CN217486475U - Phase-locked loop circuit, local oscillator and electronic equipment - Google Patents

Phase-locked loop circuit, local oscillator and electronic equipment Download PDF

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CN217486475U
CN217486475U CN202221640710.7U CN202221640710U CN217486475U CN 217486475 U CN217486475 U CN 217486475U CN 202221640710 U CN202221640710 U CN 202221640710U CN 217486475 U CN217486475 U CN 217486475U
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黄胜
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Zhejiang Geoforcechip Technology Co Ltd
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Abstract

The application discloses phase-locked loop circuit, local oscillator and electronic equipment, wherein the phase-locked loop circuit includes: an initial phase-locked loop, a phase fast locked loop, and a frequency fast locked loop. The initial phase-locked loop comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator and a feedback frequency divider which are connected in sequence; the first input end of the phase fast lock loop is connected with the reference clock input end of the phase frequency detector, the second input end of the phase fast lock loop is used for receiving an externally input phase fast lock control signal, and the output end of the phase fast lock loop is connected with the phase fast lock end of the voltage-controlled oscillator; the input end of the frequency fast locking loop is used for receiving frequency band setting parameters input from outside, and the output end of the frequency fast locking loop is connected with the frequency fast locking end of the loop filter. In the application, the frequency fast locking loop enables the phase-locked loop to quickly lock the clock frequency, and the phase fast locking loop enables the phase-locked loop to quickly lock the clock phase, so that the locking time is reduced.

Description

Phase-locked loop circuit, local oscillator and electronic equipment
Technical Field
The application belongs to the technical field of electronic circuits, and particularly relates to a phase-locked loop circuit, a local oscillator and electronic equipment.
Background
A phase-locked loop circuit is commonly used in a local clock generation loop, which generates a frequency several times that of a clock, and a conventional phase-locked loop circuit architecture is shown in fig. 1 and includes a Phase Frequency Detector (PFD), a Charge Pump (CP), a Loop Filter (LF), a feedback frequency Divider (DIV), and a Voltage Controlled Oscillator (VCO). However, the entire process from frequency discrimination to phase discrimination of the actual pll consumes too much time, and other modules need to set aside the pll locking time. Therefore, how to reduce the locking time of the pll is an urgent technical problem to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
In view of this, embodiments of the present disclosure provide a method for reducing a locking time of a phase-locked loop, a phase-locked loop circuit, a local oscillator, and an electronic device, so as to solve the problem of an excessively long locking time of the phase-locked loop in the prior art.
In a first aspect, an embodiment of the present application provides a phase-locked loop circuit, including:
the system comprises an initial phase-locked loop, a phase fast locking loop and a frequency fast locking loop;
the initial phase-locked loop comprises a phase frequency detector PFD, a charge pump CP, a loop filter LF, a voltage controlled oscillator VCO and a feedback frequency divider DIV which are connected in sequence;
a first input end of the phase fast lock loop is connected to a reference clock input end of the Phase Frequency Detector (PFD), and a second input end of the phase fast lock loop is used for receiving an externally input phase fast lock control signal; the output end of the phase fast locking loop is connected with the phase fast locking end of a VCO (voltage controlled oscillator);
the input end of the frequency fast-locking loop is used for receiving externally input frequency band setting parameters; and the output end of the frequency fast locking loop is connected with the frequency fast locking end of the loop filter LF.
In one possible implementation, the phase locked loop includes: the delay unit, the first AND gate and the second AND gate;
the input end of the delay unit is a first input end of the phase fast lock loop, and the output end of the delay unit is connected to a first input end of the first AND gate;
the second input end of the first AND gate is connected to the input end of the delay unit, and the output end of the first AND gate is connected to the first input end of the second AND gate;
the second input end of the second and gate is the second input end of the phase fast lock loop, and the output end of the second and gate is the output end of the phase fast lock loop.
In one possible implementation, the frequency fast loop circuit includes: a digital-to-analog converter DAC and an output Buffer;
the input end of the digital-to-analog converter DAC is the input end of the frequency fast-locking loop, and the output end of the digital-to-analog converter DAC is connected to the positive input end of the output Buffer;
and the negative input end of the output Buffer is connected with the output end of the output Buffer, and the output end of the output Buffer is the output end of the frequency fast lock loop.
According to the phase-locked loop circuit of the embodiment of the first aspect of the application, the phase-locked loop circuit and the frequency-locked loop circuit are added on the basis of the initial phase-locked loop circuit, the frequency-locked loop circuit enables the phase-locked loop circuit to quickly lock the clock frequency, and the phase-locked loop circuit enables the phase-locked loop circuit to quickly lock the clock phase, so that the locking time is reduced.
In a second aspect, an embodiment of the present application provides a method for reducing a locking time of a phase-locked loop, where the phase-locked loop circuit according to the first aspect is applied, and the method includes:
the frequency fast locking loop receives frequency section setting parameters input from the outside so that the initial phase-locked loop can quickly lock a corresponding frequency section in the starting process, and after the initial phase-locked loop locks the corresponding frequency section, the frequency fast locking loop is disconnected with the loop filter LF;
after the initial phase-locked loop is locked in a corresponding frequency section, the phase fast-locking loop enters a phase fast-locking stage according to an externally input phase fast-locking control signal; in the phase fast lock phase, the phase fast lock loop injects a rising edge of the reference clock to the voltage controlled oscillator VCO, so that the initial phase lock loop performs phase lock quickly.
In one possible implementation, the frequency fast-locking loop receives an externally input frequency segment setting parameter to enable an initial phase-locked loop to fast lock a corresponding frequency segment during a startup process, and includes:
the DAC sets the DAC to the corresponding frequency band according to the frequency band setting parameters input from the outside, so that the initial phase-locked loop can quickly lock the corresponding frequency band in the starting process.
In one possible implementation, the disconnecting of the frequency fast-locked loop from the loop filter LF after the initial phase-locked loop locks in the corresponding frequency segment includes:
after the initial phase-locked loop is locked at the corresponding frequency band, the output Buffer is set to a high resistance state, so that the frequency fast-locked loop is disconnected from the loop filter LF.
In a third aspect, an embodiment of the present application provides a local oscillator including the phase-locked loop circuit of the first aspect.
In a possible implementation manner, the local oscillator further includes a first control switch, a frequency divider, and a second control switch, which are connected in sequence; the output end of the second control switch is connected to the reference signal input end of the phase-locked loop circuit;
the first control switch is used for switching an accessed external on-chip oscillator or an accessed external clock;
and the second control switch is used for controlling whether the clock signal from the first control switch passes through the frequency divider or is directly connected with the phase-locked loop circuit.
In one possible implementation, the frequency divider is a divide-by-two frequency divider.
In the local oscillator according to the third aspect of the present application, a phase fast-locking loop and a frequency fast-locking loop are added on the basis of an initial phase-locked loop, the frequency fast-locking loop enables the phase-locked loop to quickly lock a clock frequency, and the phase fast-locking loop enables the phase-locked loop to quickly lock a clock phase, thereby reducing a locking time.
In a fourth aspect, an embodiment of the present application provides an electronic device, which includes the local oscillator of the third aspect.
According to the electronic equipment in the fourth aspect of the application, the phase fast locking loop and the frequency fast locking loop are added on the basis of the initial phase-locked loop, the frequency fast locking loop enables the phase-locked loop to fast lock the clock frequency, and the phase fast locking loop enables the phase-locked loop to fast lock the clock phase, so that the locking time is reduced.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic diagram of a prior art phase-locked loop;
FIG. 2 illustrates a schematic diagram of a phase locked loop circuit of the present application;
fig. 3 shows a circuit diagram of a charge pump CP, a loop filter LF and a voltage controlled oscillator VCO of the present application;
FIG. 4 is a flow chart of a method of reducing phase-locked loop lock time of the present application;
FIG. 5 shows a schematic diagram of a local oscillator of the present application;
fig. 6 shows a circuit diagram of an on-chip oscillator of the present application.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As shown in fig. 2, an embodiment of the present application provides a phase-locked loop circuit 10, including: an initial phase locked loop, a phase locked loop 100, and a frequency locked loop 200.
Specifically, the initial phase-locked loop includes a phase frequency detector PFD, a charge pump CP, a loop filter LF, a voltage controlled oscillator VCO, and a feedback frequency divider DIV, which are connected in sequence.
The initial phase-locked loop is the same as the conventional phase-locked loop shown in fig. 1, and the phase fast-locked loop 100 and the frequency fast-locked loop 200 are added to the initial phase-locked loop, which will be described in detail below.
The first input end 101 of the phase fast-locking loop 100 is connected to the reference clock input end of the phase frequency detector PFD, the second input end 102 of the phase fast-locking loop 100 is used for receiving an externally input phase fast-locking control signal LK, the phase fast-locking control signal LK can control the phase fast-locking loop 100 to work or not work according to actual requirements, and the phase fast-locking control signal LK can enable the initial phase-locking loop to perform a fast phase-locking stage during work and is disconnected from the initial phase-locking loop during non-work. The output terminal 103 of the phase fast lock loop 100 is connected to the phase fast lock terminal PL of the voltage controlled oscillator VCO. The phase locked loop 100 may utilize an injection locking manner to input a rising edge of a reference clock to the VCO through the phase locked terminal PL, so that the initial phase locked loop performs phase locking quickly.
The input end 201 of the frequency fast-locking loop 200 is used for receiving an externally input frequency band setting parameter. The output 202 of the frequency fast lock loop 200 is connected to the frequency fast lock end FL of the loop filter LF.
It should be mentioned that, the voltage-frequency conversion curve of the voltage-controlled oscillator VCO may be divided into 2 to 4 equal parts or more equal parts according to the frequency range in advance according to the actual requirement, and each equal part is divided into a frequency segment, so that the frequency locking range of the frequency fast-locking loop 200 may be set, thereby facilitating fast frequency locking. For example, if the frequency locking range of the frequency fast lock loop 200 is preset to 90-110Hz, the frequency fast lock loop 200 can help the initial phase lock loop to quickly lock the frequency at 100Hz through the frequency fast lock end FL, if the frequency of the reference clock is 100 Hz.
The phase-locked loop circuit provided by the application has the following specific working process:
the frequency fast-lock loop 200 receives a frequency band setting parameter inputted from the outside, so that the initial phase-lock loop rapidly locks the corresponding frequency band during the starting process, and after the initial phase-lock loop locks the corresponding frequency band, the frequency fast-lock loop 200 disconnects from the loop filter LF.
The phase fast lock loop 100 enters the phase fast lock stage according to the externally input phase fast lock control signal LK after the initial phase lock loop locks at the corresponding frequency segment. In the phase fast lock phase, the phase fast lock loop 100 injects a rising edge of the reference clock to the voltage controlled oscillator VCO, so that the initial phase lock loop performs phase lock quickly.
Referring to fig. 3, a circuit diagram of the charge pump CP, the loop filter LF, and the voltage controlled oscillator VCO according to some embodiments of the present application is shown. As shown in fig. 3, the charge pump CP, the loop filter LF, and the voltage controlled oscillator VCO are integrally designed as a module in the present application, which makes the circuit design easier to implement.
Specifically, as shown in fig. 2 and 3, the current on-time of the charge pump CP is controlled by DP and DN output from the phase frequency detector PFD, and the current of the charge pump CP is Icp generated by the mirror current array, and the current of the charge pump CP can be modified by modifying Icp. The phase fast lock terminal PL is the location where the phase fast lock loop 100 is accessed, and the frequency fast lock terminal FL is the location where the frequency fast loop 200 is accessed.
In some embodiments according to the present application, as shown in fig. 2, the phase fast lock loop 100 may include: delay unit 110, first and gate 120, and second and gate 130.
The input of the delay unit 110 is the first input 101 of the phase locked loop, and the output of the delay unit 110 is connected to the first input of the first and gate 120.
A second input terminal of the first and gate 120 is connected to the input terminal of the delay unit 110, and an output terminal of the first and gate 120 is connected to a first input terminal of the second and gate 130.
The second input terminal of the second and gate 130 is the second input terminal 102 of the phase locked loop, and the output terminal of the second and gate 130 is the output terminal 103 of the phase locked loop.
Specifically, one path of the reference clock enters the delay unit 110 to generate a certain delay and then enters the first and gate 120, the other path of the reference clock directly enters the first and gate 120, the delayed reference clock and the undelayed reference clock are subjected to phase-and-then enter the second and gate 130, and the rising edge of the reference clock enters the voltage controlled oscillator VCO by means of injection locking through the phase lock port PL after the phase-and-phase of the second and gate 130 and the phase lock control signal LK.
According to some embodiments of the present application, as shown in fig. 2, the frequency fast-lock loop 200 may include: a digital-to-analog converter DAC 210 and an output Buffer 220;
the input end of the digital-to-analog converter 210 is the input end 201 of the frequency fast-locking loop 200, and the output end of the digital-to-analog converter 210 is connected to the positive input end of the output buffer 220;
the negative input of the output buffer 220 is connected to its output, and the output of the output buffer 220 is the output 202 of the frequency fast lock loop 200.
Specifically, the DAC 210 may adopt a 4-bit DAC, and the DAC 210 sets itself in a corresponding frequency band according to an externally input frequency band setting parameter, so that the initial phase-locked loop can quickly lock the corresponding frequency band in the starting process. After the initial phase-locked loop locks at the corresponding frequency band, the output buffer 220 is set to a high resistance state, so that the frequency fast-locked loop 200 is disconnected from the loop filter LF.
According to the phase-locked loop circuit, the phase fast locking loop and the frequency fast locking loop are added on the basis of the initial phase-locked loop, the frequency fast locking loop enables the phase-locked loop to quickly lock the clock frequency, and the phase fast locking loop enables the phase-locked loop to quickly lock the clock phase, so that the locking time of the phase-locked loop is shortened.
Based on the phase-locked loop circuit of the above embodiment, an embodiment of the present application further provides a method for reducing a locking time of a phase-locked loop, as shown in fig. 4, the method includes the following steps:
s101, a frequency fast locking loop receives frequency band setting parameters input from the outside so as to enable an initial phase-locked loop to quickly lock a corresponding frequency band in the starting process, and after the initial phase-locked loop locks the corresponding frequency band, the frequency fast locking loop is disconnected from a loop filter LF;
s102, after the initial phase-locked loop is locked in a corresponding frequency section, the phase fast lock loop enters a phase fast lock stage according to an externally input phase fast lock control signal; in the phase fast lock phase, the phase fast lock loop injects a rising edge of the reference clock to the voltage controlled oscillator VCO, so that the initial phase lock loop performs phase lock quickly.
In a possible implementation manner, in step S101, the frequency fast-locking loop receives a frequency band setting parameter input from the outside, so that the initial phase-locked loop quickly locks a corresponding frequency band in the starting process, specifically including:
the DAC sets itself in the corresponding frequency band according to the frequency band setting parameters input from outside, so that the initial phase-locked loop can lock the corresponding frequency band quickly in the starting process.
In one possible implementation manner, in step S101, after the initial phase-locked loop locks in the corresponding frequency band, the disconnecting of the frequency fast-locked loop from the loop filter LF specifically includes:
after the initial phase-locked loop is locked at the corresponding frequency band, the output Buffer is set to a high resistance state, so that the frequency fast-locked loop is disconnected from the loop filter LF.
According to the method for shortening the locking time of the phase-locked loop, the phase-locked loop and the frequency-locked loop are added on the basis of the initial phase-locked loop, the frequency-locked loop enables the phase-locked loop to quickly lock the clock frequency, and the phase-locked loop enables the phase-locked loop to quickly lock the clock phase, so that the locking time of the phase-locked loop is shortened.
The embodiment of the present application provides a local oscillator including the phase-locked loop circuit 10 of the above embodiment. It can be seen that the present application also designs a complete local oscillation generation loop, i.e. the local oscillator, based on the phase-locked loop circuit 10.
According to some implementations of the present application, as shown in fig. 5, the local oscillator further includes a first control switch 20, a frequency divider 30, and a second control switch 40 connected in sequence; the output terminal of the second control switch 40 is connected to the reference signal input terminal of the phase-locked loop circuit 10.
The first control switch 20 is used for switching an external on-chip oscillator or an external clock, and may adopt a 2-way gate MUX.
The second control switch 40 is used to control whether the clock signal from the first control switch 20 passes through the frequency divider 30 or passes through the phase-locked loop circuit 10, and a 2-way gate MUX may be used.
In some implementations according to the application, the frequency divider is a divide-by-two divider. Of course, it may be a frequency tripler or a frequency quadrupler, which is not limited in this application.
As shown in fig. 6, a circuit diagram of an on-chip oscillator is adopted in the local oscillation generating loop of the present application, the on-chip oscillator shown in fig. 6 is used, and the bias of the on-chip oscillator is mainly determined by the devices M1, M2 and R1 shown in fig. 6.
As can be known from the related art, the current I1 and the resistor R1 in fig. 6 have an inverse square relationship, and therefore R1 can be set as a controllable resistor array to realize the adjustment of the current I1. The core circuit of the on-chip oscillator is formed by an oscillator in the form of a comparator, the frequency Fre of which is:
Figure BDA0003717331690000081
Figure BDA0003717331690000082
wherein Vref is a reference voltage, and I is a current of a core circuit of the oscillator. The Vref voltage is a comparator reference voltage that is controlled by a resistor array of R2.
The local oscillator provided by the embodiment of the application has the advantages that the phase fast locking loop and the frequency fast locking loop are added on the basis of the initial phase-locked loop, the frequency fast locking loop enables the phase-locked loop to rapidly lock the clock frequency, and the phase fast locking loop enables the phase-locked loop to rapidly lock the clock phase, so that the locking time is reduced.
An embodiment of the present application further provides an electronic device, which includes the local oscillator of the above embodiment. The electronic device may be any electronic device that employs a local oscillator, such as a communication device.
The electronic equipment provided by the embodiment of the application is additionally provided with the phase fast locking loop and the frequency fast locking loop on the basis of the initial phase-locked loop, the frequency fast locking loop enables the phase-locked loop to quickly lock the clock frequency, and the phase fast locking loop enables the phase-locked loop to quickly lock the clock phase, so that the locking time is reduced.
It should be noted that:
in the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the application and aiding in the understanding of one or more of the various application aspects. However, the disclosed method should not be construed to reflect the intent: this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Rather, as the following claims reflect, application is directed to less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this application.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
The various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components in the creation apparatus of a virtual machine according to embodiments of the present application. The present application may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present application may be stored on a computer readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (7)

1. A phase-locked loop circuit, comprising:
the system comprises an initial phase-locked loop, a phase fast locking loop and a frequency fast locking loop;
the initial phase-locked loop comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator and a feedback frequency divider which are connected in sequence;
the first input end of the phase fast lock loop is connected with the reference clock input end of the phase frequency detector, the second input end of the phase fast lock loop is used for receiving an externally input phase fast lock control signal, and the output end of the phase fast lock loop is connected with the phase fast lock end of the voltage-controlled oscillator;
the input end of the frequency fast locking loop is used for receiving frequency band setting parameters input from the outside, and the output end of the frequency fast locking loop is connected to the frequency fast locking end of the loop filter.
2. The phase-locked loop circuit of claim 1, wherein the phase-locked loop circuit comprises: the delay unit, the first AND gate and the second AND gate;
the input end of the delay unit is a first input end of the phase fast lock loop, and the output end of the delay unit is connected to a first input end of the first AND gate;
the second input end of the first AND gate is connected to the input end of the delay unit, and the output end of the first AND gate is connected to the first input end of the second AND gate;
the second input end of the second and gate is the second input end of the phase fast lock loop, and the output end of the second and gate is the output end of the phase fast lock loop.
3. The phase-locked loop circuit of claim 1 or 2, wherein the frequency-fast loop circuit comprises: a digital-to-analog converter and an output buffer;
the input end of the digital-to-analog converter is the input end of the frequency fast lock loop, and the output end of the digital-to-analog converter is connected to the positive input end of the output buffer;
the negative input end of the output Buffer is connected with the output end of the output Buffer, and the output end of the output Buffer is the output end of the frequency fast-locking loop.
4. A local oscillator comprising a phase locked loop circuit as claimed in any one of claims 1 to 3.
5. The local oscillator of claim 4, further comprising a first control switch, a frequency divider, and a second control switch connected in sequence; the output end of the second control switch is connected to the reference signal input end of the phase-locked loop circuit;
the first control switch is used for switching an accessed external on-chip oscillator or an accessed external clock;
and the second control switch is used for controlling whether the clock signal from the first control switch passes through the frequency divider or is directly connected with the phase-locked loop circuit.
6. The local oscillator of claim 5, wherein the frequency divider is a divide-by-two divider.
7. An electronic device, characterized in that it comprises a local oscillator according to any one of claims 4 to 6.
CN202221640710.7U 2022-06-28 2022-06-28 Phase-locked loop circuit, local oscillator and electronic equipment Active CN217486475U (en)

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