CN113630116B - Phase-locked loop feedback circuit, phase-locked loop circuit and intercom communication device - Google Patents

Phase-locked loop feedback circuit, phase-locked loop circuit and intercom communication device Download PDF

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Publication number
CN113630116B
CN113630116B CN202010381170.4A CN202010381170A CN113630116B CN 113630116 B CN113630116 B CN 113630116B CN 202010381170 A CN202010381170 A CN 202010381170A CN 113630116 B CN113630116 B CN 113630116B
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circuit
phase
locked
low
capacitor
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CN113630116A (en
Inventor
胡展威
郭锡荣
马晓波
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Guangzhou Haige Communication Group Inc Co
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Guangzhou Haige Communication Group Inc Co
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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
    • H03L7/0802—Details of the phase-locked loop the loop being adapted for reducing power consumption
    • 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
    • H03L7/0805—Details of the phase-locked loop the loop being adapted to provide an additional control signal for use outside the loop
    • 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
    • H03L7/085—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal
    • H03L7/093—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal using special filtering or amplification characteristics in the loop

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Abstract

The application relates to a phase-locked loop feedback circuit, a phase-locked loop circuit and intercom communication equipment, wherein the phase-locked loop feedback circuit comprises a low-pass filter circuit which is used for respectively connecting a resonance circuit and the phase-locked loop circuit; the low-pass filter circuit is used for carrying out low-pass filtering on the phase-locked signal output by the resonance circuit and outputting the phase-locked signal after filtering to the phase-locked circuit; the switching circuit is connected with the low-pass filter circuit; the trap circuit is connected with the switch circuit and used for filtering harmonic signals in the phase-locked signals; and the controller is connected with the switching circuit and used for acquiring a target frequency point, when the target frequency point is in a low-frequency range, the switching circuit is turned on, and when the target frequency point is in a high-frequency range, the switching circuit is turned off, so that the low-pass filter circuit can be utilized to carry out low-pass filter processing on a high-frequency range or low-frequency range phase-locked signal, and the trap circuit is utilized to inhibit the harmonic wave of the low-frequency range phase-locked signal, so that the harmonic suppression degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.

Description

Phase-locked loop feedback circuit, phase-locked loop circuit and intercom communication device
Technical Field
The present invention relates to the field of electronic circuits, and in particular, to a phase-locked loop feedback circuit, a phase-locked loop circuit, and intercom communication equipment.
Background
Currently, three models are generally required for communication devices such as interphones, vehicle-mounted stations, and intermediate stations in private networks to cover a U frequency band (330 MHz to 527 MHz). In order to save the hardware development cost and improve the product competitiveness, a broadband scheme supporting the feedback of a broadband phase-locked loop is developed, and the broadband phase-locked loop can be realized by sharing a set of hardware platform and only being configured to a corresponding frequency band when leaving a factory.
The conventional feedback circuit of the phase-locked loop is mostly implemented by adopting a bandpass scheme, that is, a bandpass filter, and the basic structure of the feedback circuit can be shown in fig. 1. However, the inventors found that there are at least the following problems in the conventional art: the traditional circuit has the problem of high lock losing risk.
Disclosure of Invention
Based on this, it is necessary to provide a phase-locked loop feedback circuit, a phase-locked loop circuit, and an intercom communication device capable of reducing the risk of losing lock.
A phase locked loop feedback circuit comprising:
The low-pass filter circuit is used for respectively connecting the resonant circuit and the phase-locked circuit; the low-pass filter circuit is used for carrying out low-pass filtering on the phase-locked signal output by the resonance circuit and outputting the phase-locked signal after filtering to the phase-locked circuit;
the switching circuit is connected with the low-pass filter circuit;
The trap circuit is connected with the switch circuit and used for filtering harmonic signals in the phase-locked signals;
and the controller is connected with the switching circuit and used for acquiring a target frequency point, switching on the switching circuit when the target frequency point is in a low-frequency range, and switching off the switching circuit when the target frequency point is in a high-frequency range.
In one embodiment, the number of trap circuits is at least two; the number of the switch circuits is the same as that of the trap circuits;
the trap circuits are connected with the switch circuits in a one-to-one correspondence.
In one embodiment, the number of trap circuits is 2; the number of the switch circuits is 2; the low-pass filter circuit comprises an input end used for being connected with the resonance circuit and an output end used for being connected with the phase-locked circuit;
Any switch circuit is connected with the input end; the other switch circuit is connected with the output end.
In one embodiment, further comprises a capacitor C1; a capacitor C1 is connected between the resonant circuit and the input terminal.
In one embodiment, the low-pass filter circuit includes an inductor L1, an inductor L2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, and a capacitor C8;
one end of the inductor L1 is respectively connected with one end of the capacitor C2, one end of the capacitor C3 and one end of the capacitor C4, and the other end of the inductor L1 is respectively connected with the other end of the capacitor C2, one end of the capacitor C5, one end of the capacitor C6 and one end of the inductor L2; the other end of the inductor L2 is respectively connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8;
the other end of the capacitor C3 is connected with the switch circuit and is used for being connected with the resonant circuit; the other end of the capacitor C7 is used for connecting a phase-locked circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are grounded.
In one embodiment, the trap circuit includes an inductance L3 and a capacitance C9;
One end of the inductor L3 is connected with one end of the capacitor C9, and the other end of the inductor L3 is connected with the switch circuit; the other end of the capacitor C9 is grounded.
In one embodiment, the switching circuit includes a resistor R1, a diode, and a resistor R2;
One end of the resistor R1 is connected with the controller, and the other end of the resistor R1 is respectively connected with the low-pass filter circuit and the anode of the diode; the negative electrode of the diode is respectively connected with the trap circuit and one end of the resistor R2; the other end of the resistor R2 is grounded.
The phase-locked loop feedback circuit comprises a low-pass filter circuit, a resonant circuit and a phase-locked circuit, wherein the low-pass filter circuit is used for being connected with the resonant circuit and the phase-locked circuit respectively; the low-pass filter circuit is used for carrying out low-pass filtering on the phase-locked signal output by the resonance circuit and outputting the phase-locked signal after filtering to the phase-locked circuit; the switching circuit is connected with the low-pass filter circuit; the trap circuit is connected with the switch circuit and used for filtering harmonic signals in the phase-locked signals; and the controller is connected with the switching circuit and used for acquiring a target frequency point, switching on the switching circuit when the target frequency point is in a low-frequency range, and switching off the switching circuit when the target frequency point is in a high-frequency range. When the target frequency point is in the low frequency range, the switch circuit is turned on, and when the target frequency point is in the high frequency range, the switch circuit is turned off, so that the low-pass filter circuit can be used for carrying out low-pass filter processing on the phase-locked signals in the high frequency range or the low frequency range, and the trap circuit is used for inhibiting the harmonic waves of the phase-locked signals in the low frequency range, so that the harmonic wave inhibition degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.
A control method for a phase-locked loop feedback circuit, for controlling the phase-locked loop feedback circuit in any of the above embodiments, the method comprising the steps of:
Acquiring a target frequency point, switching on a switching circuit when the target frequency point is in a low-frequency range, and switching off the switching circuit when the target frequency point is in a high-frequency range; the switch circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for respectively connecting the resonance circuit and the phase-locked circuit, performing low-pass filtering on the phase-locked signal output by the resonance circuit, and outputting the filtered phase-locked signal to the phase-locked circuit; the trap circuit is used for filtering harmonic signals in the phase-locked signals.
According to the phase-locked loop feedback circuit control method, the target frequency point is obtained, when the target frequency point is in the low-frequency range, the switch circuit is turned on, and when the target frequency point is in the high-frequency range, the switch circuit is turned off; the switch circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for respectively connecting the resonance circuit and the phase-locked circuit, performing low-pass filtering on the phase-locked signal output by the resonance circuit, and outputting the filtered phase-locked signal to the phase-locked circuit; the trap circuit is used for filtering harmonic signals in the phase-locked signals, so that the low-pass filter circuit can be used for carrying out low-pass filter processing on the high-frequency band or low-frequency band phase-locked signals, and the trap circuit is used for inhibiting the harmonic waves of the low-frequency band phase-locked signals, so that the harmonic suppression degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.
A phase-locked loop circuit comprising a phase-locked loop circuit, a loop filter, a resonant circuit, and a phase-locked loop feedback circuit according to any of the above embodiments;
the phase-locked circuit is respectively connected with the low-pass filter circuit and the loop filter; the loop filter is connected with the resonant circuit; the resonant circuit connects the low pass filter circuit and the switch circuit.
The phase-locked loop circuit comprises a phase-locked circuit, a loop filter, a resonance circuit and a phase-locked loop feedback circuit; the phase-locked circuit is respectively connected with the low-pass filter circuit and the loop filter; the loop filter is connected with the resonant circuit; the resonant circuit connects the low pass filter circuit and the switch circuit. The application can filter the phase-locked signal of the high frequency band through the low-pass filter circuit in the phase-locked loop feedback circuit, and filter and harmonic suppression are carried out on the phase-locked signal of the low frequency band through the low-pass filter circuit and the harmonic circuit, thereby reducing the insertion loss, lowering the output power of the resonant circuit, and further reducing the power consumption of the phase-locked loop circuit while reducing the risk of losing lock.
An intercom communication device comprising a phase-locked loop circuit as in any one of the embodiments described above.
The intercom communication equipment comprises the phase-locked loop circuit, the low-pass filter circuit in the phase-locked loop feedback circuit is used for filtering the phase-locked signal in the high frequency band, and the low-pass filter circuit and the harmonic circuit are used for filtering and harmonic suppression of the phase-locked signal in the low frequency band, so that the insertion loss can be reduced, the output power of the resonance circuit is reduced, and the power consumption of the phase-locked loop circuit can be reduced while the unlocking risk is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments or the conventional techniques of the present application, the drawings required for the descriptions of the embodiments or the conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.
FIG. 1 is a circuit diagram of a conventional phase-locked loop feedback circuit;
FIG. 2 is a schematic diagram of a conventional phase-locked loop feedback circuit;
FIG. 3 is a diagram of simulation results of a conventional PLL feedback circuit;
FIG. 4 is a schematic block diagram of a phase-locked loop feedback circuit in one embodiment;
FIG. 5 is a first circuit diagram of a phase-locked loop feedback circuit in one embodiment;
FIG. 6 is a second circuit diagram of a phase locked loop feedback circuit in one embodiment;
FIG. 7 is a schematic diagram of a simulation of the circuit diagram of FIG. 6 in one embodiment;
FIG. 8 is a diagram of the low-band simulation result of the circuit diagram of FIG. 6 in one embodiment;
FIG. 9 is a diagram of the results of the high-band simulation of the circuit diagram of FIG. 6 in one embodiment;
FIG. 10 is a third circuit diagram of a phase locked loop feedback circuit in one embodiment;
fig. 11 is a circuit diagram of a phase locked loop circuit in one embodiment.
Reference numerals illustrate:
a low pass filter circuit 100; a switching circuit 200; a trap circuit 300; a controller 400.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that the terms first, second, etc. as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, the resistor R1 may be referred to as a resistor R2, and similarly, the resistor R2 may be referred to as a resistor R1, without departing from the scope of the present application. Both resistors R1 and R2 are resistors, but they are not the same resistor.
It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them. "filtering" and "filtering" are understood to mean attenuation of a signal of a specific frequency/specific frequency band. The "plurality" may be at least two.
As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, the term "and/or" as used in this specification includes any and all combinations of the associated listed items.
As described in the background art, the phase-locked loop feedback circuit in the prior art has the problem of high risk of losing lock, and most of the phase-locked loop circuit is implemented by using an external VCO (Voltage Controller Oscillator, voltage-controlled oscillator), so that the effects of low insertion loss and high harmonic suppression ratio in the useful frequency band are realized when the radio frequency feedback signal of the wideband phase-locked loop is designed, and the difficulty is high. The inventor researches and discovers that the reason for the problem is that the traditional circuit suppresses out-of-band signals by singly utilizing the trap point of the band pass, the insertion loss of high-frequency points is large, and the suppression ratio of low-frequency harmonic waves is low. The risk of losing lock of the phase-locked loop circuit is increased when harmonic suppression, particularly low-end harmonic suppression, is low, and particularly the risk of losing lock is greatly increased in a high-low-temperature working environment.
The circuit structure shown in fig. 1 is simulated by using radio frequency simulation software ADS, a simulation schematic diagram may be shown in fig. 2, and a simulation result may be shown in fig. 3. Referring to fig. 3, the conventional circuit has a suppression degree of less than 20dB (decibel) at a harmonic suppression, for example, a harmonic of 330MHz and a frequency of 660MHz, and a insertion loss in a frequency band of 330MHz to 527MHz is as high as 1.5dB to 3dB, and in an actual circuit implementation, the insertion loss value of the frequency band is larger than that obtained by simulation, so that the power consumption of the phase-locked loop circuit is greatly increased.
Based on the reasons, the invention provides the phase-locked loop feedback circuit, and the switch circuit is turned on when the target frequency band is in the low frequency band range, so that the low-pass filter circuit can be used for carrying out low-pass filter processing on the phase-locked signal, and the trap circuit is used for inhibiting the harmonic wave of the phase-locked signal, so that the harmonic wave inhibition degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.
In one embodiment, as shown in fig. 4, a phase locked loop feedback circuit is provided, comprising:
A low-pass filter circuit 100 for connecting the resonant circuit and the phase-locked circuit, respectively; the low-pass filter circuit 100 is configured to perform low-pass filtering on the phase-locked signal output by the resonant circuit, and output the filtered phase-locked signal to the phase-locked circuit;
a switching circuit 200 connected to the low-pass filter circuit 100;
The trap circuit 300 is connected with the switch circuit 200 and is used for filtering harmonic signals in the phase-locked signals;
The controller 400 is connected to the switch circuit 200, and is configured to obtain a target frequency point, turn on the switch circuit 200 when the target frequency point is in a low frequency range, and turn off the switch circuit 200 when the target frequency point is in a high frequency range.
Specifically, the phase-locked loop feedback circuit includes a low-pass filter circuit 100, a switch circuit 200, a trap circuit 300, and a controller 400, wherein the low-pass filter circuit 100 can be used to filter out high frequency components in the phase-locked signal and retain low frequency components. The low pass filter circuit 100 may be any form of filter including, but not limited to, a butterworth filter, a chebyshev filter, or an elliptic filter.
Meanwhile, the low-pass filter circuit 100 may be implemented by connecting a plurality of separate elements, or may be implemented by using an integrated device. It should be noted that, the device parameters of the low-pass filter circuit 100 in the present application may be determined according to the filter indexes, such as passband cutoff frequency, stopband cutoff frequency, passband maximum attenuation, stopband minimum attenuation, 3dB cutoff frequency, etc., and any filter design method in the prior art may be used to obtain the low-pass filter circuit 100 in the present application.
The switching circuit 200, including an on state and an off state, can adjust its own switching state according to the received signal. The switching circuit 200 may be implemented by a combination of a plurality of electronic components, or may be implemented by a single controllable switching device. The controllable switching device may be implemented as any type and model of switching device, including, but not limited to, a transistor, a MOS transistor, a diode D, IGBT (Insulated Gate Bipolar Transistor, an insulated gate bipolar transistor), and the like, for example.
The trap circuit 300 may be used to filter out signals of a specific frequency/specific frequency band, and in the present application, the trap circuit 300 may be used to filter out harmonic signals in a phase-locked circuit, such as a second harmonic and a third harmonic. The controller 400 is configured to obtain a target frequency point, and control a switching state of the switching circuit 200 according to a frequency band where the target frequency point is located.
Specifically, referring to fig. 1, the low-pass filter circuit 100 is connected to the switch circuit 200 and is used to connect the resonant circuit and the phase-locked circuit, respectively. The switching circuit 200 is connected to the trap circuit 300 and the controller 400, respectively, and is used to connect a resonant circuit and/or a phase-locked circuit. The controller 400 is configured to obtain a target frequency point, and when the target frequency point is in a low frequency range, the controller 400 may control the switch circuit 200 to be turned on, and the trap circuit 300 is connected to the low-pass filter circuit 100 through the switch circuit 200. When the phase-locked signal output by the resonance circuit is received, the high-frequency component in the phase-locked signal can be filtered by the low-pass filter circuit 100, and the harmonic signal in the low-frequency band phase-locked signal can be filtered by the trap circuit 300.
When the target frequency point is in the high-band range, the controller 400 may control the switching circuit 200 to enter the off state. When the switch circuit 200 is in the off state, the trap circuit 300, the switch circuit 200 and the low-pass filter circuit 100 are in the off state, the trap circuit 300 is not connected with the low-pass filter circuit, the low-pass filter circuit 100 filters out high-frequency components in the phase-locked signal output by the resonant circuit, and the phase-locked signal after the low-pass filter treatment enters the phase-locked circuit. According to the application, whether the notch point is introduced or not can be controlled according to the frequency range of the target frequency point, instead of adopting a fixed notch suppression circuit, the harmonic notch circuit 300 can be reasonably introduced in the aspect of harmonic suppression, so that the suppression degree of the harmonic wave can be improved, the risk of losing lock of the phase-locked loop is reduced, and the feedback modes of high harmonic suppression, low passband insertion loss and wide frequency bandwidth are realized.
Further, the number of the trap circuits 300 in the present application may be one or more, for example, 1,2, or 3. When the number of the notches is 1, the switch circuit 200 may be connected to the low-pass filter circuit 100 through a capacitor, or an equivalent circuit of the capacitor. When the number of the trap circuits 300 is plural, one or more switch circuits 200 may be used to control the connection states of the respective trap circuits 300 and the low-pass filter circuit 100. The low-frequency range and the high-frequency range can be determined according to an application scenario and/or a communication frequency range, for example, when the phase-locked loop circuit is applied to a broadband intercom system covering a U frequency range, the low-frequency range can be 330MHz to 428MHz, and the high-frequency range can be 428MHz to 527MHz.
The phase-locked loop feedback circuit comprises a low-pass filter circuit 100, which is used for respectively connecting a resonance circuit and a phase-locked circuit; the low-pass filter circuit 100 is configured to perform low-pass filtering on the phase-locked signal output by the resonant circuit, and output the filtered phase-locked signal to the phase-locked circuit; a switching circuit 200 connected to the low-pass filter circuit 100; the trap circuit 300 is connected with the switch circuit 200 and is used for filtering harmonic signals in the phase-locked signals; the controller 400 is connected to the switch circuit 200, and is configured to obtain a target frequency point, turn on the switch circuit 200 when the target frequency point is in a low frequency range, and turn off the switch circuit 200 when the target frequency point is in a high frequency range. In the application, when the target frequency point is in the low frequency range, the switch circuit 200 is turned on, and when the target frequency point is in the high frequency range, the switch circuit 200 is turned off, so that the low-pass filter circuit 100 can be utilized to carry out low-pass filter processing on the high frequency range or the low frequency range phase-locked signal, and the trap circuit 300 is utilized to inhibit the harmonic wave of the low frequency range phase-locked signal, thereby improving the harmonic suppression degree and reducing the risk of losing lock of the phase-locked loop.
In one embodiment, the number of trap circuits 300 is at least two; the number of switching circuits 200 is the same as the number of trap circuits 300;
The trap circuits 300 and the switch circuits 200 are connected in one-to-one correspondence.
Specifically, the number of the trap circuits 300 may be at least two, the circuit structures of any two trap circuits 300 may be the same or different, and the filter parameters of any two trap circuits 300 may be the same or different. The number of switching circuits 200 may also be at least two and may be the same as the number of trap circuits 300.
The switch circuits 200 are connected to the trap circuits 300 in a one-to-one correspondence, and the switch circuits 200 are connected to the controller 400, and the switch circuits 200 are connected to the low-pass filter circuit 100, so that the connection state between the trap circuits 300 and the low-pass filter circuit 100 can be controlled by controlling the on-off state of the switch circuits 200.
In the feedback circuit of the phase-locked loop, the number of the trap circuits 300 and the number of the switch circuits 200 are at least two, and each trap circuit 300 and each switch circuit 200 are connected in a one-to-one correspondence manner, so that harmonic components in phase-locked signals can be suppressed through the plurality of trap circuits 300, and further, low-frequency-band harmonics can be effectively suppressed, and the unlocking risk of the phase-locked loop is further reduced.
In one embodiment, the number of trap circuits 300 is 2; the number of the switching circuits 200 is 2; the low-pass filter circuit 100 comprises an input for connection to a resonant circuit and an output for connection to a phase-locked circuit;
any switch circuit 200 is connected with an input end; the other switching circuit 200 is connected to the output terminal.
Specifically, the low-pass filter circuit 100 may include an input end and an output end, where the input end is one end of the low-pass filter circuit 100 for connecting to a resonant circuit, and the output end is one end of the low-pass filter circuit 100 for connecting to a phase-locked circuit. The 2 trap circuits 300 are connected to the 2 switch circuits 200 in a one-to-one correspondence. Any one of the switch circuits 200 is connected to the input terminal of the low-pass filter circuit 100 and is used for connecting to a resonance circuit. The other switch circuit 200 is connected to the output terminal of the low-pass filter circuit 100 and is used for connecting to a phase-locked circuit.
When the target frequency band is in the low frequency band range, the controller 400 transmits a turn-on control signal to the 2 switch circuits 200, and controls the 2 switch circuits 200 to be in a turned-on state. At this time, one trap circuit 300 is connected to the input terminal of the low-pass filter circuit 100, and the other trap circuit 300 is connected to the output terminal of the low-pass filter circuit 100. The phase-locked signal output by the resonant circuit flows through the low-pass filter circuit 100 and the two trap circuits 300, high-frequency components are filtered through the low-pass filter circuit 100, harmonic components are filtered through the two trap circuits 300, the filtered phase-locked signal enters the phase-locked circuit, and the phase-locked circuit can adjust a voltage signal output to the resonant circuit according to the phase-locked signal output by the resonant circuit so as to tune the resonant circuit, so that the resonant circuit can output a phase-locked signal of a target frequency point.
In the phase-locked loop feedback circuit, the number of the trap circuits 300 is 2, the number of the switch circuits 200 is 2, the switch circuits 200 are connected with the trap circuits 300 in a one-to-one correspondence manner, any one switch circuit 200 is connected with the input end of the low-pass filter circuit 100, and the other switch circuit 200 is connected with the output end of the low-pass filter circuit 100, so that the harmonic signals can be filtered, meanwhile, the excessive insertion loss of useful signals is avoided, and the unlocking risk is further reduced.
In one embodiment, further comprising a capacitor C1; a capacitor C1 is connected between the resonant circuit and the input terminal.
Specifically, the phase-locked loop feedback circuit may further include a capacitor C1, where one end of the capacitor C1 is connected to the resonant circuit, and the other end of the capacitor C1 is connected to the input end of the low-pass filter circuit 100 and the switch circuit 200, respectively.
In one embodiment, the low-pass filter circuit 100 includes an inductance L1, an inductance L2, a capacitance C3, a capacitance C4, a capacitance C5, a capacitance C6, a capacitance C7, and a capacitance C8;
one end of the inductor L1 is respectively connected with one end of the capacitor C2, one end of the capacitor C3 and one end of the capacitor C4, and the other end of the inductor L1 is respectively connected with the other end of the capacitor C2, one end of the capacitor C5, one end of the capacitor C6 and one end of the inductor L2; the other end of the inductor L2 is respectively connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8;
The other end of the capacitor C3 is connected with the switch circuit 200 and is used for being connected with a resonance circuit; the other end of the capacitor C7 is used for connecting a phase-locked circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are grounded.
Specifically, in the low-pass filter circuit 100, a capacitor C2 is connected in parallel with the inductor L1, and one end of the capacitor C2 is connected to one end of a capacitor C3 and one end of a capacitor C4, respectively; the other end of the capacitor C3 is connected with the switch circuit 200 and is used for connecting with a resonance circuit; the other end of the capacitor C4 is grounded.
The other end of the capacitor C2 is respectively connected with one end of the inductor L2, one end of the capacitor C5 and one end of the capacitor C6; the capacitor C5 is connected with the inductor L2 in parallel; the other end of the capacitor C5 is respectively connected with one end of the capacitor C7 and one end of the capacitor C8; the other end of the capacitor C8 is grounded, and the other end of the capacitor C6 is grounded. The other end of the capacitor C7 is used for connecting a phase-locked circuit.
Further, the other end of the capacitor C3 is an input end of the low-pass filter circuit 100, and the other end of the capacitor C7 is an output end of the low-pass filter circuit 100. When the number of trap circuits 300 is plural, the other end of the capacitor C3 may be connected to any one of the trap circuits 300, and the other end of the capacitor C7 may be connected to the other trap circuits 300.
In the phase-locked loop feedback circuit, the low-pass filter circuit 100 is formed by the inductor L1, the inductor L2, the capacitor C3, the capacitor C4, the capacitor C5, the capacitor C6, the capacitor C7 and the capacitor C8, which is easy to implement.
In one embodiment, trap circuit 300 includes an inductance L3 and a capacitance C9;
one end of the inductor L3 is connected with one end of the capacitor C9, and the other end of the inductor L3 is connected with the switch circuit 200; the other end of the capacitor C9 is grounded.
Specifically, the trap circuit 300 may be formed by connecting an inductor L3 and a capacitor C9 in series, one end of the inductor L3 is connected to one end of the capacitor C9, the other end of the inductor L3 is connected to the switch circuit 200, and the other end of the capacitor C9 is grounded. The trap circuit 300 is formed by an inductor and a capacitor, and the circuit is easy to realize.
When the pll feedback circuit includes a plurality of notch circuits 300, the circuit structures of the notch circuits 300 may be the same, and each notch circuit 300 may be formed by an inductance and a capacitance.
In one embodiment, the switching circuit 200 includes a resistor R1, a diode D, and a resistor R2;
One end of the resistor R1 is connected with the controller 400, and the other end is respectively connected with the low-pass filter circuit 100 and the anode of the diode D; the cathode of the diode D is respectively connected with the trap circuit 300 and one end of the resistor R2; the other end of the resistor R2 is grounded.
Specifically, the switch circuit 200 includes a resistor R1, a resistor R2, and a diode D, one end of the resistor R1 is connected to the controller 400, the other end of the resistor R1 is connected to the low-pass filter circuit 100 and the positive electrode of the diode D, the negative electrode of the diode D is connected to the trap circuit 300 and one end of the resistor R2, and the other end of the resistor R2 is grounded.
The turn-on control signal may be a high level signal, and when the controller 400 outputs the high level signal, the positive voltage of the diode D is greater than the negative voltage, and the diode D is turned on. Trap circuit 300 is connected to low pass filter circuit 100 via a conducting diode D. When the controller 400 outputs no signal or a low level signal, the diode D is turned off, and the trap circuit 300 and the low-pass filter circuit 100 are disconnected.
In the phase-locked loop feedback circuit, the switch circuit 200 is formed by the resistor R1, the resistor R2 and the diode D, so that the cost of the phase-locked loop feedback circuit can be reduced while the switch is controllable.
In a specific example, as shown in fig. 5, a phase-locked loop feedback circuit with 1 number of trap circuits 300 is provided, including a low-pass filter circuit 100 composed of an inductor L1, an inductor L2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8, a switch circuit 200 composed of a resistor R1, a diode D and a resistor R2, a trap circuit 300 composed of an inductor L3 and a capacitor C9, and a resistor R3.
The connection relationship between the low-pass filter circuit 100, the switch circuit 200 and the trap circuit 300 may be as described in the above embodiments, and will not be described here again. The resistor R3 is connected between the resistor R1 and the controller 400, namely one end of the resistor R3 is connected with the controller 400, the other end of the resistor R3 is connected with one end of the resistor R1, and the other end of the resistor R1 is respectively connected with the other end of the capacitor C3 and the anode of the diode D. The negative electrode of the diode D is connected to one end of the resistor R2 and the other end of the inductor L3.
In one specific example, as shown in fig. 6, a phase-locked loop feedback circuit having a number of trap circuits 300 of 2 is provided, including a low-pass filter circuit 100, a switch circuit 200, a trap circuit 300, a capacitor C1, and a resistor R3. The connection relation of the respective devices in the low-pass filter circuit 100, the switch circuit 200, and the trap circuit 300 may be as described in the above examples. The switching circuit 200 and the trap circuit 300 are connected in one-to-one correspondence, and the specific connection relationship between the switching circuit 200 and the trap circuit 300 may be as described in the above examples.
In any switching circuit 200, the positive electrode of the diode D is connected to the other end of the capacitor C3 and the other end of the capacitor C1, respectively; one end of the capacitor C1 is used for connecting the resonant circuit. In the other switch circuit 200, the anode of the diode D is connected to the other end of the capacitor C7 and is used for connecting to a phase-locked circuit.
One end of the resistor R3 is connected to the controller 400, and the other end of the resistor R3 is connected to one end of the resistor R1 in the two switch circuits 200, that is, the resistor R1 in the two switch circuits 200 is connected to the controller 400 through the resistor R3.
In the low frequency band (330 MHz to 428 MHz), the controller 400 outputs a high level signal, and the simulation schematic diagram can be shown in fig. 7, when the controller 400 outputs a high level signal, the diodes D in the two switch circuits 200 are all turned on, the a module trap circuit 300 and the B module trap circuit 300 participate in the feedback circuit, and the harmonic wave of the low frequency band is suppressed, so that the defect of insufficient suppression of the fixed harmonic wave trap point of the current low frequency band is overcome. As shown in FIG. 8, the simulation result shows that the insertion loss is between 1dB and 2dB, the harmonic suppression is more than 43dB, and the simulation result is improved by more than 20dB compared with the traditional circuit, so that the feedback insertion loss is small, and the high harmonic suppression ratio is realized.
In the high frequency band (428 MHz to 527 MHz), the controller 400 outputs a low level signal, the a-module trap circuit 300 and the B-module trap circuit 300 do not participate in the feedback circuit, and the simulation result can be shown in fig. 9, and it can be seen that in the high frequency band, the main wave and the harmonic wave are far apart, the harmonic wave is suppressed to 43dB or more, and the in-band interpolation loss is small.
In a specific example, as shown in fig. 10, a phase-locked loop feedback circuit having 3 or more trap circuits 300 is provided, including a low-pass filter circuit 100, a switch circuit 200, a trap circuit 300, a resistor R3, and a capacitor C10. The connection relation of the respective devices in the low-pass filter circuit 100, the switch circuit 200, and the trap circuit 300 may be as described in the above examples. The switching circuit 200 and the trap circuit 300 are connected in one-to-one correspondence, and the specific connection relationship between the switching circuit 200 and the trap circuit 300 may be as described in the above examples.
In the first switch circuit 200, the positive electrode of the diode D is connected to the other end of the capacitor C3 and the other end of the capacitor C1, respectively; one end of the capacitor C1 is used for connecting the resonant circuit. In the second switching circuit 200, the anode of the diode D is connected to the other end of the capacitor C7 and one end of the capacitor C10, respectively. In the third switching circuit 200, the anode of the diode D is connected to the other end of the capacitor C10 and is used for a phase-locked circuit.
One end of the resistor R3 is connected to the controller 400, and the other end of the resistor R3 is connected to one end of the resistor R1 in the 3 switch circuits 200, that is, the resistor R1 in the 3 switch circuits 200 is connected to the controller 400 through the resistor R3.
A control method for a phase-locked loop feedback circuit, for controlling the phase-locked loop feedback circuit in any of the above embodiments, the method comprising the steps of:
Acquiring a target frequency point, switching on the switching circuit 200 when the target frequency point is in a low-frequency range, and switching off the switching circuit 200 when the target frequency point is in a high-frequency range; the switch circuit 200 is connected to the low-pass filter circuit 100 and the trap circuit 300, respectively; the low-pass filter circuit 100 is configured to be connected to the resonant circuit and the phase-locked circuit, respectively, and configured to perform low-pass filtering on a phase-locked signal output by the resonant circuit, and output the filtered phase-locked signal to the phase-locked circuit; the trap circuit 300 is used to filter out harmonic signals in the phase-locked signal.
In the phase-locked loop feedback circuit control method, the target frequency point is obtained, when the target frequency point is in the low-frequency range, the switch circuit 200 is turned on, and when the target frequency point is in the high-frequency range, the switch circuit 200 is turned off; the switch circuit 200 is connected to the low-pass filter circuit 100 and the trap circuit 300, respectively; the low-pass filter circuit 100 is configured to be connected to the resonant circuit and the phase-locked circuit, respectively, and configured to perform low-pass filtering on a phase-locked signal output by the resonant circuit, and output the filtered phase-locked signal to the phase-locked circuit; the trap circuit 300 is used for filtering harmonic signals in the phase-locked signal, so that the low-pass filter circuit 100 can be used for performing low-pass filtering on the high-frequency band or low-frequency band phase-locked signal, and the trap circuit 300 is used for suppressing the harmonic of the low-frequency band phase-locked signal, so that the harmonic suppression degree can be improved, and the risk of losing lock of the phase-locked loop can be reduced.
In one embodiment, a phase-locked loop circuit is provided, comprising a phase-locked loop circuit, a loop filter, a resonant circuit, and a phase-locked loop feedback circuit of any of the above embodiments;
The phase-locked circuit is respectively connected with the low-pass filter circuit 100 and the loop filter; the loop filter is connected with the resonant circuit; the resonant circuit connects the low-pass filter circuit 100 and the switching circuit 200.
Specifically, the phase-locked circuit is connected to the low-pass filter circuit 100 and the loop filter, respectively, the loop filter is connected to the resonance circuit, and the resonance circuit is connected to the low-pass filter circuit 100 and the switch circuit 200, respectively. Further, the phase-locked circuit may be further connected to the controller 400, and configured to receive a configuration parameter transmitted by the controller 400, where the configuration parameter may be obtained according to the target frequency point.
The phase-locked circuit can be used for realizing the functions of frequency division, phase detection, frequency multiplication and the like. The phase-locked circuit is used for receiving the phase-locked signal output by the resonance circuit and outputting a voltage signal to the loop filter according to the phase-locked signal. After the loop filter carries out filtering processing on the voltage signal, the filtered voltage signal is output to the resonant circuit, and the resonant circuit is tuned according to the received voltage signal, so that a signal of a target frequency point can be generated. The phase-locked circuit may be obtained by separate devices, circuits or combinations, or may be implemented using integrated devices.
In one example, the phase-locked circuit may be implemented using a PLL (Phase Locked Loop, phase-locked loop) chip model SKY72300, and the resonant circuit is a VCO resonant circuit. As shown in fig. 11, the phase-locked chip includes an SPI (SERIAL PERIPHERAL INTERFACE ), a lock indication lamp pll_ld, a loop filter for phase-locked loop pump current output, a VCO resonant circuit, and a phase-locked loop feedback circuit. The controller 400 in the phase-locked loop feedback circuit is connected to the SPI interface, the lock indicator lamp pll_ld, and the switching circuit 200, respectively.
The phase-locked circuit of the application adopts a low-pass filter, the switch circuit 200 is conducted in a low frequency band, the low-pass filter circuit 100 is connected with the notch circuit 300, the switch circuit 200 is disconnected in a high frequency band, the low-pass filter performs filtering treatment on a phase-locked signal, the notch circuit 300 controls whether a notch point is introduced or not through an I/O (Input/Output) port instead of a fixed notch suppression circuit by adopting a low-pass notch feedback circuit mode, thereby realizing low insertion loss and high suppression, the low insertion loss can reduce the Output power of a VCO, further reducing the power consumption of the phase-locked circuit, realizing wideband frequency synthesis and eliminating the risk of losing lock of the phase-locked loop caused by insufficient amplitude.
The phase-locked loop circuit comprises a phase-locked circuit, a loop filter, a resonance circuit and a phase-locked loop feedback circuit; the phase-locked circuit is respectively connected with the low-pass filter circuit 100 and the loop filter; the loop filter is connected with the resonant circuit; the resonant circuit connects the low pass filter circuit 100 and the switching circuit 200. The application can filter the phase-locked signal of the high frequency band through the low-pass filter circuit 100 in the phase-locked loop feedback circuit, and filter and harmonic suppression are carried out on the phase-locked signal of the low frequency band through the low-pass filter circuit 100 and the harmonic circuit, so that the insertion loss can be reduced, the output power of the harmonic circuit can be reduced, and the power consumption of the phase-locked loop circuit can be reduced while the unlocking risk is reduced.
In one embodiment, an intercom communication device is provided, including the phase-locked loop circuit of any of the embodiments described above.
Specifically, the intercom communication device may be any device in an intercom communication system, including, but not limited to, an intercom, a turntable, a car-mounted station, and the like.
The intercom communication equipment comprises the phase-locked loop circuit, the low-pass filter circuit 100 in the phase-locked loop feedback circuit is used for filtering the phase-locked signal in the high frequency band, and the low-pass filter circuit 100 and the harmonic circuit are used for filtering and harmonic suppression of the phase-locked signal in the low frequency band, so that the insertion loss can be reduced, the output power of the harmonic circuit is reduced, and the power consumption of the phase-locked loop circuit can be reduced while the risk of losing lock is reduced.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (10)

1. A phase locked loop feedback circuit comprising:
The low-pass filter circuit is used for respectively connecting the resonant circuit and the phase-locked circuit; the low-pass filter circuit is used for carrying out low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the phase-locked signal after filtering to the phase-locked circuit;
a switching circuit connected to the low-pass filter circuit;
the trap circuit is connected with the switch circuit and is used for filtering harmonic signals of a low frequency band in the phase-locked signals;
the controller is connected with the switching circuit and used for acquiring a target frequency point, switching on the switching circuit when the target frequency point is in a low-frequency range, and switching off the switching circuit when the target frequency point is in a high-frequency range; the phase-locked circuit comprises a phase-locked loop SKY72300 circuit, the phase-locked loop SKY72300 circuit is respectively connected with the low-pass filter circuit and the loop filter, the loop filter is connected with the resonant circuit, the phase-locked loop SKY72300 circuit is used for receiving a phase-locked signal output by the resonant circuit and outputting a voltage signal to the loop filter according to the phase-locked signal, the loop filter carries out filtering processing on the voltage signal and then outputs the filtered voltage signal to the resonant circuit, and the resonant circuit is tuned according to the received filtered voltage signal to generate a signal of the target frequency point.
2. The phase-locked loop feedback circuit of claim 1 wherein the number of trap circuits is at least two; the number of the switch circuits is the same as that of the trap circuits;
The trap circuits are connected with the switch circuits in a one-to-one correspondence.
3. The phase-locked loop feedback circuit of claim 2 wherein the number of trap circuits is 2; the number of the switching circuits is 2; the low-pass filter circuit comprises an input end used for being connected with the resonance circuit and an output end used for being connected with the phase-locked circuit;
Any one of the switch circuits is connected with the input end; the other switching circuit is connected with the output end.
4. A phase locked loop feedback circuit as claimed in claim 3, further comprising a capacitor C1; the capacitor C1 is connected between the resonant circuit and the input terminal.
5. The phase-locked loop feedback circuit of claim 1, wherein the low-pass filter circuit comprises an inductance L1, an inductance L2, a capacitance C3, a capacitance C4, a capacitance C5, a capacitance C6, a capacitance C7, and a capacitance C8;
One end of the inductor L1 is respectively connected with one end of the capacitor C2, one end of the capacitor C3 and one end of the capacitor C4, and the other end of the inductor L1 is respectively connected with the other end of the capacitor C2, one end of the capacitor C5, one end of the capacitor C6 and one end of the inductor L2; the other end of the inductor L2 is respectively connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8;
the other end of the capacitor C3 is connected with the switch circuit and is used for being connected with the resonance circuit; the other end of the capacitor C7 is used for being connected with the phase-locked circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are grounded.
6. A phase locked loop feedback circuit as claimed in any one of claims 1 to 5, wherein the trap circuit comprises an inductance L3 and a capacitance C9;
one end of the inductor L3 is connected with one end of the capacitor C9, and the other end of the inductor L3 is connected with the switching circuit; the other end of the capacitor C9 is grounded.
7. A phase locked loop feedback circuit as claimed in any one of claims 1 to 5, wherein the switching circuit comprises a resistor R1, a diode and a resistor R2;
One end of the resistor R1 is connected with the controller, and the other end of the resistor R1 is respectively connected with the low-pass filter circuit and the anode of the diode; the negative electrode of the diode is respectively connected with the trap circuit and one end of the resistor R2; the other end of the resistor R2 is grounded.
8. A control method of a phase locked loop feedback circuit, characterized by being used for controlling the phase locked loop feedback circuit of any one of claims 1 to 7, the method comprising the steps of:
Acquiring a target frequency point, switching on a switching circuit when the target frequency point is in a low-frequency range, and switching off the switching circuit when the target frequency point is in a high-frequency range; the switch circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for being connected with the resonance circuit and the phase-locked circuit respectively, and is used for carrying out low-pass filtering on the phase-locked signal output by the resonance circuit and outputting the phase-locked signal after filtering to the phase-locked circuit; the trap circuit is used for filtering harmonic signals of a low frequency band in the phase-locked signals; the phase-locked circuit is respectively connected with the low-pass filter circuit and the loop filter, the loop filter is connected with the resonant circuit, the phase-locked circuit is used for receiving a phase-locked signal output by the resonant circuit and outputting a voltage signal to the loop filter according to the phase-locked signal, the loop filter outputs the filtered voltage signal to the resonant circuit after filtering the voltage signal, and the resonant circuit is tuned according to the received filtered voltage signal to generate a signal of the target frequency point.
9. A phase locked loop circuit comprising a phase locked loop circuit, a loop filter, a resonant circuit and a phase locked loop feedback circuit as claimed in any one of claims 1 to 7;
The phase-locked circuit is respectively connected with the low-pass filter circuit and the loop filter; the loop filter is connected with the resonant circuit; the resonant circuit connects the low pass filter circuit and the switching circuit.
10. An intercom communication device comprising a phase locked loop circuit as claimed in claim 9.
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