KR100570510B1 - Third distortion control method due to leakage signal in portable internet time division duplexing antenna part and the antenna part - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage, and an antenna stage thereof. The present invention relates to a base station and an access point (AP) of a portable internet service system using a time division duplex scheme. In the transmission and reception using a circulator in each device that transmit power has a large output, such as a repeater), intermodulation and tertiary distortion components generated by the limiter due to leakage of transmit power In combination with the transmission power, the signal purity of the transmission signal is prevented from being lowered.

Portable Internet, TDD, Antenna, Tertiary Distortion, Intermodulation, Circulator

Description

THIRD DISTORTION CONTROL METHOD DUE TO LEAKAGE SIGNAL IN PORTABLE INTERNET TIME DIVISION DUPLEXING ANTENNA PART AND THE ANTENNA PART}             

1 is a block diagram of a portable Internet time division duplex antenna stage using a circulator according to the prior art.

Figure 2a is a block diagram for explaining the generation of intermodulation and third-order distortion of the transmission power due to the leakage signal of the circulator and the reflected wave of the limiter according to the prior art.

2b is a view showing the change in output in the frequency domain according to FIG.

Figure 3a is a block diagram of a portable Internet time division duplex antenna stage according to the present invention.

3b is a view showing an output change in the frequency domain according to FIG.

4 is a flowchart of a method for suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage according to the present invention;

Explanation of symbols on the main parts of the drawings

100: antenna

110: low noise amplifier (LNA)

120: power amplifier (PA)

130: antenna stage circulator

130a: transmitter circulator

130b: receiver circulator

140: limiter

The present invention relates to a method for suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage, and an antenna stage thereof, and more particularly, to a base station and an access point of a portable internet service system using a time division duplex scheme. In the case of AP (Access Point), repeater, etc., the transmission power is shared by one antenna by using circulator in each device that uses large output, intermodulation and tertiary generation occurred in the limiter due to leakage of transmission power. The present invention relates to a method for suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage for preventing the distortion component from being combined with the transmission power again to reduce the signal purity of a transmission signal.

Recently, wireless communication network has evolved from 3rd generation (3G) asynchronous wideband code division multiple access (CDMA) system that processes voice and video together in synchronous code division multiple access (CDMA) system mainly for voice calls. Furthermore, the Portable Internet technology, which enables users to access the Internet anytime and anywhere to obtain the necessary information by allowing them to use the Internet wirelessly while maintaining high speed mobility and high speed data transmission, has emerged as a major concern. Doing. The mobile Internet is now called Wi Bro, and service providers and equipment manufacturers form research groups to set international standards.

The wireless communication network constituting the portable Internet service system commonly adopts a code division multiple access (CDMA) method, and uses a frequency division duplex (FDD) according to a division duplex (DD) method. Division Duplex (TD) and Time Division Duplex (TDD) are largely divided. Recently, with Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme for processing high speed data while maintaining high mobility, time division duplexing (TDD) considering the frequency efficiency of the user The method is commercially available. The frequency division duplex method is a full duplexer that transmits and receives frequency bands differently so that transmission and reception do not affect each other simultaneously. The frequency band is used but the transmission time is different so that it does not interfere with transmission and reception.

For devices that use large output power such as base stations, access points (APs), and repeaters in portable Internet service systems that use the time-division duplex method, the device is used to transmit and receive with one antenna. The use of circulators has been considered.

1 is a view showing the configuration of a time division duplex antenna stage using a circulator according to the prior art.

In each apparatus (base station, access point, repeater, etc.) of the portable Internet service system using the time division duplex method, the prior art for sharing the transmitting and receiving antennas is provided with an antenna stage circulator 130 as shown in FIG. By using the directionality of the antenna stage circulator 130, the transmission and reception signals do not affect each other. The circulator, which is a three-terminal signal branch circuit element, has three terminals surrounded by a 120 degree angle, and a magnetic body such as a resonance plate and a ferrite is disposed therein. Power is incident on one of the three terminals configured in the circulator, and only one of the other two terminals is output, and the other is not output. Thus, a three-terminal device transmits energy only to a terminal in a specific direction as if rotating in a directional manner.

The power amplifier 120 is turned on during the transmission cycle using the directionality of the antenna stage circulator 130 so that the transmission power is transmitted toward the antenna 100 and the reception signal coming from the antenna 100 during the reception cycle. Is to be received in the direction of the low noise amplifier (110). However, the actual circulator has a leakage signal (leakage signal) for the reverse direction in addition to the directivity, the power amplifier 120 is turned on (On) during the transmission cycle to transmit the transmission power through the antenna stage circulator 130 antenna 100 In case of transmitting by), -20dB of transmit power is applied to the receiver in reverse direction. A base station, an access point, a repeater, and the like of a portable Internet service system require 43dBm, that is, 20W or more transmission power. As a result of this leakage signal, a power of about 23dBm (200mW) is applied to the receiving end.

In the prior art as shown in Figure 1, by reducing the antenna and the antenna coaxial cable than using two antennas, such as installation cost can be reduced, the leakage signal of the transmission power through the antenna stage circulator 130 during operation During the transmission cycle, a leakage signal having a size of several tens of mW is applied to the receiver low noise amplifier 110, so that the low noise amplifier 110 may be saturated or the internal circuit may be destroyed.

FIG. 2A is a block diagram illustrating intermodulation and third-order distortion generation of transmission power due to leakage signals of a circulator and reflected waves of a limiter according to the prior art, and FIG. 2B is a diagram illustrating output variation in a frequency domain according to FIG. The figure shown.

The third order distortion component and intermodulation will be briefly described as follows. Inter-Modulation (IM) is caused by non-linear elements (transistors, diodes, etc.) included in active circuits present in the system. When two or more frequencies pass through a non-linear circuit, signals that are not present at the output stage It means to come out. When a signal component of one frequency is input into a nonlinear circuit, nonlinear signals having a harmonic characteristic are output, such as y = a + bx + cx ^ 2 + dx ^ 3 ... due to the nonlinearity of the circuit. If two frequencies pass through a system, the two frequencies are influenced by each other, and frequency energy components corresponding to the sum and difference of harmonics are generated and output. For example, if two frequencies f1 and f2 are input at the same time, f1, f2 as well as f1-f2, f1 + f2, 2 * f1-f2, 2 * f2-f1, 3 * f1-2 * f2, etc. Many frequency components are output. That is, a signal having a frequency of f1 and f2 is mainly output at the output, but signals such as quadratic terms, tertiary terms, and quadratic terms are simultaneously generated and output. This phenomenon or its parasitic frequency components are called intermodulation.

Distortion itself due to intermodulation components is expressed in terms of intermodulation distortion (IMD). In digital communication such as synchronous code division multiple access, such intermodulation distortion becomes a very important problem because, unlike analog communication, one signal does not use one frequency, that is, one channel, but multiple signals share a wide channel bandwidth. This is because when multiple frequency signals are simultaneously input to a system that processes one frequency band, signals of each frequency are mixed with each other and output signals of multiple frequencies, so that signal processing is not properly performed.

Taking the two frequencies f1 and f2 as examples, the output shows a mixed signal, but the perfect multiple harmonics such as 2 * f1 and 3 * f2 can be filtered. However, third order terms, 2 * f1-f2 and 2 * f2-f1, are a big problem because they are so close to the f1 and f2 signals. Therefore, signals commonly referred to as intermodulation distortion often mean only third-order distortion components except for the remaining components that do not interfere with signal transmission. In particular, since this third order distortion component increases by three squared as the input signal increases, the distortion is small at first, but when the input signal increases, it increases with a much faster slope than the original signal. This will occur until the power is close (IP3 point).

In the case of the configuration as shown in FIG. 1, as described above, when the transmission power is output through the antenna stage circulator 130, power of several hundred mW is applied to the receiver low noise amplifier 110 due to a leakage signal in the opposite direction. . When a few hundred mW of power is applied to the receiver low noise amplifier 110, the low noise amplifier 110 may be damaged due to saturation or high power applied thereto. In order to prevent this, a low noise amplifier (see FIG. The limiter 140 circuit is configured in front of the limiter so that the low noise amplifier 110 is protected even when high power is applied by the limiter 140 circuit. In addition, the low noise amplifier 110 is turned off during the transmission cycle in order to prevent a small power transmitter noise, which is not suppressed by the limiter 140, from leaking and being amplified at the receiver through the low noise amplifier 110. It is designed to maximize the isolation of transmission and reception signals by turning it off. Isolation of the signal (isolation) is the degree to which each signal separates when multiple signals are used in the same circuit at the same time, a measure of how much less interference between each signal. In the case of the reception period, the low noise amplifier 110 is turned on to amplify the received signal from the antenna 100. In this case, the transmitter power amplifier 120 is designed to be in an off state.

However, according to this conventional technology, even when the leakage signal of the transmission power leaked during the transmission cycle is suppressed by the limiter 140, the low noise amplifier 110 is in an off state and is not a 50 kHz characteristic impedance, thereby suppressing the leakage signal. There is a problem that causes the reflection back to the antenna stage. Further, the limiter 140 circuit is composed of a diode which is a nonlinear element, so that intermodulation such as third order distortion component is generated in addition to the reflected leakage signal. The limiter reflected wave having the third-order distortion component travels back to the antenna terminal along the reverse direction of the receiving end circulator 130b, and is reflected from the transmitting signal and the limiter 140 amplified by the power amplifier 120 of the transmitting end. In addition to the on-leakage signal, the third order distortion component generated while passing through the limiter 140 is combined.

Referring to FIGS. 2A and 2B, a step of outputting 43 dBm transmission power at a transmitting end (S100), a reverse leakage signal of transmit power is applied to a receiving end, and a loss of 20 dB is generated (S110). When the limiter reflected wave combined with the intermodulation and tertiary distortion components is reflected at the limiter 140 (S120), the limiter reflected wave passes through the receiving end circulator 130b (S130), and the limiter reflected wave is coupled to the transmission power. It can be seen that the step (S140) and the like are performed in which the final transmission power having the intermodulation and third order distortion components is output to the antenna stage.

As a result, even if only the transmission signal is output from the transmitter power amplifier 120, the final transmission power is radiated through the antenna 100 with the intermodulation and third distortion components at the antenna stage according to the influence of the peripheral circuit configuration, Due to the generation of intermodulation and third-order distortion components that affect the signal purity, which is very important, the performance of the mobile Internet service system is degraded due to the deterioration of the bit error rate (BER) and the waveform quality. And data corruption can occur.

Accordingly, an object of the present invention is to solve the conventional problems as described above, and transmit power such as a base station, an access point (AP), a repeater, and the like of a portable Internet service system using a time division duplex method. In each device using the circulator, the transmission and reception are shared by one antenna, and the intermodulation and tertiary distortion components generated by the limiter due to leakage of the transmission power are combined with the transmission power again, and the signal purity of the transmission signal is The present invention provides a method of suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage, and an antenna stage thereof, for preventing the deterioration thereof.

The portable Internet time division duplex antenna stage for suppressing the third-order distortion caused by the leakage signal according to the present invention for achieving the above object is applied to a base station, an access point, a repeater for providing a mobile Internet service as a single antenna In the antenna terminal sharing transmission and reception, the transmission and reception antenna (100), the transmission power amplifier 120 for radiating transmission power to the outside through the antenna 100, and through the antenna 100 The receiver low noise amplifier 110 to which a received signal is applied from the outside and the power amplifier 120 is turned on during the transmission cycle, and the low noise amplifier 110 is turned off to transmit the transmission power and receive the received signal. In the cycle, the low noise amplifier 110 is turned on, the power amplifier 120 is turned off, and the antenna stage circulator 130 to receive the received signal is applied to the front end of the low noise amplifier 110. Limiter 140 is configured to prevent the low noise amplifier 110 from saturating or breaking the internal circuit due to the reverse leakage signal applied to the low noise amplifier 110 when the transmission power is output through the antenna stage circulator 130 And a receiving end circulator 130b configured between the antenna end circulator 130 and the front end of the limiter 140.

Preferably, the receiving end circulator 130b is a low noise amplifier 110 after the reverse leakage signal of the transmission power applied to the receiving end through the antenna end circulator 130 passes through the limiter 140 in the transmission period. ), When the intermodulation and tertiary distortion components are combined and reflected by the limiter reflected wave, the intermodulation and tertiary distortion components are transmitted by consuming the reflected wave power at 50 ter termination by directionality. By preventing the increase in coupling to the power, it is characterized in that the signal purity of the transmission power finally output to the antenna terminal.

Preferably, the antenna-end circulator 130 and the receiver-end circulator 130b ensure isolation of 20 dB or more, respectively, so that the reflected wave of the transmission power is returned through the limiter 140 of the receiving end again. 100), 20dB of the antenna stage circulator 130, 20dB of the receiver stage circulator 130b, and 20dB of the antenna stage circulator 130 are added to ensure an isolation. In addition, the intermodulation and third-order distortion components generated by the limiter 140 are also characterized in that a value obtained by adding 20 dB of the receiver end circulator 130b and 20 dB of the antenna end circulator 130 is secured.

According to the present invention, the method for suppressing the third-order distortion caused by the leakage signal of the portable Internet time division duplex antenna stage includes the steps of outputting 43 dBm transmission power from the transmitting end in a transmission period (S200) and leaking signal of the transmission power to the receiving end. 50 dB characteristic impedance due to a 20 dB loss of the transmission power applied and outputted from the transmitting end, and a leakage signal applied to the receiving end passes through the limiter 140 and then turned off of the low noise amplifier 110. In step S220, the limiter wave combined with the intermodulation and tertiary distortion components is output from the limiter 140 and the directionality of the receiver circulator 130b coupled to the front end is 50 Ω ( (S230) minimizing intermodulation and tertiary distortion components due to the consumption of reflected wave power through termination, and the leakage signal for the limiter reflected wave is received at the receiving end circulator 130b and the antenna end circular. It characterized in that comprises the 130 step (S240) and a step (S250) the output is the final transmit power of the leakage signal to the reflected wave limiter coupled to the antenna terminal to the transmission power that passes through the.

In the following description of the preferred embodiments of the present invention in detail with reference to the accompanying drawings, when it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Do it.

FIG. 3A is a block diagram of a portable Internet time division duplex antenna stage according to the present invention, and FIG. 3B is a diagram illustrating an output change in a frequency domain according to FIG. 3A.

Referring to FIG. 3A, the receiver circulator 130b is added to the front of the limiter 140 so that the low noise amplifier 110 is turned off and does not match the 50 kHz characteristic impedance. And even if the intermodulation and cubic distortion components thereof cause reflection, the reflected wave power is consumed by 50 kHz termination due to the directionality of the receiving end circulator 130b.

In addition, even if a reverse leakage signal is generated at the receiving end circulator 130b, an isolation of 20 dB or more is ensured, and when the reflected wave of the transmission power is coupled back to the antenna 100 through the limiter 140 of the receiving end, 20dB of antenna stage circulator 130 + 20dB of receiver circulator 130b + 20dB "of antenna stage circulator 130 are ensured again, and the intermodulation generated by the limiter 140 is ensured. And the third-order distortion component also adds "20dB of the receiver end circulator 130b + 20dB of the antenna end circulator 130" to ensure a total of 40dB or more, so that the final transmission power having sufficient signal purity is output.

In the present invention, in order to improve the isolation of the transmission and reception signals and to protect the receiver low noise amplifier 110, the receiver circulator 130b is further configured before the limiter 140 circuit to transmit the signal. The signal purity of the transmission signal is secured in response to an increase in intermodulation and third distortion of the transmission power caused by the addition of the limiter 140 circuit in a state where the receiver low noise amplifier 110 is turned off during the period. . In addition, by using the directionality of the received receiving end circulator 130b, the intermodulation and third order distortion components reflected from the limiter 140 are prevented from being reflected back to the antenna end and combined with the transmission signal, thereby outputting the final output. It is designed to improve the waveform characteristics (Waveform Quality) and spectrum mask (Spectrum Mask) characteristics by securing sufficient signal purity for the transmitted signal. The improvement of the transmission output through the present invention is an item that must be secured in digital communication, and through such a configuration, it is possible to perform reliable mobile Internet service by preventing data from being broken.

4 is a flowchart illustrating a method for suppressing third-order distortion caused by a leakage signal of a portable Internet time division duplex antenna stage according to the present invention.

Referring to FIG. 4, the third-order distortion suppression method of the portable Internet time division duplex antenna stage according to the leakage signal is a step of outputting 43 dBm transmission power from the transmitting end in a transmission period (S200), After the leakage signal is applied to the receiving end and the transmission power output from the transmitting end is lost 20dB (S210), and the leakage signal applied to the receiving end passes through the limiter 140, the low noise amplifier 110 (Off) state (Off) (S220) outputting a limiter reflected wave in which the intermodulation and tertiary distortion components are combined in the limiter 140 as not matched to the 50 kHz characteristic impedance by the directionality of the receiver circulator 130b coupled to the front end. Due to the 50 kHz termination (reflection wave power) is consumed to minimize the cross-modulation and third-order distortion component (S230), and the leakage signal for the limiter reflected wave is received in the receiver circulator 130b and Nathan, and comprises a step (S240) through the circulator 130, and step (S250) is the final transmit power of the leakage signal is coupled to the limiter reflected wave on the transmission power to be output to the antenna terminal. The limiter reflected wave is a signal in which intermodulation and tertiary distortion components are combined with a reverse leakage signal of transmit power applied to a receiver.

The present invention may be modified in various ways without departing from the basic concept according to the needs of those skilled in the art.

As described above, according to the present invention, a circulator is used in each apparatus that uses a large output power such as a base station, an access point (AP), a repeater, and the like in a portable Internet service system using a time division duplex method. In the transmission and reception sharing of the antenna, the mobile Internet time division which prevents the signal purity of the transmission signal from being deteriorated by combining the modulation and tertiary distortion components generated by the limiter with the transmission power again due to leakage of the transmission power. There is an effect that the third-order distortion suppression method and the antenna stage are provided by the leakage signal of the dual antenna stage.

Claims (4)

In the antenna stage is applied to a base station, an access point, a repeater for providing a mobile Internet service, sharing the transmission and reception with one antenna, Transmitting and receiving antenna (100); A transmitter power amplifier 120 radiating transmit power to the outside through the antenna 100; A receiver low noise amplifier (110) to which a received signal from the outside is applied through the antenna (100); In the transmission cycle, the power amplifier 120 is turned on and the low noise amplifier 110 is turned off to transmit the transmission power, and in the reception cycle, the low noise amplifier 110 is turned on and the power is turned on. An antenna stage circulator 130 for turning off the amplifier 120 and receiving a received signal; The low noise amplifier 110 is saturated due to a reverse leakage signal which is configured in front of the low noise amplifier 110 and applied to the low noise amplifier 110 when outputting the transmission power through the antenna stage circulator 130, or the internal circuit. Limiter 140 to prevent the destruction; And a receiving end circulator (130b) configured between the antenna end circulator (130) and the front end of the limiter (140). Antenna stage. The method of claim 1, The receiving end circulator 130b, After the reverse leakage signal of the transmission power applied to the receiver through the antenna stage circulator 130 passes through the limiter 140 in the transmission cycle, the low noise amplifier 110 is in an off state. When the third-order distortion component is combined and reflected by the limiter reflected wave, the reflected wave power is consumed by 50 Ω termination by the directionality to prevent the intermodulation and third-order distortion components from being combined with the transmission power, resulting in the end of the antenna. A portable Internet time division duplex antenna stage for suppressing third-order distortion caused by leakage signals, characterized by increasing signal purity of output transmission power. The method of claim 1, The antenna-end circulator 130 and the receiver-end circulator 130b respectively secure 20dB or more of isolation, and the reflected wave of the transmission power is coupled back to the antenna 100 through the limiter 140 of the receiver. In this case, the isolation of the numerical value obtained by adding 20 dB of the antenna stage circulator 130, 20 dB of the receiving stage circulator 130b, and 20 dB of the antenna stage circulator 130 is further secured. The intermodulation and tertiary distortion components generated at 140 are also obtained by combining the 20 dB of the receiver end circulator 130b and the 20 dB of the antenna end circulator 130 to obtain a numerical value of the third order distortion due to the leakage signal. The portable Internet time division duplex antenna stage. In step S200, 43dBm transmission power is output from a transmitting end; A leakage signal of the transmission power is applied to the receiving end so that the transmitting power output from the transmitting end is lost by 20 dB (S210); After the leakage signal applied to the receiver passes through the limiter 140, the intermodulation and tertiary distortion of the limiter 140 is not matched to the 50 kHz characteristic impedance by the off state of the low noise amplifier 110. Outputting a limiter reflected wave combined with components (S220); Step S230 of minimizing intermodulation and tertiary distortion components by dissipating reflected wave power due to 50 kHz termination due to the orientation of the receiving end circulator 130b coupled to the front end; Passing the leakage signal for the limiter reflected wave through the receiving end circulator (130b) and the antenna end circulator (130); Terminating distortion due to leakage signal of the portable Internet time division duplex antenna stage, comprising: outputting the final transmission power combined with the transmission power and the leakage signal for the limiter reflected wave to the antenna stage (S250); Inhibition method.

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