JP2003110372A - Distortion compensated amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set up a redundant configuration with only an amplifier to realize a low cost, low power consumption, reduced space and the improvement in reliability. SOLUTION: An input signal a is distributed by a distributor 2, one of the signals is amplified by a main amplifier 3, the other is time-adjusted by a delay line 5, and the signals are respectively supplied to a distributor 4. In the distributor 4, a part of the output signal of the amplifier 3 and the output signal of the line 5 are processed to detect a difference signal d, consisting of distortion components generated in the amplifier 3. The signal d passes through a protection circuit 20, is amplified by an error amplifier 7 and is supplied to a distributor 8, and cancel the distortion components from the output signal of the line 6. In this case, if the amplifier 3 has troubles, excessive large signals are supplied to the amplifier 7 from the distributor 4, and the circuit 20 is brought into an operation state for interrupting the excessive large signals, to prevent the trouble of the amplifier 7.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion compensating amplifying device used for a base station amplifying device such as a radio communication system, a repeater, etc. Feed forward that compensates for distortion components such as intermodulation distortion
d: hereinafter referred to as FF). 2. Description of the Related Art A base station or a repeater of a radio communication system that handles a multicarrier signal composed of a plurality of carriers at predetermined frequency intervals receives the multicarrier signal and amplifies the multicarrier signal. Later, wireless transmission is performed. If the linearity of the amplifier used for the high-frequency amplification is not sufficiently good, various distortions such as intermodulation distortion between carriers occur. In order to prevent this, conventionally, an FF type distortion compensation amplifier has been proposed. FIG. 8 is a block diagram showing a conventional example of such a distortion compensation amplifier, wherein 1 is a preamplifier, and 2 is a distributor.
(Directional coupler), 3 is a main amplifier, 4 is a distributor (directional coupler), 5, 6 are delay lines, 7 is an error amplifier, 8 is a distributor (directional coupler), and 9 is a terminator. Reference numeral 10 denotes a distributor, 11 denotes a detector, and 12 denotes an A / D (analog / digital) converter. FIG. 9 is a diagram showing a spectrum of a signal of each part in FIG. 1. In FIG. 9, signals corresponding to those in FIG. In FIG. 8 and FIG. 9, signals passing from a distributor 2 comprising a directional coupler to a main amplifier 3, a distributor 4 comprising a directional coupler 4, a delay line 6 and a distributor 8 comprising a directional coupler are shown. The path forms the main line. In this main line, the input signal a amplified by the preamplifier 1 (here, a multicarrier signal. In FIG. 9, the two carriers are indicated by solid lines) is partially distributed by the distributor 2. After that, the signal is supplied to the main amplifier 3 and amplified at a high frequency. The multicarrier signal b output from the main amplifier 3 is partially distributed by the distributor 4, delayed by a predetermined delay amount on the delay line 6, and output through the distributor 8. In the case where good linearity cannot be obtained in the main amplifier 3 in such a main line, for example, intermodulation occurs in the multicarrier signal, and various kinds of distortion such as distortion (intermodulation distortion) occur. The multi-carrier signal output from the main amplifier 3 includes, as shown by a broken line in FIG.
A distortion component is mixed. In order to remove such a distortion component, in each of the distortion compensation amplifiers, a distortion detection loop L1 and a distortion removal loop L2 of an FF loop are provided, and the distortion detection loop L1 generates a multicarrier signal generated by the main amplifier 3. The distortion component mixed in the signal is detected, and the distortion component mixed in the multicarrier signal is removed by the distortion removal loop L2 using the detected distortion component. The distortion detection loop L1 is connected to the main amplifier 3 on the main line.
, Delay line 5 and distributors 2 and 4. In the distortion detection loop L1 having such a configuration, the multicarrier signal a input from the preamplifier 1 is supplied to the distributor 2, a part of which is distributed, and the rest is supplied to the main line. The distributed signal is delayed by a predetermined delay amount in the delay line 5 and then supplied to the distributor 4 as a distributed signal c. [0008] The distributor 4 outputs the output signal b of the main amplifier 3.
And a subtraction function of subtracting the distribution signal c from the delay line 5 from the distribution signal of the output signal b of the main amplifier 3 in addition to the distribution function of distributing a part of the distribution signal and supplying the remainder to the main delay line 6. Have. Therefore, in the distributor 4, the main amplifier 3
From the output signal b, the distribution signal c from the delay line 5 is subtracted from the signal (not shown, this is hereinafter referred to as distribution signal b '). As shown in FIG. 9, the difference signal d obtained by this subtraction processing is composed of only the distortion component generated in the main amplifier 3, and is supplied to the error amplifier 7 via the distributor 10 in the distortion removal loop L2. Supplied. Here, the delay amount of the delay line 5 is set equal to the sum of the delay amounts of the main amplifier 3 and the like in the main line. The distribution signal b ′ distributed by the distributor 4 from the output signal b of the main amplifier 3 and the delay line 5 are output by means (not shown) on the main line.
Is set to have the same amplitude as that of the distribution signal c, and the phases of the distribution signals b 'and c are also set to be the same. Therefore, the difference signal d output from the distributor 4 is a distortion component such as intermodulation distortion generated in the main amplifier 3, as shown in FIG. The distortion removal loop L2 is composed of a main delay line 6, a distributor 10, an error amplifier 7, distributors 4, 8, and the like. Of the four ports of the distributor 8, one unused one is used. A terminator 9 for preventing reflection is connected to the port. The same applies to the distributor 2;
Although not shown, a terminator is connected to one unused port. In the distortion removal loop L2 having such a configuration, after the multi-scan signal other than the distribution signal b 'of the output signal b of the main amplifier 3 is delayed by the delay line 6 by a predetermined delay amount in the distributor 4, , To the distributor 8. After a part of the distortion component d obtained by the distributor 4 is distributed by the distributor 10, the distortion component d is supplied to the error amplifier 7, amplified, and supplied to the distributor 8. The distributor 8 has a subtraction function, and subtracts the distortion component from the error amplifier 7 from the multi-scan signal from the delay line 6. As a result, as shown in FIG. 9, a multi-scan signal e from which distortion generated in the main amplifier 3 has been removed is obtained. Here, the delay amount of the delay line 6 is set equal to the sum of the delay amounts of the error amplifier 7 and the like. The distortion component mixed in the multi-scan signal E output from the delay line 6 and the distortion component output from the error amplifier 7 are adjusted by means (not shown) so that they have the same amplitude.
The distortion components are adjusted so that their phases match. Accordingly, when the amplitude and the phase are set with high accuracy in this way, the multi-scan signal e from which the distortion component is accurately removed is obtained from the distributor 8. It should be noted that Japanese Patent Application Laid-Open No. 7-303050 discloses that, as described above, in the distortion detection loop L1, the distribution signal b 'distributed from the output signal b of the main amplifier 3 by the distributor.
And the distribution signal c output from the delay line 5 are matched in amplitude and phase, and the distortion component mixed in the multicarrier signal delayed by the delay line 6 and output from the error amplifier 7 in the distortion removal loop L2. A method of matching the amplitude and the phase with the distortion component is disclosed. This is because, for such adjustment, the output signal b of the main amplifier 3 is used as an input signal as a first pilot signal.
, A part of the difference signal d from the distributor 4 is distributed by the distributor 10, the first pilot is detected by the detector 11, and the first pilot is detected by the A / D converter 12. Digital data is obtained, and based on the digital data, the amplitude and phase are adjusted on the input side of the main amplifier 3 by means (not shown) so that the detected first pilot signal becomes 0. Similarly, a second pilot signal is detected from the output signal e of the distributor 8, and the amplitude and phase are detected by means (not shown) on the input side of the error signal 7 so that the detected pilot signal becomes zero. Is to adjust. Here, the amplitude,
In general, the amount of cancellation due to the deviation of each phase is shown in FIG.
Which is expressed by the following equation: cancellation amount = 10 × log ｛1 + 10 ^{d /} 10−2 × 10
^{d / 20} × cos (p)｝ where d = amplitude deviation (dB) and p = phase deviation (deg). [0016] Such a distortion compensation amplifier of the FF system is, for example, a multi-carrier common amplifier of a base station for mobile communication, in particular, the second, second, 2.5 and third generation ( I
The use of MT-2000) as an amplifier is drawing attention. Further, as typified by digital mobile phones, recent wireless communication systems have various applications such as data transmission / reception and crime prevention, not only as radiotelephones, but also There is a strong demand for reliability for wireless base stations. In particular, the reliability of the amplifier is important for securing a stable communication area. If the amplifier fails, the communication area cannot be secured. Referring to FIG. 11, if three base stations S1, S2, and S3 adjacent to each other are viewed, the communication areas (cells) E1 and E in which they can communicate.
Although E2 and E3 partially overlap each other to prevent the occurrence of a non-communicable area, if the amplification device of the base station S1 fails and cannot communicate with the base station, the base station S1 and the base station S2 cannot communicate with the base station S1. The base station S2 in the communication area E1 of S1
A call cannot be made in a hatched area excluding an overlapping area with the call areas E2 and E3 in S3. That is, a call cannot be made over substantially the entire area of the call area E1. Usually, in order to ensure reliability, a full-duplex configuration or a redundant configuration such as a working spare configuration is provided. However, in recent years, base station amplifiers and repeaters of wireless devices have been installed in duplicate with conventional equipment, making it impossible to secure an installation space. For example, even when the system is installed in a room of an apartment, there is a problem that the installation location cannot be freely selected, and when the system is fully duplexed, the power consumption increases and the running cost increases. There is a problem such as high. As described above, various devices have been devised to enhance the reliability. However, there is a trade-off between the cost and size of the device and the reliability, and there is no decisive measure at present. is there. An object of the present invention is to solve such a problem, construct a redundant configuration by using only the apparatus, and realize distortion compensation which can realize both low cost, low power consumption, space saving and improved reliability. An amplifying device is provided. [0023] In order to achieve the above object, the present invention is intended to continue the amplifying operation by using an operable amplifier even if a failure occurs in the inside. In addition, a protection circuit for suppressing excessive input is provided between a distributor for extracting a distortion component generated in the main amplifier and an error amplifier for amplifying the distortion component. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a distortion compensation amplification apparatus according to the present invention. Reference numerals 13 to 15 denote on / off switches, and portions corresponding to those in FIG. I do. In FIG. 1, a terminator 9 is connected to one port of a directional coupler via an open / close switch 15. Further, an open / close switch 13 connected to the main amplifier 3
And an open / close switch 14 connected to the error amplifier 14, schematically showing the function of turning on and off the power of the amplifiers 3 and 7, respectively. As will be described later, in this embodiment, even during operation, the state is monitored for each unit, here, for each of the distortion detection loop L1 and the distortion removal loop L2 (FIG. 8). The other configuration is the same as that of the conventional distortion compensation amplifier shown in FIG. In the embodiment having such a configuration, the main cause of the failure is the failure of the main amplifier 3 and the error amplifier 7. Therefore, assuming that the main amplifier 3 has failed on the distortion detection loop L1 side, the output amplitude of the main amplifier 3 increases,
The amplitude of the difference signal d output from the distributor 4 also increases, and the error amplifier 7 has an input at, for example, several tens of dB higher than usual. For this reason, there is a possibility that the error amplifier 7 also fails. Therefore, in this embodiment, when a failure of the distortion detection loop is detected from the monitoring result of the distortion detection loop L1, the power of the main amplifier 3 is turned off by the on / off switch 13. Thus, part of the input signal a distributed by the distributor 2 is output from the distributor 8 through the delay line 5, the distributor 4, and the error amplifier 7. At this time, the error amplifier 7
Is supplied to the divider 8 from the receiver, not the distortion component but a multi-carrier signal having a different frequency from the distorted component. 5 will be degraded. In order to prevent this reflected wave, the open / close switch 15 is also turned off, and the terminator 9 is disconnected from the distributor 8. In this way, even if the main amplifier 3 fails, the input multicarrier signal is obtained from the distributor 8. The multicarrier signal e obtained from the distributor 8 is 2, the amplitude is smaller than that of the multicarrier signal e obtained through the main line when the main amplifier 3 operates normally and passes through the delay line 5. However, the transmission of the multicarrier signal e is still performed, and there is a communication area in which communication is possible. For example, in FIG. 2, in three base stations S1, S2, and S3 adjacent to each other,
When the above-described failure occurs in the distortion compensation amplification device of the base station S3, the distortion compensation amplification device is the above-described embodiment, and when operated as described above, the communication area E3 of the base station S3 is narrow. However, it is possible to communicate within the communication area E3, and the communication area E3 and the base stations S1, S3
Only the non-communicable area ER is generated between the communication areas E1 and E2, and the non-communication area can be minimized. In FIG. 1, the distortion removal loop L2
When the error amplifier 7 in FIG. 8 is out of order, the amplitude of the distortion component to be output from the amplifier also abnormally increases, and the distortion component increases in the output signal e of the distributor 8. Therefore, in this embodiment, when the failure of the distortion compensation loop is detected from the monitoring result of the distortion removal loop L2, the power supply of the error amplifier 7 is turned off by the on / off switch 14. Also in this case, the open / close switch 15 may be turned off to disconnect the terminator 9 from the distributor 8. Thus, a part of the input signal a distributed by the distributor 2 is output from the distributor 8 through the main amplifier 3, the distributor 4, and the delay line 6. At this time, since the distortion component is not canceled by the distributor 8, the multicarrier signal e is transmitted with the distortion component mixed therein.
The size of the communication area of the base station provided with this embodiment does not change, no communication-disabled area does not occur, and although there is an effect due to the distortion component, the influence is obtained by turning off the power of the error amplifier 7. It can be minimized without increasing it. FIG. 3 is a diagram showing a specific example of the monitoring system of each unit in the embodiment shown in FIG. 1, wherein 16 is an input unit, 17 is a distributor, 18 is a receiving device, and 19 is a control device. 1 are given the same reference numerals. In the same figure, as in the conventional distortion compensating amplifier shown in FIG. 8, a control device 19 uses a distributor 10, a detector 11 and an A / D converter 12 to output a difference signal from the distributor 4. The power of d (the amount of cancellation of the distortion component) is detected, and the detected power is used to monitor the distortion detection loop L1. When the detected power exceeds a predetermined set power value, the control device 19 outputs a control signal C1, and thereby the main amplifier 3
Is turned off (the open / close switch 13 in FIG. 1 is turned off). The control device 19 also includes a distortion removal loop L2
Is monitored, the pilot signal P is input to the main line at the input side of the main amplifier 3, and at the same time, the signal distributed from the output signal e of the distributor 8 by the distributor 17 is received by the receiver 18.
To get through. The receiving device 18 receives the pilot signal P from the signal from the distributor 17. The control device 19 detects the power of the pilot signal P received by the receiving device 18, and monitors the distortion removal loop L2 using the detected power. When the detected power exceeds a predetermined set power value, the control device 19 outputs a control signal C2, thereby turning off the power supply of the error amplifier 7 (turning off the open / close switch 14 in FIG. 1). As described above, in this embodiment, when a failure is detected on the distortion detection loop L1, the power supply of the main amplifier 3 is turned off to minimize the occurrence of the communication disabled area. The communication can be continued while the communication is suppressed, and when a failure is detected on the distortion compensation loop side, the communication can be continued with the influence of the distortion being minimized while maintaining the communication area as it is. FIG. 4 is a block diagram showing another embodiment of the distortion compensation amplifying device according to the present invention. Reference numeral 20 denotes a protection circuit, and portions corresponding to those in FIG. Omitted. In the figure, a protection circuit 20 is provided between the distributor 4 and the error amplifier 7 to protect the error amplifier 7 when the main amplifier 3 fails in the distortion detection loop L1. In this embodiment, even if the main amplifier 3 fails, its power is not turned off, and the error amplifier 7 is protected by the protection circuit 20 at this time. First, this point is different from the embodiment shown in FIG. That is, even if the main amplifier 3 fails and its output increases abnormally, the monitoring system shown in FIG. 3 detects this from the difference signal d output from the distributor 4 and activates the protection circuit 20. It operates to attenuate the difference signal d. As a result, the difference signal d is suppressed and input to the error amplifier 7, so that the error amplifier 7 is smudged. When the main amplifier 3 becomes normal, the protection circuit 20 stops its operation, and the distortion removal loop L2 returns to the normal operation. FIG. 5 is a block diagram showing a specific example of the protection circuit 20 in FIG. 4, wherein 20a is a λ / 4 microstrip line, 20b is a changeover switch, and 20c is a capacitor. Parts are given the same reference numerals. In the figure, the difference signal d output from the distributor 4 (FIG. 4) is sent to the error amplifier 7 by a microstrip line, and a λ / 4 microstrip line 20a is provided in the middle of the microstrip line. With the provision, the protection circuit 20 is formed. In the protection circuit 20, the tip of the λ / 4 microstrip line 20a is connected to a fixed contact of an on / off switch 20b, one movable contact a is opened, and the other movable contact B is grounded via a capacitor 20c. Have been. When the distortion detection loop L1 (FIG. 4) is operating normally, the changeover switch 20b is closed to the movable contact B side, and the λ / 4 microstrip line 20a is grounded via the capacitor 20c. Accordingly, the protection circuit 20 is in a state of not operating. FIG. 6A shows the attenuation characteristic of the protection circuit 20 at this time, and shows the difference signal d.
Is supplied to the error amplifier 7 almost without being affected by the protection circuit 20. When the operation of the distortion detection loop L1 (FIG. 4) is abnormal due to the failure of the main amplifier 3 (FIG. 4), the changeover switch 20b switches to the movable contact A side. This allows
The protection circuit 20 operates with the tip of the λ / 4 microstrip line 20a opened. The characteristic of the protection circuit 20 at this time is as shown by a curve B in FIG. 6, and a large attenuation characteristic appears in a predetermined frequency band. Therefore, by setting this frequency band in the carrier frequency region of the multi-carrier signal, even if the main amplifier 3 (FIG. 4) fails and a large-amplitude carrier is mixed in the difference signal d, the protection circuit 20 removes this. It is greatly attenuated, the carrier is cut off, and the error amplifier 7 can be protected. Although not shown in FIGS. 4 and 5, a distributor 10, a detector 11, an A / D converter 12, and a control device as shown in FIG. A monitoring device consisting of 19 monitors the amplitude of the difference signal d, and determines whether or not the operation of the distortion detection loop L1 is normal depending on whether or not the amplitude is equal to or less than a predetermined set value. The changeover switch 20b in FIG. 5 is controlled according to the result of this determination. Therefore, when the operation of the distortion detection loop L1 becomes normal, the protection circuit 20 becomes inactive and the distortion removal loop L1 becomes inactive.
2, and the entire distortion compensation amplifying device is in a normal operation state. FIG. 4 is a block diagram showing still another embodiment of the distortion compensating amplifying device according to the present invention. Reference numeral 21 denotes an open / close switch, and portions corresponding to those in FIG. Is omitted. In the figure, a terminator 9 connected to an isolation port of a distributor (directional coupler) 8 absorbs the signal distributed by the distributor 8 from the output signal of the error amplifier 7, and To prevent the reflection of light. By the way, when the characteristic at the time of the operation is the characteristic A in FIG. 6, the protection circuit 20 largely attenuates the carrier having the abnormal amplitude, but passes the distortion component to some extent. Protection circuit 2
The distortion component that has passed 0 is amplified by the error amplifier 7 and supplied to the distributor 8. In this embodiment, such a distortion component can be used effectively. If the terminator 9 is directly connected to the isolation port of the distributor 8, a part of the distortion component output from the error amplifier 7 is consumed by the terminator 9. . Also, in the protection circuit 20, this distortion component is attenuated to some extent. For this reason, the distortion component output from the amplifier 7 has a small contribution to the removal of the distortion component mixed in the multicarrier signal from the delay line 6. Therefore, in this embodiment, the terminator 9 is connected to the distributor 8 via the open / close switch 21 so that the protection circuit 2
With the operation of “0”, the open / close switch 21 is turned off to disconnect the terminator 9 from the distributor 8. As a result, the distributor 8 distributes the distortion component supplied from the error amplifier 7 and sends a part of the distortion component to the isolation port to which the open / close switch 21 is connected. Since the isolation port is open, Then, the light is reflected there and acts on the multicarrier signal from the delay line 6 to cancel the distortion component mixed therein. When the operation of the distortion detection loop L1 becomes normal and the protection circuit 20 is disconnected from the distortion removal loop L2 as described above, the open / close switch 21 is turned on and the terminator 9 is connected to the distributor 8. In this way, even if the distortion detection loop L1 operates abnormally, it is possible to increase the cancellation amount of the distortion component purchased in the multicarrier signal e output from the distributor 8. As described above, according to the present invention,
In order to reduce costs, reduce power consumption, and save space, the distortion detection loop can be realized by constructing a redundant configuration by itself, such as providing a protection circuit in the distortion removal loop against a failure on the distortion detection loop side. Even if a failure occurs on the side, the operation can be continued, and the reliability is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of a distortion compensation amplification device according to the present invention. FIG. 2 is a diagram showing an effect of the embodiment shown in FIG. 1 used for a base station on a failure on the distortion detection loop side. FIG. 3 is a configuration diagram showing a specific example of a monitoring system of each unit in the embodiment shown in FIG. 1; FIG. 4 is a configuration diagram showing another embodiment of the distortion compensation amplifying device according to the present invention. FIG. 5 is a configuration diagram illustrating a specific example of a protection circuit in FIG. 4; 6 is a characteristic diagram of the specific example shown in FIG. FIG. 7 is a configuration diagram showing still another embodiment of the distortion compensation amplification device according to the present invention. FIG. 8 is a configuration diagram illustrating an example of a conventional distortion compensation amplification device. FIG. 9 is a diagram showing a distortion component removing operation of the conventional example shown in FIG. FIG. 10 is a diagram showing a cancellation amount due to a deviation of each of amplitude and phase in the conventional example shown in FIG. 8; FIG. 11 is a diagram illustrating an effect when a failure occurs in the conventional example shown in FIG. 8 used for a base station. [Explanation of Signs] 2 Divider (directional coupler) 3 Main amplifier 4 Divider (directional coupler) 5, 6 Delay line 7 Error amplifier 8 Divider (directional coupler) 9 Terminator 13 to 15 Open / close Switch 20 Protection circuit 21 Open / close switch

Continuation of front page    F term (reference) 5J067 AA01 AA04 CA21 CA36 CA56                       CA87 CA92 FA00 HA29 HA38                       KA15 KA34 KA68 KS01 LS12                       MA14 SA13 TA01 TA02 TA03                 5J090 AA01 AA04 CA21 CA36 CA56                       CA87 CA92 FA00 GN07 HA29                       HA38 KA15 KA34 KA68 MA14                       SA13 TA01 TA02 TA03                 5J091 AA01 AA04 CA21 CA36 CA56                       CA87 CA92 FA00 HA29 HA38                       KA15 KA34 KA68 MA14 SA13                       TA01 TA02 TA03                 5J500 AA01 AA04 AC21 AC36 AC56                       AC87 AC92 AF00 AH29 AH38                       AK15 AK34 AK68 AM14 AS13                       AT01 AT02 AT03

Claims (1)

Claims: 1. A first splitter for splitting an input signal into two signals, a main amplifier for amplifying a first split signal output from the first splitter, A first delay unit for delaying a second distribution signal output from the first distributor, and a first delay unit for distributing an output signal of the main amplifier into third and fourth distribution signals;
A second distributor that processes the distributed signal of the first delay unit and the output signal of the first delay unit to extract a distortion component mixed in the main amplifier;
An error amplifier that amplifies the distortion component output from the second distributor; a second delay device that delays the fourth distribution signal output from the second distributor; A distortion compensating and amplifying device comprising: a third distributor that processes the output signal and the output signal of the second delay device and removes the distortion component from the output signal of the second delay device; Wherein a protection circuit for suppressing excessive input is provided between the distributor and the error amplifier.