CN216356688U - Matching circuit and wireless communication device - Google Patents
Matching circuit and wireless communication device Download PDFInfo
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- CN216356688U CN216356688U CN202122677897.XU CN202122677897U CN216356688U CN 216356688 U CN216356688 U CN 216356688U CN 202122677897 U CN202122677897 U CN 202122677897U CN 216356688 U CN216356688 U CN 216356688U
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Abstract
The utility model discloses a matching circuit and a wireless communication device, belonging to the technical field of wireless communication, wherein the circuit comprises an impedance matching unit which receives a first radio frequency signal sent by an LoRa module, performs impedance transformation on the first radio frequency signal according to preset impedance and outputs a second radio frequency signal; the resonance filtering unit is used for filtering a harmonic frequency band of the first radio frequency signal and inhibiting a harmonic component in the second radio frequency signal; and the phase adjustment unit is used for carrying out phase adjustment on the second radio frequency signal and outputting a third radio frequency signal to a radio frequency output port; the impedance matching unit is connected with the LoRa module and the phase adjusting unit respectively, the phase adjusting unit is connected with the radio frequency output port, and the resonance filtering unit is connected at two ends of the impedance matching unit in parallel. The utility model solves the problems of higher cost, larger size and complex circuit in the mode of inhibiting the harmonic component in the radio frequency signal output by the LoRa module in the prior art, and has the technical effects of lower cost and smaller volume.
Description
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a matching circuit and a wireless communication device.
Background
The working frequency of a large-power LoRa (Long Range Radio) module is generally 430MHz-470MHz, and the transmitting power is 30 dBm. At present, in order to make all high frequency signal homoenergetic that the loRa module sent transmit to the radio frequency delivery outlet, promote energy efficiency, generally all be provided with matching circuit between loRa module and radio frequency delivery outlet.
In the prior art, a manner of suppressing a harmonic component in a radio frequency signal output by an LoRa module is to add a filter or a harmonic suppression circuit between a matching circuit and a radio frequency output port to suppress the harmonic component, as shown in fig. 1, which is a schematic circuit connection diagram of the prior art for suppressing the harmonic component. This way of adding extra filter or harmonic suppression circuit not only can increase the cost, increases LoRa wireless communication device's volume, still can increase circuit complexity and the debugging degree of difficulty, especially to low-cost small-size LoRa module, above-mentioned problem is more outstanding.
SUMMERY OF THE UTILITY MODEL
The main purposes of the utility model are as follows: the utility model provides a matching circuit and wireless communication device, aim at solving and have the technical problem that the cost is higher, the size is great and the circuit is complicated in the mode of suppressing the harmonic component in the radio frequency signal of loRa module output among the prior art.
In order to achieve the purpose, the utility model adopts the following technical scheme:
in a first aspect, the present invention provides a matching circuit, where an input end of the circuit is connected to an LoRa module, and an output end of the circuit is connected to a radio frequency output port, the circuit includes an impedance matching unit, a resonance filtering unit, and a phase adjusting unit, the impedance matching unit is connected to the LoRa module and the phase adjusting unit, the phase adjusting unit is connected to the radio frequency output port, and the resonance filtering unit is connected in parallel to two ends of the impedance matching unit;
the impedance matching unit is used for receiving a first radio frequency signal sent by the LoRa module, performing impedance transformation on the first radio frequency signal according to preset impedance and outputting a second radio frequency signal;
the resonance filtering unit is used for filtering a harmonic frequency band of the first radio frequency signal and suppressing a harmonic component in the second radio frequency signal;
and the phase adjusting unit is used for adjusting the phase of the second radio frequency signal and outputting a third radio frequency signal to the radio frequency output port.
Optionally, in the matching circuit, the impedance matching unit includes an inductor L1, a capacitor C1, and a capacitor C2;
one end of the inductor L1 is connected with the capacitor C1, the LoRa module and the resonance filtering unit respectively, and the other end of the inductor L1 is connected with the capacitor C2, the impedance matching unit and the resonance filtering unit respectively.
Optionally, in the matching circuit, the resonant filtering unit includes a capacitor C3;
the capacitor C3 is connected in parallel across the inductor L1.
Optionally, in the matching circuit, the phase adjusting unit includes an inductor L2;
one end of the inductor L2 is connected with the impedance matching unit, and the other end is connected with the radio frequency output port.
Optionally, in the matching circuit, an inductance value of the inductor L2 may be adjusted and the minimum value is zero.
Optionally, in the matching circuit, the circuit further includes a filtering unit connected between the phase adjusting unit and the radio frequency output port;
and the filtering unit is used for filtering the third radio frequency signal and then outputting the third radio frequency signal to the radio frequency output port.
Optionally, in the matching circuit, the filtering unit employs a cascade filter.
In a second aspect, the present invention further provides a wireless communication device, where the wireless communication device includes an LoRa module, a circuit board, and a radio frequency output interface, which are connected in sequence;
the circuit board is provided with the matching circuit.
One or more technical solutions provided by the present invention may have the following advantages or at least achieve the following technical effects:
according to the matching circuit and the wireless communication device, when the impedance matching unit performs impedance transformation on a first radio-frequency signal and outputs a second radio-frequency signal, the resonance filtering unit connected to the impedance matching unit in parallel is used for filtering a harmonic frequency band of the first radio-frequency signal, so that harmonic components in the second radio-frequency signal are suppressed, and harmonic suppression of the radio-frequency signal is realized; the phase of the second radio frequency signal is adjusted through the phase adjusting unit, and a third radio frequency signal is output, so that the purpose of eliminating the phase difference of the radio frequency signals is achieved; compared with the prior art that a filter or a harmonic suppression circuit is added on a matching circuit, the resonant filtering unit and the phase adjusting unit are simple in circuit structure and convenient to debug, and the size of a circuit board does not need to be increased, so that the size of a wireless communication device does not need to be increased, and the technical effects of lower cost and smaller size are achieved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art circuit connection for suppressing harmonic components;
FIG. 2 is a circuit diagram of a matching circuit according to a first embodiment of the present invention;
FIG. 3 is a graph of S-parameter variation of the matching circuit of FIG. 1;
FIG. 4 is a graph of the change in reflection coefficient of the matching circuit of FIG. 1;
FIG. 5 is a graph of S-parameter variation of the matching circuit of FIG. 2;
FIG. 6 is a graph of the change in reflection coefficient of the matching circuit of FIG. 2;
fig. 7 is a circuit connection diagram of a matching circuit according to a second embodiment of the utility model.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, in the present invention, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element. In addition, in the present invention, unless explicitly stated or limited otherwise, the terms "connected," "fixed," and the like are to be construed broadly, e.g., "connected" may be fixedly connected, or detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium; either internally or in interactive relation.
In the present invention, suffixes such as "module", "part", or "unit" used to represent elements are used only for facilitating the description of the present invention, and have no specific meaning in themselves. Thus, "module", "component" or "unit" may be used mixedly. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations. In addition, the technical solutions of the respective embodiments may be combined with each other, but must be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should be considered to be absent and not be within the protection scope of the present invention.
The LoRa technology is a wireless Internet of things access layer network transmission technology, under the same power consumption condition, the transmission distance is farther than that of other wireless transmission modes, and low power consumption and long distance unification are realized, so that the LoRa technology is widely used for wireless communication devices. The working frequency of the high-power LoRa module is generally 430MHz-470MHz, and the transmitting power is 30 dBm. At present, in order to make all high frequency signal homoenergetic that the loRa module sent transmit to the radio frequency delivery outlet, promote energy efficiency, generally all be provided with matching circuit between loRa module and radio frequency delivery outlet.
In the radio frequency signal output by the radio frequency front end of the LoRa module, the harmonic component index often does not meet the requirement, and the harmonic component needs to be suppressed. In the prior art, a filter or a harmonic suppression circuit is added between a matching circuit and a radio frequency output port to suppress a harmonic component, and fig. 1 is a schematic circuit connection diagram of the prior art for suppressing a harmonic component. The problem that this kind of mode exists is once find the harmonic exceeds standard when the radio frequency test, under the condition that does not sacrifice transmit power, just can have the problem of debugging difficulty to, add extra wave filter or harmonic suppression circuit, not only can increase the cost, increase LoRa wireless communication device's volume, still can increase circuit complexity and debugging the degree of difficulty, especially to low-cost small-size LoRa module, the shortcoming is comparatively obvious.
In view of the technical problems of high cost, large size and complex circuit in the prior art of suppressing harmonic components in the radio frequency signal output by the LoRa module, the present invention provides a matching circuit and a wireless communication device, and specific embodiments and embodiments thereof are as follows.
Example one
Referring to fig. 2, fig. 2 is a circuit connection diagram of a matching circuit according to a first embodiment of the present invention; the present embodiment proposes a matching circuit. The input end of the circuit is connected with the LoRa module, the output end of the circuit is connected with the radio frequency output port, the circuit comprises an impedance matching unit, a resonance filtering unit and a phase adjusting unit, the impedance matching unit is respectively connected with the LoRa module and the phase adjusting unit, the phase adjusting unit is connected with the radio frequency output port, and the resonance filtering unit is connected with two ends of the impedance matching unit in parallel;
the impedance matching unit is used for receiving a first radio frequency signal sent by the LoRa module, performing impedance transformation on the first radio frequency signal according to preset impedance and outputting a second radio frequency signal;
the resonance filtering unit is used for filtering a harmonic frequency band of the first radio frequency signal and suppressing a harmonic component in the second radio frequency signal;
and the phase adjusting unit is used for adjusting the phase of the second radio frequency signal and outputting a third radio frequency signal to the radio frequency output port.
The LoRa module transmits a first radio frequency signal, the impedance matching unit receives the first radio frequency signal, and carries out impedance transformation on the first radio frequency signal according to preset impedance to output a second radio frequency signal; meanwhile, the resonance filtering unit filters a harmonic frequency band of the first radio frequency signal and suppresses a harmonic component in the output second radio frequency signal; and the phase adjusting unit performs phase adjustment on the second radio frequency signal and outputs the second radio frequency signal to the radio frequency output port, so that when a third radio frequency signal transmitted by the radio frequency output port is drawn on the Smith chart, the impedance of the harmonic frequency point is seen at the short circuit point of the Smith chart when the impedance matching unit is seen from the radio frequency output port.
Further, the impedance matching unit includes an inductor L1, a capacitor C1, and a capacitor C2;
one end of the inductor L1 is connected with the capacitor C1, the LoRa module and the resonance filtering unit respectively, and the other end of the inductor L1 is connected with the capacitor C2, the impedance matching unit and the resonance filtering unit respectively.
In this embodiment, one end of the inductor L1 is connected to one end of the capacitor C1, the LoRa module, and the resonant filtering unit, the other end of the capacitor C1 is grounded, the other end of the inductor L1 is connected to one end of the capacitor C2, the impedance matching unit, and the resonant filtering unit, and the other end of the capacitor C2 is grounded.
The pi-type matching circuit formed by the inductor L1 and the capacitors C1 and C2 converts the impedance of the first radio-frequency signal to 50 ohms according to preset impedance, and impedance matching is achieved. In the pi-type matching circuit formed by the inductor L1, the capacitors C1 and C2 of the impedance matching unit, specific parameter values are the same as those of the conventional pi-type matching circuit, and are set according to practical situations, which is not limited here.
Further, the resonance filtering unit includes a capacitor C3;
the capacitor C3 is connected in parallel across the inductor L1.
In this embodiment, the resonance filtering unit and the inductor L1 of the impedance matching unit form a parallel resonance structure, so that the resonance frequency point is approximately short-circuited, the harmonic filtering of the first radio frequency signal is realized, and the harmonic component in the output second radio frequency signal is suppressed. The values of the capacitor C3 and the inductor L1 can be obtained according to a resonance formula, which is as follows:
wherein f represents the resonance frequency, L1The inductance value, C, of the inductor L13Representing the capacitance value of the capacitor C3.
The n-shaped matching circuit in the prior art is improved, so that the n-shaped matching circuit has an additional harmonic suppression capability on the basis of having a normal impedance matching function.
Further, the phase adjustment unit includes an inductance L2;
one end of the inductor L2 is connected with the impedance matching unit, and the other end is connected with the radio frequency output port.
Further, the inductance value of the inductor L2 is adjustable and has a minimum value of zero.
In this embodiment, the inductor L2 performs phase adjustment on the second rf signal, so that when the third rf signal transmitted by the rf output port is plotted on the smith chart, the impedance of the harmonic frequency point seen from the rf output port to the impedance matching unit is at the short-circuit point of the smith chart. The inductance value of the inductor L2 can be adjusted according to the phase, and the minimum value can be zero, or an inductor with lower cost can be selected, thereby further achieving the effect of low cost.
The matching circuit of this embodiment not only has the matching effect of ordinary pi type matching circuit at the fundamental frequency channel of radio frequency signal, can also carry out harmonic component to the harmonic frequency channel of radio frequency signal and restrain, can not cause great influence to the matching effect of fundamental frequency channel, has guaranteed the matching effect of the fundamental frequency channel of radio frequency signal, to the module class design that the power index is sensitive, can reduce transmission loss when providing harmonic suppression ability, has the advantage that the debugging degree of difficulty is low. Compared with a pure n-type matching circuit, namely the prior art without adding a filter or a harmonic suppression circuit, the matching circuit of the embodiment has the advantages that not only is the matching effect not affected, but also the harmonic suppression function is added.
In order to verify the above effect, the present embodiment performs S-parameter and reflectance detection on the matching circuit of the prior art shown in fig. 1 and the matching circuit of the present embodiment shown in fig. 2, respectively, to obtain an S-parameter variation curve of the matching circuit of the prior art shown in fig. 3, a reflectance variation curve plotted on a smith chart of the matching circuit of the prior art shown in fig. 4, an S-parameter variation curve of the matching circuit of the present embodiment shown in fig. 5, and a reflectance variation curve plotted on a smith chart of the matching circuit of the present embodiment shown in fig. 6.
In fig. 3, the abscissa is a frequency band, the ordinate is a value of an S parameter, two curves in the graph are a loss curve and a standing wave curve obtained by the matching circuit according to the prior art in fig. 1, points m1 and m2 are marked on the loss curve, m2 represents insertion loss in a frequency band from 430MHz to 470MHz, i.e., insertion loss of a fundamental frequency point, and m1 represents a second harmonic suppression situation. Fig. 4 is a graph of the change in reflection coefficient plotted on a smith chart according to the loss curve in fig. 3, labeled with points m1 and m2 in fig. 3, where m1 represents the fundamental frequency point match and m2 represents the second harmonic match in fig. 4. As can be seen from fig. 3 and 4, at point m2, that is, at the frequency band of 470MHz, the loss is low, and is only 0.06dB, at this time, the corresponding matching effect is about-20 dB, and it can be seen that the matching effect of the matching circuit is good; but as can be seen from the point m1, the second harmonic suppression of the matching circuit is only 4.6dB, and the second harmonic suppression capability of the matching circuit is poor.
In fig. 5, the abscissa is a frequency band, the ordinate is a value of an S parameter, the two curves in the graph are a loss curve and a standing wave curve respectively obtained by the matching circuit of the embodiment in fig. 2, points m1 and m2 are marked on the loss curve, m2 represents insertion loss in a frequency band from 430MHz to 470MHz, and m1 represents a second harmonic suppression situation. It should be noted that fig. 5 shows the corresponding curve in fig. 3 by a curve with lighter color, and the curve in fig. 3 is retained for the convenience of contrast parameter variation. Fig. 6 is a graph of the change in reflection coefficient plotted on a smith chart according to the loss curve in fig. 5, labeled at points m1 and m2 in fig. 5, where m1 represents the fundamental frequency point match and m2 represents the second harmonic match in fig. 6. As can be seen from fig. 5 and fig. 6, at point m2, that is, at the frequency band of 470MHz, the loss is low, only 0.1dB, and at this time, the corresponding matching effect is still about-20 dB, which shows that the matching effect of the matching circuit of this embodiment has a smaller variation range than that of the prior art, which indicates that even though the device is added in this embodiment compared with the prior art, the matching effect of the matching circuit is not affected; however, as can be seen from the point m1, the second harmonic suppression of the matching circuit of the present embodiment is changed to 49.2dB, and it can be seen that the second harmonic suppression capability of the matching circuit is greatly increased compared with that of the matching circuit of the prior art.
In summary, as can be seen from a comparison between fig. 3 and 4 and fig. 5 and 6, the matching effect of the matching circuit of the present embodiment is not affected by the prior art, but the second harmonic suppression capability of the matching circuit of the present embodiment is significantly improved compared to the prior art. According to the embodiment, an additional filter is not needed, harmonic suppression can be realized only by using simple electronic devices, the circuit structure is simple, and the cost is lower.
In the matching circuit of this embodiment, when the impedance matching unit performs impedance transformation on the first radio frequency signal and outputs the second radio frequency signal, the resonance filtering unit connected in parallel to the impedance matching unit is used to filter the harmonic frequency band of the first radio frequency signal, so as to suppress the harmonic component in the second radio frequency signal and realize harmonic suppression of the radio frequency signal; the phase of the second radio frequency signal is adjusted through the phase adjusting unit, and a third radio frequency signal is output, so that the purpose of eliminating the phase difference of the radio frequency signals is achieved; compared with the prior art that a filter or a harmonic suppression circuit is added on a matching circuit, the resonant filtering unit and the phase adjusting unit are simple in circuit structure and convenient to debug, and the size of a circuit board does not need to be increased, so that the size of a wireless communication device does not need to be increased, and the technical effects of lower cost and smaller size are achieved. The matching circuit of the embodiment can be used for directly transforming the existing n-shaped matching circuit and has the advantages of small modification amplitude and low modification difficulty.
Example two
Referring to fig. 7, fig. 7 is a circuit connection diagram of a matching circuit according to a second embodiment of the present invention. On the basis of the first embodiment, the present embodiment further provides a matching circuit.
Furthermore, the circuit also comprises a filtering unit connected between the phase adjusting unit and the radio frequency output port;
and the filtering unit is used for filtering the third radio frequency signal and then outputting the third radio frequency signal to the radio frequency output port.
Further, the filtering unit employs a cascade filter.
In the matching circuit of the present embodiment, the cascade filter is added after the inductor L2 of the first embodiment, so that the harmonic suppression capability of the circuit can be further improved.
EXAMPLE III
The embodiment provides a wireless communication device, which comprises an LoRa module, a circuit board and a radio frequency output interface which are sequentially connected; wherein the content of the first and second substances,
the circuit board is provided with the matching circuit as described in the first embodiment or the second embodiment.
The specific structure of the matching circuit refers to the above embodiments, and since this embodiment adopts all technical solutions of all the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are achieved, and are not described in detail herein.
It should be noted that the above-mentioned serial numbers of the embodiments of the present invention are merely for description, and do not represent the merits of the embodiments.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (8)
1. A matching circuit is characterized in that the circuit comprises an impedance matching unit, a resonance filtering unit and a phase adjusting unit, wherein the impedance matching unit is respectively connected with the LoRa module and the phase adjusting unit, the phase adjusting unit is connected with the radio frequency output port, and the resonance filtering unit is connected in parallel at two ends of the impedance matching unit;
the impedance matching unit is used for receiving a first radio frequency signal sent by the LoRa module, performing impedance transformation on the first radio frequency signal according to preset impedance and outputting a second radio frequency signal;
the resonance filtering unit is used for filtering a harmonic frequency band of the first radio frequency signal and suppressing a harmonic component in the second radio frequency signal;
and the phase adjusting unit is used for adjusting the phase of the second radio frequency signal and outputting a third radio frequency signal to the radio frequency output port.
2. The matching circuit of claim 1, wherein the impedance matching unit includes an inductor L1, a capacitor C1, and a capacitor C2;
one end of the inductor L1 is connected with the capacitor C1, the LoRa module and the resonance filtering unit respectively, and the other end of the inductor L1 is connected with the capacitor C2, the impedance matching unit and the resonance filtering unit respectively.
3. The matching circuit of claim 2, wherein the resonant filtering unit comprises a capacitor C3;
the capacitor C3 is connected in parallel across the inductor L1.
4. The matching circuit of claim 1, wherein the phase adjustment unit comprises an inductance L2;
one end of the inductor L2 is connected with the impedance matching unit, and the other end is connected with the radio frequency output port.
5. The matching circuit of claim 4, wherein the inductance value of the inductor L2 is adjustable and has a minimum value of zero.
6. The matching circuit of claim 1, wherein the circuit further comprises a filtering unit connected between the phase adjustment unit and the radio frequency output port;
and the filtering unit is used for filtering the third radio frequency signal and then outputting the third radio frequency signal to the radio frequency output port.
7. The matching circuit of claim 6, wherein the filtering unit employs a cascaded filter.
8. A wireless communication device is characterized by comprising an LoRa module, a circuit board and a radio frequency output interface which are sequentially connected;
the circuit board is provided with a matching circuit as claimed in any one of claims 1 to 7.
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| CN202122677897.XU CN216356688U (en) | 2021-11-03 | 2021-11-03 | Matching circuit and wireless communication device |
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| CN202122677897.XU CN216356688U (en) | 2021-11-03 | 2021-11-03 | Matching circuit and wireless communication device |
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