JP2008079249A - Transmission amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission amplifier which satisfies a CPRI standard by preventing the generation of spurious waveforms in output waveforms of the amplifier even if an IC malfunction occurs. <P>SOLUTION: When an instruction to change a CPRI link from a physical connection line 1 to a physical connection line 2 is issued, a prestage IC 3 changes the CPRI link performing soft control from the physical connection line 1 to the physical connection line 2 according to the instruction from a base station 11. This switchover is recognized by a switchover recognition function of the prestage IC 3, and a timing signal 7 is transmitted to a poststage IC 5 by a timing signal supply means. The poststage IC 5 which has received the timing signal 7 from the prestage IC 3 prevents the generation of a spurious waveform by outputting 0-data as transmission data 10 by a spurious waveform prevention level data output means for predetermined duration when an intermediate stage IC 4 malfunctions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission amplifier connected by a CPRI (Common Public Radio Interface) link.

  In recent years, the wireless part has been remoted using the CPRI standard. In this CPRI standard, it is encouraged to use SerDes (Serializer / Deserializer) as a physical connection method between a base station and an amplifier. In addition, in the CPRI standard, one base station and one amplifier can be connected by a plurality of CPRI links, and IQ data output from the amplifier is carried by one CPR1 link, which is clearly different from other CPRI links. It is stipulated that they are distinguished from each other. This indicates that one CPRI link used for soft control can be selected from a plurality of physical connection lines.

  However, SerDes has the property that the processing time changes due to manufacturing variations. As an example, the processing time in TLK1501 (manufactured by TI) is 34 to 38 CLK (@ 1.2288 GHz) at the time of transmission and 76 to 107 CLK (@ 1.2288 GHz) at the time of reception. This means that by using SerDes, a time lag occurs at the time of switchover for switching the CPRI link to another physical connection line by software control. Since the amplifier operates with the clock from the base station, a change in the clock used in the amplifier causes a synchronization signal between the ICs used in the amplifier to shift and induce a malfunction. There was a problem that spurious was generated in the waveform output from the amplifier.

  An object of the present invention is to provide a transmission amplifier that satisfies the CPRI standard by preventing spurious output waveform from being generated even if an IC malfunction occurs.

  In order to achieve the above object, the present invention achieves at least one front-stage IC that receives data input from a CPRI link having a plurality of physical connection lines, and at least one front-end IC that transmits transmission data and a synchronization signal. In a transmission amplifier having a middle stage IC and at least one latter stage IC that receives transmission data transmitted by the middle stage IC and outputs transmission data, a timing signal is sent to the latter stage IC when a switchover for switching the physical connection line occurs. And a spurious prevention level data for outputting spurious prevention level data instead of transmission data received from the middle stage IC for a predetermined time when the subsequent IC receives the timing signal from the timing signal providing means. An output means is provided.

  According to the transmission amplifier of the present invention, when the post-stage IC receives the timing signal from the timing signal providing means when the switchover occurs when the physical connection line is switched, the spurious prevention level data output means is based on the received timing signal. In this case, spurious prevention level data, for example, 0 data, is output instead of transmission data received from the middle stage IC for a predetermined time, so even if the synchronization signal is shifted due to switching of physical connection lines, the middle stage IC malfunctions. Generation of spurious can be prevented by the prevention level data output means. As a result, a transmission amplifier satisfying the CPRI standard can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a main part of an amplifier used in a transmission amplifier according to an embodiment of the present invention.
Now, it is assumed that the control unit and the radio unit are connected by a CPRI link, and this CPRI link has two physical connection lines 1 and 2. At least one pre-stage IC3 having a switchover recognition function for recognizing the occurrence of a switchover in which a physical connection line as a transmission line for IQ data is switched and a switchover occurrence notification function for outputting a timing signal 10 simultaneously with the occurrence of this switchover The physical connection line is formed by at least one middle stage IC 4 that receives the transmission data 7 and synchronization signal 6 transmitted by the preceding stage IC 3, the transmission data 8 that is transmitted by the middle stage IC 4, and the switchover occurrence notification function of the preceding stage IC 3 described above. And at least one post-stage IC 5 that receives a timing signal 10 to be transmitted when switching. Here, a timing signal applying means for applying the timing signal 10 to the subsequent IC 5 is configured using the switchover recognition function and the switchover occurrence notification function described above. When the rear stage IC 5 receives the transmission data 8 received from the middle stage IC 4 and receives the normal data output means that normally outputs the transmission data 9 as the corresponding transmission data 9 and the timing signal 10 from the previous stage IC 3, The time has spurious prevention level data, for example, spurious prevention level data output means for outputting zero data instead of the transmission data 8 received from the middle stage IC 4.

FIG. 2 shows a block diagram of a transmission amplifier configured using the amplifier described above.
The base station 11 and the transmission amplifier 12 are connected by a CPRI link, and IQ data is transmitted to the pre-stage IC 3 via the SerDes 13 and 14. The pre-stage IC3 decodes the CPRI-formatted IQ data sent from the base station 11, and transmits the transmission data 7 and the synchronization signal 6 to the middle stage IC4. The middle stage IC 4 receives the transmission data 7 and the synchronization signal 6, performs orthogonal modulation and carrier synthesis on the received transmission data 7 in accordance with the synchronization signal 6, and transmits the result to the subsequent stage IC 5. The subsequent stage IC 5 performs distortion compensation on the transmission data 8 received from the middle stage IC 4 using a digital pre-distortion (DPD) method, and transmits it to the analog processing unit 16 through the D / A converter 15.

  If an instruction to switch the CPRI link used from the base station 11 from the physical connection line 1 to the physical connection line 2 is issued due to the occurrence of a shortage, etc., the preceding IC 3 receives the instruction from the base station 11 and performs the soft control. The connected CPRI link is switched from the physical connection line 1 to the physical connection line 2. Since the pre-stage IC3 can recognize this switchover by the switchover recognition function, the timing signal applying means transmits the timing signal 10 to the post-stage IC5. Due to the occurrence of the switchover at this time, the synchronization signal 6 is shifted to cause a malfunction of the middle stage IC4 and cause spurious. However, the rear stage IC5 that receives the timing signal 10 from the previous stage IC3 causes the middle stage IC4 to have The zero data is output as transmission data 9 by the spurious prevention level data output means described above for a predetermined time during which malfunction occurs.

  As shown in FIG. 3, which is a time chart waveform comparison diagram when this switchover occurs, a very large irregular value 17 is generated when a switchover occurs according to the conventional configuration, and FIG. 4 is a waveform comparison diagram after FFT. Thus, the spurious 18 is generated by the irregular value 17. However, as shown in FIGS. 1 and 2, when the post-stage IC 5 that has received the timing signal 10 at the time of the switchover occurs outputs 0 data by the spurious prevention level data output function of the post-stage IC 5 for a predetermined time. As shown in FIG. 4, the very large irregular value 17 is replaced with 0 data 19, and the occurrence of spurious 18 can be prevented as shown in the spurious generation prevention waveform diagram 20 of FIG. 4 which is a waveform comparison diagram after FFT. it can.

  The post-stage IC 5 that has received the timing signal 10 when the switchover occurs outputs 0 data 19 for a predetermined time by the spurious prevention level data output means. This predetermined time is the generation time of the irregular value 17 in the actual transmission amplifier. Alternatively, it can be set by an estimated time taking into account variations of each transmission amplifier. In the embodiment described above, the post-stage IC 5 outputs the 0 data 19 for a predetermined time by the spurious prevention level data output means when receiving the timing signal 10, but the spurious 18 shown in FIG. Other data other than 0 may be used as long as the data does not generate.

  When the CPRI link is used in this way, spurious 18 is generated when the physical connection line is switched, but the occurrence of a switchover for switching the physical connection line is controlled, for example, in the previous stage where the switching is controlled by software. Since it is detected by the switchover recognition function of the IC 3 and the timing signal is given to the subsequent stage IC 5 by the timing signal applying means at the time of detection, the spurious prevention level data is output, so that it corresponds to the generation time of the irregular value 17. Thus, the transmission data 9 can be replaced with data at a level that does not generate spurious, for example, 0 data 19, and it becomes possible to easily prevent the occurrence of spurious at the time of switchover in the CPRI link. Sometimes spurious occurs There it is possible to obtain an amplifier.

  The transmission amplifier according to the present invention is not limited to the illustrated configuration but can be applied to other configurations.

It is a principal block block diagram of the amplifier used for the transmission amplifier by one embodiment of this invention. It is a block block diagram of the transmission amplifier comprised using the amplifier shown in FIG. It is a time chart comparison figure at the time of switchover occurrence. It is a waveform comparison figure after FFT.

Explanation of symbols

1, 2 Physical connection line 3 Previous IC
4 Middle IC
5 Later IC
6 Sync signal 7, 8, 10 Transmission data 9 Timing signal 17 Irregular value 18 Spurious 19 0 Data 20 Spurious generation prevention waveform

Claims (1)

  At least one front-stage IC that receives data input from a CPRI link having a plurality of physical connection lines, at least one middle-stage IC that receives transmission data and a synchronization signal transmitted by the front-stage IC, and transmission that the middle-stage IC transmits. A transmission amplifier having at least one post-stage IC for receiving data and outputting transmission data, a timing signal applying means for giving a timing signal to the post-stage IC when a switchover for switching the physical connection line occurs, and the post-stage IC Is provided with spurious prevention level data output means for outputting spurious prevention level data instead of transmission data received from the middle stage IC for a predetermined time when the timing signal is received from the timing signal applying means. amplifier.

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