KR20130121493A - Rf front-end apparatus for isolating tx and rx signal - Google Patents

Abstract

The present invention relates to an RF front-end apparatus for separating transmitting and receiving signals and, specifically, to an RF front-end apparatus for separating TX and RX signals which maximizes call quality by minimizing leakage signal interference in a receiving signal, wherein the leakage signal is generated due to directional coupler usage when transmitting and receiving signals are separated in a system using Time Division Duplex (TDD). The disclosed RF front-end apparatus for separating transmitting and receiving signals is characterized by comprising: a coupling means (100) for separating a transmitting signal and a receiving signal by coupling inputted transmitting and receiving signals through respective coupling paths and coupling a signal leaked from the transmitting signal through a different path; an adjusting means for generating at least one offset signal by adjusting a coupled signal from the transmitting signal in order to correspond to the leaked signal; and a combining means (300) for offsetting a leakage signal by combining at least one leakage signal and at least one offset signal through at least one offset path. [Reference numerals] (10) Transmitting unit;(20) Receiving unit;(AA) Offset signal;(BB) Leakage signal

Description

RF front-end apparatus for isolating TX and RX signal}

The present invention relates to a high-frequency front end apparatus for separating transmission and reception signals, and more particularly, to interference of leakage signals caused by the use of a directional coupler in isolation of transmission and reception signals in a system using a time devision duplex (TDD) scheme. The present invention relates to a high frequency front end apparatus that separates a transmission / reception signal to maximize communication quality by minimizing the reception signal.

Recently, a system such as WiBro, WiMAX, WiFi, or a radio, which is a time devision duplex (TDD) type wireless communication system, secures communication quality by minimizing interference with each other by equalizing a frequency of a transmission signal and a reception signal. In this case, since a duplex cannot be used in a TDD system to separate a transmission signal and a reception signal, a circulator or an RF switch is usually used, but the circulator has a narrow frequency band. There is a problem that becomes complicated.

Therefore, the directional coupler is used as a method of separating transmission and reception signals over a wide band, and the directional coupler has a limited isolation performance and thus has a limitation in the wireless system that can be used.

That is, the general directional coupler generates a leakage signal in the directional coupler as shown in FIG. This is because the size of the isolation signal (isolation) of the directional coupler is about -20 ~ -30dB, and when used as a high frequency front end device, the transmission signal leaks to the receiver, thereby degrading the quality of the reception signal. That is, since the general received signal is very small and the transmitted signal is very large, the leaked transmitted signal may affect the received signal. In particular, a communication system using the same transmission / reception frequency and a communication device having a large transmission power have a problem of degrading the quality of a received signal.

According to the Republic of Korea Patent Publication No. 10-2011-0096435 (name of the invention: ultra-wideband directional coupler) of the prior art document relates to an invention for providing an ultra-wideband directional coupler that can be used in ultra-wideband communication. The prior art document is an invention on how to design a directional coupler, and the present invention differs from each other as an invention on how to cancel the leakage signal generated by the directional coupler.

Accordingly, an object of the present invention is to provide a high frequency front end device of a broadband communication device which cannot use a circulator and an RF switch by increasing the isolation of the high frequency directional coupler.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

The object of the present invention described above is to separate the transmission signal and the reception signal by coupling an input transmission signal and a reception signal through respective coupling paths, and to separate the signal leaked from the transmission signal into a path different from the coupling path. Coupling means (100) for coupling; Adjusting means (200) for generating one or more cancellation signals by adjusting the coupled signal from the transmitted signal to correspond to the leaked signal; And a coupling means (300) for canceling the leaked signal by combining the at least one leaked signal and the at least one canceled signal through at least one canceling path. This can be achieved by.

In addition, the magnitude and the delay time of the offset signal is adjusted in a direction coinciding with the leaked signal so that the coupling means 300 cancels the leaked signal, and the phase of the offset signal is adjusted by the coupling means 300. And to adjust in a direction opposite to the leaked signal to cancel.

In addition, the adjusting means 200, the size adjuster 210 for adjusting the magnitude of the signal coupled from the transmission signal; A phase adjuster 220 for adjusting a phase of a signal coupled from the transmission signal; And a time delay unit 230 for delaying the arrival time of the coupled signal from the transmission signal.

Further, when there are a plurality of cancellation paths, the adjusting means 200 includes: a separator 205 for separating the coupled signal from the transmission signal into a plurality of signals; A plurality of scalers 210 for adjusting the magnitude of the signal separated from the separator 205; A plurality of phase adjusters 220 for adjusting the phase of the signal separated from the separator 205; And a plurality of time delays 230 for delaying the arrival time of the signal separated from the separator 205.

In addition, when there are a plurality of cancellation paths, the leakage signal separator 400 for separating the leaked signal into a plurality of signals; A plurality of coupling means (410, 410 ') for coupling at least one signal separated from the leakage signal separator 400 and at least one signal separated from the separator 205; And a plurality of filters 420 and 420 'that receive at least one signal from the plurality of coupling means 410 and 410' and filter the predetermined frequency.

According to the present invention as described above by increasing the isolation of the high-frequency directional coupler has an effect that can be configured a high-frequency shear device without using a circulator or RF switch.

In addition, according to the present invention, there is an effect of improving communication quality by canceling a leakage signal using a plurality of offset paths.

In addition, according to the present invention, by applying to the existing directional coupler as well as the high-frequency shearing device, there is an effect that can improve the performance of the directional coupler.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description, serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
1 is a view showing a leakage signal generated when using a conventional directional coupler,
2 is a block diagram showing the configuration of a high frequency shear apparatus for separating transmission and reception signals according to a first embodiment of the present invention,
3 is a view showing a frequency spectrum at point a of FIG.
4 is a view showing a frequency spectrum at point c of FIG.
5 is a diagram illustrating a frequency spectrum at point b of FIG. 2,
6 is a diagram illustrating a frequency canceling characteristic according to a first embodiment of the present invention;
7 is a block diagram showing the configuration of a high frequency shear apparatus for separating transmission and reception signals according to a second embodiment of the present invention,
8 is a diagram illustrating frequency cancellation characteristics according to a second embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In addition, the embodiment described below does not unduly limit the content of the present invention described in the claims, and the entire structure described in this embodiment is not necessarily essential as the solution means of the present invention.

<Configuration of high frequency shear device to separate transmission and reception signal>

Although the first and second embodiments of the present invention have been described on the assumption that the transmission signal and the reception signal are different frequencies (for example, a CDMA system), the transmission and reception calls and the reception signal have the same frequency (for example, a TDD system). The same can be applied to.

( First Embodiment )

As shown in FIG. 2, the high-frequency shear apparatus for separating transmission and reception signals according to the first embodiment of the present invention may improve the call quality of the receiver 20 by canceling the leakage signal accompanying by using a directional coupler. Hereinafter, with reference to Figures 2 to 6 will be described the configuration and function of the high-frequency shearing apparatus for separating the transmission and reception signals according to the present invention.

The first embodiment according to the present invention will be described on the assumption that there is only one offset path, and the second embodiment to be described below will be described with an example of the case where there are a plurality of offset paths.

As shown in FIG. 2 and FIG. 3, the coupling means 100 couples some power (dBm) of the transmission signal f ₁ transmitted from the transmitter to the control means 200 which will be described later, and sends the remaining power ( Most transmission signal power) radiates the transmission signal by transmitting to the antenna 40. In addition, the coupling means 100 couples the reception signal f ₂ received from the antenna 40 to a path different from the coupling path of the transmission signal, and transmits the signal to the reception unit 20. Therefore, the coupling means 100 isolates the transmission signal from the reception signal.

However, the coupling means 100 may be implemented by, for example, a directional coupler. The isolation size of a typical directional coupler is about -20 to -30 dB, as shown in FIG. 4 when used as a high frequency shearing device. The leakage signal f ₁ ″ leaks to the receiver to degrade the quality of the received signal.

Therefore, in order to cancel the leakage signal f ₁ ′, in the first embodiment of the present invention, the adjustment means 200 includes the offset signal of FIG. 5 having the same magnitude and delay time as the leakage signal and having a phase of 180 °. To cancel the leakage signal. Let's take a closer look below.

The adjusting means 200 first reduces the power (dBm) by using the fixed attenuator 211 to the signal coupled from the transmission signal. This is because the variable attenuator 213 and the phase adjuster 220 to be described later operate at a low power level, and thus may be damaged when a high power signal is input. After the signal level is greatly attenuated by the fixed attenuator 211, the arrival time of the offset signal is adjusted using a delay line such that the leakage signal reaches the coupling means 300 described later.

The variable attenuator 213 matches the magnitude of the cancellation signal with the magnitude of the leakage signal, and the phase adjuster adjusts the phase of the cancellation signal to be 180 degrees different from the phase of the leakage signal. The offset signal thus adjusted is shown in FIG. 5. The coupling means 300 cancels the leakage signal by combining the offset signal and the leakage signal with each other, and transmits only the reception signal f ₂ to the reception unit 20. The above-described variable attenuator 213 and phase adjuster 220 may be automatically controlled by receiving an analog signal from a receiver side and configuring an analog circuit or a digital circuit.

Coupling means 300 can be implemented using a combiner or the like, the configuration of the above-described adjusting means 200 can be used in any order and combination without regard to the above-described order. That is, the variable attenuator 213 may be located before the time delay 230.

As shown in FIG. 6, when implemented as in the first embodiment of the present invention, the frequency band for canceling the leakage signal by more than -30 dB is only about 10%. In general, the band characteristics of directional couplers are much broader than this. Therefore, the directional coupler may be used with only such isolation characteristics, but when a directional coupler having improved isolation characteristics is required within a wider band, a plurality of offset paths for canceling leakage signals should be implemented.

( Second Embodiment )

Compared to the first embodiment, the second embodiment according to the present invention has a plurality of offset paths, and the same configuration and function will be replaced with the first embodiment, and the same reference numerals will be used for the convenience of description. do.

The transmission-side coupling signal coupled by the directional coupler, which is the coupling means 100, lowers the power level using the fixed attenuator 211. The transmitting side coupling signal whose power level is attenuated is separated into a first signal and a second signal by the separator 205. The first and second signals are controlled through time delays 230 and 230 ', phase adjusters 220 and 220', and variable attenuators 213 and 213 ', respectively. In this case, the adjusted first signal has the same magnitude (dBm) and time delay as the third signal shown in FIG. 7, and is adjusted so that the phase is 180 ° apart, and the adjusted second signal has the magnitude equal to the fourth signal. The time delay is the same and the phases are adjusted so that they are 180 ° out of phase. The third signal and the fourth signal are signals that are separated by the leakage signal separator 400 as leakage signals leaked by the directional coupler 100.

The first signal and the third signal having a 180 ° out of phase are combined by the combining means 410 to cancel the third signal, and the second and fourth signals having a 180 ° out of phase are combined with each other. 410 ') cancels the fourth signal to cancel all leakage signals flowing to the receiving side.

However, the directional coupler 100 described above is coupled not only to the leakage signal but also to the received signal like the leakage signal. Therefore, the received signal is also separated by the leakage signal separator 400, and the received signal from which the signal is separated is combined by the combining means 300 through a filter 420,420 '(in the present invention, a bandpass filter), thereby receiving the original received signal. Can be restored.

In this case, when there are a plurality of offset paths, the reason for passing through the filters 420 and 420 'according to the offset paths is that the positions of the frequencies canceled by the respective offset paths are different from each other. If combined by the coupling means 300 without passing through the filters 420 and 420 ', there is a problem that the degree of cancellation of the final leakage signal is not greatly reduced because the level of the leakage signal that is not at the offset frequency position is relatively large.

The above-described coupling means 300, 410, 410 ′ may be implemented using an element such as a power combiner, and the leakage signal separator 400 may be implemented by a power divider.

The second embodiment of the present invention has been described with two offset paths, and when implemented with two offset paths, final offset characteristics as shown in FIG. 8 may be implemented. At this time, the frequency position of the offset bandwidth can be adjusted by a time delay, a phase adjuster, and a variable attenuator. For example, if you want to achieve twice the bandwidth while satisfying the offset characteristic of -30dB or more, two offset paths may be configured around the frequency of the offset band of -30dB. Each path is canceled by a -30dB realizable bandwidth and then combined after passing through the filter. Finally, the combined receiver signal cancels more than -30dB.

On the other hand, by implementing three or more offset paths to implement the offset characteristics in a wider band can be infinitely extended.

Although the present invention has been described with reference to the embodiment thereof, the present invention is not limited thereto, and various modifications and applications are possible. In other words, those skilled in the art can easily understand that many variations are possible without departing from the gist of the present invention.

10:
20: receiver
30: filter
40: antenna
50: directional coupler
100: coupling means
200: control means
205: separator
210: size adjuster
211: fixed attenuator
213,213 ': Variable damper
220,220 ': Phase adjuster
230,230 ': Time delay
300: coupling means
400: leakage signal separator
410, 410 ': coupling means
420, 420 ': Filter

Claims (5)

Coupling means for coupling the transmitted signal and the received signal through the respective coupling path to separate the transmission signal and the received signal, and coupling the signal leaked from the transmission signal to a path different from the coupling path 100;
Adjusting means (200) for generating one or more cancellation signals by adjusting a coupled signal from the transmitted signal to correspond to the leaked signal; And
And a coupling means (300) for canceling the leaked signal by combining at least one leaked signal and at least one canceled signal through at least one cancelation path.
The method of claim 1,
The magnitude and delay time of the cancellation signal are adjusted in a direction coinciding with the leaked signal such that the coupling means 300 cancels the leaked signal,
The phase of the cancel signal is a high frequency shearing device for separating the transmission and reception signals, characterized in that the coupling means 300 is adjusted in a direction opposite to the leaked signal so as to cancel the leaked signal.
The method of claim 1,
The adjusting means 200,
A size adjuster 210 for adjusting a magnitude of a signal coupled from the transmission signal;
A phase adjuster 220 for adjusting a phase of a signal coupled from the transmission signal; And
And a time delay (230) for delaying the arrival time of the coupled signal from the transmission signal.
The method of claim 1,
If there are a plurality of offset paths,
The adjusting means 200,
A separator 205 for separating the coupled signal from the transmission signal into a plurality of signals;
A plurality of scalers 210 for adjusting the magnitude of the signal separated from the separator 205;
A plurality of phase adjusters 220 for adjusting a phase of a signal separated from the separator 205; And
And a plurality of time delays (230) for delaying the arrival time of the signal separated from the separator (205).
5. The method of claim 4,
If there are a plurality of offset paths,
A leak signal separator 400 for separating the leaked signal into a plurality of signals;
A plurality of coupling means (410, 410 ') for coupling at least one signal separated from the leakage signal separator 400 and at least one signal separated from the separator 205; And
And a plurality of filters (420, 420 ') for receiving at least one signal from the plurality of coupling means (410, 410') and filtering a predetermined frequency.

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