CN109450484B - Signal reflection eliminating circuit and method - Google Patents
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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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- 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
- H04B1/005—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
- H04B1/0053—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band
- H04B1/006—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 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band using switches for selecting the desired band
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- 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
Abstract
The embodiment of the invention discloses a signal reflection eliminating circuit and a method thereof, comprising a combining unit and a power distribution unit which are connected in sequence; the combiner unit is used for combining output signals of the two first transmission links into a signal, wherein the two first transmission links are obtained by combining the plurality of first transmission links in pairs; the signal transmission directions of the plurality of first transmission links are consistent; the power distribution unit is used for dividing the one-path signal into two paths of signals with equal amplitude phase difference of 90 degrees for output, so that the phase difference of two reflection signals received by the rear-end circuit is 90 degrees, and further when the two reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two reflection signals of 180 degrees. The characteristics of the same multi-path design of the radio frequency front-end circuit of the existing product are utilized to change a multi-path transmitting or multi-path receiving link into a multi-path transmitting or multi-path receiving link which is combined together through the signal reflection eliminating circuit to eliminate the back-stage reflection, so that the reflected signal is effectively eliminated without being limited by the frequency range.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to a signal reflection eliminating circuit and a signal reflection eliminating method.
Background
The number of global wireless connections will be multiplied in the future driven by the application of the internet of things. High-throughput the number of terminal devices that implement wireless connectivity worldwide is expected to exceed 250 billion by 2020. The future world is a world with all wireless connections, which are more demanding. With the large trend of wireless networking end devices increasing from 36 to 250 billion in 2015, the market for rf front-end modules is growing strongly and the opportunities for the rf device industry are also continuing. The radio frequency front end module is composed of a Power Amplifier (PA), a filter, a duplexer, a radio frequency switch, a low noise amplifier, a receiver/transmitter and the like. The radio frequency device is the core of wireless connection, and the radio frequency device is necessary to be arranged at any place needing the wireless connection.
In the existing rf front-end circuit architecture, the design scheme of the rf front-end circuit is generally as follows: chip signal output + power amplifier/low noise amplifier + coupler/filter/balun + radio frequency switch + antenna, referring to fig. 1, the design of multiple paths of a general radio frequency front-end circuit is the same, and the most common two-path 2.4G link and two-path 5G link are used for explanation, and the two-path 2G design scheme is completely the same, and the two-path 5G design scheme is also completely the same. Generally, the input and output impedances of the radio frequency wiring and the radio frequency device are both guaranteed to be 50 Ω, and in such an ideal case, no reflected signal exists on the link. However, in practical application, the input/output impedance of the rf device cannot be guaranteed to be 50 Ω. Therefore, a matching circuit is added between the connections of each stage of radio frequency device to match the output impedance of the previous stage of radio frequency device with the input impedance of the next stage of radio frequency device, so as to eliminate reflection. As can be seen from fig. 1, there are multiple matching circuits on a link, and any one matching circuit mismatch may cause signal reflection, thereby affecting performance.
The inventor finds that the prior art has the following defects when implementing the embodiment of the invention, and generally designs the matching circuit by adopting lumped elements such as capacitance and inductance and the like when building the matching circuit. For example, when the radio frequency circuit works, the radio frequency circuit needs to work in a frequency band of 2.4-2.5G and 5.1-5.8G. Due to the frequency characteristics (impedance changes along with frequency) of the devices such as capacitance and inductance in the matching circuit, all channels in the working frequency band can not be ideally matched, and only good matching of some channels can be met. However, ideal complete matching does not exist in practice, that is, the design of the matching circuit cannot effectively eliminate reflection, and only can reduce reflection, so that the application scenario of the matching circuit has limitations. The design of the matching circuit needs to be tested and debugged repeatedly and is limited by the frequency characteristics of the device, the debugged matching circuit can only meet the matching performance in a certain frequency band, for example, when the device generates harmonic waves far away from a matching frequency point, reflection can be generated and directly enters the device to cause performance reduction, for a power amplifier, the matching requirement on a radio frequency input and output end is high, the matching is poor, the reflection signal of a rear-stage device influences the performance of power amplification and low-noise amplification, and even the device is burnt.
Disclosure of Invention
The embodiment of the invention provides a signal reflection eliminating circuit and a signal reflection eliminating method, which can realize reflection cancellation, effectively eliminate reflection signals and are not limited by a frequency range.
The embodiment of the invention provides a signal reflection eliminating circuit, which comprises a combining unit and a power distribution unit which are sequentially connected;
the combiner unit is used for combining output signals of two first transmission links into one signal, wherein the two first transmission links are obtained by combining a plurality of first transmission links in pairs; wherein the signal transmission directions of the plurality of first transmission links are consistent;
the power distribution unit is used for dividing the one-path signal into two-path signal output with equal amplitude phase difference of 90 degrees, so that the phase difference of two-path reflection signals received by the rear-end circuit is 90 degrees, and further when the two-path reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflection signals of 180 degrees.
In one embodiment, the power distribution unit is a directional coupler.
In one embodiment, the directional coupler is a 3db coupler.
In one embodiment, the 3db coupler comprises a port 1, a port 2, a port 3 and a port 4, wherein the port 1 is used for receiving the one-path signal, the port 2 and the port 4 are used for outputting the signal, and the reflected signal is received when a back-end circuit generates a reflection; the equal amplitude phase difference of the signals output by the port 2 and the port 4 is 90 degrees, and the equal amplitude phase difference of the reflected signals received by the port 2 and the port 4 is 90 degrees;
when the two paths of reflection signals are synthesized and output, reflection cancellation is realized at the port 1 when the phase difference of the two paths of reflection signals is 180 degrees, the two paths of reflection signals are superposed and output in a constant amplitude mode at the port 3, and the reflection signals are absorbed by externally connecting a load to the port 3.
In one embodiment, the combining unit includes a phase shifting unit and a power combining unit;
the phase shifting unit is used for shifting the phase of one of the two first transmission links, so that the phase difference between the phase-shifted signal and the signal of the other transmission link is 90 degrees, and the equal-amplitude phase difference of the two paths of signals accessed to the power synthesis unit is 90 degrees;
the power synthesis unit is used for synthesizing the two paths of accessed signals with the equal amplitude phase difference of 90 degrees into one path of signal and outputting the signal.
In one embodiment, the power combining unit includes any one of a 3db coupler or a two-way power divider.
In one embodiment, when the first transmission link is a transmission link, the signal reflection cancellation circuit is connected between the power amplifier and the back-end circuit thereof, and is used for canceling a reflection signal output by the power amplifier.
In one embodiment, when the first transmission link is a transmission link, the signal reflection cancellation circuit is connected between the back-end circuits of the rf chips, and is configured to cancel a reflection signal output by the rf chips.
In one embodiment, when the first transmission link is a receiving link, the signal reflection cancellation circuit is connected between the back end circuits of the low noise amplifiers, and is used for canceling the reflection signals output by the low noise amplifiers.
Correspondingly, the embodiment of the invention also provides a signal reflection eliminating method, which comprises the following steps:
the combining unit combines output signals of two first transmission links into a signal, wherein the two first transmission links are obtained by combining a plurality of first transmission links in pairs; wherein the signal transmission directions of the plurality of first transmission links are consistent;
the power distribution unit divides the one path of signal into two paths of signals with equal amplitude phase difference of 90 degrees, so that the phase difference of the two paths of reflection signals received by the rear end circuit is 90 degrees, and when the two paths of reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two paths of reflection signals being 180 degrees.
The embodiment of the invention has the following beneficial effects:
the circuit and the method for eliminating signal reflection provided by the embodiment of the invention comprise a combining unit and a power distribution unit which are connected in sequence; the combiner unit is used for combining output signals of two first transmission links into one signal, wherein the two first transmission links are obtained by combining a plurality of first transmission links in pairs; the signal transmission directions of the two first transmission links are consistent; the power distribution unit is used for dividing the one-path signal into two-path signal output with equal amplitude phase difference of 90 degrees, so that the phase difference of two-path reflection signals received by the rear-end circuit is 90 degrees, and further when the two-path reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflection signals of 180 degrees. Effectively eliminate the reflected signal and is not limited by the frequency range.
Drawings
FIG. 1 is a schematic diagram of a conventional RF front-end circuit;
FIG. 2 is a schematic diagram of a signal reflection elimination circuit provided in the present invention;
FIG. 3 is a schematic structural diagram of the working principle of the directional coupler provided by the present invention;
FIG. 4 is a schematic structural diagram illustrating the operation principle of the signal reflection eliminating circuit according to the present invention when receiving the reflected signal;
FIG. 5 is a schematic structural diagram illustrating the operation principle of the signal reflection eliminating circuit according to the present invention when receiving the reflected signal;
fig. 6 is a schematic structural diagram of a combining unit provided by the present invention;
FIG. 7 is a schematic diagram of an application of a signal reflection elimination circuit provided in the present invention;
FIG. 8 is a schematic diagram of another application of the signal reflection elimination circuit provided by the present invention;
FIG. 9 is a schematic diagram of another application of the signal reflection elimination circuit provided by the present invention;
FIG. 10 is a schematic diagram of another application of the signal reflection elimination circuit provided by the present invention;
FIG. 11 is a schematic diagram of another application of the signal reflection elimination circuit provided by the present invention;
fig. 12 is a schematic flow chart of a signal reflection eliminating method provided by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the 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.
Example one
Referring to fig. 2, which is a schematic structural diagram of a signal reflection eliminating circuit according to a first embodiment of the present invention, as shown in the figure, the signal reflection eliminating circuit includes:
a combiner unit 01 and a power distribution unit 02 connected in sequence;
the combining unit 01 is configured to combine output signals of two first transmission links into one signal, where the two first transmission links are obtained by combining two of the first transmission links; wherein the signal transmission directions of the plurality of first transmission links are consistent;
the power distribution unit 02 is configured to divide the one-path signal into two-path signals with a constant amplitude phase difference of 90 degrees, and output the two-path signals, so that the phase difference of the two-path reflected signals received by the back-end circuit is 90 degrees, and further, when the two-path reflected signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflected signals being 180 degrees.
It should be noted that, in the existing design of the rf front-end circuit, multiple paths are designed identically, taking multiple paths of 2.4G links as an example, devices and wires used on a transmitting link of each path are the same, and devices and wires used on a receiving link of each path are also the same, so as to ensure that phase delays of reflected signals input to the power distribution unit 02 are the same, because when matching circuits, rf devices, and wire lengths in the back-end circuit connected to the power distribution are the same, the generated reflection positions and sizes are also the same, and phase delays of corresponding reflected signals are the same.
In the embodiment of the invention, the original way that one way of signal works independently through a radio frequency switch by transmitting and receiving is changed into the way that two ways of signal are transmitted and combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection, and two ways of signal are received and combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection. For example, assuming that the two 2G transmission links include a first transmission link and a second transmission link, the first transmission link and the second transmission link are combined in pairs to be changed into two transmission paths, and the two transmission paths are combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection; when four ABCD transmitting links exist in the 2G transmitting transmission link, the two transmitting links are randomly combined, such as AB and CD; or AC, BD, etc., which are not specifically limited in the present invention, the two transmission links are combined together to eliminate the post-stage reflection, and the phase difference of the reflected signal at the output end of the power distribution unit 02 is 180 degrees to realize reflection cancellation, thereby realizing reflection elimination. The receiving link is the same, and the description thereof is omitted.
In the embodiment of the present invention, after a plurality of first transmission links are combined in pairs, two first transmission links are in one combination, and the combining unit 01 is configured to combine output signals of the two first transmission links in one combination into one signal to be output, where the signal transmission directions of the plurality of first transmission links are the same, the first transmission links may be both reflection links and both reception links, but the first transmission links may not include a transmission link and a reception link at the same time, because the signal transmission directions of the transmission link and the reception link are not the same.
In the embodiment of the present invention, the power distribution unit 02 is a device that divides one path of input signal energy into two or more paths of output equal or unequal energy, and may also combine the multiple paths of signal energy into one path of output in reverse.
To briefly explain the working principle of the embodiment of the present invention, the combining unit 01 combines two output signals of the two first transmission links, that is, two signals, into one signal, and outputs the one signal to the power distributing unit 02, the power distributing unit 02 divides the one signal into two output signals with equal amplitude phase difference of 90 degrees, wherein 90 degrees is determined according to the selected power distributing unit 02, and the value of the 90 degrees can be selected according to actual needs, the 90 degrees ensure that after the two signals are output, the power distributing unit 02 receives two reflected signals with phase difference of 90 degrees of the rear-end circuit, that is, two dashed reflected signals in fig. 2, when the two reflected signals are combined and output, the two reflected signals cancel each other because the phase difference of the two reflected signals is 180 degrees, reflection phase cancellation is realized, and the two paths of reflection signals are not output through the power distribution unit 02.
In one embodiment, the power distribution unit 02 is a directional coupler 21. It should be noted that the directional coupler 21 is a general microwave/millimeter wave component, and can be used for signal isolation, separation, and mixing, such as power monitoring, source output power stabilization, signal source isolation, frequency sweep test of transmission and reflection, and the like. The directional coupler 21 is a directional power coupling (distribution) element, and is also a device having four ports, and the number of the corresponding first transmission links is two.
The working principle of the directional coupler 21 is explained below:
referring to fig. 3, the directional coupler 21 is a stripline coupler for illustration, the stripline directional coupler 21 is a four-port device, which is composed of two pairs of transmission lines, generally the line length is 1/4 wavelength corresponding to the center frequency, when a signal is input from port 1 of the stripline, an alternating current I1 flows through striplines 1-4, and since striplines 2-3 and striplines 1-4 are close to each other, energy is coupled in the 2-3 lines, and the energy is coupled through an electric field (represented by coupling capacitor C) and a magnetic field. The coupling through C causes currents in striplines 2-3 of IC1, IC2, to flow to port 2 and port 3, respectively. Meanwhile, due to the action of the alternating magnetic field, a current IL is induced on the 2-3 lines, and according to the law of electromagnetic induction, the direction of the induced current IL is opposite to that of the current I1. When energy is input from port 1, port 2 has coupled energy output, so port 2 is called coupled end. At port 3, since the directions of the electric field coupling current IC2 and the magnetic field coupling current IL are opposite, if IC2 is just made to be IL, the energies cancel each other out, so that port 3 outputs no energy, and port 4 directly transmits energy through the λ g/4 strip line, and also outputs energy, which is called a through port. In the ideal case, it can be shown that when the strip line length is λ g/4, the coupling between the two lines is maximum, and the input port 1 and the output ports 2, 4 are matched to the coupler, port 3 has no energy output, while each of ports 2 and 4 outputs half the signal source power, U2U 4U 1, the voltage U2 at port 2 is in phase with the voltage U1 at port 1, the voltage U4 at port 4 lags the voltage U1 at port 1 by 90 °, and since the line lengths 1-4 are λ g/4, the signal phase between U2 and U4 differs by 90 °.
The directional coupler 21 can be used as power distribution or power synthesis, when the input power is injected from the port 1 as power distribution, half of the input power is obtained at the port 2 and the port 4 respectively, because the power is reduced by one time at the ports 2 and 4, namely reduced by 3 dB. When power combining is performed, two signal sources can be respectively added to the ports of the directional coupler 21, such as port 1 and port 3, or port 2 and port 4, which are isolated from each other, and the phase difference between the two signal sources is 90 degrees. Referring to fig. 4, according to the characteristics of the directional coupler 21, the port 2 and the port 4 are isolated from each other, and the signals input to the port 2 and the port 4, respectively, have no influence between the two signal sources. For the signal source voltage U applied to port 22＝U2ej0For the port 3 is a through port, the output voltage is
Port 1 is a coupling port and the output voltage is
For signal source voltage U applied to port 44＝U4e-j90°In other words, the port 3 is a coupling terminal, and the output voltage is
Port 1 is a through port, outputAt a voltage of
It can be seen that when the two signal sources have equal voltage amplitudes and 90 degrees phase difference, and signals are applied to port 2 and port 4 simultaneously, the output voltages at port 1 and port 3 are:
specifically, when the one-path signal needs to be divided into multiple paths of signals with equal-amplitude phase difference of 90 degrees, the directional coupler 21 is used for power distribution, the one-path signal is input to the port 1, and then the two paths of signals with equal-amplitude phase difference of 90 degrees are respectively output to the port 2 and the port 4; when the directional coupler 21 receives a reflected signal of the back-end circuit, the two reflected signals are respectively received in the port 2 and the port 4 which are isolated from each other, the voltage output by the port 1 is 0, and the reflected signals are superposed and output by the port 3.
In one embodiment, the directional coupler is a 3db coupler. The 3db quadrature coupler 22 comprises a port 1, a port 2, a port 3 and a port 4, wherein the port 1 is used for receiving the one-path signal, the port 2 and the port 4 are used for outputting the signal, and receiving the reflected signal when the back-end circuit generates a reflection; the equal amplitude phase difference of the signals output by the port 2 and the port 4 is 90 degrees, and the equal amplitude phase difference of the reflected signals received by the port 2 and the port 4 is 90 degrees;
when the two paths of reflection signals are synthesized and output, reflection cancellation is realized at the port 1 when the phase difference of the two paths of reflection signals is 180 degrees, the two paths of reflection signals are superposed and output in a constant amplitude mode at the port 3, and the reflection signals are absorbed by externally connecting a load to the port 3.
The working principle of the 3db quadrature coupler 22 when applied in the embodiment of the present invention is explained as follows:
referring to fig. 5, it is assumed that the phases of the constant amplitude signals output from the ports 2 and 4 of the 3db quadrature coupler 22 are-90 ° and-180 °, respectively. Since the two paths behind the 3db quadrature coupler 22 have the same design, the phase delay experienced by the reflected signal is the same as D, and the amplitudes are the same, when the reflected signal loaded at the rear end of the 3db quadrature coupler 22 is reflected, the signal connected into the 3db quadrature coupler 22 is still in equal-amplitude quadrature, as can be seen from fig. 5, the phases of the reflected signal entering the port 2 at the port 1 and the port 3 are-180 ° + D and-270 ° + D, respectively, the phases of the reflected signal entering the port 4 at the port 1 and the port 3 are-360 ° + D and-270 ° + D, respectively, since the two reflected signals at the port 1 are in equal amplitude and 180 ° out of phase, the two reflected signals cancel each other, and are not output through the 3db quadrature coupler 22, thereby achieving zero reflection. The two reflected signals have equal amplitude at the port 3 and have a phase difference of 0 degree, so that the reflected signals are superposed and output, the port 3 is externally connected with a load, the load absorbs the superposed reflected signals through the externally connected load, the reflected signals are dissipated, and the port 3 can be externally connected with a resistor or grounded.
In one embodiment, the combining unit 01 includes a phase shifting unit 12 and a power combining unit 13;
the phase shifting unit 12 is configured to shift a phase of one transmission link, so that a phase difference between a phase-shifted signal and a signal of the other transmission link is 90 degrees, and a phase difference between two paths of signals accessed to the power combining unit 13 is 90 degrees;
the power synthesis unit 13 is configured to synthesize the two accessed signals with a constant amplitude phase difference of 90 degrees into one signal and output the signal.
In the embodiment of the present invention, referring to fig. 6, the power combining unit 13 has four ports, in order to ensure that two link signals can be combined in equal amplitude at the output port 2 through the power combining unit 13, the phase shifting unit 12 performs phase shifting on one of the two link signals at the output port 4, so that the phase difference is 90 degrees when the two link signals enter the port 1 and the port 3 of the power combining unit 13, the power distributing unit 02 can match corresponding modules according to 90 degrees, and according to 90 degrees, the signals input at the port 1 and the port 3 will be superimposed and output in equal amplitude at the port 2, and output one link signal, and vice versa in equal amplitude at the port 4.
In one embodiment, the power combining unit 13 includes any one of a 3db quadrature coupler or a two-way power divider.
In this embodiment of the present invention, when the phase difference of the signal connected to the power combining unit 13 is 90 degrees, the power combining unit 13 includes any one of a 3db quadrature coupler and a two-power splitter.
In one embodiment, when the first transmission link is a transmission link, the signal reflection cancellation circuit is connected between the power amplifier and the back-end circuit thereof, and is used for canceling a reflection signal output by the power amplifier.
Referring to fig. 7, the signal reflection eliminating circuit is connected between the power amplifier and the back-end circuit thereof, so that the reflection after the power amplifier is amplified can be eliminated, and the performance of the power amplifier can be ensured.
In one embodiment, when the first transmission link is a transmission link, the signal reflection cancellation circuit is connected between the back-end circuits of the rf chips, and is configured to cancel a reflection signal output by the rf chips.
Referring to fig. 8, the signal reflection eliminating circuit is connected between the back end circuits of the rf chips, so that when matching mismatch occurs, a reflection signal is prevented from being connected to the rf chips, which affects the performance of the chips.
In one embodiment, when the first transmission link is a receiving link, the signal reflection cancellation circuit is connected between the back end circuits of the low noise amplifiers, and is used for canceling the reflection signals output by the low noise amplifiers.
Referring to fig. 9, the signal reflection eliminating circuit is connected between the back end circuits of the low noise amplifiers, so that the output back reflection of the low noise amplifiers can be eliminated, and the performance of the low noise amplifiers can be ensured.
It should be noted that, fig. 7 to fig. 9 may be combined, and referring to fig. 10, the signal reflection eliminating circuit may be connected to the position 1, the position 2, and the position 3 in fig. 9, respectively, and the signal reflection eliminating circuit in fig. 11 may be connected to the position where there is reflection, which is not limited in the present invention.
In the embodiment of the invention, the original one-path signal is changed from single work of transmission and reception through a radio frequency switch to multi-path transmission through the combination unit 01 and the power distribution unit 02 and combined together to eliminate the rear-stage reflection, and the multi-path reception through the combination unit 01 and the power distribution unit 02 and combined together to eliminate the rear-stage reflection. The phase difference of the reflected signals at the output end of the power distribution unit 02 is 180 degrees to realize reflection cancellation, and further realize reflection elimination.
The embodiment has the following beneficial effects:
in the circuit for eliminating signal reflection provided in the embodiment of the present invention, the combining unit 01 combines output signals of two first transmission links into one signal, where the two first transmission links are obtained by combining two of the plurality of first transmission links; wherein the signal transmission directions of the plurality of first transmission links are consistent; the power distribution unit 02 divides the one-path signal into two-path signals with equal amplitude phase difference for output, so that the phase difference of the two-path reflected signals received by the back-end circuit is 90 degrees, and further, when the two-path reflected signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflected signals being 180 degrees. By utilizing the same characteristics of the multi-path design of the radio frequency front-end circuit of the existing product, the original condition that one path of signal is transmitted and received through a radio frequency switch to work independently is changed into two paths of transmission through the combining unit 01 and the power distribution unit 02 to be combined together to eliminate the rear-stage reflection, and two paths of reception through the combining unit 01 and the power distribution unit 02 to be combined together to eliminate the rear-stage reflection under the condition that no additional signal extraction and processing unit is added. Effectively eliminate the reflected signal and is not limited by the frequency range.
Example two
Accordingly, an embodiment of the present invention further provides a signal reflection eliminating method, with reference to fig. 12, including:
s11, combining unit 01 combines output signals of two first transmission links into one signal, where the two first transmission links are obtained by combining multiple first transmission links two by two; wherein the signal transmission directions of the plurality of first transmission links are consistent;
s12 and the power distribution unit 02 divide the one-path signal into two-path signals with a constant amplitude phase difference of 90 degrees, so that the phase difference of the two-path reflected signals received by the back-end circuit is 90 degrees, and when the two-path reflected signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflected signals being 180 degrees.
It should be noted that, in the existing design of the rf front-end circuit, multiple paths are designed identically, taking multiple paths of 2.4G links as an example, devices and wires used on a transmitting link of each path are the same, and devices and wires used on a receiving link of each path are also the same, so as to ensure that phase delays of reflected signals input to the power distribution unit 02 are the same, because when matching circuits, rf devices, and wire lengths in the back-end circuit connected to the power distribution are the same, the generated reflection positions and sizes are also the same, and phase delays of corresponding reflected signals are the same.
In the embodiment of the invention, the original way that one way of signal works independently through a radio frequency switch by transmitting and receiving is changed into the way that two ways of signal are transmitted and combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection, and two ways of signal are received and combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection. For example, assuming that the two 2G transmission links include a first transmission link and a second transmission link, the first transmission link and the second transmission link are combined in pairs to be two-way transmission, and the two-way transmission is combined together through the combining unit 01 and the power distribution unit 02 to eliminate the back-stage reflection; when four ABCD transmitting links exist in the 2G transmitting transmission link, the two transmitting links are randomly combined, such as AB and CD; or AC, BD, etc., which are not specifically limited in the present invention, the two transmission links are combined together to eliminate the post-stage reflection, and the phase difference of the reflected signal at the output end of the power distribution unit 02 is 180 degrees to realize reflection cancellation, thereby realizing reflection elimination. The receiving link is the same, and the description thereof is omitted.
The embodiment has the following beneficial effects:
in the method for eliminating signal reflection provided in the embodiment of the present invention, the combining unit 01 combines output signals of two first transmission links into one signal, where the two first transmission links are obtained by combining two of the plurality of first transmission links; wherein the signal transmission directions of the plurality of first transmission links are consistent; the power distribution unit 02 divides the one-path signal into two-path signals with a constant amplitude phase difference of 90 degrees for output, so that the phase difference of the two-path reflected signals received by the back-end circuit is 90 degrees, and further, when the two-path reflected signals are synthesized and output, reflection cancellation is realized according to the phase difference of the two-path reflected signals of 180 degrees. By utilizing the same characteristics of the multi-path design of the radio frequency front-end circuit of the existing product, the original condition that one path of signal is transmitted and received through a radio frequency switch to work independently is changed into two paths of transmission through the combining unit 01 and the power distribution unit 02 to be combined together to eliminate the rear-stage reflection, and two paths of reception through the combining unit 01 and the power distribution unit 02 to be combined together to eliminate the rear-stage reflection under the condition that no additional signal extraction and processing unit is added. Effectively eliminate the reflected signal and is not limited by the frequency range. It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (7)
1. A signal reflection eliminating circuit is characterized by comprising a combining unit and a power distribution unit which are connected in sequence; the combining unit is used for combining output signals of two first transmission links in one combination into one signal, wherein the two first transmission links in the one combination are obtained by combining a plurality of first transmission links in pairs, and each combination comprises two first transmission links; wherein the signal transmission directions of the plurality of first transmission links are consistent;
the power distribution unit is used for dividing the one-path signal into two-path signal output with equal amplitude phase difference of 90 degrees, so that the phase difference of two-path reflection signals received by the rear-end circuit is 90 degrees, and further when the two-path reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two-path reflection signals of 180 degrees;
wherein the power distribution unit is a directional coupler; the directional coupler is a 3db coupler; the 3db coupler comprises a port 1, a port 2, a port 3 and a port 4, wherein the port 1 is used for receiving the one-path signal, the port 2 and the port 4 are used for outputting the signal, and the reflected signal is received when the back-end circuit generates reflection; the equal amplitude phase difference of the signals output by the port 2 and the port 4 is 90 degrees, and the equal amplitude phase difference of the reflected signals received by the port 2 and the port 4 is 90 degrees;
when the two paths of reflection signals are synthesized and output, reflection cancellation is realized at the port 1 when the phase difference of the two paths of reflection signals is 180 degrees, the two paths of reflection signals are superposed and output in a constant amplitude mode at the port 3, and the reflection signals are absorbed by externally connecting a load to the port 3.
2. The signal reflection cancellation circuit of claim 1, wherein the combining unit includes a phase shifting unit and a power combining unit;
the phase shifting unit is used for shifting the phase of one of the two first transmission links, so that the phase difference between the phase-shifted signal and the signal of the other transmission link is 90 degrees, and the equal-amplitude phase difference of the two paths of signals accessed to the power synthesis unit is 90 degrees;
the power synthesis unit is used for synthesizing the two paths of accessed signals with the equal amplitude phase difference of 90 degrees into one path of signal and outputting the signal.
3. The signal reflection cancellation circuit of claim 2, wherein the power combining unit includes any one of a 3db coupler or a two-way power divider.
4. A signal reflection cancellation circuit according to any one of claims 1 to 3, wherein when said first transmission link is a transmit link, said signal reflection cancellation circuit is coupled between a power amplifier and its back-end circuit for canceling a reflected signal output from said power amplifier.
5. The circuit of any of claims 1 to 3, wherein when the first transmission link is a transmission link, the circuit is connected between the back-end circuits of the RF chips for canceling the reflected signals output by the RF chips.
6. A signal reflection canceling circuit according to any one of claims 1 to 3, wherein when the first transmission link is a reception link, the signal reflection canceling circuit is connected between a back end circuit of a low noise amplifier for canceling a reflection signal output from the low noise amplifier.
7. A method for signal reflection cancellation, comprising:
the combining unit combines output signals of two first transmission links in a combination into a signal, wherein the two first transmission links in the combination are obtained by combining a plurality of first transmission links in pairs, and each combination comprises two first transmission links; wherein the signal transmission directions of the plurality of first transmission links are consistent;
the power distribution unit divides the one path of signal into two paths of signals with equal amplitude phase difference of 90 degrees for output, so that the phase difference of the two paths of reflection signals received by the rear end circuit is 90 degrees, and further when the two paths of reflection signals are synthesized and output, reflection cancellation is achieved according to the phase difference of the two paths of reflection signals being 180 degrees;
wherein the power distribution unit is a directional coupler; the directional coupler is a 3db coupler; the 3db coupler comprises a port 1, a port 2, a port 3 and a port 4, wherein the port 1 is used for receiving the one-path signal, the port 2 and the port 4 are used for outputting the signal, and the reflected signal is received when the back-end circuit generates reflection; the equal amplitude phase difference of the signals output by the port 2 and the port 4 is 90 degrees, and the equal amplitude phase difference of the reflected signals received by the port 2 and the port 4 is 90 degrees;
when the two paths of reflection signals are synthesized and output, reflection cancellation is realized at the port 1 when the phase difference of the two paths of reflection signals is 180 degrees, the two paths of reflection signals are superposed and output in a constant amplitude mode at the port 3, and the reflection signals are absorbed by externally connecting a load to the port 3.
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| CN112272018A (en) * | 2020-12-11 | 2021-01-26 | 南京元络芯科技有限公司 | Phase-shifting high-power switch |
| CN113381783B (en) * | 2021-06-21 | 2022-07-05 | 普联国际有限公司 | Radio frequency front-end circuit |
| CN115549746A (en) * | 2021-06-30 | 2022-12-30 | 中国移动通信集团广东有限公司 | Multi-frequency combining and splitting circuit and signal transmitting system |
| CN113739931B (en) * | 2021-08-30 | 2022-11-22 | 华中科技大学 | Radiometer based on zero reflection network |
| CN116886122A (en) * | 2022-12-08 | 2023-10-13 | 荣耀终端有限公司 | Radio frequency transmission circuit and electronic equipment |
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| US20150333709A1 (en) * | 2012-09-18 | 2015-11-19 | Nec Corporation | Power combining circuit and power combining method |
| JP6176333B2 (en) * | 2013-11-14 | 2017-08-09 | 日本電気株式会社 | Power amplifier and power amplification method |
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