CN109039369B - Radio frequency circuit and electronic device - Google Patents
Radio frequency circuit and electronic device Download PDFInfo
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- CN109039369B CN109039369B CN201810934423.9A CN201810934423A CN109039369B CN 109039369 B CN109039369 B CN 109039369B CN 201810934423 A CN201810934423 A CN 201810934423A CN 109039369 B CN109039369 B CN 109039369B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/401—Circuits for selecting or indicating operating mode
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/50—Circuits using different frequencies for the two directions of communication
- H04B1/52—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
- H04B1/525—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa with means for reducing leakage of transmitter signal into the receiver
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Abstract
The embodiment of the application discloses radio frequency circuit and electronic equipment, radio frequency circuit includes: the radio frequency transceiver, the antenna, the first switch and the short-circuit branch impedance converter; the radio frequency transceiver is connected with the antenna to form a path, one end of the short-circuit stub impedance converter is connected with the path through the first switch, and the other end of the short-circuit stub impedance converter is directly grounded; the first switch is used for controlling the short-circuit branch impedance converter to enter a working state or exit the working state; when the first switch is closed, the short-circuit branch impedance converter performs harmonic suppression processing on a first frequency band radio frequency signal transmitted by the radio frequency transceiver, and conducts an even harmonic signal in the first frequency band radio frequency signal to the ground, so that the antenna transmits a main frequency signal after suppressing the even harmonic signal in the first frequency band radio frequency signal outwards; therefore, the purpose of inhibiting even harmonic waves can be achieved under the condition of not increasing the material cost.
Description
Technical Field
The present application relates to the field of communications technologies, and in particular, to a radio frequency circuit and an electronic device.
Background
With the continuous development of communication technology, the communication frequency range that the intelligent terminal can use is also wider and wider. However, for all intelligent terminals, the radio frequency system inside the intelligent terminal inevitably generates harmonics of the main frequency signal due to the nonlinearity of the active device, and the harmonic signal not only affects the signal quality and transmission efficiency of the intelligent terminal itself, but also causes interference to communication equipment in other frequency bands; among them, in all harmonic signals accompanying the main frequency signal, the second harmonic (even harmonic) component is often the largest, and the influence on the communication system is the largest. Thus, how to suppress the harmonic signals of the rf system is an important task in the design of the rf circuit.
At present, a first-stage duplexer/filter is generally arranged on each radio frequency link of the existing intelligent terminal, and if the suppression degree of harmonic signals is insufficient, a first-stage filter and a corresponding matching network need to be added. The solution for suppressing the harmonic signals can lead to the increase of material cost on one hand, and can bring at least 2dB intensity attenuation to the main frequency signals while improving the suppression degree of the harmonic signals on the other hand.
Disclosure of Invention
In view of the above, a main object of the present invention is to provide a radio frequency circuit and an electronic device, which can improve a harmonic signal suppression degree without increasing material cost and without causing attenuation to a main frequency signal, so as to achieve the purpose of suppressing even harmonic components; and further, the signal quality of a radio frequency transceiving link in the electronic equipment is improved.
In order to achieve the purpose, the technical scheme of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a radio frequency circuit, where the radio frequency circuit includes: the radio frequency transceiver, the antenna, the first switch and the short-circuit branch impedance converter; the radio frequency transceiver is connected with the antenna to form a path, one end of the short-circuit stub impedance converter is connected with the path through the first switch, and the other end of the short-circuit stub impedance converter is directly grounded; wherein the content of the first and second substances,
the first switch is used for controlling the short-circuit branch impedance converter to enter a working state or exit the working state;
when the first switch is closed, the short-circuit branch impedance converter performs harmonic suppression processing on a first frequency band radio frequency signal transmitted by the radio frequency transceiver, and conducts an even harmonic signal in the first frequency band radio frequency signal to the ground, so that the antenna transmits a main frequency signal after suppressing the even harmonic signal in the first frequency band radio frequency signal outwards.
In the above scheme, the short-circuit stub impedance transformer includes a quarter first wavelength microstrip line; the microstrip line with the quarter of the first wavelength is located on the circuit board corresponding to the radio frequency circuit, and the first wavelength is a wavelength corresponding to a central frequency of the radio frequency signal of the first frequency band.
In the above scheme, the first switch is a single-pole single-throw switch, wherein a first port of the single-pole single-throw switch is connected to the path, and a second port of the single-pole single-throw switch is connected to the quarter microstrip line with the first wavelength.
In the above scheme, the short-circuit stub impedance transformer includes a plurality of quarter M-th wavelength microstrip lines, each of which is individually grounded; the plurality of quarter M-th wavelength microstrip lines are all located on a circuit board corresponding to the radio frequency circuit, the M-th wavelength is a wavelength corresponding to a central frequency of an M-th frequency band radio frequency signal, and M is used for representing the number of different frequency bands corresponding to the radio frequency signal transmitted by the radio frequency transceiver.
In the above scheme, the first switch is a single-pole multi-throw switch, wherein a fixed port of the single-pole multi-throw switch is connected to the via, and a plurality of gating ports of the single-pole multi-throw switch are respectively connected to the plurality of quarter M-th wavelength microstrip lines.
In the above scheme, the first switch is a multi-pole multi-throw switch, wherein a fixed port of the multi-pole multi-throw switch is connected to the via, and a plurality of gating ports of the multi-pole multi-throw switch are respectively connected to the plurality of quarter M-th wavelength microstrip lines.
In the above scheme, the short-circuit stub impedance converter includes (N-1) second switches and N microstrip lines; the second switch is a single-pole double-throw switch, and the (N-1) second switches and the N microstrip lines are connected in series at intervals.
In the above solution, the (N-1) second switches and the N microstrip lines are connected in series at intervals, and include:
one end of the 1 st microstrip line is connected with the first switch, and the other end of the 1 st microstrip line is connected with the fixed port of the 1 st second switch;
when 1< i < N and i is an integer, one end of the ith microstrip line is connected with the first gating port of the (i-1) th second switch, the other end of the ith microstrip line is connected with the fixed port of the ith second switch, and the second gating port of the (i-1) th second switch is grounded; wherein i is a reference number;
one end of the Nth microstrip line is connected with the first gating port of the (N-1) th second switch, and the other end of the Nth microstrip line and the second gating port of the (N-1) th second switch are grounded.
In the above scheme, among the N microstrip lines, the microstrip line of the high frequency band is multiplexed with the microstrip line of the low frequency band, and the N microstrip lines are serially connected and overlapped through the (N-1) second switches to realize the suppression of the even harmonic signal in the radio frequency signal of the lower frequency band.
In the above scheme, the radio frequency circuit further includes a control circuit; the control circuit is connected with the first switch and is used for controlling the first switch to be opened and closed.
In a second aspect, an embodiment of the present application provides an electronic device, where the electronic device includes a housing and a circuit board, where the circuit board is installed inside the housing, and the radio frequency circuit in any one of the first aspect is placed on the circuit board.
The embodiment of the application provides a radio frequency circuit and electronic equipment, the radio frequency circuit includes: the radio frequency transceiver, the antenna, the first switch and the short-circuit branch impedance converter; the radio frequency transceiver is connected with the antenna to form a path, one end of the short-circuit stub impedance converter is connected with the path through the first switch, and the other end of the short-circuit stub impedance converter is directly grounded; the first switch is used for controlling the short-circuit branch impedance converter to enter a working state or exit the working state; when the first switch is closed, the short-circuit branch impedance converter performs harmonic suppression processing on a first frequency band radio frequency signal transmitted by the radio frequency transceiver, and conducts an even harmonic signal in the first frequency band radio frequency signal to the ground, so that the antenna transmits a main frequency signal after suppressing the even harmonic signal in the first frequency band radio frequency signal outwards; therefore, under the conditions that the material cost is not increased and the attenuation is not caused to the main frequency signal, the harmonic signal suppression degree is improved, and the purpose of suppressing the even harmonic component is achieved; and further, the signal quality of a radio frequency transceiving link in the electronic equipment is improved.
Drawings
Fig. 1 is a schematic structural diagram of a radio frequency circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another radio frequency circuit according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of another radio frequency circuit according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of another radio frequency circuit according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of another radio frequency circuit according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of another radio frequency circuit according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
Referring to fig. 1, which shows a schematic structural diagram of a radio frequency circuit 100 provided in an embodiment of the present application, the radio frequency circuit 100 may include: a radio frequency transceiver 101, an antenna 102, a first switch 103 and a short-circuited stub impedance transformer 104; the radio frequency transceiver 101 is connected with the antenna 102, one end of the short-circuit stub impedance converter 104 is connected with the antenna 102 through the first switch 103, and the other end of the short-circuit stub impedance converter 104 is directly grounded; wherein the content of the first and second substances,
the radio frequency transceiver 101 is configured to transmit a radio frequency signal (uplink signal) and receive a radio frequency signal (downlink signal);
the antenna 102 is configured to transmit an uplink signal sent by the radio frequency transceiver 101 to the outside, or receive a radio frequency signal from the outside, and send a received downlink signal to the radio frequency transceiver 101;
the first switch 103 is used for controlling the short-circuit branch impedance converter 104 to enter the working state or exit the working state;
when the first switch 103 is closed, the short-circuit stub impedance converter 104 enters a working state, that is, the short-circuit stub impedance converter 104 performs harmonic suppression processing on the first frequency band radio-frequency signal transmitted by the radio-frequency transceiver 101, and conducts the even harmonic signal in the first frequency band radio-frequency signal to the ground, so that the antenna 102 transmits the main frequency signal after suppressing the even harmonic signal in the first frequency band radio-frequency signal to the outside.
Further, when the harmonic suppression processing is not required for the radio frequency signal in the first frequency band, the first switch 103 may be turned off, and the short-circuit stub impedance converter 104 exits the operating state, i.e., the short-circuit stub impedance converter 104 does not function.
It should be noted that the radio frequency transceiver 101 may generate radio frequency signals of different frequency bands, for example, a Global System for Mobile Communication (GSM) network may include radio frequency signals of different frequency bands such as GSM850, GSM900, GSM1800, and GSM 1900; taking Long Term Evolution (LTE) network as an example, the LTE network may include radio frequency signals of different frequency bands, such as LTE B3, LTE B7, LTE B39, and LTE B41; a Code Division Multiple Access 2000 (CDMA 2000) network or a Wideband Code Division Multiple Access (WCDMA) network may also be taken as an example, and correspondingly, radio frequency signals of other different frequency bands may also be included; in the embodiments of the present application, this is not particularly limited.
On the basis of the technical solution shown in fig. 1, refer to fig. 2, which shows a schematic structural diagram of another radio frequency circuit 100 provided in the embodiment of the present application; the short-circuit stub impedance transformer 104 includes a microstrip line 201 with a quarter of a first wavelength; the microstrip line 201 is located on a circuit board corresponding to the radio frequency circuit 100, and the first wavelength is a wavelength corresponding to a center frequency of the radio frequency signal in the first frequency band.
It should be noted that the short-circuited stub impedance transformer 104 is used to suppress even harmonic signals in the first frequency band radio frequency signals transmitted by the radio frequency transceiver 101, so as to prevent interference of the even harmonic. Specifically, the main working principle is as follows: the first band RF signal is exemplified by a GSM850 band RF signal, assuming that the center frequency is f0Corresponding to a wavelength of λ0According to λ0The impedance conversion characteristic of the/4 microstrip line is known due to the λ0One end of the/4 microstrip line is grounded, and for a main frequency signal, the branch circuit presents an infinite impedance trend, namely the branch circuit is in an open circuit state, so that the main frequency signal cannot pass through the branch circuit; that is, the short-circuited stub impedance transformer 104 theoretically does not attenuate the main frequency signal; for the second harmonic 2f0(or even harmonic 2 nf)0(n is an integer greater than or equal to 1), and the equivalent electrical length of the short-circuit stub impedance converter is lambda0/2 (even harmonic corresponding to equivalent electrical length of n.lambda)02) according to λ0The impedance repetition characteristic of the/2 microstrip line shows that the branch has an infinite impedance trend for the second harmonic (or even harmonic), that is, the branch is in a short circuitTherefore, even harmonic signals can be conducted to the ground through the branch, so that even harmonic signals can be suppressed, and the antenna 102 emits outwards a main frequency signal after suppressing the even harmonic signals in the GSM850 frequency band radio frequency signals, thereby preventing the interference of the even harmonic signals in the GSM frequency band radio frequency signals to other signals.
Here, for the solution shown in fig. 2, the radio frequency transceiver 101 is connected to the antenna 102 to form a path, and the first switch 103 is a single-pole single-throw switch, wherein a first port of the single-pole single-throw switch is connected to the path, and a second port of the single-pole single-throw switch is connected to the microstrip line 201 of the quarter of the first wavelength.
It is understood that the short-circuit stub impedance transformer 104 may include a plurality of quarter-wave microstrip lines, each of which is used to suppress even harmonic signals in a radio frequency signal of a specific frequency band, and each of which is individually grounded; the plurality of quarter M-th microstrip lines are all located on a circuit board corresponding to the radio frequency circuit 100, the M-th wavelength is a wavelength corresponding to a center frequency of an M-th frequency band radio frequency signal, and the M is used for representing the number of different frequency bands corresponding to the radio frequency signal transmitted by the radio frequency transceiver 101.
Correspondingly, the first switch 103 may be a single-pole multi-throw switch, a fixed port of the single-pole multi-throw switch is connected to the via, and a plurality of gating ports of the single-pole multi-throw switch are respectively connected to a plurality of quarter of mth wavelength microstrip lines; that is, each gate port of the single-pole multi-throw switch is connected with a microstrip line of quarter of the mth wavelength.
For example, taking a Single Pole Double Throw (SPDT) switch as an example, referring to fig. 3, which shows a schematic structural diagram of another rf circuit 100 provided in the embodiment of the present application, the first switch 103 is a Single Pole Double Throw switch, the short-circuit stub impedance transformer 104 includes a quarter-first-wavelength microstrip line 301 and a quarter-second-wavelength microstrip line 302, wherein the rf transceiver 101 is connected to the antenna 102 to form a path, a fixed port of the Single Pole Double Throw switch is connected to the path,one end of the quarter-first-wavelength microstrip line 301 is connected to the first gating port (mark k1 in fig. 3) of the single-pole double-throw switch, the other end of the quarter-first-wavelength microstrip line 301 is connected to ground, one end of the quarter-second-wavelength microstrip line 302 is connected to the second gating port (mark k2 in fig. 3) of the single-pole double-throw switch, and the other end of the quarter-second-wavelength microstrip line 302 is connected to ground; the first wavelength corresponding to the quarter first wavelength microstrip line 301 is assumed to be λ1I.e. corresponding to a center frequency of f1And f is1The center frequency of the radio frequency signal of the GSM900 frequency band; the microstrip line 302 with a quarter of the second wavelength corresponds to a second wavelength λ2I.e. corresponding to a center frequency of f2And f is2The center frequency of the radio frequency signal of the GSM1800 frequency band; when the single-pole multi-throw switch is closed to the first gating port, the short-circuit stub impedance converter 104 can suppress even harmonic signals in the radio frequency signals of the GSM900 frequency band; when the single-pole multi-throw switch is closed to the second gating port, the short-circuit stub impedance converter 104 can suppress even harmonic signals in the radio frequency signals of the GSM1800 frequency band; therefore, the suppression of even harmonic signals in radio frequency signals of different frequency bands can be realized according to different microstrip lines.
It can be understood that, when the radio frequency signal transmitted by the radio frequency transceiver 101 includes multiple frequency bands, the first switch 103 may also be a multi-pole multi-throw switch, where a fixed port of the multi-pole multi-throw switch is connected to the path, and multiple gating ports of the multi-pole multi-throw switch are respectively connected to multiple quarter wavelength microstrip lines.
For example, taking a Double Pole Double Throw (DPDT) switch as an example, referring to fig. 4, which shows a schematic structural diagram of another rf circuit 100 provided in the embodiment of the present application, the first switch 103 is a Double Pole Double Throw switch, the short-circuit stub impedance transformer 104 includes a quarter microstrip line 401 with a first wavelength and a quarter microstrip line 402 with a second wavelength, wherein the rf transceiver 101 is connected to the antenna 102 to form a channel, a fixed port of the Double Pole Double Throw switch is connected to the channel, and a quarter of the first wavelength is connected to the microstrip line 402 with the second wavelengthOne end of the microstrip line 401 is connected to a first gating port (mark a1 in fig. 4) of the double-pole double-throw switch, the other end of the microstrip line 401 with a quarter first wavelength is connected to ground, one end of the microstrip line 402 with a quarter second wavelength is connected to a second gating port (mark a2 in fig. 4) of the double-pole double-throw switch, and the other end of the microstrip line 402 with a quarter second wavelength is connected to ground; the first wavelength corresponding to the quarter first wavelength microstrip line 401 is assumed to be λ1I.e. corresponding to a center frequency of f1And f is1The center frequency of the radio frequency signal of the GSM900 frequency band; the microstrip line 402 with a quarter of the second wavelength has a corresponding second wavelength λ2I.e. corresponding to a center frequency of f2And f is2The center frequency of the radio frequency signal of the GSM1800 frequency band; when the double-pole double-throw switch is closed to the first gating port and the second gating port, the short-circuit stub impedance converter 104 can simultaneously suppress even harmonic signals in radio frequency signals of a GSM900 frequency band and a GSM1800 frequency band; based on the characteristics of the double-pole double-throw switch, if the third gating port (the symbol b1 in fig. 4) of the double-pole double-throw switch is connected to the second gating port (the symbol a2 in fig. 4) (the connection is not shown in fig. 4), and the fourth gating port (the symbol b2 in fig. 4) of the double-pole double-throw switch is connected to the first gating port (the symbol a1 in fig. 4) (the connection is not shown in fig. 4), when the double-pole double-throw switch is closed to the third gating port and the fourth gating port, the short-circuit stub impedance converter 104 may also suppress even harmonic signals in the radio frequency signals of the GSM900 band and the GSM1800 band at the same time; therefore, the suppression of even harmonic signals in radio frequency signals of different frequency bands can be realized according to different microstrip lines.
It should be noted that, for the technical solution shown in fig. 1, when the radio frequency signal transmitted by the radio frequency transceiver 101 includes multiple frequency bands, the short-circuit stub impedance converter 104 may not only perform even harmonic signal suppression in the parallel connection form of the multiple microstrip lines (for example, fig. 3 and 4), but also perform even harmonic signal suppression in the series connection form of the multiple microstrip lines, and may suppress even harmonic signals in lower frequency bands by performing superposition processing on the multiple microstrip lines.
For the technical solution shown in fig. 1, if a series connection form of a plurality of microstrip lines is adopted, the short-circuit stub impedance converter 104 may include (N-1) second switches and N microstrip lines, where the second switches are single-pole double-throw switches, and the (N-1) second switches and the N microstrip lines are connected in series at intervals, so as to suppress even harmonic signals in radio frequency signals of different frequency bands; here, N is used to represent the number of different frequency bands corresponding to the radio frequency signal transmitted by the radio frequency transceiver 101, where N is greater than or equal to 2 and is an integer.
It can be understood that the (N-1) second switches and the N microstrip lines are connected in series at intervals, and include:
one end of the 1 st microstrip line is connected with the first switch 103, and the other end of the 1 st microstrip line is connected with the fixed port of the 1 st second switch;
when 1< i < N and i is an integer, one end of the ith microstrip line is connected with the first gating port of the (i-1) th second switch, the other end of the ith microstrip line is connected with the fixed port of the ith second switch, and the second gating port of the (i-1) th second switch is grounded; wherein i is a reference number;
one end of the Nth microstrip line is connected with the first gating port of the (N-1) th second switch, and the other end of the Nth microstrip line and the second gating port of the (N-1) th second switch are grounded.
It should be noted that, for a plurality of microstrip lines, the length of each microstrip line is different, and the microstrip line of the high frequency band can be multiplexed with the microstrip line of the low frequency band, and N microstrip lines are stacked in series through (N-1) second switches to realize the suppression of even harmonic signals in the radio frequency signals of the lower frequency band. That is, the radio frequency signals transmitted by the radio frequency transceiver 101 are arranged from high to low according to the frequency band, the highest frequency band is the first frequency band, and the second highest frequency band is the second frequency band; the length of the first microstrip line is obtained according to a quarter of a first wavelength, and the first wavelength is a wavelength corresponding to a center frequency of a first frequency band radio frequency signal in the radio frequency signal; the length of the second microstrip line is obtained by calculating the difference value according to a quarter of second wavelength and the length of the first microstrip line, wherein the second wavelength is the wavelength corresponding to the central frequency of a second frequency band radio frequency signal in the radio frequency signal; in this way, the length of the lth microstrip line is obtained by calculating the difference value according to the length accumulated by the quarter of the lth wavelength and the previous (L-1) microstrip lines, and the lth wavelength is the wavelength corresponding to the center frequency of the lth-band radio-frequency signal in the radio-frequency signals.
For example, taking the form of series connection of three microstrip lines as an example, refer to fig. 5, which shows a schematic structural diagram of a radio frequency circuit 100 provided in the embodiment of the present application; wherein, the first switch 103 is a single-pole single-throw switch, and the short-circuit stub impedance transformer 104 includes: a first microstrip line 501, a first single-pole double-throw switch 502, a second microstrip line 503, a second single-pole double-throw switch 504 and a third microstrip line 505; it is assumed that the radio frequency signal transmitted by the radio frequency transceiver 101 includes three frequency bands, namely, a GSM900 frequency band, a GSM1800 frequency band, and a GSM1900 frequency band, wherein a center frequency (i.e., a main frequency) of the GSM1900 frequency band radio frequency signal is f1Corresponding first wavelength is λ1(ii) a The center frequency (i.e. main frequency) of the GSM1800 frequency band radio frequency signal is f2Corresponding to a second wavelength λ2(ii) a The center frequency (main frequency) of the GSM900 frequency band radio frequency signal is f3Corresponding to a third wavelength of λ3(ii) a I.e. f1>f2>f3Corresponding to λ1<λ2<λ3Then it can be obtained that the length L1 of the first microstrip line 501 is λ1The length L2 of the second microstrip line 503 is (λ)2/4)-(λ1/4), the length L3 of the third microstrip line 505 is (λ)3/4)-(λ2/4), that is to say L1 ═ λ1/4，L1+L2＝λ2/4，L1+L2+L3＝λ3(ii)/4; thus, when the radio frequency circuit 100 operates in the GSM1900 frequency band, the first switch 103 is closed to put the short-circuited stub impedance converter 104 into an operating state, the first single-pole double-throw switch 502 turns on the first microstrip line 501 and the ground, and the circuit behind the second microstrip line 503 is in an off state at this time, since L1 ═ λ1The/4 shows that the short-circuit branch impedance converter 104 can suppress even harmonic signals in the GSM1900 frequency band; when the RF circuit 100 operates in the GSM1800 bandWhen the switch 103 is closed to make the short-circuited stub impedance converter 104 enter the working state, the first single-pole double-throw switch 502 connects the first microstrip line 501 and the second microstrip line 503, the second single-pole double-throw switch 504 connects the second microstrip line 503 and the ground, and the circuit behind the third microstrip line 505 is in the off state at this time, because L1+ L2 is λ2The/4 shows that the short-circuit branch impedance converter 104 can suppress even harmonic signals in the GSM1800 frequency band; when the radio frequency circuit 100 operates in the GSM900 frequency band, the first switch 103 is closed to enable the short-circuited stub impedance converter 104 to enter the operating state, the first single-pole double-throw switch 502 is connected with the first microstrip line 501 and the second microstrip line 503, the second single-pole double-throw switch 504 is connected with the second microstrip line 503 and the third microstrip line 505, and the third microstrip line 505 is connected with the ground, since L1+ L2+ L3 is λ3And 4, the short-circuit stub impedance converter 104 can suppress even harmonic signals of the GSM900 frequency band.
When the radio frequency signal transmitted by the radio frequency transceiver 101 includes a plurality of frequency bands, the short-circuit stub impedance converter 104 may adopt a parallel connection form of a plurality of microstrip lines, and at this time, although the microstrip lines cannot be multiplexed, the routing of the circuit board is complicated, the length calculation of each microstrip line is simple, and the combination of the lengths does not need to be considered; the short-circuit stub impedance converter 104 can also adopt a series connection form of a plurality of microstrip lines, at this time, although the length of each microstrip line needs to consider the combination of the lengths and needs to be added with a plurality of single-pole double-throw switches, the microstrip line of a high frequency band can be multiplexed with the microstrip line of a low frequency band, and the design complexity of the circuit board is reduced; in addition, the short-circuited stub impedance transformer 104 may be replaced with another microstrip filter exhibiting a band-pass characteristic in the even harmonic band; in the embodiments of the present application, this is not particularly limited.
On the basis of the technical solution shown in fig. 1, referring to fig. 6, which shows a schematic structural diagram of a further radio frequency circuit 100 provided in the embodiment of the present application, the radio frequency circuit 100 may further include a control circuit 105; the control circuit 105 is connected to the first switch 103, and the control circuit 105 is configured to control opening and closing of the first switch 103.
It should be noted that, when the radio frequency transceiver 101 transmits a radio frequency signal in a first frequency band to the outside, the control circuit 105 outputs a first control signal (for example, a high level signal) to close the first switch 103, so that the short-circuit stub impedance transformer 104 enters an operating state, and an even harmonic signal in the radio frequency signal in the first frequency band is conducted to the ground through the first switch 103 and the short-circuit stub impedance transformer 104, that is, the antenna 102 transmits a main frequency signal after suppressing the even harmonic signal in the radio frequency signal in the first frequency band to the outside; when the rf transceiver 101 stops transmitting the rf signal of the first frequency band, the control circuit 105 outputs a second control signal (e.g. a low level signal) to turn off the first switch 103, so that the short-circuited stub impedance converter 104 exits the operating state, i.e. the short-circuited stub impedance converter 104 does not function; therefore, the control circuit 105 also realizes effective control of suppressing even harmonic signals in the radio frequency signals of the first frequency band.
It should be further noted that the radio frequency circuit 100 described above can be applied to electronic devices. In the embodiments of the present application, the electronic device may be implemented in various forms. For example, the electronic devices described in the present application may include mobile electronic devices such as mobile phones, tablet computers, notebook computers, palmtop computers, Personal Digital Assistants (PDAs), Portable Media Players (PMPs), navigation devices, wearable devices, and the like, and stationary electronic devices such as Digital TVs, desktop computers, and the like.
Referring to fig. 7, which shows a schematic structural diagram of an electronic device 700 for implementing various embodiments of the present application, the electronic device 700 includes a cover plate 701, a display screen 702, a circuit board 703 and a housing 704; wherein, the cover plate 701 is installed on the display screen 702 to cover the display screen 702, and the cover plate 701 may be a transparent glass cover plate; a display screen 702 is mounted on the housing 704 to form a display surface of the electronic device 700, the display screen 702 being used for displaying information such as images and texts; the circuit board 703 is installed inside the housing 704, the circuit board 703 may be a motherboard of the electronic device 700, and functional components such as a camera, a memory, a processor and the like may be integrated on the circuit board 703; meanwhile, a radio frequency circuit is also placed on the circuit board 703, and the radio frequency circuit may be the radio frequency circuit 100 described in any of the foregoing embodiments; the radio frequency circuit can also communicate with a network device or other devices through wireless communication, so that information can be transmitted and received between the electronic device 700 and the network device or other devices.
While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A radio frequency circuit, characterized in that the radio frequency circuit comprises: the radio frequency transceiver, the antenna, the first switch and the short-circuit branch impedance converter; the radio frequency transceiver is connected with the antenna to form a path, one end of the short-circuit stub impedance converter is connected with the path through the first switch, and the other end of the short-circuit stub impedance converter is directly grounded; wherein the content of the first and second substances,
the first switch is used for controlling the short-circuit branch impedance converter to enter a working state or exit the working state;
when the first switch is closed, the short-circuit branch impedance converter performs harmonic suppression processing on a first frequency band radio frequency signal transmitted by the radio frequency transceiver, and conducts an even harmonic signal in the first frequency band radio frequency signal to the ground, so that the antenna transmits a main frequency signal after suppressing the even harmonic signal in the first frequency band radio frequency signal outwards;
wherein the short-circuit stub impedance transformer comprises (N-1) second switches and N microstrip lines; the second switches are single-pole double-throw switches, and the (N-1) second switches and the N microstrip lines are connected in series at intervals; and in the N microstrip lines, the microstrip line of the high frequency band is multiplexed with the microstrip line of the low frequency band, and the N microstrip lines are serially connected and overlapped through the (N-1) second switches to realize the suppression of even harmonic signals in the radio frequency signals of the lower frequency band.
2. The radio frequency circuit of claim 1, wherein the short stub impedance transformer comprises a quarter first wavelength microstrip line; the microstrip line with the quarter of the first wavelength is located on the circuit board corresponding to the radio frequency circuit, and the first wavelength is a wavelength corresponding to a central frequency of the radio frequency signal of the first frequency band.
3. The radio frequency circuit according to claim 2, wherein the first switch is a single-pole single-throw switch, wherein a first port of the single-pole single-throw switch is connected to the via and a second port of the single-pole single-throw switch is connected to the quarter first wavelength microstrip line.
4. The radio frequency circuit of claim 1, wherein the short stub impedance transformer comprises a plurality of quarter-wave mth microstrip lines, each quarter-wave mth microstrip line being individually grounded; the plurality of quarter M-th wavelength microstrip lines are all located on a circuit board corresponding to the radio frequency circuit, the M-th wavelength is a wavelength corresponding to a central frequency of an M-th frequency band radio frequency signal, and M is used for representing the number of different frequency bands corresponding to the radio frequency signal transmitted by the radio frequency transceiver.
5. The RF circuit of claim 4, wherein the first switch is a single-pole-multiple-throw switch, wherein a fixed port of the single-pole-multiple-throw switch is connected to the via, and a plurality of gated ports of the single-pole-multiple-throw switch are respectively connected to the plurality of quarter-wave microstrip lines.
6. The RF circuit of claim 4, wherein the first switch is a multi-pole multi-throw switch, wherein a fixed port of the multi-pole multi-throw switch is connected to the via, and a plurality of gated ports of the multi-pole multi-throw switch are respectively connected to the plurality of quarter-wave microstrip lines.
7. The radio frequency circuit according to claim 1, wherein the (N-1) second switches and the N microstrip lines are connected in spaced series, comprising:
one end of the 1 st microstrip line is connected with the first switch, and the other end of the 1 st microstrip line is connected with the fixed port of the 1 st second switch;
when 1< i < N and i is an integer, one end of the ith microstrip line is connected with the first gating port of the (i-1) th second switch, the other end of the ith microstrip line is connected with the fixed port of the ith second switch, and the second gating port of the (i-1) th second switch is grounded; wherein i is a reference number;
one end of the Nth microstrip line is connected with the first gating port of the (N-1) th second switch, and the other end of the Nth microstrip line and the second gating port of the (N-1) th second switch are grounded.
8. The radio frequency circuit of claim 1, further comprising a control circuit; the control circuit is connected with the first switch and is used for controlling the first switch to be opened and closed.
9. An electronic device comprising a housing and a circuit board mounted inside the housing, the circuit board having the radio frequency circuit of any one of claims 1 to 8 placed thereon.
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| CN201810934423.9A CN109039369B (en) | 2018-08-16 | 2018-08-16 | Radio frequency circuit and electronic device |
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| CN201810934423.9A CN109039369B (en) | 2018-08-16 | 2018-08-16 | Radio frequency circuit and electronic device |
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| CN109755748B (en) * | 2019-01-21 | 2021-09-14 | 联想(北京)有限公司 | Electronic device |
| CN111864411B (en) | 2019-04-30 | 2022-08-05 | 北京小米移动软件有限公司 | Antenna module, terminal, control method, control device and storage medium |
| CN111181590B (en) * | 2020-01-07 | 2021-11-05 | 维沃移动通信有限公司 | Radio frequency control circuit and electronic equipment |
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| EP1120905A2 (en) * | 2000-01-11 | 2001-08-01 | Alps Electric Co., Ltd. | Output amplifier for a voltage controlled oscillator |
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| US8135145B2 (en) * | 2009-07-22 | 2012-03-13 | National Yunlin University Of Science And Technology | Multi-level output signal converter |
| CN202218193U (en) * | 2011-08-16 | 2012-05-09 | 雷良军 | Multiple band power amplifier |
| CN103391057A (en) * | 2012-05-11 | 2013-11-13 | 京信通信系统（中国）有限公司 | Reverse F-type power amplifier and emitter as well as processing method |
| CN110313245B (en) * | 2012-10-18 | 2015-04-22 | 中国航天科工集团第二研究院二十三所 | A kind of meter wave band T/R switch of PIN-based diode |
| CN104967436A (en) * | 2015-07-01 | 2015-10-07 | 上海斐讯数据通信技术有限公司 | Circuit for improving performance of mobile terminal |
| CN107425818A (en) * | 2017-04-17 | 2017-12-01 | 东莞赛唯莱特电子技术有限公司 | A kind of output matching circuit structure for improving radio-frequency power amplifier harmonic performance |
| CN107332528A (en) * | 2017-08-11 | 2017-11-07 | 华中科技大学 | A kind of tunable multiple frequency section power amplifier |
| CN107634766A (en) * | 2017-08-25 | 2018-01-26 | 广东欧珀移动通信有限公司 | Radio circuit, antenna assembly and electronic equipment |
| CN108063604A (en) * | 2017-12-12 | 2018-05-22 | 重庆西南集成电路设计有限责任公司 | A kind of filter with low insertion loss millimeter wave digital pad |
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| EP1120905A2 (en) * | 2000-01-11 | 2001-08-01 | Alps Electric Co., Ltd. | Output amplifier for a voltage controlled oscillator |
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