CN109391264A - The calibration system and method for voltage controlled oscillator in phase-locked loop - Google Patents
The calibration system and method for voltage controlled oscillator in phase-locked loop Download PDFInfo
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- CN109391264A CN109391264A CN201710652082.1A CN201710652082A CN109391264A CN 109391264 A CN109391264 A CN 109391264A CN 201710652082 A CN201710652082 A CN 201710652082A CN 109391264 A CN109391264 A CN 109391264A
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- voltage
- controlled oscillator
- voltage controlled
- phase
- control signal
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- 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
- H03L7/08—Details of the phase-locked loop
- H03L7/099—Details of the phase-locked loop concerning mainly the controlled oscillator of the loop
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- 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
- H03L7/18—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop
Abstract
The invention discloses the calibration systems and method of voltage controlled oscillator in a kind of phase-locked loop.Wherein, the calibration system includes: the gain regulation unit being connected with voltage controlled oscillator input terminal, for before the phase stabilization that the phase-locked loop is tracked, indicating that the voltage controlled oscillator exports the voltage control signal of the first loop bandwidth；The calibration detection unit being connected with the voltage controlled oscillator, for acquiring the voltage in the voltage controlled oscillator, based on the comparison result to voltage collected and preset detection voltage window, the loop bandwidth of the voltage control signal is calibrated, when determining the phase stabilization that the voltage controlled oscillator is tracked, indicate that the voltage control signal is down to the second loop bandwidth by the first loop bandwidth by the gain regulation unit.
Description
Technical field
The present invention relates to electronic circuit technologies, calibration system more particularly to voltage controlled oscillator in a kind of phase-locked loop and
Method.
Background technique
It is more and more wider with communication system operating frequency range, and more and more the relevant technologies use low work
The phaselocked loop (PLL) and voltage controlled oscillator (VCO) of voltage.In order to adapt to the Phase Tracking of phaselocked loop, voltage controlled oscillator (VCO)
Tuning gain (Kvco) must just be increased accordingly.Many circuit designers use the frequency tuning sub-band of multiple overlappings
(small Kvco) carrys out coverage goal frequency range.
When it is this topology when covering wider frequency tuning range, can get the tuning gain (Kvco) of small VCO, but
This needs a kind of VCO calibration method to select the frequency tuning sub-band of coverage goal frequency range.It is spent by calibration
Time includes defining in the intrinsic locking time of phaselocked loop, or by system (especially with the system of frequency hop spread spectrum)
In the locking time of restriction, therefore a kind of quick calibration method is realized to reduce time overhead during tuning be particularly significant
's.
In order to shorten calibration the time it takes, the first the relevant technologies is, as shown in Figure 1, Vtune is switched to one
Predefined value, such as Vdd/2, to be breaking at the voltage controlled oscillator at Vtune, and using counter to frequency Fref and Fvco/N
It is counted.Then compare the count value of Fref and Fvco/N.According to comparison result, change is made to the capacitor array in VCO.
Although this method shortens the prover time after phase-locked loop is stablized, but the restriction by Fref and Ncal frequency divider.When
When Fref frequency values are lower, counter must add up enough count values to ensure certain calibration accuracy.This means that school
It needs more to calibrate number between meeting the deadline, while extending the distribution time calibrated every time.For Ncal frequency divider, when being
When system is using fractional frequency division, frequency synthesizer with sigma-delta modulator, frequency division value Ncal will be often sigma-delta
Modulator is changed.This leads to counter and obtains taking more time the average value of Ncal.
Second of the relevant technologies be, as shown in Fig. 2, using the open-loop calibration method of analog form, with to frequency Fref and
Fvco/N is compared.This method carries out clock division to Fref and Fvco/N to obtain 50% duty ratio first.Then it adopts
Fref/2 and Fvco/N/2 are found out with the converter (TVC) of a time to voltage in rise/fall along upper difference, and will
The rise/fall is input in charge pump along signal, and charge pump outputs have a charging capacitor, and charge value Vc can be obtained.
Finally, after making comparisons to Vref and Vc, can knowing Fref and Fvco/N the two frequencies, which is faster or slower, then
The capacitor array in VCO is controlled with logic circuit.This method needs to have two TVC output circuits and two in circuit output end
A bulky capacitor, this will occupy a sheet of area in integrated circuit；In addition, when system is using a fractional frequency division, band
When the frequency synthesizer of sigma-delta modulator, frequency division value N will be often sigma-delta modulator and be changed, and result in the complexity of system
And the average value of N is obtained taking more time.
Therefore, above-mentioned two scheme is all effectively shortening defective in prover time, needs to improve the relevant technologies.
Summary of the invention
The calibration system and method for voltage controlled oscillator in a kind of phase-locked loop of technology to be solved by this invention, to solve to press
Control the long defect of the prover time of oscillator.
To solve the above problems, the present invention provides a kind of calibration systems of voltage controlled oscillator in phase-locked loop, comprising:
The gain regulation unit being connected with voltage controlled oscillator input terminal, for before the phase stabilization that the phase-locked loop is tracked,
Indicate that the voltage controlled oscillator exports the voltage control signal of the first loop bandwidth；The calibration detection being connected with the voltage controlled oscillator is single
Member, for acquiring the voltage in the voltage controlled oscillator, based on to voltage collected compared with preset detection voltage window
As a result, being calibrated to the loop bandwidth of the voltage control signal, when determining the phase stabilization that the phase-locked loop is tracked, refer to
Show that the voltage control signal is down to the second loop bandwidth by the first loop bandwidth by the gain regulation unit.
Preferably, the gain regulation unit includes: charge pump regulation module and/or low-pass filtering regulation module；
Wherein, charge pump regulation module is connected with the voltage controlled oscillator input terminal, for by adjusting the voltage-controlled vibration
The mode for swinging the input current of device, the loop bandwidth for adjusting the voltage control signal that the voltage controlled oscillator is exported is the first loop band
Wide or the second loop bandwidth；And
Low-pass filtering regulation module is connected with the voltage controlled oscillator input terminal, for by adjusting in the phase-locked loop
The mode of the load resistor value of low-pass filter, the loop bandwidth for adjusting the voltage control signal that the voltage controlled oscillator is exported is the
One loop bandwidth or the second loop bandwidth.
Preferably, the calibration detection unit includes:
Tuning voltage determining module determines voltage-controlled for the frequency of oscillation according to voltage controlled oscillator in the phase-locked loop
The tuning voltage of signal.
Preferably, the calibration detection unit includes: the capacitor in the voltage threshold section for label detection voltage window, two
It a comparator, the logical device being connect with the output end of the output end of first comparator and the second comparator and is patrolled by described
It collects device control and connects the capacitor array of the voltage controlled oscillator；
Wherein, the first input end of the first input end of first comparator and the second comparator is separately connected the capacitor
Different electrodes, the second input terminal of first comparator and the second input terminal of the second comparator receive voltage collected jointly；
And
The comparison result that the logical device is exported according to two comparators adjusts in the capacitor array and accesses voltage-controlled vibration
Swing the capacitance in device.
Preferably, accessing capacitor range half when initial in trend in parallel between each capacitor in the capacitor array
Capacitor element.
Preferably, the logical device is when detecting voltage collected not when detecting in voltage window by adjusting electricity
Hold the mode for accessing the capacitance of voltage controlled oscillator in array, increases the tuning gain of the voltage control signal of voltage controlled oscillator output.
Preferably, adjustment mode of the logical device according to dichotomy, instruction capacitor array is being currently accessed capacitor
The capacitor element quantity that increase/reduction is accessed on the basis of number of packages amount.
Preferably, the logical device verifying is subsequent to adopt when detecting that voltage collected is fallen into detection voltage window
Whether the voltage of collection still falls in the detection voltage window；When falling into the detection voltage window, it is determined that the voltage controlled oscillation
The phase stabilization that device is tracked, and indicate that the voltage control signal exported is down to by the gain regulation unit by the first loop bandwidth
Second loop bandwidth；When not falling in the detection voltage window, then continue the capacitor for adjusting capacitor array access voltage controlled oscillator
Value
To solve the above problems, the present invention also provides a kind of calibration methods of voltage controlled oscillator in phase-locked loop, comprising:
Before the phase stabilization that phase-locked loop is tracked, indicate that voltage controlled oscillator exports the first loop bandwidth in the phase-locked loop
Voltage control signal, and acquire the voltage of the voltage controlled oscillator；Based on the ratio to voltage collected and preset detection voltage window
Compared with as a result, being calibrated to the loop bandwidth of the voltage control signal；When determining the phase stabilization that the phase-locked loop is tracked,
The voltage control signal is down to the second loop bandwidth by the first loop bandwidth.
Further, the voltage control signal of instruction voltage controlled oscillator first loop bandwidth of output includes:
By way of adjusting the input current of the voltage controlled oscillator, adjust the voltage controlled oscillator exported it is voltage-controlled
The loop bandwidth of signal is the first loop bandwidth or the second loop bandwidth；
Either, adjusting in the voltage controlled oscillator by way of the load resistor value of low-pass filter, described in adjustment
The loop bandwidth for the voltage control signal that voltage controlled oscillator is exported is the first loop bandwidth or the second loop bandwidth.
Further, voltage collected is the tuning voltage based on determined by the frequency of oscillation of the voltage controlled oscillator.
Further, the comparison result based on to voltage collected and preset detection voltage window, to the pressure
The loop bandwidth of control signal carries out calibration
When detecting voltage collected not when detecting in voltage window, by adjusting the capacitance of access voltage controlled oscillator
Mode, increase voltage controlled oscillator output voltage control signal gain.
Further, the mode of the capacitance by adjusting access voltage controlled oscillator, increases voltage controlled oscillator output
The gain of voltage control signal include:
The capacitor element of capacitor range half is accessed when initial power-on in voltage controlled oscillator；And
According to the adjustment mode of dichotomy, increase/reduction is accessed on the basis of being currently accessed capacitor element quantity
Capacitor element quantity.
Further, the comparison result based on to voltage collected and preset detection voltage window, to the pressure
The loop bandwidth of control signal carries out calibration
When detecting that voltage collected is fallen into detection voltage window, whether the voltage for verifying subsequent acquisition still falls within institute
It states in detection voltage window；When falling into the detection voltage window, it is determined that the phase stabilization that the phase-locked loop is tracked, and will
The voltage control signal exported is down to the second loop bandwidth by the first loop bandwidth；When not falling in the detection voltage window, then after
It is continuous to adjust the capacitance for being electrically accessed voltage controlled oscillator
The present invention accelerates phase convergence speed by big bandwidth (i.e. the first loop bandwidth), improves phase-locked loop phase
Lock speed；Meanwhile calibration detection is intervened in the voltage controlled oscillator duration of oscillation, Phase Tracking, which is converged to, in phase-locked loop stablizes
When, it determines that calibration finishes, effectively shortens the phase-detection time limit of phase-locked loop.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the first calibration system in the related technology；
Fig. 2 is the structural schematic diagram of second of calibration system in the related technology
Fig. 3 is the structural schematic diagram of the calibration system of voltage controlled oscillator in phase-locked loop in the embodiment of the present invention one；
Fig. 4 is the calibration system of voltage controlled oscillator in phase-locked loop in one of the embodiment of the present invention one optinal plan
Structural schematic diagram；
Fig. 5 is in the embodiment of the present invention one when collection voltages are higher than the waveform diagram of the detection voltage window upper limit；
Fig. 6 is in the embodiment of the present invention one when waveform diagram of the collection voltages lower than detection voltage window lower limit；
Fig. 7 is in the embodiment of the present invention one when collection voltages fall into the waveform diagram in detection voltage window；
Fig. 8 is the flow chart of the calibration method of voltage controlled oscillator in phase-locked loop in the embodiment of the present invention two.
Specific embodiment
It elaborates with reference to the accompanying drawings and examples to the present invention.It is understood that implementation described herein
Example is used only for explaining the present invention rather than limiting the invention.It also should be noted that for ease of description, attached drawing
In only the parts related to the present invention are shown rather than entire infrastructure.
Embodiment one
The structural schematic diagram of the calibration system of voltage controlled oscillator in the phase-locked loop that Fig. 3 provides for the embodiment of the present invention one,
The present embodiment is applicable to the adjustment during phase-locked loop is restrained through the voltage control signal to voltage controlled oscillator 2, to calibrate lock
The Phase Tracking situation of phase loop, the calibration system include: gain regulation unit 11 and calibration detection unit 12.
The gain regulation unit 11 is connected with 2 input terminal of voltage controlled oscillator, for what is tracked in the phase-locked loop
Before phase stabilization, indicate that the voltage controlled oscillator 2 exports the voltage control signal of the first loop bandwidth.
Optionally, gain regulation unit 11 after voltage controlled oscillator 2 powers on biggish gain to voltage controlled oscillator 2
Electric current is provided, so that the voltage control signal that voltage controlled oscillator 2 is exported has biggish loop bandwidth.When phase-locked loop is calibrated really
After phase bit tracking is stablized, the gain regulation unit 11 by way of reducing the gain of supply current, makes voltage controlled oscillation again
The loop bandwidth of device 2 is down to the second loop bandwidth from the first loop bandwidth.
At least three kinds of modes can be used to realize that gain regulation unit 11 regulates and controls loop bandwidth in the first loop in the present embodiment
Switching between bandwidth and the second loop bandwidth.
The first optinal plan are as follows: the gain regulation unit 11 includes: charge pump regulation module 111.
The charge pump regulation module 111 is connected with 2 input terminal of voltage controlled oscillator, for described voltage-controlled by adjusting
The mode of the input current of oscillator 2, the loop bandwidth for adjusting the voltage control signal that the voltage controlled oscillator 2 is exported is the first ring
Road bandwidth or the second loop bandwidth.
Optionally, the charge pump regulation module 111 is mountable in the charge pump.For example, the charge pump regulates and controls module
111 be the control device and logic circuit for adjusting voltage in charge pump.When charge pump works on power, the charge pump regulates and controls mould
Block 111 by voltage tune in the first gear so that after the low-pass filtered device filtering of electric current that charge pump is exported, still have gain compared with
Greatly.The loop bandwidth for the voltage control signal that the voltage controlled oscillator 2 is exported based on the electric current is the first loop bandwidth.Work as charge pump
When regulation module 111 receives determining calibration command, voltage is adjusted to second from the first gear by the charge pump regulation module 111
Gear, so that charge pump exports the current gain to voltage controlled oscillator 2 smaller, the voltage-controlled letter that the voltage controlled oscillator 2 is exported
Number loop bandwidth be the second loop bandwidth.
Second of optinal plan is that the gain regulation unit 11 includes: low-pass filtering regulation module 112.
The low-pass filtering regulation module 112 is connected with 2 input terminal of voltage controlled oscillator, for by adjusting the lock
The mode of the load resistor value of low-pass filter in phase loop adjusts the ring for the voltage control signal that the voltage controlled oscillator 2 is exported
Road bandwidth is the first loop bandwidth or the second loop bandwidth.
Optionally, low-pass filtering regulation module 112 it is mountable low-pass filter institute in circuit.For example, described
Low-pass filtering regulation module 112 is to adjust the control device and logic circuit of resistance in low-pass filter.When on low-pass filter
When electricity work, the low-pass filtering regulates and controls module 112 for resistance tune in the first gear, so that low-pass filtering regulation module 112 is defeated
It is larger to the current gain of voltage controlled oscillator 2 out.The loop bandwidth of the voltage control signal of the corresponding output of the voltage controlled oscillator 2 is the
One loop bandwidth.When low-pass filtering regulation module 112 receives determining calibration command, the low-pass filtering regulates and controls module 112
Resistance is adjusted to the second gear from the first gear, so that low-pass filter exports the current gain to voltage controlled oscillator 2 smaller, institute
The loop bandwidth for stating the voltage control signal that voltage controlled oscillator 2 is exported is the second loop bandwidth.
The third optinal plan is, as shown in figure 4, gain regulation unit 11 includes that charge pump regulates and controls 111 He of module
Low-pass filtering regulates and controls module 112.The gain regulation unit 11, which passes through while adjusting this two regulation module realizations, enables voltage-controlled vibration
The loop bandwidth for swinging the voltage control signal that device 2 is exported is the first loop bandwidth or the second loop bandwidth.
The calibration detection unit 12 is connected with the voltage controlled oscillator 2, for acquiring the electricity of the voltage controlled oscillator 2
Pressure, based on the comparison result to voltage collected and preset detection voltage window, to the loop bandwidth of the voltage control signal into
Row calibration indicates that gain regulation unit 11 will be exported when determining the phase stabilization that the phase-locked loop is tracked
Voltage control signal is down to the second loop bandwidth by the first loop bandwidth.
Here, the calibration detection unit 12 can connect the input terminal of voltage controlled oscillator 2 in voltage controlled oscillator 2, with acquisition
Input the voltage of voltage controlled oscillator 2.The calibration detection unit 12 can also connect the output end of voltage controlled oscillator 2, to acquire pressure
Control the output voltage of signal.
Optionally, the calibration detection unit 12 is preset with the detection voltage window designed using capacitance characteristic.For example, choosing
Take suitable capacitor element, first end ground connection, the second preset voltage (such as Vdd) of termination.When voltage controlled oscillator 2 powers on, institute
It states calibration detection unit 12 to start to acquire the voltage in voltage controlled oscillator 2 in real time at once, and by voltage collected and detects electricity
Pressure window is compared.When obtained comparison result is each fallen in the detection voltage window, it is determined that phase-locked loop institute with
The phase stabilization (determining that calibration finishes) of track, it is on the contrary, it is determined that the phase-locked loop is unstable (needing to continue to calibrate).
When determining that needs continue calibration, adjusted by adjusting capacitor, resistance etc. of voltage controlled oscillator 2 is accessed in itself
The tuning gain of voltage controlled oscillator 2, and tuning voltage is continued to test, until determining that calibration finishes.
When determining phase stabilization, the calibration detection unit 12 exports to gain regulation unit 11 and determines calibration command,
So that gain regulation unit 11 is by adjusting the voltage of charge pump and the resistance of low-pass filter, by the voltage control signal by first
Loop bandwidth is down to the second loop bandwidth.
It should be noted that those skilled in the art not necessarily use above-mentioned acquisition mode, in order to improve calibration accuracy,
Tuning voltage can be therefrom chosen, then by tuning voltage and examine by analyzing each voltage collected in predetermined period
Voltage window is surveyed to be compared.
In order to ensure calibration accuracy, the window width of default detection voltage window is less than the concussion breadth of acquired electric signal.
The first optinal plan is that the calibration detection unit 12 includes: tuning voltage determining module, for according to the voltage controlled oscillation
The frequency of oscillation of device 2 determines the tuning voltage of voltage control signal.
Optionally, the phase margin and the voltage-controlled vibration of access of voltage controlled oscillator 2 are preset in the tuning voltage determining module
Swing the resistance value and capacitance in device 2.According to above-mentioned parameter, the tuning voltage determining module is previously obtained the vibration of voltage control signal
Frequency is swung, and acquires the tuning voltage (Vtune) of voltage control signal according to obtained frequency of oscillation.
For example, the tuning voltage determining module utilizes formula:
With ω c=2 ζ ω n
To calculate frequency of oscillation.Wherein, ζ is damping factor, φ is phase margin, ω is resistance value, c is capacitance, ω c
It is cycle of oscillation for frequency of oscillation, ω n.
The calibration detection unit 12 can acquire tuning voltage (Vtune) according to the frequency of oscillation, and according to being adopted
The tuning voltage of collection and the comparison result of detection voltage window are calibrated.
In second of optinal plan, the calibration detection unit 12 includes: the voltage door for label detection voltage window
121, two comparators 122 of capacitor for limiting section, the logical device 123 that is connect with each 122 output end of comparator and by described
Logical device 123 controls and connects the capacitor array 124 of the voltage controlled oscillator 2.
Wherein, an input terminal of each comparator 122 is separately connected the Different electrodes of the capacitor, each comparator 122
Another input terminal receives voltage collected jointly.
The comparison result that the logical device 123 is exported according to two comparators 122 adjusts to be connect in the capacitor array 124
Enter the capacitance in voltage controlled oscillator 2.
Here, each comparator 122 can receive according to the tuning voltage determining module tuning voltage collected.It is described
Logical device 123 when determining that current tuning voltage is located at except detection voltage window, then adjust accessed in capacitor array 124 it is voltage-controlled
The quantity (adjusting the capacitance accessed in voltage controlled oscillator 2 in the capacitor array 124) of the capacitor element of oscillator 2, when
Determine that current tuning voltage is located within detection voltage window, it is determined that calibration finishes.
Alternatively, each comparator 122 can voltage control signal provided by real-time reception voltage controlled oscillator 2.The logic
Device 123 detects each comparator 122 according to the period corresponding to frequency of oscillation determined by the tuning voltage determining module
Output about tuning voltage and detection voltage window between comparison result, determine whether to have calibrated according still further to comparison result
Finish.
The logical device 123, which is worked as, detects voltage collected (i.e. determination still needs to calibrate) not in detection voltage window
When, by way of gradually adjusting and accessing the capacitance of voltage controlled oscillator 2 in capacitor array 124, increases voltage controlled oscillator 2 and export
Voltage control signal tuning gain.
Optionally, in trend in parallel between each capacitor in the capacitor array 124, capacitor element in parallel is equipped with control
System switch.When initial the capacitor array 124 can all access/do not access capacitor element so that the increasing of voltage controlled oscillator 2
Beneficial maximum/minimum, then suitable gain is gradually adjusted to by maximum/minimum, to reach alignment purpose.
As shown in figure 5, when tuning voltage detected is higher than the upper limit (Vref1) of detection voltage window, the logic device
Part 123 reduces the capacitance that voltage controlled oscillator 2 is accessed in capacitor array 124 according to preset step-length, and detects next week again
The tuning voltage of phase reduced capacitance according to step-length again, and was so stepped up pressure on the basis of the capacitance in a upper period
The tuning gain for controlling oscillator 2, until tuning voltage detected is fallen into voltage window.
As shown in fig. 6, as lower limit (Vref2) of the tuning voltage detected lower than detection voltage window, the logic device
Part 123 increases the capacitance that voltage controlled oscillator 2 is accessed in capacitor array 124 according to preset step-length, and detects next week again
The tuning voltage of phase increased capacitance according to step-length again, and was so stepped up pressure on the basis of the capacitance in a upper period
The tuning gain for controlling oscillator 2, until tuning voltage detected is fallen into voltage window.
In a kind of optional way, the logical device 123 indicates capacitor array according to the gradually adjustment mode of dichotomy
The 124 capacitor element quantity that increase/reduction is accessed on the basis of being currently accessed capacitor element quantity.
Optionally, for quick adjust gain, the capacitor array 124 accesses the capacitor element of capacitor range half.When
When tuning voltage detected is higher than the upper limit of detection voltage window, the logical device 123 uses dichotomy by capacitor array 124
In currently do not access in the shunt capacitance of voltage controlled oscillator 2 half access voltage controlled oscillator 2.
When detection tuning voltage is still higher than the upper limit of detection voltage window again, the logical device 123 is again by capacitor battle array
The half access voltage controlled oscillator 2 in the shunt capacitance of voltage controlled oscillator 2 is not accessed in column 124 currently.So gradually adjustment increases
Benefit, so that tuning voltage detected falls into detection voltage window.
When detection tuning voltage is lower than the lower limit for detecting voltage window again, the logical device 123 disconnects capacitance present
The half in the shunt capacitance of voltage controlled oscillator 2 has been accessed in array 124.Such gradually adjust gain, so that tune detected
Humorous voltage falls into detection voltage window.
Alternatively, when the logical device 123 is when detecting lower limit of the voltage collected lower than detection voltage window, from electricity
Hold and access the shunt capacitance of voltage controlled oscillator 2 in array 124 and start, first reduces and wherein accessed the half of voltage controlled oscillator 2 simultaneously
Join capacitor.When detection tuning voltage is lower than the lower limit for detecting voltage window again, the logical device 123 had accessed simultaneously in last time
The access amount of half capacitor is reduced on the basis of connection capacitor again, to reduce the gain of voltage controlled oscillator 2, is adopted until detecting
The voltage of collection is higher than the upper limit of detection voltage window or voltage collected falls into detection voltage window.
Unceasingly, when detection tuning voltage again is higher than the upper limit of detection voltage window, then the logical device 123 was in last time
It has accessed on the basis of shunt capacitance, the half in the shunt capacitance device not accessed has been accessed into voltage controlled oscillator 2, to improve
Gain is stated, until detecting that voltage collected falls into detection voltage window.
As shown in fig. 7, the logical device 123 can determine when tuning voltage detected is fallen into detection voltage window
Calibration finishes, and exports to gain regulation unit 11 and determine calibration command, so that gain regulation unit 11 controls the pressure
Control the voltage control signal that oscillator 2 exports the second loop bandwidth.
A kind of optional situation is, the logical device 123 is detecting that voltage collected (such as tuning voltage) falls into inspection
When surveying in voltage window, whether the voltage for verifying subsequent acquisition is still fallen in the detection voltage window；When falling into the detection voltage
In window, it is determined that the phase stabilization that the voltage controlled oscillator 2 is tracked, and indicate that gain regulation unit 11 will be exported
Voltage control signal is down to the second loop bandwidth by the first loop bandwidth；When not falling in the detection voltage window, then according to above-mentioned each
One of kind mode continues to adjust the capacitance that capacitor array 124 accesses voltage controlled oscillator 2.
When determine calibration finish when and phase-locked loop phase tracking convergence time.
The present embodiment accelerates phase by enabling voltage controlled oscillator export the voltage control signal of big bandwidth (i.e. the first loop bandwidth)
Position convergence rate, improves phase-locked loop PGC demodulation speed；Meanwhile calibration detection is intervened in the phase-locked loop duration of oscillation,
When phase-locked loop converges to Phase Tracking stabilization, determines that calibration finishes, effectively shorten the phase-detection time limit of phase-locked loop.Separately
Outside, by adjust charge pump and low-pass filter in the way of change the loop bandwidth of voltage control signal, locking phase can not changed
In the case where the circuit structure of loop, the adjustment of loop bandwidth is realized, effectively reduce the complexity of the circuit structure of phase-locked loop
Degree.In addition, determining tuning voltage using the frequency of oscillation of voltage control signal, the stability of collection voltages can be effectively improved, is kept away
Exempt from the interference of signal amplitude compared result.In addition, capacitor array is gradually adjusted using dichotomy, it can accurately and efficiently really
Determine calibration result, reduce the number adjusted repeatedly, shortens the calibration time limit.
Embodiment two
As shown in figure 8, the present embodiment two provides a kind of calibration method of voltage controlled oscillator in phase-locked loop.The calibration
Method can based on the above embodiment in any optinal plan designed by calibration system execute.It can also be by according to as follows
Other calibration systems of step execute.
Step S110, before the phase stabilization that phase-locked loop is tracked, indicate that the voltage controlled oscillator exports the first ring
The voltage control signal of road bandwidth, and acquire the voltage of the voltage controlled oscillator.
Optionally, electric current is provided to voltage controlled oscillator with biggish gain after voltage controlled oscillator powers on, so that voltage-controlled vibration
Swinging the voltage control signal that device is exported has biggish loop bandwidth.After the calibrated determining Phase Tracking of voltage controlled oscillator is stablized,
Again by way of reducing the gain of supply current, the loop bandwidth of voltage controlled oscillator is made to be down to the second ring from the first loop bandwidth
Road bandwidth.
At least three kinds of modes can be used to realize loop bandwidth in the first loop bandwidth and the second loop bandwidth in the present embodiment
Between switching.
A kind of optinal plan are as follows: by way of adjusting the input current of the voltage controlled oscillator, adjust the voltage-controlled vibration
The loop bandwidth for swinging the voltage control signal that device is exported is the first loop bandwidth or the second loop bandwidth.
Optionally, the charge pump regulation module is installed in the charge pump.For example, the charge pump regulation module is adjustment
The control device and logic circuit of voltage in charge pump.When charge pump works on power, the charge pump regulates and controls module for voltage
It adjusts in the first gear, so that still there is larger gain after the low-pass filtered device filtering of electric current that charge pump is exported.It is described voltage-controlled
The loop bandwidth for the voltage control signal that oscillator is exported based on the electric current is the first loop bandwidth.When charge pump regulation module receives
To when determining calibration command, voltage is adjusted to the second gear from the first gear by the charge pump regulation module, so that charge pump is defeated
Smaller to the current gain of voltage controlled oscillator out, the loop bandwidth for the voltage control signal that the voltage controlled oscillator is exported is reduced to second
Loop bandwidth.
Second of optinal plan is, by the side for adjusting the load resistor value of low-pass filter in the voltage controlled oscillator
Formula, the loop bandwidth for adjusting the voltage control signal that the voltage controlled oscillator is exported is the first loop bandwidth or the second loop bandwidth.
Optionally, low-pass filtering regulation module is installed in circuit in low-pass filter.For example, the low-pass filtering tune
Control module is to adjust the control device and logic circuit of resistance in low-pass filter.It is described when low-pass filter works on power
Low-pass filtering regulates and controls module for resistance tune in the first gear, so that low-pass filtering regulation module is exported to the electric current of voltage controlled oscillator
Gain is larger.The loop bandwidth of the voltage control signal of the corresponding output of the voltage controlled oscillator is the first loop bandwidth.Work as low-pass filtering
When regulation module receives determining calibration command, resistance is adjusted to second gear from the first gear by the low-pass filtering regulation module
Position, so that low-pass filter exports the current gain to voltage controlled oscillator smaller, the voltage-controlled letter that the voltage controlled oscillator is exported
Number loop bandwidth be reduced to the second loop bandwidth.
The third optinal plan is, while installing above-mentioned charge pump regulation module and low-pass filtering regulation module.Pass through
This two regulation modules are adjusted simultaneously realizes that the loop bandwidth for the voltage control signal for enabling voltage controlled oscillator be exported is the first loop band
Wide or the second loop bandwidth.
Step S120, based on the comparison result to voltage collected and preset detection voltage window, to the voltage-controlled letter
Number loop bandwidth calibrated.
Here, voltage collected can be the voltage of input voltage controlled oscillator, it is also possible to the voltage of voltage control signal.
Optionally, it is preset with the detection voltage window designed using capacitance characteristic.For example, suitable capacitor element is chosen,
First end ground connection, the second preset voltage (such as Vdd) of termination.When voltage controlled oscillator powers on, start to acquire in real time at once voltage-controlled
Voltage in oscillator, and voltage collected is compared with detection voltage window.When obtained comparison result is each fallen within
In the detection voltage window, it is determined that the phase stabilization (determining that calibration finishes) that the voltage controlled oscillator is tracked works as gained
The comparison result arrived is located at except the detection voltage window, it is determined that the voltage controlled oscillator is unstable (to be needed to continue school
It is quasi-).
When determining that needs continue calibration, adjusted by adjusting capacitor, resistance etc. of voltage controlled oscillator is accessed in itself
The tuning gain of voltage controlled oscillator, and tuning voltage is continued to test, until determining that calibration finishes.
It should be noted that those skilled in the art not necessarily use above-mentioned acquisition mode, in order to improve calibration accuracy,
Tuning voltage can be therefrom chosen, then by tuning voltage and examine by analyzing each voltage collected in predetermined period
Voltage window is surveyed to be compared.
In order to ensure calibration accuracy, the window width of default detection voltage window is less than the concussion breadth of acquired electric signal.
A kind of optinal plan is, according to the frequency of oscillation of the voltage controlled oscillator, to determine the tuning voltage of voltage control signal.
Optionally, the resistance value and capacitance being preset in the phase margin and access voltage controlled oscillator of voltage controlled oscillator.
According to above-mentioned parameter, it is previously obtained the frequency of oscillation of voltage control signal, and acquires voltage control signal according to obtained frequency of oscillation
Tuning voltage.
For example, utilizing formula:
With ω c=2 ζ ω n
To calculate frequency of oscillation.Wherein, ζ is damping factor, φ is phase margin, ω is resistance value, c is capacitance, ω c
It is cycle of oscillation for frequency of oscillation, ω n.
The calibration system can acquire tuning voltage according to the frequency of oscillation, and according to tuning voltage collected with
The comparison result of detection voltage window is calibrated.
In another optional situation, include in the calibration system: the voltage threshold section of label detection voltage window
It capacitor, two comparators, the logical device being connect with each comparator output terminal and is controlled by the logical device and connects institute
State the capacitor array of voltage controlled oscillator.
Wherein, an input terminal of each comparator is separately connected an electrode of the capacitor, each comparator another
Input terminal receives voltage collected jointly.
The comparison result that the logical device is exported according to two comparators adjusts in the capacitor array and accesses voltage-controlled vibration
Swing the capacitance in device.
Here, each comparator can receive according to tuning voltage collected.The logical device is current when determining
Tuning voltage be located at detection voltage window except, then adjust in capacitor array access voltage controlled oscillator capacitor element quantity
(adjusting the capacitance accessed in voltage controlled oscillator in the capacitor array), when determining that it is electric that tuning voltage each falls within the detection
It presses within window, it is determined that calibration finishes.
Alternatively, each comparator can voltage control signal provided by real-time reception voltage controlled oscillator.The logical device
According to identified frequency of oscillation, detect each comparator output about tuning voltage compared between detection voltage window knot
Fruit determines whether that calibration is finished according still further to comparison result.
When detecting voltage collected not when detecting in voltage window (i.e. determination still needs to calibrate), the logical device is logical
The mode for gradually adjusting the capacitance for accessing voltage controlled oscillator in capacitor array is crossed, the voltage control signal of voltage controlled oscillator output is increased
Tuning gain.
Optionally, in trend in parallel between each capacitor in the capacitor array, capacitor element in parallel is equipped with control
Switch.When initial the capacitor array can all access/do not access capacitor element so that the gain of voltage controlled oscillator is most
Greatly/minimum, then suitable gain is gradually adjusted to by maximum/minimum, to reach alignment purpose.
When tuning voltage detected is higher than the upper limit of detection voltage window, the logical device subtracts according to preset step-length
The capacitance of voltage controlled oscillator was accessed in few capacitor array, and detects the tuning voltage in next period again, in a upper period
On the basis of capacitance, capacitance is reduced again according to step-length, is so stepped up the tuning gain of voltage controlled oscillator, Zhi Daosuo
The tuning voltage of detection is fallen into voltage window.
When lower limit of the tuning voltage detected lower than detection voltage window, the logical device increases according to preset step-length
Added the capacitance for accessing voltage controlled oscillator in capacitor array, and detect the tuning voltage in next period again, in a upper period
On the basis of capacitance, increases capacitance again according to step-length, be so stepped up the tuning gain of voltage controlled oscillator, Zhi Daosuo
The tuning voltage of detection is fallen into voltage window.
In a kind of optional way, the logical device indicates that capacitor array exists according to the gradually adjustment mode of dichotomy
It is currently accessed the capacitor element quantity that increase/reduction on the basis of capacitor element quantity is accessed.
Optionally, for quick adjust gain, the capacitor element of the capacitor array access capacitor range half.When being examined
When the tuning voltage of survey is higher than the upper limit of detection voltage window, the logical device currently will not be connect using dichotomy in capacitor array
Enter the half access voltage controlled oscillator in the shunt capacitance of voltage controlled oscillator.
When detection tuning voltage is still higher than the upper limit of detection voltage window again, the logical device again will be in capacitor array
The half access voltage controlled oscillator in the shunt capacitance of voltage controlled oscillator is not accessed currently.Such gradually adjust gain, so that institute
The tuning voltage of detection falls into detection voltage window.
When detection tuning voltage is lower than the lower limit for detecting voltage window again, the logical device disconnects capacitance present array
In accessed the half in the shunt capacitance of voltage controlled oscillator.Such gradually adjust gain, so that tuning voltage detected is fallen
Enter to detect voltage window.
Alternatively, when the logical device is when detecting lower limit of the voltage collected lower than detection voltage window, from capacitor
The shunt capacitance that voltage controlled oscillator is accessed in array starts, and first reduces the half shunt capacitance for wherein having accessed voltage controlled oscillator.
When detection tuning voltage is lower than the lower limit for detecting voltage window again, the logical device had accessed the base of shunt capacitance in last time
The access amount of half capacitor is reduced on plinth again, to reduce the gain of voltage controlled oscillator, until detecting that voltage collected is high
Detection voltage window is fallen into the upper limit of detection voltage window or voltage collected.
When detection tuning voltage is higher than the upper limit of detection voltage window again, the logical device had accessed parallel connection in last time
On the basis of capacitor, the half in the shunt capacitance device not accessed is accessed into voltage controlled oscillator, to improve the gain, until
Detect that voltage collected falls into detection voltage window.
When determining phase stabilization, step S130 is executed.
Step S130, when determining the phase stabilization that the voltage controlled oscillator is tracked, by the voltage control signal by first
Loop bandwidth is down to the second loop bandwidth.
Optionally, when tuning voltage detected is fallen into detection voltage window, the logical device, which can determine, have been calibrated
It is complete, and exported to gain regulation unit and determine calibration command, so that the gain regulation unit control voltage controlled oscillator is defeated
The voltage control signal of second loop bandwidth out.
A kind of optional situation is, the logical device is detecting that voltage collected (such as tuning voltage) falls into detection electricity
When pressing in window, whether the voltage for verifying subsequent acquisition is still fallen in the detection voltage window；When falling into the detection voltage window,
It then determines the phase stabilization that the voltage controlled oscillator is tracked, and indicates the voltage control signal that the gain regulation unit will be exported
Second loop bandwidth is down to by the first loop bandwidth；When not falling in the detection voltage window, then according to described in step S120
One of various modes continue to adjust the capacitance of capacitor array access voltage controlled oscillator.
When determine calibration finish when and phase-locked loop phase tracking convergence time.
The above is only a preferred embodiment of the present invention, is not intended to limit the present invention.Come for those skilled in the art
It says, the invention may be variously modified and varied.All within the spirits and principles of the present invention, made any modification, equivalent
Replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (14)
1. the calibration system of voltage controlled oscillator in a kind of phase-locked loop, comprising: gain regulates and controls unit and calibration detection unit, special
Sign is:
Gain regulation unit is connected with the voltage controlled oscillator input terminal in phase-locked loop, for what is tracked in the phase-locked loop
Before phase stabilization, indicate that the voltage controlled oscillator exports the voltage control signal of the first loop bandwidth；And
Calibration detection unit is connected with the voltage controlled oscillator, for acquiring the voltage in the voltage controlled oscillator, based on to institute
The comparison result of the voltage of acquisition and preset detection voltage window, calibrates the loop bandwidth of the voltage control signal, when true
When the phase stabilization that the fixed phase-locked loop is tracked, indicate the gain regulation unit by the voltage control signal by the first loop
Bandwidth is down to the second loop bandwidth.
2. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 1, it is characterised in that: the gain tune
Control unit includes: charge pump regulation module and/or low-pass filtering regulation module；
Wherein, charge pump regulation module is connected with the voltage controlled oscillator input terminal, for by adjusting the voltage controlled oscillator
Input current mode, adjust the voltage control signal that the voltage controlled oscillator is exported loop bandwidth be the first loop bandwidth or
Second loop bandwidth；And
Low-pass filtering regulation module is connected with the voltage controlled oscillator input terminal, for by adjusting low pass in the phase-locked loop
The mode of the load resistor value of filter, the loop bandwidth for adjusting the voltage control signal that the voltage controlled oscillator is exported is the first ring
Road bandwidth or the second loop bandwidth.
3. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 1, it is characterised in that: the calibration inspection
Surveying unit includes:
Tuning voltage determining module determines voltage control signal for the frequency of oscillation according to voltage controlled oscillator in the phase-locked loop
Tuning voltage.
4. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 1 or 3, it is characterised in that: the school
Quasi- detection unit includes: the capacitor in the voltage threshold section for label detection voltage window, two comparators and first comparator
Output end and the second comparator output end connection logical device and controlled by the logical device and connect the pressure
Control the capacitor array of oscillator；
Wherein, the first input end of the first input end of first comparator and the second comparator is separately connected the difference of the capacitor
Electrode, the second input terminal of first comparator and the second input terminal of the second comparator receive voltage collected jointly；And
The comparison result that the logical device is exported according to two comparators adjusts in the capacitor array and accesses voltage controlled oscillator
In capacitance.
5. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 4, it is characterised in that: the capacitor battle array
In trend in parallel between each capacitor in column, the capacitor element of capacitor range half is accessed when initial.
6. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 4, it is characterised in that: when detecting
The voltage of acquisition is not when detecting in voltage window, and the logical device is by adjusting the electricity for accessing voltage controlled oscillator in capacitor array
The mode of capacitance increases the tuning gain of the voltage control signal of voltage controlled oscillator output.
7. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 6, it is characterised in that: the logic device
Part indicates capacitor array increase/reduction institute on the basis of being currently accessed capacitor element quantity according to the adjustment mode of dichotomy
The capacitor element quantity of access.
8. the calibration system of voltage controlled oscillator in phase-locked loop according to claim 4, it is characterised in that: when detecting
When the voltage of acquisition is fallen into detection voltage window, whether the voltage of the logical device verifying subsequent acquisition still falls within the detection
In voltage window；When falling into the detection voltage window, it is determined that the phase stabilization that the voltage controlled oscillator is tracked, and indicate institute
It states gain regulation unit and the voltage control signal exported is down to the second loop bandwidth by the first loop bandwidth；When not falling within the inspection
It surveys in voltage window, then continues the capacitance for adjusting capacitor array access voltage controlled oscillator.
9. the calibration method of voltage controlled oscillator in a kind of phase-locked loop, it is characterised in that: include:
Before the phase stabilization that phase-locked loop is tracked, indicate that the voltage controlled oscillator in the phase-locked loop exports the first loop
The voltage control signal of bandwidth, and acquire the voltage of the voltage controlled oscillator；
Based on the comparison result to voltage collected and preset detection voltage window, to the loop bandwidth of the voltage control signal into
Row calibration；And
When determining the phase stabilization that the phase-locked loop is tracked, the voltage control signal is down to second by the first loop bandwidth
Loop bandwidth.
10. the calibration method of voltage controlled oscillator in phase-locked loop according to claim 9, it is characterised in that: the instruction
Voltage controlled oscillator export the first loop bandwidth voltage control signal include:
By way of adjusting the input current of the voltage controlled oscillator, the voltage control signal that the voltage controlled oscillator is exported is adjusted
Loop bandwidth be the first loop bandwidth or the second loop bandwidth；
Either, it adjusting in the voltage controlled oscillator by way of the load resistor value of low-pass filter, adjusts described voltage-controlled
The loop bandwidth for the voltage control signal that oscillator is exported is the first loop bandwidth or the second loop bandwidth.
11. the calibration method of voltage controlled oscillator in phase-locked loop according to claim 9, it is characterised in that: collected
Voltage is the tuning voltage based on determined by the frequency of oscillation of the voltage controlled oscillator.
12. the calibration method of voltage controlled oscillator in the phase-locked loop according to claim 9 or 11, it is characterised in that: described
Based on the comparison result to voltage collected and preset detection voltage window, school is carried out to the loop bandwidth of the voltage control signal
Standard includes:
When detecting voltage collected not when detecting in voltage window, by adjusting the side of the capacitance of access voltage controlled oscillator
Formula increases the gain of the voltage control signal of voltage controlled oscillator output.
13. the calibration method of voltage controlled oscillator in phase-locked loop according to claim 12, it is characterised in that: described to pass through
The mode of the capacitance of adjustment access voltage controlled oscillator, the gain for increasing the voltage control signal of voltage controlled oscillator output include:
The capacitor element of capacitor range half is accessed when initial power-on in voltage controlled oscillator；And
According to the adjustment mode of dichotomy, the capacitor that increase/reduction is accessed on the basis of being currently accessed capacitor element quantity
Number of devices.
14. the calibration method of voltage controlled oscillator in the phase-locked loop according to claim 9 or 11, it is characterised in that: described
Based on the comparison result to voltage collected and preset detection voltage window, school is carried out to the loop bandwidth of the voltage control signal
Standard includes:
When detecting that voltage collected is fallen into detection voltage window, whether the voltage for verifying subsequent acquisition still falls within the inspection
It surveys in voltage window；When falling into the detection voltage window, it is determined that the phase stabilization that the phase-locked loop is tracked, and institute is defeated
Voltage control signal out is down to the second loop bandwidth by the first loop bandwidth；When not falling in the detection voltage window, then continue to adjust
The whole capacitance for being electrically accessed voltage controlled oscillator.
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Cited By (1)
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| CN112152610A (en) * | 2020-09-22 | 2020-12-29 | 西安交通大学 | Phase-locked loop with broadband rapid frequency hopping function |
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| US20100127739A1 (en) * | 2007-05-30 | 2010-05-27 | Tsuyoshi Ebuchi | Spread spectrum control pll circuit and its start-up method |
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