CN101753135A - Method for selection of frequency band of voltage control oscillator in phase locked loop and related device - Google Patents
Method for selection of frequency band of voltage control oscillator in phase locked loop and related device Download PDFInfo
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- CN101753135A CN101753135A CN 200810183417 CN200810183417A CN101753135A CN 101753135 A CN101753135 A CN 101753135A CN 200810183417 CN200810183417 CN 200810183417 CN 200810183417 A CN200810183417 A CN 200810183417A CN 101753135 A CN101753135 A CN 101753135A
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Abstract
The invention discloses a method for selection of the frequency band of a voltage control oscillator in a phase locked loop and a related device, which can prevent the phase locked loop from locking loss in the environment with large changes in the operating temperature. The device is in the open loop state of the phase locked loop, and an even number of frequency bands are arranged in the voltage control oscillator for selection. The method for selection of the frequency band comprises the following steps: generating an open loop control voltage according to temperature signals; inputting the open loop control voltage into the voltage control oscillator; switching the frequency bands in the voltage control oscillator in sequence, so that the voltage control oscillator can generate an even number of voltage control signals with different voltage control frequencies; and selecting an optimal voltage control signal from the voltage control signals and a corresponding frequency band as the operating frequency band of the phase locked loop in the closed loop state.
Description
Technical field
The present invention relates to a kind of phase-locked loop (phase locked loop circuit is called for short PLL), refer to method for selection of frequency band and the relevant apparatus of voltage control oscillator in a kind of phase-locked loop (voltage controlled oscillator) especially.
Background technology
Please refer to Fig. 1, it is the phase-locked loop schematic diagram, comprises phase frequency detector (Phase FrequencyDetector) 10, charge pump (Charge Pump) 20, loop filter (Loop Filter) 30, voltage control oscillator (Voltage Controlled Oscillator) 40, frequency elimination unit (FrequencyDividing Unit) 45.Reference signal with reference frequency (Fref) is by reference oscillator (ReferenceOscillator, not shown) produce and the frequency elimination signal (Frequency Divided Signal) exported of this reference signal and frequency elimination unit 45 input phase frequency detector 10 simultaneously.Phase frequency detector 10 can be detected the phase place between reference signal and the frequency elimination signal and the difference of frequency, afterwards, exports a phase signal (Phase Difference Signal) to charge pump 20.Then, charge pump 20 produces according to the size of this phase signal and is relevant to one of this phase signal and outputs current to loop filter 30.Loop filter 30 mild (Smooth) these output currents, and be converted to a control voltage (Vctrl) to voltage control oscillator 40.Voltage control oscillator 40 can produce according to control voltage (Vctrl) has the voltage-controlled output signal (voltage controlled signal) of a voltage controlled frequency (Fvco).Frequency elimination unit 45 receives voltage-controlled output signal and its frequency (Fvco) is produced the frequency elimination signal divided by N, and wherein, N is integer and Fvco=N*Fref.
In general, voltage control oscillator 40 is divided into LC oscillator (LC oscillator) and ring oscillator (ring oscillator).And in order to allow voltage control oscillator 40 have higher frequency adjustment range, usually all can comprise a transfiguration storehouse (varactor bank) or switch-capacitor storehouse (switch capacitance bank) in the voltage control oscillator 40 in order to changeable capacitance to be provided, make the voltage controlled frequency (Fvco) that voltage control oscillator 40 can provide a plurality of frequency ranges (band) to adjust voltage-controlled output signal.Please refer to Fig. 2, it is the control voltage (Vctrl) of known voltage control oscillator and the schematic diagram of voltage controlled frequency (Fvco).
As shown in Figure 2, the control voltage (Vctrl) of voltage control oscillator has a Linear Control interval, that is between the VL to VH.When voltage control oscillator selected frequency range 1 to operate, the voltage controlled frequency of voltage control oscillator (Fvco) excursion was F1L to F1H; When voltage control oscillator selected frequency range 2 to operate, the voltage controlled frequency of voltage control oscillator (Fvco) excursion was F2L to F2H; When voltage control oscillator selected frequency range 3 to operate, the voltage controlled frequency of voltage control oscillator (Fvco) excursion was F3L to F3H; And when voltage control oscillator selected frequency range 4 to operate, the voltage controlled frequency of voltage control oscillator (Fvco) excursion was F4L to F4H.That is to say that the voltage controlled frequency of the voltage control oscillator of Fig. 2 (Fvco) excursion can be expanded as and be F1H to F4L.In like manner, when voltage control oscillator provided more frequency range, the excursion of voltage controlled frequency (Fvco) was bigger.
In general, when the phase-locked loop operated in peripheral temperature and changes sizable environment, in order to keep fixing voltage controlled frequency (Fvco), control voltage (Vctrl) will change along with temperature change.The control voltage (Vctrl) when for instance, Fig. 3 (a), Fig. 3 (b), Fig. 3 (c) operate in different temperatures (T1, T2, T3) for its voltage control oscillator of same phase-locked loop and the schematic diagram of voltage controlled frequency (Fvco).Suppose the frequency range that voltage control oscillator selects frequency range 3 to be used as selecting, and VL=1V, VH=2V, voltage controlled frequency (Fvco) are fixed on 4GHz, and T1＜T2＜T3.By Fig. 3 (a) as can be known, when T1, when controlling voltage (Vctrl) at 1.5V, the voltage controlled frequency of voltage control oscillator (Fvco) may operate in 4GHz.Along with the increase of temperature, the down drift of all frequency ranges of voltage control oscillator, therefore, by Fig. 3 (b) as can be known, when T2, for the voltage controlled frequency (Fvco) that makes voltage control oscillator operates in 4GHz, control voltage (Vctrl) can be adjusted to 1.9V automatically.If temperature continues to rise to T3 again, then control voltage (Vctrl) and can continue up to adjust to surpass 2V up to control voltage (Vctrl), just exceed the Linear Control interval, and cause the phase-locked loop to lose locking.
Therefore, it is extremely important that the frequency range of voltage control oscillator is roughly selected (coarse selection) program.That is to say.Utilize the frequency range program of roughly selecting to select a suitable frequency range, make the control voltage (Vctrl) of voltage control oscillator be not easy to exceed the Linear Control interval.In general, before the phase-locked loop begins operation, that is during electric power starting or circuit when being reset (reset), voltage control oscillator must be earlier selected after the specific frequency range through a frequency range program of roughly selecting, and the phase-locked loop just can begin to move.
Roughly select program and open loop (openloop) and roughly select program and the frequency range program of roughly selecting can be divided into loop circuit (close loop).Roughly select program for the loop circuit, the selection of frequency range seems more inessential, because when operating in the phase-locked loop, can provide an observation circuit to come Monitoring and Controlling voltage (Vctrl) at any time, when control voltage (Vctrl) surpassed the Linear Control interval, the frequency range that observation circuit can change voltage control oscillator made control voltage (Vctrl) can get back to the Linear Control interval.
That is to say, when temperature T 3, when monitoring circuit monitors control voltage (Vctrl) surpasses the Linear Control interval, observation circuit selects the frequency range 2 of voltage control oscillator to operate, shown in Fig. 3 (c), therefore, control voltage (Vctrl) can be got back to 1.45V, and it is interval and can not lose locking just to enter Linear Control once more.
Yet observation circuit continues to monitor control voltage (Vctrl) in the time of must operating in the phase-locked loop, and therefore, observation circuit is power consumption constantly, and for the circuit of low power consumption demand, the phase-locked loop can't use observation circuit to detect control voltage (Vctrl).
Moreover the frequency range of opening the loop program of roughly selecting only needs when electric power starting or circuit carries out Frequency Band Selection when being reset (reset), and frequency range just can not change again afterwards, does not therefore have the problem that continues power consumption.Therefore, the frequency range of opening the loop is roughly selected program for very important of the normal operation of phase-locked loop.Otherwise probably the process in the phase-locked loop running loses locking.
The Linear Control interval of supposing the phase-locked loop is then set 1/2 (VL+VH) and is out that circuit controls voltage carries out frequency range and roughly selects program between VL and VH.Moreover the annexation of opening between (open) loop filter 30 and the voltage control oscillator 40 makes phase-locked loop formation open the loop.Then, select the different frequency range of voltage control oscillator 40 and make voltage control oscillator 40 can export the voltage-controlled output signal of corresponding different voltage controlled frequency (Fvco) in regular turn to open circuit controls voltage input voltage control oscillator 40.The voltage-controlled output signal of different voltage controlled frequencies (Fvco) is carried out frequency via frequency elimination unit 45 with different voltage-controlled output signals and is produced different frequency elimination signals after divided by the action of N.At last, the frequency of all frequency elimination signals and the reference frequency of reference signal (Fref) are compared, and selected near the frequency range of the frequency elimination signal of reference frequency (Fref) and corresponding voltage control oscillator 40 thereof as the coarse adjustment frequency range.
Please refer to Fig. 4 (a), it roughly selects the program schematic diagram for the known frequency range of opening the loop.Suppose that voltage control oscillator 40 has four frequency ranges (1,2,3,4), VL is that 1V, VH are 2V, and reference frequency (Fref) is 40MHz, and the N of frequency elimination unit 45 is 100.Therefore, opening circuit controls voltage is 1/2 (VL+VH)=1.5V.
When the loop is opened in the phase-locked loop, (I) after first frequency range (1) of selection voltage control oscillator, first voltage controlled frequency (Fvco1) that produces the first voltage-controlled output signal after circuit controls voltage is opened in input be 4.49G, and the first frequency elimination frequency (FD1) that can detect the first frequency elimination signal is 44.9MHz.(II) after second frequency range (2) of selection voltage control oscillator, second voltage controlled frequency (Fvco2) that produces the second voltage-controlled output signal after circuit controls voltage is opened in input be 4.26G, and the second frequency elimination frequency (FD2) that can detect the second frequency elimination signal is 42.6MHz.(III) after the 3rd frequency range (3) of selection voltage control oscillator, the 3rd voltage controlled frequency (Fvco3) that produces the 3rd voltage-controlled output signal after circuit controls voltage is opened in input be 4.03G, and the 3rd frequency elimination frequency (FD3) that can detect the 3rd frequency elimination signal is 40.3MHz.(IV) after the 4th frequency range (4) of selection voltage control oscillator, the 4th voltage controlled frequency (Fvco4) that produces the 4th voltage-controlled output signal after circuit controls voltage is opened in input be 3.81G, and the 4th frequency elimination frequency (FD4) that can detect the 4th frequency elimination signal is 38.1MHz.
Because the 3rd frequency elimination frequency (FD3) of the 3rd frequency elimination signal is 40.3MHz, near the reference frequency (Fref) of 40MHz, therefore, the phase-locked loop can be roughly selected the 3rd frequency range (3) of voltage control oscillator and be operated.And, shown in Fig. 4 (b), when annexation between (close) loop filter 30 and the voltage control oscillator 40 is closed when making that the phase-locked loop forms the loop circuit in the phase-locked loop, the 3rd frequency range (3) is operation frequency range and controls voltage (Vctrl) and will be adjusted to 1.4V voluntarily, makes the phase-locked loop stably export the voltage controlled frequency of 4GHz (Fvco).
It is to wish to find out a special frequency channel that the frequency range of opening the loop of known phase-locked loop is roughly selected the main purpose of program, and control voltage (Vctrl) can maintain near the interval central authorities of Linear Control when the phase-locked loop enters the loop circuit.Yet the known frequency range program of roughly selecting of holding the loop applies to can cause the phase-locked loop to lose locking when operating temperature changes too big environment.The frequency range program of roughly selecting with Fig. 4 (a) and Fig. 4 (b) explains, and supposes that the phase-locked loop opens the frequency range in loop and roughly select program when low temperature (for example 0 ℃), and finishes roughly selecting of the 3rd frequency range.Clearly, when the loop circuit, phase-locked loop began to operate, because temperature continues to rise, the phase-locked loop was in order to continue to be locked in 4GHz, and control voltage (Vctrl) can be begun to increase progressively by 1.4V.Because only there is 0.6V on control voltage (Vctrl) distance linear control interval border, therefore, when the phase-locked loop when high temperature (for example 100 ℃), it is interval and make the phase-locked loop lose locking to cause control voltage (Vctrl) to leave Linear Control.
Otherwise, suppose that the phase-locked loop opens the frequency range in loop and roughly select program when high temperature (for example 125 ℃), and finish roughly selecting of the 3rd frequency range.Clearly, when the loop circuit, phase-locked loop operated in low temperature, the phase-locked loop was in order to continue to be locked in 4GHz, and control voltage (Vctrl) can be begun to successively decrease by 1.4V.Because only there is 0.4V on control voltage (Vctrl) distance linear control interval border, therefore, when the phase-locked loop when low temperature (for example 0 ℃, the alpine region), it is interval and then make the phase-locked loop lose locking to cause control voltage (Vctrl) to leave Linear Control.
Summary of the invention
Technical problem to be solved by this invention provides the method for selection of frequency band and the relevant apparatus of voltage control oscillator in a kind of phase-locked loop, makes that the phase-locked loop applies to can not lose locking when operating temperature changes too big environment.
In order to solve above technical problem, the invention provides following technical scheme:
The invention provides the method for selection of frequency band of voltage control oscillator in a kind of phase-locked loop, applying to opening in loop state and this voltage control oscillator of this phase-locked loop has a plurality of frequency ranges available, comprising: produce according to temperature signal and open circuit controls voltage; Input is opened circuit controls voltage to voltage control oscillator; Switch those frequency ranges in this voltage control oscillator in regular turn, make this voltage control oscillator produce a plurality of voltage-controlled signals in regular turn and those voltage-controlled signals have different voltage controlled frequency; And, the operation frequency range when selecting a preferable voltage-controlled signal and corresponding frequency range thereof in those voltage-controlled signals as the loop circuit state of this phase-locked loop.
The invention provides a kind of phase-locked loop, comprising: loop filter, the exportable first control voltage; Open the circuit controls voltage generation circuit, the exportable second control voltage that is relevant to ambient temperature; Multiplexer can be opened the circuit controls signal according to 1 the first control voltage and the second control voltage are exported the 3rd control voltage alternatively; Voltage control oscillator produces voltage-controlled output signal according to the 3rd control voltage; The frequency elimination unit receives voltage-controlled output signal and carries out frequency elimination to produce the frequency elimination signal; The phase frequency detector produces phase signal according to frequency elimination signal and reference signal; Charge pump outputs current to this loop filter to produce the first control voltage in order to produce according to phase signal; Frequency comparator produces the difference on the frequency signal according to frequency elimination signal and reference signal; And frequency band is selected logic, when opening circuit controls signal opinion, a plurality of frequency ranges in the switched voltage control oscillator, and select a working frequency range of those frequency ranges in the voltage control oscillator according to a plurality of difference on the frequency signals of frequency comparator output, separate when advocating and open the circuit controls signal in this, the control voltage control oscillator produces voltage-controlled output signal according to working frequency range and the 3rd control voltage.For example, open the circuit controls voltage generation circuit and comprise that temperature detection circuit is in order to provide temperature signal, and make the second control voltage be relevant to temperature signal, perhaps, temperature detection circuit produces circuit for the absolute temperature proportional current and temperature signal produces the current signal that circuit produces for the absolute temperature proportional current, perhaps, temperature detection circuit is produced by the absolute temperature proportional current resistance of flowing through for the absolute temperature proportional current produces circuit and temperature signal.
The method for selection of frequency band of voltage control oscillator and relevant apparatus can make the phase-locked loop can not lose locking when applying to the too big environment of operating temperature variation in the phase-locked loop that the present invention adopts.
Description of drawings
Fig. 1 is the phase-locked loop schematic diagram.
Fig. 2 is the control voltage (Vctrl) of known voltage control oscillator and the schematic diagram of voltage controlled frequency (Fvco).
The control voltage (Vctrl) when Fig. 3 (a), Fig. 3 (b), Fig. 3 (c) operate in different temperatures (T1, T2, T3) for its voltage control oscillator of same phase-locked loop and the schematic diagram of voltage controlled frequency (Fvco).
Fig. 4 (a) and Fig. 4 (b) roughly select the program schematic diagram for known frequency range.
Fig. 5 produces circuit diagram for the absolute temperature proportional current.
Fig. 6 (a), Fig. 6 (b), Fig. 6 (c) are that the preferred embodiment frequency range is roughly selected the program schematic diagram according to the present invention.
Fig. 7 (a), Fig. 7 (b), Fig. 7 (c) are that the preferred embodiment frequency range is roughly selected the program schematic diagram according to the present invention.
Fig. 8 is the method for selection of frequency band flow chart of voltage control oscillator in according to a preferred embodiment of the present invention the phase-locked loop.
Fig. 9 is phase-locked loop according to a preferred embodiment of the present invention.
[primary clustering symbol description]
Each assembly that is comprised during this case is graphic lists as follows:
10 phase frequency detectors, 20 charge pumps
30 loop filters, 40 voltage control oscillators
45 frequency elimination unit, 60 mirror circuit
65 operational amplifiers, 70 input circuits
910 phase frequency detectors, 920 charge pumps
930 loop filters 932 are opened the circuit controls voltage generation circuit
933 temperature detection circuits, 935 multiplexers
940 voltage control oscillators, 945 frequency elimination unit
950 frequency comparators, 960 frequency bands are selected logic
Embodiment
Before introducing method for selection of frequency band of the present invention, introduce absolute temperature ratio (ProportionalTo Absolute Temperature is called for short PTAT) current generating circuit earlier.Please refer to Fig. 5, it produces circuit diagram for the absolute temperature proportional current of forming by PMOS field-effect transistor, PNP two-carrier transistor, with operational amplifier.In general, the PTAT current generating circuit comprises mirror circuit (MirroringCircuit) 60, operational amplifier (Operation Amplifier) 65 and input circuit (InputCircuit) 70.Comprise three PMOS field-effect transistor M1, M2, M3 in the mirror circuit 60, in this example, M1, M2 have identical length-width ratio (W/L) with M3.Wherein, the gate of M1, M2 and M3 (Gate) interconnects, and the source electrode of M1, M2 and M3 (Source) is connected to power supply (Vss), and the drain of M1, M2 and M3 (Drain) can be exported the electric current of Ix, Iy and Iptat respectively.In addition, the output of operational amplifier 65 can be connected to the gate (Gate) of M1 and M2, and the electrode input end of operational amplifier 65 is connected to the drain of M1, and the negative input of operational amplifier 65 is connected with the drain of M2.
By the PTAT current generating circuit of Fig. 5 as can be known.Because M1, M2, M3 have identical length-width ratio, therefore, the output current Iptat of M3 drain, the output current Iy of M2 drain are identical with the output current Ix of M1 drain, just:
I
x＝I
y＝p
tat---(1)
Have under the infinitely-great gain at operational amplifier 65, the negative input voltage (Vy) of operational amplifier 65 can equate with electrode input end voltage (Vx).Therefore:
R
1I
x+V
EB1＝V
EB2---(2)
Because Q1 and Q2 form that diode is connected and the Q1 area is m a times of Q2 area, so,
With
And then derive:
V
BE1＝V
Tln(I
x/m?I
s)---(3)
V
BE2＝V
Tln(I
y/I
s)---(4)
Wherein, I
sSaturation current (Saturation Current) for Q2 is thermal voltage (ThermalVoltage).
In conjunction with (1), (2), (3), (4), finally can obtain:
I
ptat＝(1/R
1)V
T?ln?m---(5)
By (5) formula as can be known, owing to thermal voltage can change along with temperature change, therefore, PTAT electric current (Iptat) only can change along with variation of temperature, that is to say that the size of PTAT electric current (Iptat) can be considered a temperature signal in order to learn the temperature of circuit operation.Perhaps, this PTAT electric current (Iptat) is flowed through also can learn the temperature of circuit operation behind the resistance according to ohmically voltage swing.
Therefore, method for selection of frequency band of the present invention utilizes temperature detection circuit, PTAT current generating circuit for example, and the temperature signal of output carries out the frequency band of voltage control oscillator and chooses program.
According to embodiments of the invention, the selection of opening circuit controls voltage is that the temperature signal that provides according to temperature detection circuit decides.That is to say, when the frequency range that will open the loop when the phase-locked loop is roughly selected program, utilize temperature signal can learn the ambient temperature that the phase-locked loop is present, and when operating according to the phase-locked loop, variation of temperature trend decides out circuit controls voltage.
For instance, suppose that the phase-locked loop opens the frequency range in loop and roughly select program when low temperature.Temperature can increase progressively when operated the loop circuit, phase-locked loop, preferably, opened circuit controls voltage and selected the voltage of linear control interval near VL.Therefore, when the loop circuit, phase-locked loop, the scope that control voltage (Vctrl) up increases progressively in linear control interval will increase.
Please refer to Fig. 6 (a), it roughly selects the program schematic diagram for the frequency range that the present invention opens the loop.Suppose that voltage control oscillator has four frequency ranges (1,2,3,4), VL is that 1V, VH are 2V, and reference frequency (Fref) is 40MHz, and the N of frequency elimination unit 45 is 100.Suppose when opening the loop frequency range and roughly select program, to learn present temperature at low temperature (T4) according to temperature signal, for example below 10 ℃, then select linear control interval border (boundary) near the magnitude of voltage of VL as opening circuit controls voltage, for example 1.1V.
When the loop is opened in the phase-locked loop, shown in Fig. 6 (a): (I) after first frequency range (1) of selection voltage control oscillator, first voltage controlled frequency (Fvco1) that produces the first voltage-controlled output signal after circuit controls voltage is opened in input be 4.25GHz, and the first frequency elimination frequency (FD1) that can detect the first frequency elimination signal is 42.5MHz.(II) after second frequency range (2) of selection voltage control oscillator, second voltage controlled frequency (Fvco2) that produces the second voltage-controlled output signal after circuit controls voltage is opened in input be 4.01GHz, and the second frequency elimination frequency (FD2) that can detect the second frequency elimination signal is 40.1MHz.(III) after the 3rd frequency range (3) of selection voltage control oscillator, the 3rd voltage controlled frequency (Fvco3) that produces the 3rd voltage-controlled output signal after circuit controls voltage is opened in input be 3.80GHz, and the 3rd frequency elimination frequency (FD3) that can detect the 3rd frequency elimination signal is 38.0MHz.(IV) after the 4th frequency range (4) of selection voltage control oscillator, the 4th voltage controlled frequency (Fvco4) that produces the 4th voltage-controlled output signal after circuit controls voltage is opened in input be 3.59GHz, and the 4th frequency elimination frequency (FD4) that can detect the 4th frequency elimination signal is 35.9MHz.
Because the second frequency elimination frequency (FD2) of the second frequency elimination signal is 40.1MHz, near the reference frequency (Fref) of 40MHz, therefore, the phase-locked loop can be roughly selected second frequency range (2) of voltage control oscillator and be operated.And, when annexation between (close) loop filter 30 and the voltage control oscillator 40 is closed when making that the phase-locked loop forms the loop circuit in the phase-locked loop, shown in Fig. 6 (b), second frequency range (2) is operation frequency range and controls voltage (Vctrl) and will be adjusted to 1.05V voluntarily, makes the voltage controlled frequency (Fvco) of the output 4GHz that the phase-locked loop is stable.
When the normal running of phase-locked loop, cumulative by the T4 of low temperature when temperature, and in order to allow the voltage controlled frequency (Fvco) of the stable output 4GHz in phase-locked loop, control voltage (Vctrl) can be cumulative by 1.05V.Because the frequency range of opening the loop of the present invention is roughly selected procedure Selection and is opened circuit controls voltage near VL, therefore another border (VH) of the cumulative linear control interval of control voltage (Vctrl) distance also has 0.95V, makes control voltage (Vctrl) be not easy to leave the Linear Control interval.Shown in Fig. 6 (c), when the temperature of phase-locked loop was increased to T5 (for example 125 ℃) by T4, the control voltage (Vctrl) of voltage control oscillator was also at the interior of linear control interval and can not lose locking.
Please refer to Fig. 7 (a), it roughly selects the program schematic diagram for the frequency range that the present invention opens the loop.Suppose that voltage control oscillator has four frequency ranges (1,2,3,4), VL is that 1V, VH are 2V, and reference frequency (Fref) is 40MHz, and the N of frequency elimination unit 45 is 100.Suppose when opening the loop frequency range and roughly select program, to learn present temperature at high temperature (T6) according to temperature signal, for example more than 125 ℃, then select linear control interval border (boundary) near the magnitude of voltage of VH as opening circuit controls voltage, for example 1.95V.
When the loop is opened in the phase-locked loop, shown in Fig. 7 (a), switch the running frequency range in regular turn: after (I) selecting first frequency range (1) of voltage control oscillator, first voltage controlled frequency (Fvco1) that produces the first voltage-controlled output signal after circuit controls voltage is opened in input be 4.70G, and the first frequency elimination frequency (FD1) that can detect the first frequency elimination signal is 47.0MHz.(II) after second frequency range (2) of selection voltage control oscillator, second voltage controlled frequency (Fvco2) that produces the second voltage-controlled output signal after circuit controls voltage is opened in input be 4.48G, and the second frequency elimination frequency (FD2) that can detect the second frequency elimination signal is 44.8MHz.(III) after the 3rd frequency range (3) of selection voltage control oscillator, the 3rd voltage controlled frequency (Fvco3) that produces the 3rd voltage-controlled output signal after circuit controls voltage is opened in input be 4.25G, and the 3rd frequency elimination frequency (FD3) that can detect the 3rd frequency elimination signal is 42.5MHz.(IV) after the 4th frequency range (4) of selection voltage control oscillator, the 4th voltage controlled frequency (Fvco4) that produces the 4th voltage-controlled output signal after circuit controls voltage is opened in input be 4.04G, and the 4th frequency elimination frequency (FD4) that can detect the 4th frequency elimination signal is 40.4MHz.
Because the 4th frequency elimination frequency (FD4) of the 4th frequency elimination signal is 40.4MHz, near the reference frequency (Fref) of 40MHz, therefore, the phase-locked loop can be roughly selected the 4th frequency range (4) of voltage control oscillator and be operated.And, when annexation between (close) loop filter 30 and the voltage control oscillator 40 is closed when making that the phase-locked loop forms the loop circuit in the phase-locked loop, shown in Fig. 7 (b), the 4th frequency range (4) is operation frequency range and controls voltage (Vctrl) and will be adjusted to 1.9V voluntarily, makes the phase-locked loop stably export the voltage controlled frequency of 4GHz (Fvco).
When the normal running of phase-locked loop, when temperature by the T6 of high temperature decrescence, and in order to make the phase-locked loop stably export the voltage controlled frequency of 4GHz (Fvco), control voltage (Vctrl) can be by 1.9V decrescence.Because the frequency range of opening the loop of the present invention is roughly selected procedure Selection and is opened circuit controls voltage near VH, therefore another border (VL) of the linear control interval of control voltage (Vctrl) distance decrescence also has 0.9V, makes control voltage (Vctrl) be not easy to leave the Linear Control interval.Shown in Fig. 7 (c), when the temperature of phase-locked loop reduced to T7 (for example 10 ℃) by T6, the control voltage (Vctrl) of voltage control oscillator also can lose locking within linear control interval and not.
Therefore, the invention has the advantages that when the phase-locked loop is opened the frequency range in loop and roughly selected program, is that the temperature signal that provides according to temperature detection circuit decides out circuit controls voltage.After the Frequency Band Selection of voltage control oscillator was finished, control voltage (Vctrl) was not easy to exceed the Linear Control interval and reduces and loses the chance that locking takes place.
Fig. 8 shows the method for selection of frequency band flow chart of voltage control oscillator in according to a preferred embodiment of the present invention the phase-locked loop, applies to the loop state of opening of phase-locked loop.This flow process begins from step 800; In step 820, circuit controls voltage is opened in generation according to temperature signal, is positioned at the Linear Control interval, for example, temperature signal is to produce the current signal that circuit produced by the absolute temperature proportional current, perhaps, opens circuit controls voltage and is by the absolute temperature proportional current resistance of flowing through and produced; In step 840, input is opened circuit controls voltage to voltage control oscillator; In step 860, voltage control oscillator produces a plurality of voltage-controlled signals respectively in a plurality of frequency ranges, and for example, voltage control oscillator switches frequency range in regular turn, makes voltage control oscillator produce voltage-controlled signal in regular turn, and each voltage-controlled signal has a voltage controlled frequency; In step 880, operation frequency range when selecting a voltage-controlled signal and corresponding frequency range thereof in those voltage-controlled signals as a loop circuit state of this phase-locked loop, for example, voltage-controlled signal is imported the frequency elimination unit in regular turn carries out behind the frequency elimination voltage-controlled signal to produce the frequency elimination signal, relatively after those frequency elimination signals and the reference signal, from those frequency elimination signals, select best frequency elimination signal, the frequency system of best frequency elimination signal is near the reference frequency of this reference signal, and the corresponding voltage-controlled signal of best frequency elimination signal is selected voltage-controlled signal.
Please refer to Fig. 9, it is phase-locked loop according to a preferred embodiment of the present invention, comprises phase frequency detector 910, charge pump 920, loop filter 930, voltage control oscillator 940, frequency elimination unit 945, multiplexer 935, opens circuit controls voltage generation circuit 932, frequency comparator 950, selects logic 960 with frequency band.
, advocate to open the circuit controls signal when opening the loop in the phase-locked loop, therefore, the control voltage (Vctrl) that circuit controls voltage generation circuit 932 is produced is opened in multiplexer 935 outputs.Open circuit controls voltage generation circuit 932 and more comprise a temperature detection circuit 933, it for example is absolute temperature ratio (PTAT) current generating circuit, make the control voltage (Vctrl) of opening 932 generations of circuit controls voltage generation circuit be relevant to the temperature signal that temperature detection circuit 933 is provided, for example, can utilize the absolute temperature proportional current to flow through resistance generation cross-pressure and use is control voltage (Vctrl).Frequency band selects logic 960 to control voltage-controlled oscillator 940 and switch a plurality of frequency ranges in regular turn according to opening the circuit controls signal, making frequency band select logic 960 to select preferable frequency range in the voltage control oscillator 940 according to a plurality of difference on the frequency signals, for example is the frequency range of difference on the frequency minimum.
When being the loop circuit, separating and advocate to open the circuit controls signal in the phase-locked loop.Because the selected frequency range of voltage-controlled oscillator 940, voltage-controlled oscillator 940 produces voltage-controlled output signal according to the control voltage (Vctrl) of selected frequency range and loop filter 930 outputs, in this embodiment, control voltage (Vctrl) in the phase-locked loop has been considered the variation of ambient temperature and has been not easy to exceed the Linear Control interval, reduce losing the chance that locking takes place, significantly improve the reliability of phase-locked loop.
The present invention discloses a kind of phase-locked loop, comprising: loop filter, the exportable first control voltage; Open the circuit controls voltage generation circuit, the exportable second control voltage that is relevant to ambient temperature; Selector, for example multiplexer or switch can be opened the circuit controls signal according to 1 the first control voltage and the second control voltage are exported the 3rd control voltage alternatively; Voltage control oscillator produces voltage-controlled output signal according to the 3rd control voltage; The frequency elimination unit receives voltage-controlled output signal and carries out frequency elimination to produce the frequency elimination signal; The phase frequency detector produces phase signal according to frequency elimination signal and reference signal; Charge pump outputs current to this loop filter to produce the first control voltage in order to produce according to phase signal; Frequency comparator produces the difference on the frequency signal according to frequency elimination signal and reference signal; And frequency band is selected logic, when opening circuit controls signal opinion, a plurality of frequency ranges in the switched voltage control oscillator, and select a working frequency range of those frequency ranges in the voltage control oscillator according to a plurality of difference on the frequency signals of frequency comparator output, separate when advocating and open the circuit controls signal in this, the control voltage control oscillator produces voltage-controlled output signal according to working frequency range and the 3rd control voltage.For example, open the circuit controls voltage generation circuit and comprise that temperature detection circuit is in order to provide temperature signal, and make the second control voltage be relevant to temperature signal, perhaps, temperature detection circuit produces circuit for the absolute temperature proportional current and temperature signal produces the current signal that circuit produces for the absolute temperature proportional current, perhaps, temperature detection circuit is produced by the absolute temperature proportional current resistance of flowing through for the absolute temperature proportional current produces circuit and temperature signal.
In sum, though the present invention discloses as above with preferred embodiment, so it is not in order to limit the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention, when can doing various changes and retouching, so protection scope of the present invention should with claim the person of being defined be as the criterion.
Claims (16)
1. the method for selection of frequency band of voltage control oscillator in the phase-locked loop applies to the loop state of opening of this phase-locked loop, it is characterized in that it comprises:
Produce one according to a temperature signal and open circuit controls voltage;
Import this and open circuit controls voltage to this voltage control oscillator;
This voltage control oscillator produces a plurality of voltage-controlled signals respectively in a plurality of frequency ranges; And
By selecting a voltage-controlled signal and corresponding frequency range thereof in those voltage-controlled signals as the operation frequency range of this phase-locked loop when the loop circuit state.
2. the method for selection of frequency band of voltage control oscillator in the phase-locked loop as claimed in claim 1, it is characterized in that, this step that produces voltage-controlled signal is to switch those frequency ranges in this voltage control oscillator in regular turn, make this voltage control oscillator produce those voltage-controlled signals in regular turn, each voltage-controlled signal has a voltage controlled frequency.
3. the method for selection of frequency band of voltage control oscillator is characterized in that in the phase-locked loop as claimed in claim 1, and wherein the step of the voltage-controlled signal of this selection more comprises:
After those voltage-controlled signals are imported a frequency elimination unit in regular turn those voltage-controlled signals are carried out frequency elimination, produce a plurality of frequency elimination signals; And
Relatively produce a best frequency elimination signal after those frequency elimination signals and the reference signal;
Wherein, the frequency of this best frequency elimination signal system is near the reference frequency of this reference signal, and should be selected voltage-controlled signal by the corresponding voltage-controlled signal of the best frequency elimination signal.
4. the method for selection of frequency band of voltage control oscillator is characterized in that in the phase-locked loop as claimed in claim 1, and this temperature signal is to produce the current signal that circuit produced by an absolute temperature proportional current.
5. the method for selection of frequency band of voltage control oscillator is characterized in that in the phase-locked loop as claimed in claim 1, and this is opened circuit controls voltage and is produced by the absolute temperature proportional current resistance of flowing through.
6. the method for selection of frequency band of voltage control oscillator is characterized in that in the phase-locked loop as claimed in claim 1, and this is opened circuit controls voltage system and is positioned at a Linear Control interval.
7. the method for selection of frequency band of voltage control oscillator in the phase-locked loop as claimed in claim 6, it is characterized in that, when this temperature signal temperature indicative during in a high temperature range or a low temperature range, this is opened circuit controls voltage system and is positioned near this Linear Control section boundaries.
8. phase-locked loop is characterized in that it comprises:
One loop filter, exportable one first control voltage;
One opens the circuit controls voltage generation circuit, and exportable one is relevant to the second control voltage of ambient temperature;
One selector can be opened the circuit controls signal according to one this first control voltage and this second control voltage are output as one the 3rd control voltage alternatively;
One voltage control oscillator produces a voltage-controlled output signal according to the 3rd control voltage;
One frequency elimination unit receives this voltage-controlled output signal and carries out frequency elimination to produce a frequency elimination signal;
One phase frequency detector produces a phase signal according to this a frequency elimination signal and a reference signal; And
One charge pump outputs current to this loop filter to produce this first control voltage in order to produce one according to this phase signal.
9. phase-locked loop as claimed in claim 8 is characterized in that, more comprises:
One frequency comparator produces a difference on the frequency signal according to this frequency elimination signal and this reference signal; And
One frequency band is selected logic, when this opens circuit controls signal opinion, switches a plurality of frequency ranges in this voltage control oscillator, and selects a working frequency range of those frequency ranges in the voltage control oscillator according to a plurality of difference on the frequency signals of this frequency comparator output; And, open the circuit controls signal in this and separate when advocating, control this voltage control oscillator and produce this voltage-controlled output signal according to this working frequency range and the 3rd control voltage.
10. phase-locked loop as claimed in claim 9 is characterized in that, the 3rd control voltage system is positioned at a Linear Control interval of this working frequency range.
11. phase-locked loop as claimed in claim 9, it is characterized in that, those frequency ranges all have a Linear Control interval, and this temperature signal temperature indicative is when a high temperature range or a low temperature range, and this second control voltage system is positioned near this Linear Control section boundaries.
12. phase-locked loop as claimed in claim 8 is characterized in that, this selector is a multiplexer.
13. phase-locked loop as claimed in claim 8 is characterized in that, this selector is a switch.
14. phase-locked loop as claimed in claim 8 is characterized in that, this is opened the circuit controls voltage generation circuit and comprises that a temperature detection circuit is in order to provide a temperature signal and to make this second control voltage be relevant to this temperature signal.
15. phase-locked loop as claimed in claim 14 is characterized in that, this temperature detection circuit is that an absolute temperature proportional current produces circuit and this temperature signal produces the current signal that circuit produces for this absolute temperature proportional current.
16. phase-locked loop as claimed in claim 14 is characterized in that, this temperature detection circuit is that an absolute temperature proportional current produces circuit and this temperature signal and produced by the absolute temperature proportional current resistance of flowing through.
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| CN 200810183417 CN101753135A (en) | 2008-12-16 | 2008-12-16 | Method for selection of frequency band of voltage control oscillator in phase locked loop and related device |
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| CN 200810183417 CN101753135A (en) | 2008-12-16 | 2008-12-16 | Method for selection of frequency band of voltage control oscillator in phase locked loop and related device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103036559A (en) * | 2011-09-28 | 2013-04-10 | 晨星软件研发(深圳)有限公司 | Phase locked loop and alignment method of relevant phase positions |
| CN110429935A (en) * | 2019-07-25 | 2019-11-08 | 深圳星河半导体技术有限公司 | A kind of algorithm cutting frequency phase-locked loop and its being used |
| CN110968146A (en) * | 2019-12-12 | 2020-04-07 | 深圳星河半导体技术有限公司 | Charge pump circuit for phase-locked loop |
| CN111917422A (en) * | 2020-08-14 | 2020-11-10 | 浙江三维通信科技有限公司 | Control method and circuit of radio frequency voltage controlled oscillator |
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2008
- 2008-12-16 CN CN 200810183417 patent/CN101753135A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103036559A (en) * | 2011-09-28 | 2013-04-10 | 晨星软件研发(深圳)有限公司 | Phase locked loop and alignment method of relevant phase positions |
| CN103036559B (en) * | 2011-09-28 | 2015-11-11 | 晨星软件研发(深圳)有限公司 | Phase-locked loop and relevant phase alignment method |
| CN110429935A (en) * | 2019-07-25 | 2019-11-08 | 深圳星河半导体技术有限公司 | A kind of algorithm cutting frequency phase-locked loop and its being used |
| CN110429935B (en) * | 2019-07-25 | 2024-04-26 | 深圳星河半导体技术有限公司 | Frequency-cutting phase-locked loop and algorithm applied by same |
| CN110968146A (en) * | 2019-12-12 | 2020-04-07 | 深圳星河半导体技术有限公司 | Charge pump circuit for phase-locked loop |
| CN111917422A (en) * | 2020-08-14 | 2020-11-10 | 浙江三维通信科技有限公司 | Control method and circuit of radio frequency voltage controlled oscillator |
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Open date: 20100623 |