divided into two-way, exports all the way as signal, is used as feedback signal all the way, the feedback signal is through excessive
Phase discriminator (PD) is exported after frequency device frequency dividing, by comparing between input reference signal and voltage controlled oscillator (VCO) output signal
Phase difference, generates the error voltage u (t) for being proportional to signal phase difference, which filters by loop filter (LPF)
The tuning tip that VCO is added to after wave (may also include amplification) believes input so as to adjust the frequency and phase of voltage controlled oscillator
Number reduction is differed between VCO signal, finally reaches dynamic and lock.
As shown in Fig. 2, broadband frequency signals in order to reduce the phase noise of output signal, cannot there is too high frequency dividing ratio,
So the existing Mixing PLL based on VCO be mixed with high frequency reference signal using the feedback signal of VCO generates intermediate frequency
Signal, the intermediate-freuqncy signal are sent by low-pass filtering and power amplification to phase discriminator, carry out phase demodulation with the reference signal after frequency dividing,
Again into loop filtering is crossed, finally send to VCO and lock.The reference signal of input mixer can be the high-purity letter of very little stepping-in amount
Number, the frequency range of output signal had not only been widened in this way, but also improve the precision of signal, reference signal is also required to introduce a locking phase
Ring is locked.
That there are complex circuit designs power consumptions is high for both the above circuit, and circuit volume is big that larger size PCB is needed to realize,
Debugging work load increases therewith, and debugging process needs repeated disassembled and assembled shielding box, reduces debugging efficiency, increases cost of labor, due to
The loop bandwidth of phaselocked loop is fixed, and relationship between phase noise and locking time can not be optimized, and application scenarios are limited.
In order to solve the above technical problems, the disclosure provides a kind of variable loop bandwidth frequency of broadband low phase noise
Synthesizer, system and method can generate the frequency sweep local vibration source of high stable, and the synthesizer integrated level is high, and stability is strong, adjust
Examination is convenient.
The present embodiment provides a kind of variable loop bandwidth frequency synthesizers of broadband low phase noise, as shown in figure 3, institute
Stating variable loop bandwidth frequency synthesizer includes phase discriminator 2, VCO signal selecting unit, coupler 9, VCO signal frequency dividing list
Member, fundamental signal frequency unit, fundamental signal multiplier unit and programmable attenuator 29.
Specifically, the input terminal of the phase discriminator 2 receives input reference signal 1, and the feedback end of the phase discriminator connects VCO
The output end of the output end of signal frequency split unit, the phase discriminator 2 connects charge pump；The phase discriminator 2 receives input with reference to letter
Number 1 and the VCO signal after VCO signal frequency unit frequency dividing, two signals with identical frequency are generated, and same to two
Frequency signal carries out phase bit comparison, according to phase difference Linear Control charge pump output current.
In the present embodiment, the input reference signal 1 is 120MHz reference clock, can be inputted by external clock,
It can be generated by internal circuit, the characteristics of clock signal is that phase noise is low, spuious few, provides purity high-frequency for phaselocked loop
Stable reference clock.
The input terminal of the programmable loop bandwidth filter 3 is connect with phase discriminator, and output end is connect with switching circuit I 4,
The charge pump current that phase discriminator 2 generates is converted to tuning voltage by programmable loop bandwidth filter and is sent into VCO signal selection
Unit.
In the present embodiment, the programmable loop bandwidth filter 3 is multiplexed by operational amplifier combination Low ESR
The feedback network composition of device composition forms 8 grades of highest different loop bandwidth filters, adjusts different usage scenario lower frequency lockings
Time and phase noise specifications are ultimately converted to tuning voltage and are sent into VCO signal selecting unit.
The VCO signal selecting unit is configured as selecting different VCO signals to participate according to output signal frequency value
Frequency synthesis achievees the purpose that widen frequency range.
In the present embodiment, the VCO signal selecting unit includes switching circuit I 4, voltage controlled oscillator VCO I 5, voltage-controlled vibration
Device VCO II 6, voltage controlled oscillator VCO III 7 and switching circuit II 8 are swung, is connected between switching circuit I 4 and switching circuit II 8
Three voltage controlled oscillators being connected in parallel control the tuning of three voltage controlled oscillators by switching circuit I 4 and switching circuit II 8
Voltage selects VCO signal corresponding with output signal frequency value to carry out frequency synthesis.
In the present embodiment, switching circuit I 4 and switching circuit II 8 are used to select different VCO signals to carry out locking phase,
It is to realize selection function by the tuning voltage of three VCO voltage controlled oscillators of control, and the isolation of switching circuit wants sufficiently high,
Guarantee the pure of output signal；VCO I 5, VCO II 6, the output frequency of III 73 voltage controlled oscillators of VCO are different, and the two combines
Coverage area together can achieve 2~6GHz, select different VCO signals by switching circuit I 4 and switching circuit II 8
Frequency synthesis is participated in, achievees the purpose that widen frequency range.
The input terminal of the coupler 9 is connect with the output end of VCO signal selecting unit, receives VCO signal selecting unit
The VCO signal of output, couples VCO signal by the way of microstrip lines, exports two paths of signals, and main signal is made all the way
The fundamental signal frequency unit and fundamental signal multiplier unit of rear end are sent into for fundamental signal, VCO signal after in addition coupling all the way
Feedback is used for locking phase to phase discriminator after VCO signal frequency unit frequency dividing.
The VCO signal frequency unit is configured as dividing VCO signal after coupling, by the VCO signal after frequency dividing
It is sent into phase discriminator.
In the present embodiment, the VCO signal frequency unit include amplifier I 10, switching circuit III 11, frequency divider I 12,
Switching circuit IV 13 and frequency divider II 14, the amplifier I 10, switching circuit III 11, switching circuit IV 13 and frequency divider II 14
It is sequentially connected in series, frequency divider I 12 is connected between switching circuit III 11 and switching circuit IV 13, the amplifier 10 is used for
By VCO signal power amplification after coupling to power level needed for phase discriminator, the switching circuit III 11 and switching circuit IV 13
It is direct through the amplified VCO signal of amplifier when selecting through path for selecting through path and except 2 pre- frequency dividing accesses
It is sent into frequency divider 14；When selection is except 2 pre- frequency dividing access, divided in advance through the amplified VCO signal of amplifier by frequency divider I 12
It is sent into frequency divider II 14 afterwards；The frequency divider II 14 has 24 decimal modulators, for carrying out decimal to the VCO signal of input
Frequency dividing, generating frequency error is 0 and the spuious extremely low fractional frequency feeding phase discriminator in channel.
The fundamental signal multiplier unit is configured as carrying out frequency multiplication to the fundamental signal of input.
In the present embodiment, the fundamental signal multiplier unit includes sequentially connected switching circuit V 15, amplifier II
16, frequency multiplier 17, bandpass filter 18 and switching circuit VIII 27, the switching circuit 15 and switching circuit 27 are for selecting frequency multiplication
Channel and frequency-shared channel export the signal synthesis after frequency multiplication and frequency dividing all the way；The amplifier II 16 is used for 2~6GHz base
The power of wave signal amplifies, the power loss of compensation rear end filtering and switching network；The frequency multiplier 17 will be for that will pass through
Amplified 2~6GHz the fundamental signal of amplifier II 16 carries out 2 frequencys multiplication, by frequency expansion to 12GHz frequency-doubled signal；The band logical
Filter 18 improves signal quality for filtering out the harmonic wave and subharmonic of frequency-doubled signal.
The fundamental signal frequency unit is configured as dividing the fundamental signal of input.
In the present embodiment, the fundamental signal frequency unit includes sequentially connected switching circuit V 15, amplifier III
19, programmable frequency divider 20, switching circuit VI 21, switching circuit VII 26 and switching circuit VIII 27, VII 26 He of switching circuit
Low-pass filter I 23, low-pass filter II 24 and the low-pass filter being connected in parallel there are three being connected between switching circuit VIII 27
III 25, the low-pass filter I 23 is in series with frequency divider III 22；The switching circuit 15 and switching circuit 27 are for selecting frequency multiplication
Channel and frequency-shared channel export the signal synthesis after frequency multiplication and frequency dividing all the way；The amplifier III 19 is used for 2~6GHz base
The power of wave signal amplifies, the power loss of compensation rear end filtering and switching network；The programmable frequency divider 20 is used for
2 frequency dividings, 4 frequency dividings and 8 frequency dividings are carried out to 2~6GHz fundamental signal, the fractional frequency signal of 250MHz~2GHz is generated, expands frequency and close
At the lower-frequency limit of device；The switching circuit VI 21 and switching circuit VII 26 are for selecting 3 filter channels and leading directly to logical
The fractional frequency signal that programmable frequency divider generates is sent directly into switching circuit VIII 27 when selecting put-through channel by road, when selection is filtered
When wave device channel, the frequency of fractional frequency signal is subjected to region filtering, passes through low-pass filter I 23, low-pass filter II 24 and low
Bandpass filter III 25 filters out the signal harmonic after frequency dividing, improves signal quality；The frequency divider III 22, for by 250MHz~
The fractional frequency signal of 1GHz carries out 4 frequency dividings, generates the signal of 62.5MHz~250MHz, further expands the frequency of apparatus for frequency synthesizing
Rate lower limit.
The programmable attenuator 29 is connect by amplifier IV 28 with the output end of switching circuit VIII 27, and amplifier 28 is passed through
The power level for the signal that switching circuit VIII 27 exports is amplified, the output power electricity of apparatus for frequency synthesizing is further increased
It is flat；The programmable attenuator 29 is used to adjust the power level by the amplified signal of amplifier 28, and then adjusts frequency and close
At device output power levels.
The course of work for the variable loop bandwidth frequency synthesizer that the present embodiment proposes are as follows:
VCO signal corresponding with output signal frequency value is selected to participate in frequency synthesis by VCO signal selecting unit,
The VCO signal of VCO signal selecting unit output is divided into two-way after coupler 9, after main path signal is sent into as fundamental signal
End group wave signal frequency split unit and fundamental signal multiplier unit, coupled signal are amplified by amplifier I 10, are then successively passed through
Frequency divider I 12 frequency dividing, II 14 fractional frequency division of frequency divider in advance are crossed, carries out phase demodulation into phase discriminator 2, the charge pump electricity that phase discriminator generates
Stream simulates 8 grades of different loop bandwidth filters by programmable loop bandwidth filter, adjusts different usage scenario lower frequency locks
It fixes time and phase noise specifications, is ultimately converted to tuning voltage and is sent into VCO signal selecting unit, lock the base of required frequency
Wave signal；The fundamental signal of 2~6GHz of locking is by fundamental signal multiplier unit and fundamental signal frequency unit, by frequency model
It encloses and is extended to 62.5MHz~12GHz, every section of frequency multiplication and fractional frequency signal are amplified by switching network, filtered and decayed, and are inhibited
Harmonic wave and subharmonic improve signal quality, and output frequency signal power controllable.
Variable loop bandwidth frequency synthesizer provided in this embodiment, by improving phase demodulation frequency and low phase being selected to make an uproar
The phase discriminator mode of sound, low spurious, effectively increase signal mutually make an uproar than with spuious index；The device has selected three frequencies can
The voltage controlled oscillator of linking selects a switch by four to select different VCO and participate in frequency synthesis, then compiling by rear class
Journey frequency dividing and frequency multiplier circuit, have greatly widened the range of the output local oscillation signal of frequency synthesis, and frequency range can reach
62.5MHz---12GHz；Phase discriminator uses 24 decimal modulators, can generate sufficiently small stepping-in amount, minimum frequency step
Into less than 1Hz.In addition, the apparatus for frequency synthesizing has the function of frequency modulation(PFM), phase-modulation and signal scanning etc..
In the present embodiment, entire apparatus for frequency synthesizing is realized by the multiplayer microwave PCB circuit board of 1 piece of 45mm × 120mm,
Circuit structure is compact, and design method is novel, and performance indicator is excellent, has extensively etc. excellent convenient for debugging, at low cost, application scenarios
Point.Since the signal frequency in circuit is up to 12GHz, for signal transmission attenuation, whole circuit board uses microwave printed board
Material, and associative simulation design has been carried out to printed board plate parameter, lamination and component, coupler and filter are carried out
Optimization design, realizes out the circuit of entire microwave portions on pcb board.Since apparatus for frequency synthesizing integrated level is high, structure is tight
It gathers, in order to prevent the crosstalk between signal, is separated between each functional unit using earth shield item, and cover shielding box reality
Show the sealing of total, be not only effectively isolated the space radiation of electromagnetic signal, but also facilitates the nearest abundant of radiofrequency signal
Ground connection, avoids microwave signal interfering with each other inside shielding box.Whole plate is using miniaturization, low-power consumption component, Suo Youqi
Part height is no more than 2mm, greatly has compressed device volume.
The present embodiment also provides a kind of variable loop bandwidth frequency synthesis system of broadband low phase noise, as shown in figure 4,
Including variable loop bandwidth frequency synthesizer, control unit and power module as described above.
Described control unit is configured as control variable loop bandwidth frequency synthesizer, according to the frequency values meter of setting
Calculate the frequency dividing ratio of the output signal frequency value needed, frequency dividing ratio and input reference signal 1.
The power module, for the power supply needed for being provided to variable loop bandwidth frequency synthesizer and control unit.
The workflow of the variable loop bandwidth frequency synthesis system for the broadband low phase noise that the present embodiment proposes are as follows:
Power on first, control unit 30 calculates the output signal frequency value of needs according to the frequency values of setting and divides
The frequency dividing ratio of frequency ratio and reference signal 1, etc. 1 frequency stabilization of reference signals and then selected by output signal frequency value corresponding
VCO participate in frequency synthesis, and set switch selection respective channels, start the frequency of variable loop bandwidth frequency synthesizer
Rate synthetic work.
VCO signal corresponding with output signal frequency value is selected to participate in frequency synthesis by VCO signal selecting unit,
The VCO signal of VCO signal selecting unit output is divided into two-way after coupler 9, after main path signal is sent into as fundamental signal
End group wave signal frequency split unit and fundamental signal multiplier unit, coupled signal are amplified by amplifier I 10, are then successively passed through
Frequency divider I 12 frequency dividing, II 14 fractional frequency division of frequency divider in advance are crossed, carries out phase demodulation into phase discriminator 2, the charge pump electricity that phase discriminator generates
Stream simulates 8 grades of different loop bandwidth filters by programmable loop bandwidth filter, adjusts different usage scenario lower frequency locks
It fixes time and phase noise specifications, is ultimately converted to tuning voltage and is sent into VCO signal selecting unit, lock the base of required frequency
Wave signal；The fundamental signal of 2~6GHz of locking is by fundamental signal multiplier unit and fundamental signal frequency unit, by frequency model
It encloses and is extended to 62.5MHz~12GHz, every section of frequency multiplication and fractional frequency signal are amplified by switching network, filtered and decayed, and are inhibited
Harmonic wave and subharmonic improve signal quality, and output frequency signal power controllable.
It can be seen from the above description that the application the above embodiments realize following technical effect:
(1) disclosure is effectively improved by improving phase demodulation frequency and selecting the phase discriminator mode of low phase noise, low spurious
Signal mutually make an uproar than with it is spuious；Using monocycle locking phase, integrated level is high, and stability is strong, and debugging is convenient, and it is small to occupy PCB surface product；
(2) VCO that the disclosure has selected three frequencies that can be connected by four selects a switch to select different VCO and join
Add frequency synthesis, then pass through the frequency programmable dividing and frequency multiplier circuit of rear class, greatly widens the output local oscillator letter of frequency synthesis
Number range, frequency range can reach 62.5MHz---12GHz；
(3) phase discriminator of the disclosure uses 24 decimal modulators, can generate sufficiently small stepping-in amount, minimum frequency
Stepping is less than 1Hz.
(4) the programmable loop bandwidth filter of the disclosure is made of operational amplifier combination Low ESR multiplexer
Feedback network composition forms 8 grades of highest different loop bandwidth filters, adjusts different usage scenario lower frequency locking times and phase
Position noise objective.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (10)
1. a kind of variable loop bandwidth frequency synthesizer of broadband low phase noise, characterized in that include:
Select the VCO signal selecting unit of VCO signal corresponding with output signal frequency value；
The VCO signal that VCO signal selecting unit exports is coupled into two paths of signals, signal is sent into fundamental wave as fundamental signal all the way
Signal frequency split unit and fundamental signal multiplier unit, another way signal feedback after VCO signal frequency unit frequency dividing arrive phase discriminator
Coupler；
Phase discriminator, receives input reference signal and VCO signal carries out phase demodulation after VCO signal frequency unit frequency dividing, generates two
The phase of two same frequency signals is compared by the signal with identical frequency, defeated according to phase difference Linear Control charge pump
Electric current out；
The fundamental signal that coupler exports is divided into the fundamental signal frequency dividing for the signal that frequency range is 62.5MHz~250MHz
Unit；
By the fundamental signal frequency multiplication of coupler output at frequency range up to the fundamental signal multiplier unit of 12GHz；With,
Programmable attenuator, the power electricity of the signal for adjusting fundamental signal frequency unit or the output of fundamental signal multiplier unit
It is flat.
2. the variable loop bandwidth frequency synthesizer of broadband low phase noise according to claim 1, characterized in that institute
VCO signal selecting unit is stated to include switching circuit I, switching circuit II and be connected between switching circuit I, switching circuit II
Three voltage controlled oscillators in parallel control the tuning voltage of three voltage controlled oscillators by switching circuit I and switching circuit II, and
VCO signal corresponding with output signal frequency value is selected to carry out frequency synthesis.
3. the variable loop bandwidth frequency synthesizer of broadband low phase noise according to claim 1, characterized in that institute
Stating VCO signal frequency unit includes sequentially connected amplifier I, switching circuit III, switching circuit IV and frequency divider II, is being switched
Frequency divider I is also connected between circuit III and switching circuit IV, the coupled signal of coupler output is amplified by amplifier I
Afterwards, through path and pre- frequency dividing access, when selecting through path, amplification are selected by switching circuit III and switching circuit IV
Signal afterwards carries out phase demodulation after II fractional frequency division of frequency divider, into phase discriminator；It is amplified when the pre- frequency dividing access of selection
Signal successively after frequency divider I in advance frequency dividing, II fractional frequency division of frequency divider, carries out phase demodulation into phase discriminator.
4. the variable loop bandwidth frequency synthesizer of broadband low phase noise according to claim 1, characterized in that also
Including may be programmed loop bandwidth filter, the input terminal of the programmable loop bandwidth filter is connect with phase discriminator, output end
It is connect with VCO signal selecting unit, the charge pump current that phase discriminator generates is converted to tune by programmable loop bandwidth filter
Humorous voltage is sent into VCO signal selecting unit.
5. the variable loop bandwidth frequency synthesizer of broadband low phase noise according to claim 1, characterized in that institute
Stating fundamental signal multiplier unit includes sequentially connected switching circuit V, amplifier II, frequency multiplier 1, bandpass filter and switch
Circuit VIII enters the fundamental signal of frequency multiplication chain by switching circuit V, successively by the amplification of amplifier II, 1 frequency multiplication of frequency multiplier
After band-pass filter, exported by switching circuit VIII.
6. the variable loop bandwidth frequency synthesizer of broadband low phase noise according to claim 1, characterized in that institute
State fundamental signal frequency unit include sequentially connected switching circuit V, amplifier III, programmable frequency divider, switching circuit VI,
Switching circuit VII and switching circuit VIII, there are three the low pass filtereds being connected in parallel for connection between switching circuit VII and switching circuit VIII
Wave device a, wherein low-pass filter is in series with frequency divider III；
Enter the fundamental signal of frequency-shared channel by switching circuit V, successively by the amplification of amplifier III, programmable frequency divider point
After frequency, 3 filter channels and through path are selected by switching circuit VI and switching circuit VII；When selecting put-through channel,
The fractional frequency signal that programmable frequency divider generates directly passes through switching circuit VIII and exports；When selecting first filter channel, can compile
The fractional frequency signal that journey frequency divider generates successively is divided by frequency divider III, after low-pass filter filtering, defeated by switching circuit VIII
Out；When selecting second filter channel or third filter channel, the fractional frequency signal that programmable frequency divider generates passes through low pass
After filter filtering, exported by switching circuit VIII.
7. a kind of frequency combining method, the variable loop based on broadband low phase noise of any of claims 1-6
Bandwidth frequency synthesizer is realized, characterized in that the following steps are included:
The VCO signal corresponding with output signal frequency value that coupler selects VCO signal selecting unit is divided into two paths of signals, and one
Road main path signal is sent into fundamental signal frequency unit and fundamental signal multiplier unit, another way coupled signal warp as fundamental signal
It after crossing the amplification of amplifier I, is successively divided in advance by frequency divider I, II fractional frequency division of frequency divider, carries out phase demodulation into phase discriminator；
The charge pump current that phase discriminator generates is converted to tuning voltage by programmable loop bandwidth filter and is sent into VCO signal choosing
Unit is selected, the fundamental signal of 2~6GHz is locked；
Frequency range is extended to by the fundamental signal of 2~6GHz by fundamental signal multiplier unit and fundamental signal frequency unit
62.5MHz~12GHz.
8. according to the method described in claim 7, it is characterized in that, the fundamental signal of 2~6GHz passes through fundamental signal multiplier unit
Amplifier II amplification and frequency multiplier frequency multiplication after, by frequency expansion to 12GHz, after filtering out frequency multiplication by band-pass filter
The harmonic wave and subharmonic of signal.
9. according to the method described in claim 7, it is characterized in that, the fundamental signal of 2~6GHz passes through fundamental signal frequency unit
Amplifier III amplification, programmable frequency divider frequency dividing after, generate 250MHz~2GHz fractional frequency signal, pass through frequency divider III will
The fractional frequency signal of 250MHz~2GHz carries out 4 frequency dividings, generates the fractional frequency signal of 62.5MHz~250MHz, passes through low-pass filter
Filter out fractional frequency signal harmonic wave.
10. a kind of variable loop bandwidth frequency synthesis system of broadband low phase noise, characterized in that including claim 1-6
Any one of described in variable loop bandwidth frequency synthesizer, control unit and power supply unit；
Described control unit is configured as control variable loop bandwidth frequency synthesizer, is calculated according to the frequency values of setting
The frequency dividing ratio of the output signal frequency value, frequency dividing ratio and the input reference signal that need；
The power supply unit, the power supply being configured as needed for being provided to variable loop bandwidth frequency synthesizer and control unit.
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| CN111585548A (en) * | 2020-06-01 | 2020-08-25 | 合肥新港海岸科技有限公司 | Clock crosstalk elimination circuit and electronic equipment |
| CN111769830A (en) * | 2020-08-06 | 2020-10-13 | 成都凌德科技有限公司 | Broadband local oscillation circuit and local oscillation signal generating method |
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| CN112953389A (en) * | 2021-02-05 | 2021-06-11 | 成都中科四点零科技有限公司 | Pre-tuning circuit of array oscillator for broadband frequency synthesizer |
| CN113489487A (en) * | 2021-06-22 | 2021-10-08 | 中国电子科技集团公司第二十九研究所 | Integrated VCO (voltage controlled oscillator) type phase discriminator and in-loop mixing type phase-locked loop circuit |
| CN114978156A (en) * | 2022-06-28 | 2022-08-30 | 成都西科微波通讯有限公司 | Method for realizing fine stepping frequency |
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Application publication date: 20190308 |