CN113630116A - 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
CN113630116A
CN113630116A CN202010381170.4A CN202010381170A CN113630116A CN 113630116 A CN113630116 A CN 113630116A CN 202010381170 A CN202010381170 A CN 202010381170A CN 113630116 A CN113630116 A CN 113630116A
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circuit
phase
low
capacitor
pass filter
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CN202010381170.4A
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CN113630116B (en
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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, a low-pass filter circuit and a tuning circuit, wherein the low-pass filter circuit is used for being respectively connected with a resonant circuit and a tuning circuit; the low-pass filter circuit is used for performing low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuned circuit; the switch circuit is connected with the low-pass filter circuit; the trap circuit is connected with the switch circuit and is used for filtering harmonic signals in the phase-locked signals; and the controller is connected with the switch circuit and used for acquiring the target frequency point, switching on the switch circuit when the target frequency point is in the low-frequency range, and switching off the switch circuit when the target frequency point is in the high-frequency range, so that the low-pass filter circuit can be used for carrying out low-pass filtering processing on the high-frequency or low-frequency phase-locked signal, the trap circuit is used for inhibiting the harmonic wave of the low-frequency phase-locked signal, the harmonic wave inhibition degree can be improved, and the risk of losing lock of the phase-locked loop can be reduced.

Description

Phase-locked loop feedback circuit, phase-locked loop circuit and intercom communication device
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a phase-locked loop feedback circuit, a phase-locked loop circuit and intercom communication equipment.
Background
At present, three communication devices such as interphones, vehicle-mounted stations, transfer stations and the like in a private network generally need to cover a U frequency band (330MHz to 527 MHz). In order to save hardware development cost and improve product competitiveness, a broadband scheme supporting broadband phase-locked loop feedback is developed, and the broadband scheme can be realized by sharing one hardware platform and only configuring the corresponding frequency band when leaving a factory.
The conventional phase-locked loop feedback circuit is mostly implemented by a band-pass scheme, that is, by a band-pass filter, and its basic structure can be as shown in fig. 1. However, the inventors have found that at least the following problems exist in the conventional techniques: the traditional circuit has the problem of high lock loss 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 tuning circuit; the low-pass filter circuit is used for performing low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuned circuit;
the switch circuit is connected with the low-pass filter circuit;
the trap circuit is connected with the switch circuit and is used for filtering harmonic signals in the phase-locked signals;
and the controller is connected with the switching circuit and is used for acquiring the target frequency point, switching on the switching circuit when the target frequency point is in the low-frequency range, and switching off the switching circuit when the target frequency point is in the high-frequency range.
In one embodiment, the number of notch circuits is at least two; the number of the switching 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 manner.
In one embodiment, the number of notch 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 tuning circuit;
any switch circuit is connected with the input end; the other switch circuit is connected with the output end.
In one embodiment, the capacitor C1 is also included; a capacitor C1 is connected between the resonant circuit and the input terminal.
In one embodiment, the low-pass filter circuit comprises an inductor L1, an inductor L2, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8;
one end of an inductor L1 is connected with one end of a capacitor C2, one end of a capacitor C3 and one end of a capacitor C4 respectively, and the other end of an inductor L1 is connected with the other end of a capacitor C2, one end of a capacitor C5, one end of a capacitor C6 and one end of an inductor L2 respectively; the other end of the inductor L2 is connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8 respectively;
the other end of the capacitor C3 is connected with the switch circuit and is used for connecting the resonance circuit; the other end of the capacitor C7 is used for connecting a tuning circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are all grounded.
In one embodiment, the trap circuit includes an inductor L3 and a capacitor 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 terminal of the capacitor C9 is connected to ground.
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 is respectively connected with the low-pass filter circuit and the anode of the diode; the cathode 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 connected to ground.
The phase-locked loop feedback circuit comprises a low-pass filter circuit which is respectively connected with the resonant circuit and the tuning circuit; the low-pass filter circuit is used for performing low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuned circuit; the switch circuit is connected with the low-pass filter circuit; the trap circuit is connected with the switch circuit and is used for filtering harmonic signals in the phase-locked signals; and the controller is connected with the switching circuit and is used for acquiring the target frequency point, switching on the switching circuit when the target frequency point is in the low-frequency range, and switching off the switching circuit when the target frequency point is in the high-frequency range. The phase-locked loop is characterized in that the target frequency point is in the low-frequency range, the switch circuit is switched on, and when the target frequency range is in the high-frequency range, the switch circuit is switched off, so that the low-pass filter circuit can be used for carrying out low-pass filtering processing on the high-frequency or low-frequency phase-locked signals, the trap circuit is used for restraining the harmonic waves of the low-frequency phase-locked signals, the harmonic wave restraining degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.
A method for controlling a phase-locked loop feedback circuit in any of the above embodiments, the method comprising:
acquiring a target frequency point, switching on a switch circuit when the target frequency point is in a low-frequency range, and switching off the switch circuit when the target frequency point is in a high-frequency range; the switching circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for being respectively connected with the resonant circuit and the tuning circuit, and is used for performing low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuning circuit; the trap circuit is used for filtering harmonic signals in the phase-locked signal.
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 switched on, and when the target frequency point is in the high-frequency range, the switch circuit is switched off; the switching circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for being respectively connected with the resonant circuit and the tuning circuit, and is used for performing low-pass filtering on the phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuning 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 filtering processing on the phase-locked signals in a high frequency band or a low frequency band, and the trap circuit is used for restraining the harmonic waves of the phase-locked signals in the low frequency band, thereby improving the harmonic wave restraining degree and reducing the risk of losing the lock of the phase-locked loop.
A phase-locked loop circuit comprises a tuning circuit, a loop filter, a resonant circuit and a phase-locked loop feedback circuit in any one of the embodiments;
the tuning 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 is connected with the low-pass filter circuit and the switch circuit.
The phase-locked loop circuit comprises a tuning circuit, a loop filter, a resonance circuit and a phase-locked loop feedback circuit; the tuning 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 is connected with the low-pass filter circuit and the switch circuit. The low-pass filter circuit in this application accessible phase-locked loop feedback circuit filters the phase-locked signal of high frequency channel to phase-locked signal through low-pass filter circuit and harmonic circuit to the low frequency channel filters and harmonic suppression, thereby can reduce the insertion loss, reduces resonant circuit's output, and then can reduce the loss of lock risk in, reduces phase-locked loop circuit's consumption.
An intercom communication device comprising the phase-locked loop circuit of any of the above embodiments.
The talkback 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 of the high frequency band, and the low-pass filter circuit and the harmonic circuit are used for filtering and suppressing the phase-locked signal of 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 risk of losing lock is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a circuit diagram of a conventional PLL feedback circuit;
FIG. 2 is a schematic diagram of a simulation of a conventional PLL feedback circuit;
FIG. 3 is a diagram of simulation results of a conventional PLL feedback circuit;
FIG. 4 is a block diagram of a schematic structure 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 low band simulation results for the circuit diagram of FIG. 6 in one embodiment;
FIG. 9 is a diagram of high band simulation results for 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.
Description of reference numerals:
a low-pass filter circuit 100; a switching circuit 200; a trap circuit 300; a controller 400.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying 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 present 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, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. 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 resistor R1 and resistor R2 are resistors, but they are not the same resistor.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other. "reject" or "rejection" is understood to mean the attenuation of a signal at a specific frequency/in a specific frequency band. The "plurality" may be at least two instances.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, as used in this specification, the term "and/or" includes any and all combinations of the associated listed items.
As described in the background art, a phase-locked loop feedback circuit in the prior art has a problem of high lock loss risk, and a phase-locked loop circuit is mostly implemented by using a Voltage Controlled Oscillator (VCO), and when designing a radio frequency feedback signal of a wideband phase-locked loop, it is difficult to implement the effects of low insertion loss and high harmonic suppression ratio in a useful frequency band. The inventor researches and finds that the problems are caused by that the traditional circuit only depends on the trap point of the band-pass to suppress out-of-band signals, the insertion loss of high frequency points is large, and the suppression ratio of low frequency harmonics is low. The harmonic suppression, especially the low-end harmonic suppression degree, increases the risk of losing lock of the phase-locked loop circuit, and especially under the high and low temperature working environment, the risk of losing lock is greatly increased.
The circuit structure shown in fig. 1 is simulated by using the radio frequency simulation software ADS, a simulation schematic diagram can be shown in fig. 2, and a simulation result can be shown in fig. 3. Referring to fig. 3, in the conventional circuit, at the harmonic suppression, for example, at the harmonic of 330MHz and the frequency of 660MHz, the suppression degree is less than 20dB (decibel), and the insertion loss in the frequency band from 330MHz to 527MHz is as high as 1.5dB to 3dB, while in the actual circuit implementation, the insertion loss value of the frequency band is larger than the insertion loss value obtained by simulation, so that the power consumption of the phase-locked loop circuit is greatly increased.
Based on the above reasons, the present invention provides a phase-locked loop feedback circuit, which turns on a switch circuit when a target frequency band is in a low frequency band range, so as to perform low-pass filtering processing on a phase-locked signal by using a low-pass filtering circuit, and suppress harmonics of the phase-locked signal by using a notch circuit, thereby improving a harmonic suppression degree and reducing a risk of losing lock of the phase-locked loop.
In one embodiment, as shown in fig. 4, there is provided a phase-locked loop feedback circuit comprising:
a low-pass filter circuit 100 for connecting the resonance circuit and the tuning 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 tuning 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 signal;
the controller 400 is connected to the switching circuit 200, and is configured to acquire a target frequency point, turn on the switching circuit 200 when the target frequency point is in the low frequency range, and turn off the switching circuit 200 when the target frequency point is in the high frequency range.
Specifically, the phase-locked loop feedback circuit includes a low-pass filter circuit 100, a switch circuit 200, a notch circuit 300, and a controller 400, wherein the low-pass filter circuit 100 may be configured to filter out high frequency components and retain low frequency components of the phase-locked signal. 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 discrete components, 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 filter indexes, such as pass band cut-off frequency, stop band cut-off frequency, pass band maximum attenuation, stop band minimum attenuation, 3dB cut-off frequency, and the low-pass filter circuit 100 in the present application may be obtained by using any filter design method in the prior art.
The switching circuit 200, which includes 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 by any type of switching device, and may be implemented by any type of switching device, for example, but not limited to, a triode, a MOS Transistor, a diode D, IGBT (Insulated Gate Bipolar Transistor), and the like.
The notch circuit 300 can be used to filter signals of a specific frequency/a specific frequency band, and in the present application, the notch circuit 300 can be used to filter harmonic signals in the phase locked loop, such as the second harmonic and the third harmonic. The controller 400 is configured to acquire a target frequency point, and control the on-off 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 resonance circuit and the tuning circuit, respectively. The switching circuit 200 is connected to the trap circuit 300 and the controller 400, respectively, and is used to connect the resonant circuit and/or the tuning circuit. The controller 400 is configured to obtain a target frequency point, and when the target frequency point is within the low frequency range, the controller 400 may control the switching circuit 200 to be turned on, and the notch circuit 300 is connected to the low pass filter circuit 100 through the switching circuit 200. When receiving the phase-locked signal output from the resonant circuit, the low-pass filter circuit 100 may filter out the high-frequency component of the phase-locked signal, and the notch circuit 300 may filter out the harmonic signal of the low-frequency phase-locked signal.
When the target frequency point is within the high frequency range, the controller 400 may control the switching circuit 200 to enter the off state. When the switching circuit 200 is in the off state, the trap circuit 300, the switching circuit 200 and the low-pass filter circuit 100 are in the off state, the trap circuit 300 is not connected to the low-pass filter circuit, the low-pass filter circuit 100 filters out a high-frequency component in the phase-locked signal output by the resonant circuit, and the phase-locked signal after the low-pass filter processing enters the tuning circuit. According to the method and the device, whether the notch point is introduced or not can be controlled according to the frequency band range of the target frequency point, instead of adopting a fixed notch suppression circuit, the notch circuit 300 of the harmonic wave can be reasonably introduced in the aspect of harmonic wave 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 mode of high harmonic wave suppression, low passband insertion loss and low frequency bandwidth is realized.
Further, the number of the wave trapping circuits 300 in the present application may be one or more, for example, may be 1, 2, or 3. When the number of 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 notch circuits 300 is plural, one or more switch circuits 200 may be used to control the connection state of each notch circuit 300 and the low-pass filter circuit 100, respectively. The low-band range and the high-band range may be determined according to an application scenario and/or a communication band, for example, when the phase-locked loop circuit is applied to a broadband intercom system covering a U band, the low-band range may be 330MHz to 428MHz, and the high-band range may be 428MHz to 527 MHz.
The phase-locked loop feedback circuit comprises a low-pass filter circuit 100 which is used for being respectively connected with a resonant circuit and a tuning 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 tuning 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 signal; the controller 400 is connected to the switching circuit 200, and is configured to acquire a target frequency point, turn on the switching circuit 200 when the target frequency point is in the low frequency range, and turn off the switching circuit 200 when the target frequency point is in the high frequency range. According to the phase-locked loop, the switch circuit 200 is switched on when the target frequency point is in the low-frequency range, and the switch circuit 200 is switched off when the target frequency range is in the high-frequency range, so that the low-pass filter circuit 100 can be used for carrying out low-pass filtering processing on the phase-locked signals of the high frequency range or the low frequency range, the harmonic wave of the phase-locked signals of the low frequency range is suppressed by the trap circuit 300, the harmonic wave suppression degree can be improved, and the risk of losing lock of the phase-locked loop is reduced.
In one embodiment, the number of notch circuits 300 is at least two; the number of switching circuits 200 is the same as the number of notch circuits 300;
the trap circuits 300 are connected to the switch circuits 200 in a one-to-one correspondence.
Specifically, the number of the notch circuits 300 may be at least two, the circuit structures of any two notch circuits 300 may be the same or different, and the filter parameters of any two notch circuits 300 may be the same or different. The number of the switching circuits 200 may also be at least two and may be the same as the number of the notch circuits 300.
Each of the switch circuits 200 is connected to each of the trap circuits 300 in a one-to-one correspondence, each of the switch circuits 200 is connected to the controller 400, each of the switch circuits 200 is connected to the low-pass filter circuit 100, and thus the connection state between each of the trap circuits 300 and the low-pass filter circuit 100 can be controlled by controlling the on/off state of each of the switch circuits 200.
In the phase-locked loop feedback circuit, the number of the notch circuits 300 and the number of the switch circuits 200 are at least two, and each notch circuit 300 is connected with each switch circuit 200 in a one-to-one correspondence manner, so that harmonic components in phase-locked signals can be suppressed through the plurality of notch circuits 300, further, the harmonic of a low frequency band can be effectively suppressed, and the risk of losing lock of the phase-locked loop is further reduced.
In one embodiment, the number of notch circuits 300 is 2; the number of the switching circuits 200 is 2; the low-pass filter circuit 100 comprises an input terminal for connecting to the resonant circuit, and an output terminal for connecting to the tuning circuit;
any one of the switching circuits 200 is connected to the input terminal; another switching circuit 200 is connected to the output terminal.
Specifically, the low pass filter circuit 100 may include an input terminal and an output terminal, the input terminal is one terminal of the low pass filter circuit 100 for connecting to the resonant circuit, and the output terminal is one terminal of the low pass filter circuit 100 for connecting to the tuning circuit. The 2 trap circuits 300 and the 2 switch circuits 200 are connected in 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 the resonance circuit. Another switching circuit 200 is connected to the output of the low-pass filter circuit 100 and is used for connecting the tuning circuit.
When the target frequency band is in the low frequency band range, the controller 400 transmits the on control signal to the 2 switch circuits 200, and controls the 2 switch circuits 200 to be in an on state. In this case, 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 notch circuits 300, high-frequency components are filtered out by the low-pass filter circuit 100, harmonic components are filtered out by the two notch circuits 300, the filtered phase-locked signal enters the tuning circuit, the tuning circuit can adjust the 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, and the resonant circuit can output the phase-locked signal of a target frequency point.
In the phase-locked loop feedback circuit, the number of the notch circuits 300 is 2, the number of the switch circuits 200 is 2, the switch circuits 200 are connected with the notch circuits 300 in a one-to-one correspondence manner, any 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 when a harmonic signal is filtered out, the phenomenon that the insertion loss of a useful signal is too large is avoided, and the risk of losing lock is further reduced.
In one embodiment, 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, one end of the capacitor C1 is used for connecting the resonant circuit, and the other end of the capacitor C1 is connected to the input terminal of the low-pass filter circuit 100 and the switch circuit 200, respectively.
In one embodiment, the low pass filter circuit 100 includes an inductor L1, an inductor L2, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, and a capacitor C8;
one end of an inductor L1 is connected with one end of a capacitor C2, one end of a capacitor C3 and one end of a capacitor C4 respectively, and the other end of an inductor L1 is connected with the other end of a capacitor C2, one end of a capacitor C5, one end of a capacitor C6 and one end of an inductor L2 respectively; the other end of the inductor L2 is connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8 respectively;
the other end of the capacitor C3 is connected with the switch circuit 200 and is used for connecting the resonance circuit; the other end of the capacitor C7 is used for connecting a tuning circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are all grounded.
Specifically, in the low-pass filter circuit 100, the capacitor C2 is connected in parallel with the inductor L1, and one end of the capacitor C2 is connected to one end of the capacitor C3 and one end of the capacitor C4, respectively; the other end of the capacitor C3 is connected with the switch circuit 200 and is used for connecting the resonance circuit; the other terminal of the capacitor C4 is connected to ground.
The other end of the capacitor C2 is connected with one end of the inductor L2, one end of the capacitor C5 and one end of the capacitor C6 respectively; the capacitor C5 is connected with the inductor L2 in parallel; the other end of the capacitor C5 is connected with one end of the capacitor C7 and one end of the capacitor C8 respectively; the other terminal of the capacitor C8 is grounded, and the other terminal of the capacitor C6 is grounded. The other end of the capacitor C7 is used for connecting a tuning 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 the notch circuits 300 is plural, the other end of the capacitor C3 may be connected to any one of the notch circuits 300, and the other end of the capacitor C7 may be connected to the remaining notch circuits 300.
In the phase-locked loop feedback circuit, the inductor L1, the inductor L2, the capacitor C2, the capacitor C3, the capacitor C4, the capacitor C5, the capacitor C6, the capacitor C7 and the capacitor C8 form the low-pass filter circuit 100, and the phase-locked loop feedback circuit is easy to implement.
In one embodiment, the 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 terminal of the capacitor C9 is connected to ground.
Specifically, the trap circuit 300 may include an inductor L3 and a capacitor C9 connected 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 structure of each notch circuit 300 may be the same, and each notch circuit 300 may be composed of an inductor and a capacitor.
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 connected to the trap circuit 300 and one end of the resistor R2, respectively; the other end of the resistor R2 is connected to ground.
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 anode of the diode D, the cathode 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 anode voltage of the diode D is greater than the cathode voltage, and the diode D is turned on. The trap circuit 300 is connected to the low pass filter circuit 100 through a diode D that is turned on. When the controller 400 does not output a signal or outputs 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 resistor R1, the resistor R2 and the diode D form the switch circuit 200, so that the cost of the phase-locked loop feedback circuit can be reduced while the controllability of the switch is ensured.
In a specific example, as shown in fig. 5, a phase-locked loop feedback circuit with 1 number of notch circuits 300 is provided, which includes a low-pass filter circuit 100 composed of an inductor L1, an inductor L2, a capacitor C2, 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 notch circuit 300 composed of an inductor L3 and a capacitor C9, and a resistor R3.
The connection relationship among the components in the low pass filter circuit 100, the switch circuit 200 and the trap circuit 300 can be as described in the above embodiments, and will not be described herein again. The resistor R3 is connected between the resistor R1 and the controller 400, that is, one end of the resistor R3 is connected to the controller 400, the other end of the resistor R3 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the other end of the capacitor C3 and the anode of the diode D, respectively. The cathode 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 2 number of phase locked loop feedback circuits with notch circuits 300 are provided, including a low pass filter circuit 100, a switch circuit 200, a notch circuit 300, a capacitor C1, and a resistor R3. The connection relationship of the devices in the low pass filter circuit 100, the switch circuit 200 and the trap circuit 300 can be as described in the above examples. The switching circuits 200 and the notch circuits 300 are connected in a one-to-one correspondence, and the specific connection relationship between the switching circuits 200 and the notch circuits 300 may be as described in the above examples.
In any of the switch circuits 200, the anode 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 to connect the resonant circuit. In the other switching circuit 200, the anode of the diode D is connected to the other end of the capacitor C7 and is used for connecting the tuning 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, i.e. the resistor R1 in the two switch circuits 200 is connected to the controller 400 through the resistor R3.
When the controller 400 outputs a high level signal in a low frequency range (330MHz to 428MHz), the simulation schematic diagram can be as shown in fig. 7, when the controller 400 outputs a high level signal, the diodes D in the two switch circuits 200 are both turned on, and the a-module notch circuit 300 and the B-module notch circuit 300 participate in the feedback circuit, so as to suppress harmonics in the low frequency range, and make up for the defect of insufficient suppression of the fixed harmonic trap point in the low frequency range. The simulation result can be shown in fig. 8, the insertion loss is between 1dB and 2dB, the harmonic suppression is over 43dB, and the improvement is over 20dB compared with the conventional circuit, so that the feedback insertion loss is small, and the harmonic suppression ratio is high.
In the high frequency band (428MHz to 527MHz), the controller 400 outputs a low level signal, the a-module notch circuit 300 and the B-module notch circuit 300 do not participate in the feedback circuit, and the simulation result can be seen as shown in fig. 9, as seen in the high frequency band, the main wave and the harmonic are far apart, the harmonic suppression is above 43dB, and the in-band insertion loss is small.
In one specific example, as shown in fig. 10, a phase-locked loop feedback circuit with 3 or more notch circuits 300 is provided, which includes a low-pass filter circuit 100, a switch circuit 200, a notch circuit 300, a resistor R3 and a capacitor C10. The connection relationship of the devices in the low pass filter circuit 100, the switch circuit 200 and the trap circuit 300 can be as described in the above examples. The switching circuits 200 and the notch circuits 300 are connected in a one-to-one correspondence, and the specific connection relationship between the switching circuits 200 and the notch circuits 300 may be as described in the above examples.
In the first switch circuit 200, the anode 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 to connect the resonant circuit. In the second switch 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 switch circuit 200, the anode of the diode D is connected to the other end of the capacitor C10, and is used for tuning the 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 resistors R1 in the 3 switch circuits 200, i.e., the resistors R1 in the 3 switch circuits 200 are all connected to the controller 400 through the resistor R3.
A method for controlling a phase-locked loop feedback circuit in any of the above embodiments, the method comprising:
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 switching circuit 200 is respectively connected with the low-pass filter circuit 100 and the trap circuit 300; the low-pass filter circuit 100 is used for respectively connecting the resonant circuit and the tuning circuit, performing low-pass filtering on the phase-locked signal output by the resonant circuit, and outputting the filtered phase-locked signal to the tuning circuit; the notch circuit 300 is used to filter out harmonic signals in the phase-locked signal.
The phase-locked loop feedback circuit control method obtains the target frequency point, switches on the switch circuit 200 when the target frequency point is in the low frequency range, and switches off the switch circuit 200 when the target frequency point is in the high frequency range; the switching circuit 200 is respectively connected with the low-pass filter circuit 100 and the trap circuit 300; the low-pass filter circuit 100 is used for respectively connecting the resonant circuit and the tuning circuit, performing low-pass filtering on the phase-locked signal output by the resonant circuit, and outputting the filtered phase-locked signal to the tuning circuit; the notch circuit 300 is used for filtering the harmonic signal in the phase-locked signal, so that the low-pass filter circuit 100 can be used for performing low-pass filtering processing on the phase-locked signal in the high frequency band or the low frequency band, and the notch circuit 300 is used for suppressing the harmonic of the phase-locked signal in the low frequency band, thereby improving the harmonic suppression degree and reducing the risk of losing the lock of the phase-locked loop.
In one embodiment, there is provided a phase-locked loop circuit comprising a tuning circuit, a loop filter, a resonant circuit, and the phase-locked loop feedback circuit of any of the above embodiments;
the tuning 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 tuning circuit is connected to the low-pass filter circuit 100 and the loop filter, respectively, the loop filter is connected to the resonant circuit, and the resonant circuit is connected to the low-pass filter circuit 100 and the switch circuit 200, respectively. Further, the tuning circuit may be further connected to the controller 400, and configured to receive the configuration parameter transmitted by the controller 400, where the configuration parameter may be obtained according to the target frequency point.
The tuning circuit can be used for realizing the functions of frequency division, phase detection, frequency multiplication and the like. The tuning 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 voltage signal after filtering is output to the resonant circuit, and the resonant circuit carries out tuning according to the received voltage signal, so that a signal of a target frequency point can be generated. The tuning circuit may be implemented by separate devices, circuits, or combinations, or may be implemented by integrated devices.
In one example, the tuning circuit may be implemented by a PLL (Phase Locked Loop) chip of the type 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 indicator PLL _ LD, a loop filter for outputting a pump current of the phase-locked loop, 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 switch circuit 200, respectively.
The phase-locked circuit of this application adopts low pass filter, switch circuit 200 switches on when the low-frequency range, low pass filter circuit 100 connects trapped wave circuit 300, switch circuit 200 breaks off when the high-frequency range, low pass filter carries out filtering treatment to the phase-locked signal, adopt the low pass and add the feedback circuit mode of trapped wave, trapped wave circuit 300 controls whether to introduce the trapped wave point through I/O (Input/Output) mouth, and non-fixed trapped wave suppression circuit, thereby realize low insertion loss and high suppression, low insertion loss can reduce VCO Output power, and then reduce phase-locked circuit's consumption, realize wide band frequency synthesis, eliminate the risk that causes the phase-locked loop to lose the lock because of the range is not enough.
The phase-locked loop circuit comprises a tuning circuit, a loop filter, a resonance circuit and a phase-locked loop feedback circuit; the tuning 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 switch circuit 200. The low-pass filter circuit 100 in this application accessible phase-locked loop feedback circuit filters the phase-locked signal of high frequency channel to the phase-locked signal of low frequency channel is filtered and harmonic suppression through low-pass filter circuit 100 and harmonic circuit, thereby can reduce the insertion loss, reduces resonant circuit's output, and then can reduce the loss of lock risk, reduces phase-locked loop circuit's consumption.
In one embodiment, there is provided an intercom communication device including the phase-locked loop circuit of any of the above embodiments.
Specifically, the intercom communication device may be any device in an intercom communication system, including but not limited to an intercom, a transfer station, an on-board station, and the like.
The talkback 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 of the high frequency band, and the low-pass filter circuit 100 and the harmonic circuit are used for filtering and suppressing the harmonic wave of the phase-locked signal of 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 risk of losing the lock is reduced.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to 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 tuning circuit; the low-pass filter circuit is used for performing low-pass filtering on the phase-locked signal output by the resonance circuit and outputting the filtered phase-locked signal to the tuning circuit;
the switch circuit is connected with the low-pass filter circuit;
the trap circuit is connected with the switch circuit and is used for filtering harmonic signals in the phase-locked signals;
and the controller is connected with the switching circuit and is 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.
2. The phase-locked loop feedback circuit of claim 1 wherein the number of said notch circuits is at least two; the number of the switching circuits is the same as the number of the trap circuits;
each trap circuit is connected with each switch circuit in a one-to-one correspondence manner.
3. The phase-locked loop feedback circuit of claim 2, wherein the number of notch 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 tuning circuit;
any one of the switch circuits is connected with the input end; and the other switch circuit is connected with the output end.
4. The phase-locked loop feedback circuit of 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 inductor L1, an inductor L2, a capacitor C2, 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 connected to one end of the capacitor C2, one end of the capacitor C3, and one end of the capacitor C4, respectively, and the other end of the inductor L1 is connected to 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, respectively; the other end of the inductor L2 is connected with the other end of the capacitor C5, one end of the capacitor C7 and one end of the capacitor C8 respectively;
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 connecting the tuning circuit; the other end of the capacitor C4, the other end of the capacitor C6 and the other end of the capacitor C8 are all grounded.
6. The phase-locked loop feedback circuit of any of claims 1 to 5, wherein the notch circuit comprises an inductor L3 and a capacitor 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.
7. The phase-locked loop feedback circuit of any 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 cathode 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 method of controlling a phase-locked loop feedback circuit, for controlling the phase-locked loop feedback circuit of any of claims 1 to 7, the method comprising the steps of:
acquiring a target frequency point, switching on a switch circuit when the target frequency point is in a low-frequency range, and switching off the switch circuit when the target frequency point is in a high-frequency range; the switching circuit is respectively connected with the low-pass filter circuit and the trap circuit; the low-pass filter circuit is used for being respectively connected with the resonant circuit and the tuning circuit, and is used for performing low-pass filtering on a phase-locked signal output by the resonant circuit and outputting the filtered phase-locked signal to the tuning circuit; the trap circuit is used for filtering harmonic signals in the phase-locked signal.
9. A phase locked loop circuit comprising a tuning 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 tuning 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 is connected with the low-pass filter circuit and the switch circuit.
10. An intercom communication device comprising the phase-locked loop circuit as claimed in claim 9.
CN202010381170.4A 2020-05-08 2020-05-08 Phase-locked loop feedback circuit, phase-locked loop circuit and intercom communication device Active CN113630116B (en)

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