JP2003046480A - Peak limiter and multi-carrier amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a peak limiter and a multi-carrier amplifier that can perform efficient peak limit in order to realize a desired peak factor in an amplifier input signal with high precision so as to enhance power efficiency of an amplifier system. SOLUTION: This invention provides the peak limiter and the multi-carrier amplifier that receive a base band signal of each carrier, obtains a peak factor of a multi-carrier signal estimated approximately when the base band signals are composited at a high frequency band and output each base band signal whose amplitude is suppressed on the basis of the peak factor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peak limiter and a multicarrier amplifying device used in a system for amplifying a multicarrier signal such as a base station device of a W-CDMA mobile communication system, and more particularly to an amplifying system. The present invention relates to a peak limiter and a multi-carrier amplifier that can improve power efficiency.

[0002]

2. Description of the Related Art Generally, W-CDMA (Wideband Cod) is used.
In a base station apparatus (CDMA base station apparatus) included in a mobile communication system that employs an e Division Multiple Access (Wideband Code Division Multiple Access) method as a mobile communication method, a mobile station apparatus (CDMA mobile station) that is physically far away is used. Since it is necessary to reach the device) with the wireless signal, it is necessary to significantly amplify the signal to be transmitted by an amplifier and output the signal. However, since the amplifier is an analog device, its input / output characteristic is a non-linear function. In particular, after the amplification limit called the saturation point, the output power becomes almost constant even if the power input to the amplifier increases. Then, this non-linear output causes non-linear distortion in the output signal.

Usually, in a transmission signal before amplification, a signal component outside the desired signal band is suppressed to a low level by a band limiting filter, but a non-linear distortion occurs in the signal after passing through the amplifier and the signal outside the desired signal band (adjacent channel). ) Signal component leaks to. For example, in the base station device, since the transmission power is high as described above, the magnitude of such leakage power to the adjacent channel is strictly regulated, and the adjacent channel leakage power (AC
P: Adjacent Channel Leakage Power) reduction technology is used.

As an example of a technique for reducing adjacent channel leakage power in an amplifier, a backoff method, a feedforward method, a predistortion method, etc. are used.
Here, the outline and operating characteristics of each method will be described with reference to FIG. FIG. 6 is an explanatory diagram for explaining the characteristics of the amplifier and the operation characteristics of each adjacent channel leakage power reduction method.
(A) shows the characteristics of the back-off method, and (b) shows the characteristics of the feedforward method and the predistortion method.

The back-off method is a method in which the operating range of the amplifier is limited to a linear region and the operating point is lowered to prevent nonlinear distortion from occurring. Specifically, FIG. 6A
As shown in Fig. 3, when the amplifier characteristic is linear and saturated halfway to become non-linear and reaches the saturated output level, the maximum output power that maintains linearity is maintained in the back-off method. Therefore, the operating point is set at a point lower by the peak factor of the amplifier input signal. Here, the peak factor is the ratio between the maximum power and the average power in the amplifier input signal as shown in FIG. 7, that is, the smaller the difference between the maximum power and the average power, the smaller the peak factor. FIG. 7 is an explanatory diagram of a peak factor of a general amplifier.

On the other hand, the feedforward method is a method for performing distortion compensation by subtracting (distortion component) amplified by an error amplifier from (desired signal + distortion component) amplified and output by the main amplifier. In addition, the predistortion method usually uses AM / AM before inputting a desired signal to the amplifier.
The desired signal is pre-distorted by the inverse characteristics of the nonlinear characteristics represented by the conversion and AM / PM conversion (desired signal + distortion component)
Is input, and distortion compensation is performed so as to cancel out (distortion component) generated in the amplifier. That is, since the feedforward method and the predistortion method compensate distortion that occurs on the assumption that a distortion component occurs, as shown in FIG. The operating point can be set at a point lower than the saturation output power (level) by the peak factor of the amplifier input signal, and the operating point can be set higher than that of the backoff method.

At present, the feed-forward method and the predistortion method are mainstream as distortion compensation methods, because the power efficiency of the system can be improved. If the operating point of the amplifier can be set high, the output power will be large and the power efficiency will be improved. However, the power efficiency will be greatly influenced by the peak factor of the amplifier input signal. When the peak factor becomes large, the size of the transistor of the power amplification circuit used becomes large, and it is necessary to greatly reduce the output level from the saturated output power before use. When the level is lowered in this way, the ratio of the DC supply power of the power amplifier and the extracted transmission power is lowered.

Therefore, in order to improve the power efficiency of the amplifier, it is important to make the peak factor as small as possible. As an example of the technique, a peak limiter is provided in the preceding stage of the amplifier to limit the maximum power (peak) signal to the amplifier. There is a method of using the input signal of. A conventional peak limiter will be described with reference to FIG. FIG. 8 is a block diagram showing a configuration example of a conventional peak limiter. As shown in FIG. 8, the conventional peak limiter 1'includes an average power detector 1
1 ', an instantaneous power detector 12', and a peak detector 13
And a limiter portion 14 '.

Each part of the conventional peak limiter 1'will be described. The average power detector 11 'detects the average power of the input signal IQ and outputs the average power information.
The instantaneous power detector 12 'detects the instantaneous power of the input signal IQ and outputs the instantaneous power information. The peak detector 13 detects the presence or absence of a peak in the input signal IQ. Specifically, for example, by calculating the ratio of the input average power information and the instantaneous power information to calculate the peak factor of the input signal, whether the calculated peak factor exceeds a predetermined peak threshold, That is, the presence or absence of a peak to be limited is detected, and the peak detection information is output. Here, the predetermined peak threshold value is a value that takes into consideration the peak factor that assumes the operating point with respect to the saturated output level in the characteristic (FIG. 6B) of the amplifier installed subsequently. .

The limiter unit 14 'limits the peak of the amplitude of the input signal IQ. Specifically, it is input when a peak to be limited is detected according to the input peak detection information. The power (amplitude) of the input signal IQ is limited to a predetermined limit power and the output signal IQ is output.

Next, the operation of the conventional peak limiter 1'will be described. In the conventional peak limiter 1 ', the input signal IQ has the average power detector 11' and the instantaneous power detector 1 '.
2 ', and the limiter unit 14', the average power detector 11 'detects the average power of the input signal and outputs the average power information, and the instantaneous power detector 12' detects the instantaneous power of the input signal. The instantaneous power information is output, the peak detection unit 13 detects the presence / absence of a peak to be limited from the average power information and the instantaneous power information, and the peak detection information is output. When a peak to be limited is detected, the output signal IQ is output in which the power of the input signal IQ to be input is limited to a predetermined limit power.

Normally, the input signal IQ input to the peak limiter 1'is a baseband signal before band limitation,
Since the limiter processing is performed by the peak limiter 1 ', the band is limited by the filter (not shown),
Since no distortion occurs and the peak value of the input signal is limited by the peak limiter 1 ', the peak factor of the input signal is reduced, and the operating point of the amplifier performed after band limitation can be increased. The power efficiency can be improved. Here, since the band limit is performed after the limiter by the peak limiter 1 ', the peak factor after the band limit is usually larger than the peak factor before the band limit. This is because the rectangular wave before the band limitation becomes dull after the band limitation, and a point where the peak becomes high appears. Therefore, it is necessary to set the peak threshold value set in the peak detection unit 13 to a low value in consideration of the increase in the peak factor after the band limitation.

Next, a conventional multicarrier amplifying apparatus using the conventional peak limiter 1'will be described with reference to FIG. FIG. 9 is a schematic block diagram of a conventional multicarrier amplifier. Note that FIG. 9 shows the configuration in the case of two carriers as an example. A conventional multi-carrier amplifying device for amplifying a multi-carrier signal includes a peak limiter 1'for limiting a signal peak as an independent sequence for each carrier and a band limiting filter 2 for limiting a band.
And an up-converter 3 that up-converts (high-frequency-modulates) the RF frequency, a combiner 4 that combines the outputs from the carrier sequences and outputs a multi-carrier signal, and an amplifier that amplifies the multi-carrier signal. 5
It consists of and.

The operation of the conventional multicarrier amplifier is as follows.
The input signal IQ of each carrier sequence corresponds to each peak limiter 1 '.
The peak factor of each input signal is calculated by the peak limiter 1 ', and when the peak factor exceeds the peak threshold, the signal peak value is limited based on a predetermined peak threshold, and the peak limiting signal A1, A2 is output, and the signal B is band-limited by each band-limiting filter 2.
1, B2 are output, and each up converter 3 outputs each R
The high frequency modulated signals (carrier signals) C1 and C2 up-converted to the F frequency are output. Then, the output signals of the up-converter 3 of each carrier series are combined by the combiner 4 to output the multi-carrier signal D, and the amplifier 5
It is amplified by and output.

As a result, in the conventional multi-carrier amplifying apparatus, the band limit is applied to the signals A1 and A2 for which the peak value of the signal is limited by the peak limiter 1'in each carrier sequence and the peak factor is reduced. , Up-conversion is performed, then combined, and the combined multi-carrier signal is amplified by the amplifier 5. Since the peak factor of the signal before combining is small, the peak factor of multi-carrier after combining is reduced. As a result, the peak factor of the input signal to the amplifier 5 is suppressed and the operating point of the amplifier 5 can be raised.

As a conventional technique for reducing distortion during amplification of a multi-carrier signal, Japanese Patent Laid-Open No. 2000-244452, “CDMA radio base station”, published on September 8, 2000 (Applicant: Kokusai Electric Co., Ltd.) , Inventor: Masahiro Hinoki and others). This prior art is a limit that sets the limiter level of the baseband signal to be high when a modulation signal with a large number of carriers and multiplex and a large individual transmission power is input to the common amplifier, and otherwise sets the limiter level to be low. This is a CDMA radio base station that performs variable level. With this, it is possible to reduce distortion that occurs when the number of carriers and the number of multiplexing are large and the individual transmission power is large, and when the number of multiplexing is small, The error rate on the receiving side can be suppressed, and since the limit level can be changed, an amplifier with low power consumption can be used, which contributes to low power consumption of the entire apparatus.

[0017]

However, in the conventional peak limiter and multicarrier amplifying apparatus, the peak limiter 1'provided for each carrier sequence is used to detect the peak factor and the peak threshold value detected from the input signal of each carrier sequence. The peak factor of the multi-carrier signal which is the output of the combiner 4 is empirically larger than the peak factor of each carrier sequence, because the peak factor is limited based on the relationship of 1. 5
It is difficult to adjust the optimum peak threshold in each peak limiter 1 ′ in order to obtain a desired peak factor for the input signal to, and the peak threshold is set lower for safety. There was a problem that the peak limit could not be performed efficiently. As an example of comparison between the peak factor of a plurality of carriers and the peak factor of one carrier, 2 to 4 in W-CDMA are used.
The peak factor of carrier input is about 2 to 6 dB larger than the peak factor of one carrier input.

Further, as another problem, for example, although the power of a multicarrier signal obtained by combining the carrier signals by the combiner 4 is actually small, the peak factor of a certain carrier signal is lower than the threshold value. Even if it becomes large, the conventional peak limiter 1'limits the peak, so that there is a problem that the modulation accuracy is deteriorated by the unnecessary peak limitation.

The present invention has been made in view of the above circumstances, and a peak limiter capable of improving the power efficiency of an amplification system by performing efficient peak limiting so as to accurately realize a desired peak factor in an amplifier input signal. Another object of the present invention is to provide a multicarrier amplifier.

[0020]

DISCLOSURE OF THE INVENTION The present invention for solving the problems of the above-mentioned conventional example is a peak limiter used in a system for amplifying a multi-carrier signal,
The average power detection unit that inputs the baseband signal of each carrier, calculates the average power of the multicarrier signal that is approximately assumed when the baseband signals are combined in the high frequency band, and outputs the average power information, and each carrier Input the baseband signal of, and calculate the instantaneous power of the multi-carrier signal that is approximately assumed when the baseband signals are combined in the high frequency band, and output the instantaneous power information. A peak detection unit that receives instantaneous power information, obtains a peak factor that is a ratio between the instantaneous power and the average power, compares the peak factor with a predetermined peak threshold value, detects a peak, and outputs peak detection information. And the baseband signal and peak detection information for each carrier are input, and when a peak is detected from the peak detection information, the baseband signal for each carrier is input. Since it has a limiter unit that outputs each signal with the signal amplitude suppressed, each baseband signal based on the peak factor of the multicarrier signal that is approximately assumed when the baseband signals are combined in the high frequency band. The amplitude of each baseband signal can be effectively and efficiently suppressed so that the peak factor of the multicarrier signal to be amplified is captured and the peak factor is reduced by limiting the amplitude of the.

The present invention for solving the above-mentioned problems of the conventional example is a multi-carrier amplifier for amplifying a multi-carrier signal, in which a base band signal of each carrier is input and each base band signal is synthesized in a high frequency band. In this case, the peak factor of the multi-carrier signal that is assumed approximately is calculated, and based on the peak factor, the peak limiter that outputs each signal that suppresses the amplitude of each baseband signal and the peak that is the output signal of the peak limiter A band-limiting filter that limits the baseband signal of each carrier that suppresses noise, an up-converter that up-converts the band-limited signal to a high-frequency band, and a signal that combines each carrier up-converted to a high-frequency band is combined. Has a combiner that outputs a carrier signal and an amplifier that amplifies a multicarrier signal. Therefore, it is necessary to limit the amplitude of each baseband signal based on the peak factor of the multicarrier signal that is approximately assumed when the baseband signals are band-limited, converted to a high-frequency band, and then combined. This effectively and efficiently suppresses the amplitude of each baseband signal so that the peak factor of the multi-carrier signal input to the amplifier is detected and the peak factor is reduced, and as a result, the desired peak in the amplifier input signal is obtained. The factor can be realized accurately.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. The function realizing means described below may be any circuit or device as long as it can realize the function, and part or all of the function can be realized by software. is there. Further, the function realizing means may be realized by a plurality of circuits, or the plurality of function realizing means may be realized by a single circuit.

To put it in a high-level conception, the peak limiter according to the present invention is a multicarrier signal that is approximately assumed when the baseband signals of the respective carriers are input and the respective baseband signals are combined in the high frequency band. The peak factor of is calculated, and based on the peak factor, each signal that suppresses the amplitude of each baseband signal is output.
The amplitude of each baseband signal can be suppressed effectively and efficiently so as to detect the peak occurrence of the multicarrier signal to be amplified and reduce the peak factor, and the power efficiency of the amplification system can be improved.

Explaining in terms of function realizing means, the peak limiter according to the present invention is a multi-carrier signal that is approximately assumed when the base band signals of the respective carriers are input and the respective base band signals are combined in the high frequency band. The average power detection unit that calculates the average power of each carrier and outputs the average power information, and the baseband signal of each carrier is input, and the instantaneous of the multicarrier signal that is approximately assumed when the baseband signals are combined in the high frequency band An instantaneous power detector that determines the power and outputs the instantaneous power information, and inputs the average power information and the instantaneous power information, calculates the peak factor that is the ratio of the instantaneous power and the average power, and determines the peak factor and the predetermined peak. A peak detector that compares the threshold value to detect peaks and outputs peak detection information, and a baseband signal and peak detection information for each carrier are input. However, when a peak is detected from the peak detection information, since it has a limiter unit that outputs each signal that suppresses the amplitude of the baseband signal of each carrier, the peak occurrence of the multicarrier signal to be amplified is detected and the peak is detected. The amplitude peak of each baseband signal can be suppressed effectively and efficiently by reducing the factor, and the power efficiency of the amplification system can be improved.

First, a multicarrier amplifying device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of a multicarrier amplification device according to an embodiment of the present invention. It should be noted that parts having the same configuration as in FIG.
As shown in FIG. 1, the multicarrier amplifying apparatus according to the present embodiment has a configuration similar to that of the conventional multicarrier amplifying apparatus, and has a band limiting filter 2 for performing band limiting as an independent sequence for each carrier, and an RF. It is composed of an up-converter 3 for up-converting to a frequency (high frequency modulation), a combiner 4 for combining outputs from respective carrier sequences to output a multi-carrier signal, and an amplifier 5 for amplifying the multi-carrier signal. Instead of the peak limiter 1'provided for each carrier series, a peak limiter 1 common to each carrier series is provided.

Here, the band limiting filter 2, the up-converter 3, the coupler 4 and the amplifier 5 are exactly the same as the conventional ones, and therefore detailed description thereof will be omitted. The peak limiter 1, which is a characteristic part of the present invention, inputs base band signals (input signals) of a plurality (two in FIG. 1) of carrier sequences, each input signal is high-frequency modulated by the up converter 3, and a combiner is used. Assuming the multicarrier signal combined (combined) in 4, the peak factor of the approximately assumed multicarrier signal is calculated, and the calculated peak factor exceeds the peak factor desired for the input signal of the amplifier 5. In case,
The peak value of each input signal is limited.

Now, a situation in which signals of different frequencies (carrier signals) are combined will be described with reference to FIG.
FIG. 2 is an explanatory diagram showing a complex space representation of a plurality of carrier signals and a combined multi-carrier signal. Generally, in multicarrier signal transmission, a plurality of input signals are modulated with a carrier having a certain frequency interval (carrier frequency difference), as shown in FIGS. 2 (a) (b) (c). Each carrier signal rotates in a complex space at different periods while changing its phase with the passage of time.
Then, in the process in which each carrier signal rotates at each frequency, the multi-carrier signal obtained by combining the carrier signals is
When the phases of the carrier signals are different from each other, the power values do not show a very large value due to cancellation in the IQ space due to the combination, but the power values increase as a plurality of carrier signals approach the same phase. When the phases match, as shown in FIG. 2D, the powers of the carrier signals may be added, and the instantaneous power may instantaneously have a large peak value. It should be noted that in FIG. 2D, the arrows of the respective signals are shifted and shown for easy understanding. That is, in the present invention, when the phases of the multiple carrier signals are different,
No limitation is imposed even if the power of each carrier signal is large, and the purpose is to detect the timing of limiting by capturing the power of the multicarrier signal at the time when the phases of the multiple carrier signals described above coincide.

The internal structure of the peak limiter 1 of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the internal configuration of the peak limiter of the present invention. It should be noted that portions having the same configurations as those in FIG. The peak limiter 1 of the present invention, as shown in FIG. 3, has an average power detection unit 11 and an instantaneous power detection unit 12
And a peak detector 13 and a limiter 14. The main constituent elements are the same as those of the conventional peak limiter shown in FIG. 8, but the function of each element is different from the conventional one.

Each part of the peak limiter 1 of the present invention will be described. The average power detection unit 11 inputs the input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) and multi-carriers that are approximately assumed when the carrier signals are combined in the high frequency (RF) band. The average power of the signal is detected and the average power information is output. Note that a method of approximately assuming a multi-carrier signal in which carrier signals are specifically combined in a high frequency (RF) band will be described later.

The instantaneous power detection unit 12 is approximately assumed when input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) are input and the carrier signals are combined in a high frequency (RF) band. The instantaneous power of the multi-carrier signal is detected and the instantaneous power information is output. A method of approximately assuming a multi-carrier signal obtained by combining the carrier signals in the high frequency (RF) band will be described later.

The peak detector 13 detects the presence or absence of a peak in the postulated composite multi-carrier signal. Specifically, the peak factor is calculated by calculating the ratio from the average power information and the instantaneous power information in the assumed combined multi-carrier signal input from the average power detection unit 11 and the instantaneous power detection unit 12, Whether or not the calculated peak factor exceeds a predetermined peak threshold value, that is, the presence or absence of a peak to be limited, is detected, and peak detection information is output. Here, the predetermined peak threshold is a characteristic of the amplifier 5 installed subsequently (see FIG. 6).
It is a value in consideration of the peak factor assuming the operating point with respect to the saturated output level in (b). The peak detection target of the peak detection unit 13 of the present invention is an approximately assumed post-synthesis multicarrier signal, but an operation of detecting the presence or absence of a peak from the input average power information and instantaneous power information Is exactly the same as the conventional peak detector 13.

The limiter unit 14 inputs the input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) and limits the peak of the amplitude of each input signal IQ.
Specifically, according to the peak detection information input from the peak detection unit 13, when a peak that should be subjected to the limit is detected for the approximately assumed combined multicarrier signal, the power of each input signal IQ ( (Amplitude) is limited to a predetermined limit power and each output signal IQ
Is output.

The operation of the peak limiter 1 of the present invention will be described. When the input signals IQ of a plurality of carrier sequences are input, the average power detector 11, the instantaneous power detector 12, and the limiter 14 are used.
The average power detection unit 11 detects the average power of the multi-carrier signals that is approximately assumed when the carrier signals are combined in the RF band, and outputs the average power information. On the other hand, the instantaneous power detector 12 similarly detects the instantaneous power of the multi-carrier signal that is approximately assumed when the carrier signals are combined in the RF band, and outputs the instantaneous power information. Then, the peak detection unit 13 detects the presence or absence of a peak to be limited in the approximately assumed multicarrier signal from the approximately assumed average power information and the instantaneous power information of the multicarrier signal, thereby performing peak detection. When information is output and the limiter unit 14 detects a peak to be limited according to the peak detection information, the power (amplitude) of each input signal IQ to be input is limited to a predetermined limit power. The output signal IQ is output.

Next, a method of approximating a multi-carrier signal obtained by synthesizing carrier signals in a high frequency (RF) band in the average power detection unit 11 and the instantaneous power detection unit 12 will be described. A first method (first assumed method) of approximately assuming a multi-carrier signal synthesized in the RF band
Is the carrier frequency difference (Δf) for each input signal
In this method, the power of the combined signal is detected at a fixed sampling interval.

This is because the input signal to the average power detection unit 11 and the instantaneous power detection unit 12 is the baseband signal IQ. Therefore, in order to assume the synthesis in the RF band, each upconverter 3 should normally be used. It is necessary to convert signals into RF frequencies that are subjected to high frequency modulation, perform signal synthesis of RF frequencies, and perform power measurement. However, since signal processing at RF frequencies requires very fast sampling, expensive signal processing devices are required. Become. However, if each carrier frequency has a carrier frequency difference (Δf) with each other, a constant sampling interval (for example, the highest frequency At a timing of one cycle of a carrier signal having a small value, it is possible to capture the state of a plurality of carriers at that time, and it is sufficient to detect the instantaneous power and the average power assuming a multicarrier signal approximately.

Here, the conventional average power detector 11 'and the instantaneous power detector 12' and the average power detector 11 of the present invention are used.
And the difference from the instantaneous power detection unit 12 will be described using mathematical expressions. First, each input signal IQ is expressed as a vector complex expression as in [Equation 1].

[0037]

[Equation 1]

Then, the instantaneous power calculated by the conventional instantaneous power detecting section 12 'and the average power calculated by the average power detecting section 11' in each peak limiter 1'of the conventional multicarrier amplifier shown in FIG. , [Equation 2].

[0039]

[Equation 2]

There are various methods for obtaining the average power, such as moving average and weighted average, but the method is not limited. On the other hand, the instantaneous power calculated by the instantaneous power detection unit 12 and the average power calculated by the average power detection unit 11 in the peak limiter 1 of the multicarrier amplifying device of the present invention shown in FIGS. When it is obtained by the first assumed method described above, it can be expressed as [Equation 3].

[0041]

[Equation 3]

In [Equation 3], Δf is the difference in carrier frequency. That is, assuming that each input signal is upconverted to each RF frequency with a difference of Δf,
Carrier frequency difference (Δf) in the input signal of each carrier sequence
An offset of only a minute is given and combined, and a signal in which signals of different RF frequencies are combined is artificially created. And
If the average power of the combined signal is detected at a fixed sampling interval (for example, one cycle of the carrier signal with the smallest frequency), the sampling interval is coarse, but by measuring for a long time, it is possible to combine multiple signals in almost the RF band. A power value close to the average power of the carrier signal can be obtained.

With respect to the instantaneous power, when an input signal of each carrier sequence division is given an offset corresponding to the carrier frequency difference (Δf) and combined, as shown in FIG. When the phases match, the instantaneous power should have a peak instantaneously, so if the instantaneous power is detected by sampling so as not to miss this timing, the multi-carrier signal synthesized in the RF band will be almost It is possible to obtain the instantaneous power value that is important for detecting the peak to be subjected to the peak limit.

Next, a configuration example of the average power detection unit 11 and the instantaneous power detection unit 12 that realizes the above-described first assumed method will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing a configuration example of the average power detection unit 11 of the present invention, and FIG. 5 is a block diagram showing a configuration example of the instantaneous power detection unit 12 of the present invention. As shown in FIG. 4, the average power detection unit 11 that implements the first assumed method of the present invention includes complex multiplication units 21, 22, 23, for applying an offset of a carrier frequency difference (Δf) to each input signal. , And an adder 24 for synthesizing the signals given the respective offsets, a power calculator 25 for obtaining the instantaneous power of the added signal, and an averaging unit 26 for obtaining the average power from the instantaneous power.

The operation of the average power detection unit 11 shown in FIG. 4 is such that the input signal-1 remains unchanged and the input signal-2 is the complex multiplication unit with respect to a plurality of input signals (four in FIG. 4). The input signal -3 is rotated by Δf and offset, the input signal -3 is rotated by 2Δf and offset by the complex multiplication unit 22, and the input signal -4 is rotated by 3Δf and offset by the complex multiplication unit 23. All signals are added (combined) by the adder 24, the power calculator 25 calculates the instantaneous power, and the averaging unit 26 calculates the average power.

Similarly, the instantaneous power detector 12 for implementing the first assumed method of the present invention, as shown in FIG. 5, is a complex multiplier for giving an offset of the carrier frequency difference (Δf) to each input signal. , 32, 33, ..., Adder 34 for synthesizing signals given respective offsets, and power calculator 35 for calculating the instantaneous power of the added signal. The operation of the instantaneous power detector 12 shown in FIG. 5 is similar to the operation of the average power detector 11.

As can be seen from the configurations of FIGS. 4 and 5, the configurations up to the complex multiplication unit, the adder, and the power calculation unit are the same. Alternatively, the power may be output as power information, the instantaneous power information may be input to the averaging unit 26, the average power may be obtained, and the average power information may be output.

Next, another method in the average power detection unit 11 and the instantaneous power detection unit 12 for approximating the multi-carrier signal after combining in the RF band will be described. RF
A second method (second assumed method) that approximately assumes a combined multi-carrier signal in a band is to capture each input signal that is input as a vector, combine the signals by vector operation, and obtain the average power. Further, it is a method of obtaining the power at the timing when the instantaneous power of the combined signal (vector) becomes maximum.

First, a method of obtaining the average power in the second assumed method will be described. In the multicarrier amplifier of FIG. 1, the input baseband signals of each carrier sequence are output from the peak limiter 1, individually upconverted to an RF frequency band by the upconverter 3, and then combined by the combiner 4 to form a multicarrier signal. Become a signal. Therefore, when measuring the average power of a multi-carrier signal,
Originally, it is necessary to measure the average of the combined power of signals rotating at each RF frequency. However, when measuring the combined power with an RF signal, very fast sampling is required, and thus an expensive signal processing device is required.
Therefore, in the present invention, the input baseband signal of each carrier is taken as a vector, sampling is performed at a fixed timing to perform a vector combining operation, an average of the electric powers of the combined vectors is calculated, and an approximation after combining in the RF band is performed. The average power of the multi-carrier signal is assumed as the target.

Next, how to obtain the instantaneous power in the second assumed method will be described. Similar to the method for obtaining the average power, as described above, when measuring the instantaneous power with the RF signal, very fast sampling is required and an expensive signal processing device is required. Therefore, in the present invention, the sum of the powers of the baseband signals of the carriers is calculated at the timing when the carrier signals of the carriers are in phase, and the instantaneous power of the approximately assumed multicarrier signal after combining in the RF band is obtained. It is supposed to do.

This is because, as shown in FIG. 2, in the process in which each carrier signal rotates at each RF frequency, a multi-carrier signal obtained by combining the carrier signals has a power value as the plurality of carrier signals approach the same phase. 2 increases, and when the phases match, as shown in FIG. 2D, the power of each carrier signal may be added and the instantaneous power may momentarily have a large peak. This is because it is only necessary to capture the instantaneous power of the multi-carrier signal at the time point and detect the timing at which the limit is applied. At this time, the power of the combined vector is equal to the sum of the individual powers of the input signals of the carrier sequences. For example, in the case of W-CDMA system,
The input signal is 3.84 [MHz] and the carrier interval is 5
Since it is [MHz], there is always a moment when the vectors of multiple carriers have the same direction.

Here, the concept of how to obtain the average power and the instantaneous power in the second assumed method will be described using mathematical expressions. As described in the first assumed method, if the carrier frequencies have a carrier frequency difference (Δf) with each other, by adding an offset corresponding to the carrier frequency difference (Δf) to each input signal and combining them. , Approximate synthesis can be performed, and the instantaneous power and average power can be expressed by [Equation 3]. In the average power of [Equation 3], when the term of e becomes the same vector and only the moment when 1 + j · 0 = 1 is sampled, the average power of [Equation 4] is obtained. This is a mathematical expression that averages the powers of the combined vectors that have been subjected to the vector combining operation for each input baseband signal. This means that the sampling is rough, but since the average power of the first assumption method becomes equal when measured for a long time, the second assumption method simplifies the hardware configuration. In addition, the instantaneous power is a mathematical expression for obtaining the sum of the powers of the input signals of the carrier sequences at the timing when the phases are simply matched, as shown in the instantaneous power of [Equation 4].

[0053]

[Equation 4]

Next, the operation of the multicarrier amplifier of the present invention will be described with reference to FIG. In the multi-carrier amplifier of the present invention, all input baseband signals IQ (two in FIG. 1) of each carrier series are input to the peak limiter 1, and the peak limiter 1 outputs each input signal at a high frequency (R).
The peak factor of the multi-carrier signal that is approximately assumed when combined in the F) band is calculated, the peak of the amplitude of each input baseband signal is limited based on a predetermined peak threshold, and the peak limiting signal a1 , A2 are output. At this time, the peak limiting signals a1 and a2 are different from the peak limiting signals A1 and A2 output from the respective peak limiters 1'of the conventional multicarrier amplifier shown in FIG. In a multi-carrier signal that is supposed to be a peak, the peak is limited only when the peak factor exceeds the peak threshold.

Then, the peak limiting signals a1 and a2 are band-limited by the band limiting filter 2 to become signals b1 and b2, which are further up-converted to respective RF frequencies by the up-converter 3 to generate high-frequency modulated signals (carrier signals) c1.
It is output as c2. Then, the output signals of the up-converters 3 of each carrier series are combined by the combiner 4 to output the multi-carrier signal d, which is amplified by the amplifier 5 and then output.

Here, the multicarrier signal d output from the combiner 4 is the multicarrier signal D output from the combiner 4 of the conventional multicarrier amplifying device shown in FIG.
Unlike the above, the peak power value in the multicarrier signal is limited by the processing in the peak limiter 1, and the other portions are signals that are not affected by the processing in the peak limiter 1.

As a result of the operation in the above multi-carrier amplifying device, in the present invention, the peak factor of the multi-carrier signal which is approximately assumed when the input signal of each carrier sequence is combined in the high frequency band by the peak limiter 1. Based on the above, the signals a1 and a2 subjected to the process of limiting the peak value of each input signal to reduce the peak factor are combined after band limitation and up-conversion, and the combined multi-carrier signal is amplified by the amplifier 5 Therefore, the peak factor of the multi-carrier signal input to the amplifier 5 is suppressed, and the operating point of the amplifier 5 can be raised.

According to the peak limiter of the present invention, the average power of the multi-carrier signals approximately assumed when the base band signals of the respective carrier sequences are input and the respective base band signals are combined in the high frequency band is calculated as the average power. The instantaneous power of the multi-carrier signal is determined by the instantaneous power detection unit 12 while being determined by the detection unit 11, and the peak detection unit 13 calculates the peak factor from the average power and compares the average power with a preset peak threshold value. The presence or absence of a peak is detected by, and when there is a peak, the limiter unit 14 outputs each signal in which the amplitude of each baseband signal is suppressed. Effectively and efficiently to reduce the peak factor, the peak limit is applied to the input signal, resulting in amplification. There is an effect that can be achieved with high accuracy desired peak factor in the input signal. Also, for example,
As an individual input signal, if the peak factor exceeds the peak factor desired by the amplifier 5 but becomes small when combined, no peak limit is applied to the input signal, so unnecessary. There is an effect that the peak limitation can be efficiently performed without causing the deterioration of the modulation accuracy due to the peak limitation.

Then, in the average power detection unit 11 and the instantaneous power detection unit 12 of the present invention, as a method of approximately assuming a multi-carrier signal when the base band signals are combined in a high frequency band, originally, each up converter is used. Although it is about to be converted into an RF frequency that is subjected to high-frequency modulation in 3 and synthesized, and very high-speed sampling is required for measuring the power of the RF signal. Since the carrier frequency difference (Δf) is given an offset to the input signal by using a complex multiplication unit and then combined to detect the instantaneous power or average power of the combined signal, the instantaneous power or average power is sampled at the frequency of the baseband signal. Can be detected, and approximates to a multi-carrier signal when combined in the high frequency band without increasing the configuration so much. There is an effect that can detect the instantaneous power and the average power of Ruchi carrier signal.

When the second assumed method is used in the average power detection unit 11 of the present invention, each input signal to be input is regarded as a vector, and sampling is performed at a constant timing, for example, the same vector. Since the signals are combined by vector operation to obtain the average power, the sampling can be roughened to an approximate level to perform the detection process efficiently, and the average power can be obtained only by the operation process to simplify the configuration. It is possible to reduce the cost and cost.

When the second assumed method is used in the instantaneous power detector 12 of the present invention, the timing when the carrier phases of a plurality of input signals match, that is, the timing when the instantaneous power of the combined signal (vector) becomes maximum. Since the electric power of is obtained by calculation, it is possible to effectively capture the instantaneous power that is the point of the peak factor, and the configuration can be simplified by calculating the instantaneous power only by calculation processing,
This has the effect of reducing the scale of hardware and reducing costs.

According to the multicarrier amplifying apparatus of the present invention, all of a plurality of input baseband signals are input to the peak limiter 1, and when the peak limiter 1 combines the respective input signals in the high frequency (RF) band, it is approximated. The assumed peak factor of the multi-carrier signal is calculated, the peak value of each input baseband signal is limited and output based on a predetermined peak threshold, the band is limited by the band limiting filter 2, and the up converter 3 Is up-converted to each RF frequency, is combined by the combiner 4 and is output as a multi-carrier signal, is amplified by the amplifier 5, and is output, so that it is indirectly input as a result to the amplifier 5. The peak factor of the multi-carrier signal is captured and the peak factor is suppressed, and the operating point of the amplifier 5 can be raised. There is an effect that it is possible to improve the power efficiency. Further, since there is no peak limitation in individual carrier sequences in the case of being erased when combined by the combiner 4, which has been a problem in the conventional technique, modulation accuracy due to unnecessary peak limitation is eliminated. There is an effect that deterioration can be avoided and the reliability of the entire system can be improved.

[0063]

According to the present invention, it is a peak limiter used in a system for amplifying a multi-carrier signal, in which an average power detection unit inputs a base band signal of each carrier and outputs each base band signal in a high frequency band. When the average power of the multi-carrier signal that is approximately assumed is calculated and the average power information is output, the instantaneous power detection unit similarly calculates the instantaneous power of the multi-carrier signal that is approximately assumed and the instantaneous power Output information, the peak detection unit obtains a peak factor that is the ratio of the instantaneous power and the average power, compares the peak factor with a predetermined peak threshold value, detects the peak, and outputs the peak detection information, A peak limiter that suppresses the amplitude of the baseband signal of each carrier and outputs each signal when the limiter detects a peak from the peak detection information. Therefore, it is effective and efficient to reduce the peak factor by catching the peak occurrence of the multi-carrier signal that is approximately assumed when combining the baseband signals in the high frequency band. This has the effect of suppressing the amplitude peak.

According to the present invention, in a multi-carrier amplifier for amplifying a multi-carrier signal, a peak limiter inputs the base band signal of each carrier and approximately combines the base band signals in a high frequency band. Obtain the expected peak factor of the multi-carrier signal, output each signal with the amplitude of each baseband signal suppressed based on the peak factor, and output the respective signals with the band-limiting filter suppressing the peak from the peak limiter. The band signal is band-limited, the up-converter up-converts each band-limited signal to a high frequency band, the combiner combines the signals of each carrier and outputs a multi-carrier signal, and the amplifier amplifies the multi-carrier signal. Since it is a multi-carrier amplifier, The peak occurrence of the multi-carrier signal that is assumed approximately when converted to the waveband and then combined is captured, and the peak factor of each baseband signal is effectively suppressed so that the peak factor is reduced effectively. hand,
As a result, a desired peak factor in the amplifier input signal can be accurately realized, and the power efficiency of the amplification system can be improved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a multicarrier amplifier according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a complex space representation of a plurality of carrier signals and a combined multi-carrier signal.

FIG. 3 is an internal block diagram of a peak limiter of the present invention.

FIG. 4 is a block diagram showing a configuration example of an average power detection unit of the present invention.

FIG. 5 is a block diagram showing a configuration example of an instantaneous power detection unit of the present invention.

FIG. 6 is an explanatory diagram illustrating characteristics of an amplifier and operation characteristics of each adjacent channel leakage power reduction method.

FIG. 7 is an explanatory diagram of a peak factor of a general amplifier.

FIG. 8 is a block diagram showing a configuration example of a conventional peak limiter.

FIG. 9 is a schematic block diagram of a conventional multicarrier amplifier.

[Explanation of symbols]

1, 1 '... peak limiter, 2 ... band limiting filter,
3 ... Up-converter, 4 ... Coupler, 5 ... Amplifier, 11, 11 '... Average power detection part, 12, 12'
... Instantaneous power detection unit, 13 ... Peak detection unit, 14, 1
4 '... Limiter unit, 21, 22, 23, 31, 32,
33 ... Complex operation part, 24, 34 ... Adder, 25, 3
5 ... Power calculation unit, 26 ... Average unit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 29, 2002 (2002.7.2)
9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Peak limiter and multi-carrier amplifier

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peak limiter and a multicarrier amplifying device used in a system for amplifying a multicarrier signal such as a base station device of a CDMA mobile communication system, and more particularly to power efficiency of the amplifying system. The present invention relates to a peak limiter and a multi-carrier amplifier that can improve the performance.

[0002]

2. Description of the Related Art Generally, CDMA (Code Division Mu
ltiple Access: code division multiple access) is used as a mobile communication system in a base station apparatus (CDMA base station apparatus) provided in a mobile communication system, even a mobile station apparatus (CDMA mobile station apparatus) that is physically far away. Since it is necessary to make a radio signal reach, it is necessary to greatly amplify the signal to be transmitted by an amplifier and transmit it. However, since the amplifier is an analog device, its input / output characteristic is a non-linear function. In particular, after the amplification limit called the saturation point, the output power becomes almost constant even if the power input to the amplifier increases.
Then, this non-linear output causes non-linear distortion in the output signal.

Usually, in a transmission signal before amplification, a signal component outside the desired signal band is suppressed to a low level by a band limiting filter, but a non-linear distortion occurs in the signal after passing through the amplifier and the signal outside the desired signal band (adjacent channel). ) Signal component leaks to. For example, in the base station device, since the transmission power is high as described above, the magnitude of such leakage power to the adjacent channel is strictly regulated, and the adjacent channel leakage power (AC
P: Adjacent Channel Leakage Power) reduction technology is used.

As an example of a technique for reducing adjacent channel leakage power in an amplifier, a backoff method, a feedforward method, a predistortion method, etc. are used.
Here, the outline and operating characteristics of each method will be described with reference to FIG. FIG. 6 is an explanatory diagram for explaining the characteristics of the amplifier and the operation characteristics of each adjacent channel leakage power reduction method.
(A) shows the characteristics of the back-off method, and (b) shows the characteristics of the feedforward method and the predistortion method.

The back-off method is a method in which the operating range of the amplifier is limited to a linear region and the operating point is lowered to prevent nonlinear distortion from occurring. Specifically, FIG. 6A
As shown in Fig. 3, when the amplifier characteristic is linear and saturated halfway to become non-linear and reaches the saturated output level, the maximum output power that maintains linearity is maintained in the back-off method. Therefore, the operating point is set at a point lower by the peak factor of the amplifier input signal. Here, the peak factor is the ratio between the maximum power and the average power in the amplifier input signal as shown in FIG. 7, that is, the smaller the difference between the maximum power and the average power, the smaller the peak factor. FIG. 7 is an explanatory diagram of a peak factor of a general amplifier.

On the other hand, the feedforward method is a method for performing distortion compensation by subtracting (distortion component) amplified by an error amplifier from (desired signal + distortion component) amplified and output by the main amplifier. In addition, the predistortion method usually uses AM / AM before inputting a desired signal to the amplifier.
The desired signal is pre-distorted by the inverse characteristics of the nonlinear characteristics represented by the conversion and AM / PM conversion (desired signal + distortion component)
Is input, and distortion compensation is performed so as to cancel out (distortion component) generated in the amplifier. That is, since the feedforward method and the predistortion method compensate distortion that occurs on the assumption that a distortion component occurs, as shown in FIG. The operating point can be set at a point lower than the saturation output power (level) by the peak factor of the amplifier input signal, and the operating point can be set higher than that of the backoff method.

At present, the feed-forward method and the predistortion method are mainstream as distortion compensation methods, because the power efficiency of the system can be improved. If the operating point of the amplifier can be set high, the output power will be large and the power efficiency will be improved. However, the power efficiency will be greatly influenced by the peak factor of the amplifier input signal. When the peak factor becomes large, the size of the transistor of the power amplification circuit used becomes large, and it is necessary to greatly reduce the output level from the saturated output power before use. When the level is lowered in this way, the ratio of the DC supply power of the power amplifier and the extracted transmission power is lowered.

Therefore, in order to improve the power efficiency of the amplifier, it is important to make the peak factor as small as possible. As an example of the technique, a peak limiter is provided in the preceding stage of the amplifier to limit the maximum power (peak) signal to the amplifier. There is a method of using the input signal of. A conventional peak limiter will be described with reference to FIG. FIG. 8 is a block diagram showing a configuration example of a conventional peak limiter. As shown in FIG. 8, the conventional peak limiter 1'includes an average power detector 1
1 ', an instantaneous power detector 12', and a peak detector 13
And a limiter portion 14 '.

Each part of the conventional peak limiter 1'will be described. The average power detector 11 'detects the average power of the input signal IQ and outputs the average power information.
The instantaneous power detector 12 'detects the instantaneous power of the input signal IQ and outputs the instantaneous power information. The peak detector 13 detects the presence or absence of a peak in the input signal IQ. Specifically, for example, the ratio of the input average power information and the instantaneous power information is calculated to calculate the instantaneous power of the input signal.
Calculate the ratio to average power and calculate the calculated instantaneous power to average power
Whether or not the ratio exceeds a predetermined peak factor threshold value , that is, the presence or absence of a peak to be limited is detected, and peak detection information is output.
Here, the predetermined peak factor threshold value is
This is a value that takes into consideration the peak factor assuming the operating point with respect to the saturated output level in the characteristic (FIG. 6B) of the amplifier installed subsequently.

The limiter unit 14 'limits the peak of the amplitude of the input signal IQ. Specifically, it is input when a peak to be limited is detected according to the input peak detection information. The power (amplitude) of the input signal IQ is limited to a predetermined limit power and the output signal IQ is output.

Next, the operation of the conventional peak limiter 1'will be described. In the conventional peak limiter 1 ', the input signal IQ has the average power detector 11' and the instantaneous power detector 1 '.
2 ', and the limiter unit 14', the average power detector 11 'detects the average power of the input signal and outputs the average power information, and the instantaneous power detector 12' detects the instantaneous power of the input signal. The instantaneous power information is output, the peak detection unit 13 detects the presence / absence of a peak to be limited from the average power information and the instantaneous power information, and the peak detection information is output. When a peak to be limited is detected, the output signal IQ is output in which the power of the input signal IQ to be input is limited to a predetermined limit power.

Normally, the input signal IQ input to the peak limiter 1'is a baseband signal before band limitation,
Since the limiter processing is performed by the peak limiter 1 ', the band is limited by the filter (not shown),
Since no distortion occurs and the peak value of the input signal is limited by the peak limiter 1 ', the peak factor of the input signal is reduced, and the operating point of the amplifier performed after band limitation can be increased. The power efficiency can be improved. Here, since the band limit is performed after the limiter by the peak limiter 1 ', the peak factor after the band limit is usually larger than the peak factor before the band limit. This is because the rectangular wave before the band limitation becomes dull after the band limitation, and a point where the peak becomes high appears. Therefore, the peak fax set by the peak detection unit 13
It is necessary to set the peak factor threshold value to a low value in consideration of the fact that the instantaneous power-to-average power ratio after band limitation increases.

Next, a conventional multicarrier amplifying apparatus using the conventional peak limiter 1'will be described with reference to FIG. FIG. 9 is a schematic block diagram of a conventional multicarrier amplifier. Note that FIG. 9 shows the configuration in the case of two carriers as an example. A conventional multi-carrier amplifying device for amplifying a multi-carrier signal includes a peak limiter 1'for limiting a signal peak as an independent sequence for each carrier and a band limiting filter 2 for limiting a band.
And an up-converter 3 that up-converts (high-frequency-modulates) the RF frequency, a combiner 4 that combines the outputs from the carrier sequences and outputs a multi-carrier signal, and an amplifier that amplifies the multi-carrier signal. 5
It consists of and.

The operation of the conventional multicarrier amplifier is as follows.
The input signal IQ of each carrier sequence corresponds to each peak limiter 1 '.
Is input to the instantaneous electric of each input signal in a peak limiter 1 '
The force-to-average power ratio is calculated and the peak power
Based on Kuta threshold, average power ratio instantaneous power pair Pikufu
When the signal threshold value is exceeded, the peak value of the signal is limited and peak limiting signals A1 and A2 are output, and signals B1 and B2 that are band limited by the band limiting filter 2 are output. Further, each up converter 3 outputs each RF frequency. High-frequency modulated signals (carrier signals) C1, C2 up-converted to
Is output. Then, the output signals of the up-converters 3 of the respective carrier series are combined by the combiner 4 to output the multi-carrier signal D, which is amplified by the amplifier 5 and output.

As a result, in the conventional multi-carrier amplifying apparatus, the peak value of the signal is limited by the peak limiter 1'in each carrier sequence, and the signals A1 and A2 are processed to reduce the instantaneous power to average power ratio. Then, band limitation and up-conversion are performed, then combined, and the combined multi-carrier signal is amplified by the amplifier 5, and the instantaneous power to average power ratio of the signal before combining is reduced, Instantaneous power of multi-carrier after combining
Since the ratio of the average power to the average power becomes small, the instantaneous power to the average power ratio of the input signal to the amplifier 5 is suppressed as a result, and the operating point of the amplifier 5 can be raised.

As a conventional technique for reducing distortion during amplification of a multi-carrier signal, Japanese Patent Laid-Open No. 2000-244452, “CDMA radio base station”, published on September 8, 2000 (Applicant: Kokusai Electric Co., Ltd.) , Inventor: Masahiro Hinoki and others). This prior art is a limit that sets the limiter level of the baseband signal to be high when a modulation signal with a large number of carriers and multiplex and a large individual transmission power is input to the common amplifier, and otherwise sets the limiter level to be low. This is a CDMA radio base station that performs variable level. With this, it is possible to reduce distortion that occurs when the number of carriers and the number of multiplexing are large and the individual transmission power is large, and when the number of multiplexing is small, The error rate on the receiving side can be suppressed, and since the limit level can be changed, an amplifier with low power consumption can be used, which contributes to low power consumption of the entire apparatus.

[0017]

However, in the conventional peak limiter and multicarrier amplifier, the peak power limiter 1'provided for each carrier sequence is used to detect the instantaneous power to average power ratio detected from the input signal of each carrier sequence. When
Since the peaks are limited based on the relationship with the peak factor threshold, and the respective bands are limited and then combined, the coupler 4
Since the ratio of the instantaneous power to the average power of the output multicarrier signal is empirically larger than the ratio of the instantaneous power to the average power of each carrier sequence, the desired instantaneous power for the input signal to the amplifier 5 is obtained. In order to obtain the average power ratio , it is difficult to adjust the optimum peak factor threshold value in each peak limiter 1 ', and for safety reasons, the peak factor threshold value must be set lower, and the peak limit can be set efficiently. There was a problem that I could not do it. Instantaneous power to average power ratio in a plurality carrier and 1 instantaneous carrier power
As an example of comparison with the average power ratio , the instantaneous power to average power ratio of 2 to 4 carrier inputs in W-CDMA is 1
2-6 compared to the instantaneous power to average power ratio of the carrier input
It increases by about dB.

Further, as another problem, for example, although the power of a multi-carrier signal obtained by combining the carrier signals by the combiner 4 is actually small, the instantaneous power-to-average power ratio of one carrier signal is reduced. Even when the value becomes larger than the peak factor threshold value , the conventional peak limiter 1'limits the peak, so that the modulation accuracy is deteriorated by unnecessary peak limitation. There was a point.

The present invention has been made in view of the above circumstances, and the desired instantaneous power to average power in the amplifier input signal is obtained.
It is an object of the present invention to provide a peak limiter and a multi-carrier amplifying device that can perform efficient peak limiting so as to realize the ratio with high accuracy and improve the power efficiency of the amplifying system.

[0020]

DISCLOSURE OF THE INVENTION The present invention for solving the problems of the above-mentioned conventional example is a peak limiter used in a system for amplifying a multi-carrier signal,
The average power detection unit that inputs the baseband signal of each carrier, calculates the average power of the multicarrier signal that is approximately assumed when the baseband signals are combined in the high frequency band, and outputs the average power information, and each carrier Input the baseband signal of, and calculate the instantaneous power of the multi-carrier signal that is approximately assumed when the baseband signals are combined in the high frequency band, and output the instantaneous power information Input the instantaneous power information and calculate the ratio of instantaneous power to average power, which is the ratio of instantaneous power to average power.
A peak detection unit that compares the average power ratio with a predetermined peak factor threshold value to detect a peak and outputs peak detection information, and inputs a baseband signal and peak detection information of each carrier. However, when a peak is detected from the peak detection information, it has a limiter unit that outputs each signal with the amplitude of the baseband signal of each carrier suppressed, so it is approximate when combining each baseband signal in the high frequency band. Power vs. instantaneous power of multicarrier signals
By limiting the amplitude of each baseband signal based on the power equalization ratio , it is possible to capture the peak occurrence of the multicarrier signal to be amplified and reduce the instantaneous power to average power ratio effectively and efficiently. The amplitude of the band signal can be suppressed.

The present invention for solving the above-mentioned problems of the conventional example is a multi-carrier amplifier for amplifying a multi-carrier signal, in which a base band signal of each carrier is input and each base band signal is synthesized in a high frequency band. Instantaneous power vs. average of multicarrier signals approximately assumed in
The power ratio is calculated, and based on the instantaneous power to average power ratio , the peak limiter that outputs each signal that suppresses the amplitude of each baseband signal and the baseband of each carrier that suppresses the peak that is the output signal of the peak limiter A band limiting filter for band limiting the signal, an up converter for up converting the band limited signal to a high frequency band, and a combiner for combining the signals of the respective carriers up converted to the high frequency band and outputting a multi-carrier signal. , And an amplifier that amplifies the multi-carrier signal, so the instantaneous power vs. the average power of the multi-carrier signal that is approximately assumed when the base band signals are band-limited and then converted into the high frequency band and then combined. by limiting the amplitude of each base band signal based on the ratio, the multi-carrier signal input to the amplifier The average electric instantaneous power to capture the over click occurred
The amplitude of each baseband signal can be suppressed effectively and efficiently so as to reduce the power ratio , and as a result, a desired peak factor in the amplifier input signal can be accurately realized.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. The function realizing means described below may be any circuit or device as long as it can realize the function, and part or all of the function can be realized by software. is there. Further, the function realizing means may be realized by a plurality of circuits, or the plurality of function realizing means may be realized by a single circuit.

To put it in a high-level conception, the peak limiter according to the present invention is a multicarrier signal that is approximately assumed when the baseband signals of the respective carriers are input and the respective baseband signals are combined in the high frequency band. Instantaneous power vs. average
Calculated power ratio, based on the instantaneous power to average power ratio,
Since each signal is output with the amplitude of each baseband signal suppressed, it is effective and efficient to reduce the instantaneous power to average power ratio by capturing the peak occurrence of the multicarrier signal to be amplified. The amplitude of the signal can be suppressed, and the power efficiency of the amplification system can be improved.

Explaining in terms of function realizing means, the peak limiter according to the present invention is a multi-carrier signal which is approximately assumed when the baseband signals of the respective carriers are input and the respective baseband signals are combined in the high frequency band. The average power detection unit that calculates the average power of each carrier and outputs the average power information, and the baseband signal of each carrier is input, and the instantaneous of the multicarrier signal that is approximately assumed when the baseband signals are combined in the high frequency band An instantaneous power detection unit that obtains electric power and outputs instantaneous electric power information, and inputs the average electric power information and the instantaneous electric power information, and outputs the ratio of the instantaneous electric power to the average electric power
Seeking force ratio, a peak detection section for outputting the peak detection information to detect the peak by comparing the peak factor threshold predetermined instantaneous power to average power ratio, the baseband signal and the peak detection of the carrier When the information is input and a peak is detected from the peak detection information, since it has a limiter section that outputs each signal in which the amplitude of the baseband signal of each carrier is suppressed, the peak occurrence of the multicarrier signal to be amplified is prevented. It is possible to effectively and efficiently suppress the peak of the amplitude of each baseband signal so as to reduce the instantaneous power to average power ratio by catching, and to improve the power efficiency of the amplification system.

First, a multicarrier amplifying device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of a multicarrier amplification device according to an embodiment of the present invention. It should be noted that parts having the same configuration as in FIG.
As shown in FIG. 1, the multicarrier amplifying apparatus according to the present embodiment has a configuration similar to that of the conventional multicarrier amplifying apparatus, and has a band limiting filter 2 for performing band limiting as an independent sequence for each carrier, and an RF. It is composed of an up-converter 3 for up-converting to a frequency (high frequency modulation), a combiner 4 for combining outputs from respective carrier sequences to output a multi-carrier signal, and an amplifier 5 for amplifying the multi-carrier signal. Instead of the peak limiter 1'provided for each carrier series, a peak limiter 1 common to each carrier series is provided.

Here, the band limiting filter 2, the up-converter 3, the coupler 4 and the amplifier 5 are exactly the same as the conventional ones, and therefore detailed description thereof will be omitted. The peak limiter 1, which is a characteristic part of the present invention, inputs base band signals (input signals) of a plurality (two in FIG. 1) of carrier sequences, each input signal is high-frequency modulated by the up converter 3, and a combiner is used. Instantaneous power of a multicarrier signal approximately assumed, assuming the multicarrier signal combined (combined) in 4.
The average power to average power ratio is calculated, and the calculated instantaneous power to average power ratio is the desired instantaneous power to average power for the input signal of the amplifier 5.
It suppresses the amplitude of each input signal when the ratio is exceeded.
is there.

Now, a situation in which signals of different frequencies (carrier signals) are combined will be described with reference to FIG.
FIG. 2 is an explanatory diagram showing a complex space representation of a plurality of carrier signals and a combined multi-carrier signal. Generally, in multicarrier signal transmission, a plurality of input signals are modulated with a carrier having a certain frequency interval (carrier frequency difference), as shown in FIGS. 2 (a) (b) (c). Each carrier signal rotates in a complex space at different periods while changing its phase with the passage of time.
Then, in the process in which each carrier signal rotates at each frequency, the multi-carrier signal obtained by combining the carrier signals is
When the phases of the carrier signals are different from each other, the power values do not show a very large value due to cancellation in the IQ space due to the combination, but the power values increase as a plurality of carrier signals approach the same phase. When the phases match, as shown in FIG. 2D, the powers of the carrier signals may be added, and the instantaneous power may instantaneously have a large peak value. It should be noted that in FIG. 2D, the arrows of the respective signals are shifted and shown for easy understanding. That is, in the present invention, when the phases of the multiple carrier signals are different,
No limitation is imposed even if the power of each carrier signal is large, and the purpose is to detect the timing of limiting by capturing the power of the multicarrier signal at the time when the phases of the multiple carrier signals described above coincide.

The internal structure of the peak limiter 1 of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the internal configuration of the peak limiter of the present invention. It should be noted that portions having the same configurations as those in FIG. The peak limiter 1 of the present invention, as shown in FIG. 3, has an average power detection unit 11 and an instantaneous power detection unit 12
And a peak detector 13 and a limiter 14. The main constituent elements are the same as those of the conventional peak limiter shown in FIG. 8, but the function of each element is different from the conventional one.

Each part of the peak limiter 1 of the present invention will be described. The average power detection unit 11 inputs the input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) and multi-carriers that are approximately assumed when the carrier signals are combined in the high frequency (RF) band. The average power of the signal is detected and the average power information is output. Note that a method of approximately assuming a multi-carrier signal in which carrier signals are specifically combined in a high frequency (RF) band will be described later.

The instantaneous power detection unit 12 is approximately assumed when input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) are input and the carrier signals are combined in a high frequency (RF) band. The instantaneous power of the multi-carrier signal is detected and the instantaneous power information is output. A method of approximately assuming a multi-carrier signal obtained by combining the carrier signals in the high frequency (RF) band will be described later.

The peak detector 13 detects the presence or absence of a peak in the postulated composite multi-carrier signal. Specifically, the ratio of the instantaneous power to the average power is calculated by calculating the ratio from the average power information and the instantaneous power information in the assumed combined multi-carrier signal input from the average power detection unit 11 and the instantaneous power detection unit 12. And whether the calculated instantaneous power-to-average power ratio exceeds a predetermined peak factor threshold , that is,
The presence / absence of a peak to be limited is detected, and peak detection information is output. Here, the predetermined peak factor threshold value is a value that takes into consideration the peak factor that assumes the operating point with respect to the saturated output level in the characteristic (FIG. 6B) of the amplifier 5 installed subsequently. Is. The peak detection target of the peak detection unit 13 of the present invention is an approximately assumed post-synthesis multicarrier signal, but an operation of detecting the presence or absence of a peak from the input average power information and instantaneous power information Is exactly the same as the conventional peak detector 13.

The limiter unit 14 inputs the input signals IQ of a plurality of carrier sequences (two carrier sequences in FIG. 3) and limits the peak of the amplitude of each input signal IQ.
Specifically, according to the peak detection information input from the peak detection unit 13, when a peak to be subjected to limit is detected in the approximately assumed combined multicarrier signal, the instantaneous power to average power ratio is calculated. Predetermined pee
Input of each carrier sequence so that it is less than or equal to the threshold factor
Suppress the signal amplitude.

The operation of the peak limiter 1 of the present invention will be described. When the input signals IQ of a plurality of carrier sequences are input, the average power detector 11, the instantaneous power detector 12, and the limiter 14 are used.
The average power detection unit 11 detects the average power of the multi-carrier signals that is approximately assumed when the carrier signals are combined in the RF band, and outputs the average power information. On the other hand, the instantaneous power detector 12 similarly detects the instantaneous power of the multi-carrier signal that is approximately assumed when the carrier signals are combined in the RF band, and outputs the instantaneous power information. Then, the peak detection unit 13 detects the presence or absence of a peak to be limited in the approximately assumed multicarrier signal from the approximately assumed average power information and the instantaneous power information of the multicarrier signal, thereby performing peak detection. When the information is output and the limiter unit 14 detects a peak to be limited according to the peak detection information, the instantaneous power-to-average power ratio is predetermined.
Keep each carrier sequence below the peak factor threshold
Suppresses the amplitude of the input signal.

Next, a method of approximating a multi-carrier signal obtained by synthesizing carrier signals in a high frequency (RF) band in the average power detection unit 11 and the instantaneous power detection unit 12 will be described. A first method (first assumed method) of approximately assuming a multi-carrier signal synthesized in the RF band
Is the carrier frequency difference (Δf) for each input signal
In this method, the power of the combined signal is detected at a fixed sampling interval.

This is because the input signal to the average power detection unit 11 and the instantaneous power detection unit 12 is the baseband signal IQ. Therefore, in order to assume the synthesis in the RF band, each upconverter 3 should normally be used. It is necessary to convert signals into RF frequencies that are subjected to high frequency modulation, perform signal synthesis of RF frequencies, and perform power measurement. However, since signal processing at RF frequencies requires very fast sampling, expensive signal processing devices are required. Become. However, if each carrier frequency has a carrier frequency difference (Δf) with each other, a constant sampling interval (for example, the highest frequency At a timing of one cycle of a carrier signal having a small value, it is possible to capture the state of a plurality of carriers at that time, and it is sufficient to detect the instantaneous power and the average power assuming a multicarrier signal approximately.

Here, the conventional average power detector 11 'and the instantaneous power detector 12' and the average power detector 11 of the present invention are used.
And the difference from the instantaneous power detection unit 12 will be described using mathematical expressions. First, each input signal IQ is expressed as a vector complex expression as in [Equation 1].

[0037]

[Equation 1]

Then, the instantaneous power calculated by the conventional instantaneous power detecting section 12 'and the average power calculated by the average power detecting section 11' in each peak limiter 1'of the conventional multicarrier amplifier shown in FIG. , [Equation 2].

[0039]

[Equation 2]

There are various methods for obtaining the average power, such as moving average and weighted average, but the method is not limited. On the other hand, the instantaneous power calculated by the instantaneous power detection unit 12 and the average power calculated by the average power detection unit 11 in the peak limiter 1 of the multicarrier amplifying device of the present invention shown in FIGS. When it is obtained by the first assumed method described above, it can be expressed as [Equation 3].

[0041]

[Equation 3]

In [Equation 3], Δf is the difference in carrier frequency. That is, assuming that each input signal is upconverted to each RF frequency with a difference of Δf,
Carrier frequency difference (Δf) in the input signal of each carrier sequence
An offset of only a minute is given and combined, and a signal in which signals of different RF frequencies are combined is artificially created. And
If the average power of the combined signal is detected at a fixed sampling interval (for example, one cycle of the carrier signal with the smallest frequency), the sampling interval is coarse, but by measuring for a long time, it is possible to combine multiple signals in almost the RF band. A power value close to the average power of the carrier signal can be obtained.

With respect to the instantaneous power, when an input signal of each carrier sequence division is given an offset corresponding to the carrier frequency difference (Δf) and combined, as shown in FIG. When the phases match, the instantaneous power should have a peak instantaneously, so if the instantaneous power is detected by sampling so as not to miss this timing, the multi-carrier signal synthesized in the RF band will be almost It is possible to obtain the instantaneous power value that is important for detecting the peak to be subjected to the peak limit.

Next, a configuration example of the average power detection unit 11 and the instantaneous power detection unit 12 that realizes the above-described first assumed method will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing a configuration example of the average power detection unit 11 of the present invention, and FIG. 5 is a block diagram showing a configuration example of the instantaneous power detection unit 12 of the present invention. As shown in FIG. 4, the average power detection unit 11 that implements the first assumed method of the present invention includes complex multiplication units 21, 22, 23, for applying an offset of a carrier frequency difference (Δf) to each input signal. , And an adder 24 for synthesizing the signals given the respective offsets, a power calculator 25 for obtaining the instantaneous power of the added signal, and an averaging unit 26 for obtaining the average power from the instantaneous power.

The operation of the average power detection unit 11 shown in FIG. 4 is such that the input signal-1 remains unchanged and the input signal-2 is the complex multiplication unit with respect to a plurality of input signals (four in FIG. 4). The input signal -3 is rotated by Δf and offset, the input signal -3 is rotated by 2Δf and offset by the complex multiplication unit 22, and the input signal -4 is rotated by 3Δf and offset by the complex multiplication unit 23. All signals are added (combined) by the adder 24, the power calculator 25 calculates the instantaneous power, and the averaging unit 26 calculates the average power.

Similarly, the instantaneous power detector 12 for implementing the first assumed method of the present invention, as shown in FIG. 5, is a complex multiplier for giving an offset of the carrier frequency difference (Δf) to each input signal. , 32, 33, ..., Adder 34 for synthesizing signals given respective offsets, and power calculator 35 for calculating the instantaneous power of the added signal. The operation of the instantaneous power detector 12 shown in FIG. 5 is similar to the operation of the average power detector 11.

As can be seen from the configurations of FIGS. 4 and 5, the configurations up to the complex multiplication unit, the adder, and the power calculation unit are the same. Alternatively, the power may be output as power information, the instantaneous power information may be input to the averaging unit 26, the average power may be obtained, and the average power information may be output.

Next, another method in the average power detection unit 11 and the instantaneous power detection unit 12 for approximating the multi-carrier signal after combining in the RF band will be described. RF
A second method (second assumed method) that approximately assumes a combined multi-carrier signal in a band is to capture each input signal that is input as a vector, combine the signals by vector operation, and obtain the average power. Further, it is a method of obtaining the power at the timing when the instantaneous power of the combined signal (vector) becomes maximum.

First, a method of obtaining the average power in the second assumed method will be described. In the multicarrier amplifier of FIG. 1, the input baseband signals of each carrier sequence are output from the peak limiter 1, individually upconverted to an RF frequency band by the upconverter 3, and then combined by the combiner 4 to form a multicarrier signal. Become a signal. Therefore, when measuring the average power of a multi-carrier signal,
Originally, it is necessary to measure the average of the combined power of signals rotating at each RF frequency. However, when measuring the combined power with an RF signal, very fast sampling is required, and thus an expensive signal processing device is required.
Therefore, in the present invention, the input baseband signal of each carrier is taken as a vector, sampling is performed at a fixed timing to perform a vector combining operation, an average of the electric powers of the combined vectors is calculated, and an approximation after combining in the RF band is performed. The average power of the multi-carrier signal is assumed as the target.

Next, how to obtain the instantaneous power in the second assumed method will be described. Similar to the method for obtaining the average power, as described above, when measuring the instantaneous power with the RF signal, very fast sampling is required and an expensive signal processing device is required. Therefore, in the present invention, the sum of the powers of the baseband signals of the carriers is calculated at the timing when the carrier signals of the carriers are in phase, and the instantaneous power of the approximately assumed multicarrier signal after combining in the RF band is obtained. It is supposed to do.

This is because, as shown in FIG. 2, in the process in which each carrier signal rotates at each RF frequency, a multi-carrier signal obtained by combining the carrier signals has a power value as the plurality of carrier signals approach the same phase. 2 increases, and when the phases match, as shown in FIG. 2D, the power of each carrier signal may be added and the instantaneous power may momentarily have a large peak. This is because it is only necessary to capture the instantaneous power of the multi-carrier signal at the time point and detect the timing at which the limit is applied. At this time, the power of the combined vector is equal to the sum of the individual powers of the input signals of the carrier sequences. For example, in the case of W-CDMA system,
The input signal is 3.84 [MHz] and the carrier interval is 5
Since it is [MHz], there is always a moment when the vectors of multiple carriers have the same direction.

Here, the concept of how to obtain the average power and the instantaneous power in the second assumed method will be described using mathematical expressions. As described in the first assumed method, if the carrier frequencies have a carrier frequency difference (Δf) with each other, by adding an offset corresponding to the carrier frequency difference (Δf) to each input signal and combining them. , Approximate synthesis can be performed, and the instantaneous power and average power can be expressed by [Equation 3]. In the average power of [Equation 3], when the term of e becomes the same vector and only the moment when 1 + j · 0 = 1 is sampled, the average power of [Equation 4] is obtained. This is a mathematical expression that averages the powers of the combined vectors that have been subjected to the vector combining operation for each input baseband signal. This means that the sampling is rough, but since the average power of the first assumption method becomes equal when measured for a long time, the second assumption method simplifies the hardware configuration. In addition, the instantaneous power is a mathematical expression for obtaining the sum of the powers of the input signals of the carrier sequences at the timing when the phases are simply matched, as shown in the instantaneous power of [Equation 4].

[0053]

[Equation 4]

Next, the operation of the multicarrier amplifier of the present invention will be described with reference to FIG. In the multi-carrier amplifier of the present invention, all input baseband signals IQ (two in FIG. 1) of each carrier series are input to the peak limiter 1, and the peak limiter 1 outputs each input signal at a high frequency (R).
An instantaneous power-to-average power ratio of a multicarrier signal that is approximately assumed when combined in the F) band is calculated, and the peak of the amplitude of each input baseband signal is limited based on a predetermined peak factor threshold value. Peak limit signal a
1, a2 are output. At this time, the peak limiting signal a1,
a2 is a peak limiting signal A output from each peak limiter 1'of the conventional multicarrier amplifying device shown in FIG.
Unlike 1 and A2, in the case of multi-carrier signals that are approximately assumed when combined in the RF band, the instantaneous power vs.
It is a signal whose peak is limited only when the power equalization ratio exceeds the peak factor threshold value .

Then, the peak limiting signals a1 and a2 are band-limited by the band limiting filter 2 to become signals b1 and b2, which are further up-converted to respective RF frequencies by the up-converter 3 to generate high-frequency modulated signals (carrier signals) c1.
It is output as c2. Then, the output signals of the up-converters 3 of each carrier series are combined by the combiner 4 to output the multi-carrier signal d, which is amplified by the amplifier 5 and then output.

Here, the multicarrier signal d output from the combiner 4 is the multicarrier signal D output from the combiner 4 of the conventional multicarrier amplifying device shown in FIG.
Unlike the above, the peak power value in the multicarrier signal is limited by the processing in the peak limiter 1, and the other portions are signals that are not affected by the processing in the peak limiter 1.

As a result of the operation in the above multi-carrier amplifying apparatus, in the present invention, the instantaneous power of the multi-carrier signal that is approximately assumed when the input signals of each carrier series are combined in the high frequency band by the peak limiter 1 is used. versus
Based on the average power ratio , the peak values of the input signals are limited, and the signals a1 and a2 subjected to the processing for reducing the instantaneous power to average power ratio are combined after band limitation and up-conversion, and then combined. The multi-carrier signal of is amplified by the amplifier 5, and as a result, the instantaneous power to average power ratio of the multi-carrier signal input to the amplifier 5 is suppressed,
The operating point of the amplifier 5 can be raised.

According to the peak limiter of the present invention, the average power of the multi-carrier signals approximately assumed when the base band signals of the respective carrier sequences are input and the base band signals are combined in the high frequency band is calculated as the average power. The peak that is set in advance by the detection unit 11 and the instantaneous power detection unit 12 that calculates the instantaneous power of the multicarrier signal, and the peak detection unit 13 that calculates the instantaneous power-to-average power ratio from the average power and the instantaneous power. The presence or absence of a peak is detected by comparison with a factor threshold value, and if there is a peak, the limiter unit 1
4 outputs each signal in which the amplitude of each baseband signal is suppressed. Therefore, it is effective and efficient to capture the peak occurrence related to the multicarrier signal to be amplified and reduce the instantaneous power to average power ratio. The input signal is often peak-limited, and as a result, the desired instantaneous power to average power ratio in the amplifier input signal can be accurately achieved. Further, for example, as the individual input signals, Shun
The instantaneous power- to-average power ratio desired by the amplifier 5
Even if it exceeds the average power ratio , if it becomes small when combined, the peak limit is not applied to the input signal, so that the peak of the peak is efficiently generated without causing deterioration of modulation accuracy due to unnecessary peak limitation. The effect is that restrictions can be made.

Then, in the average power detection unit 11 and the instantaneous power detection unit 12 of the present invention, as a method of approximately assuming a multi-carrier signal when the base band signals are combined in a high frequency band, originally, each up converter is used. Although it is about to be converted into an RF frequency that is subjected to high-frequency modulation in 3 and synthesized, and very high-speed sampling is required for measuring the power of the RF signal. Since the carrier frequency difference (Δf) is given an offset to the input signal by using a complex multiplication unit and then combined to detect the instantaneous power or average power of the combined signal, the instantaneous power or average power is sampled at the frequency of the baseband signal. Can be detected, and approximates to a multi-carrier signal when combined in the high frequency band without increasing the configuration so much. There is an effect that can detect the instantaneous power and the average power of Ruchi carrier signal.

When the second assumed method is used in the average power detection unit 11 of the present invention, each input signal to be input is regarded as a vector, and sampling is performed at a constant timing, for example, the same vector. Since the signals are combined by vector operation to obtain the average power, the sampling can be roughened to an approximate level to perform the detection process efficiently, and the average power can be obtained only by the operation process to simplify the configuration. It is possible to reduce the cost and cost.

When the second assumed method is used in the instantaneous power detector 12 of the present invention, the timing when the carrier phases of a plurality of input signals match, that is, the timing when the instantaneous power of the combined signal (vector) becomes maximum. Since the electric power of is obtained by calculation, it is possible to effectively capture the instantaneous power that is the point of the peak factor, and the configuration can be simplified by calculating the instantaneous power only by calculation processing,
This has the effect of reducing the scale of hardware and reducing costs.

According to the multicarrier amplifying apparatus of the present invention, a plurality of input baseband signals are all input to the peak limiter 1, and when the peak limiter 1 synthesizes the respective input signals in the high frequency (RF) band, it is approximated. The assumed instantaneous power-to-average power ratio of the multi-carrier signal is calculated, the peak value of each input baseband signal is limited and output based on a predetermined peak factor threshold value, and band-limited by the band-limiting filter 2. Further, the up-converter 3 up-converts to each RF frequency, the combiner 4 combines them to output a multi-carrier signal, and the amplifier 5 outputs the amplified multi-carrier signal. The peak power of the multi-carrier signal input to 5 is detected, the instantaneous power to average power ratio is suppressed, and the amplifier 5
There is an effect that the operating point can be raised and the power efficiency of the amplification system can be improved. Further, since there is no peak limitation in individual carrier sequences in the case of being erased when combined by the combiner 4, which has been a problem in the conventional technique, modulation accuracy due to unnecessary peak limitation is eliminated. There is an effect that deterioration can be avoided and the reliability of the entire system can be improved.

[0063]

According to the present invention, it is a peak limiter used in a system for amplifying a multi-carrier signal, in which an average power detecting section inputs a base band signal of each carrier and outputs each base band signal in a high frequency band. When the average power of the multi-carrier signal that is approximately assumed is calculated and the average power information is output, the instantaneous power detection unit similarly calculates the instantaneous power of the multi-carrier signal that is approximately assumed and the instantaneous power The information is output, the peak detection unit obtains an instantaneous power-to-average power ratio , which is the ratio of the instantaneous power to the average power , and the instantaneous power-to-average power ratio and the predetermined peak
The peak is detected by comparing with the factor threshold and the peak detection information is output. When the peak is detected by the limiter section from the peak detection information, the peak that suppresses the amplitude of the baseband signal of each carrier and outputs each signal Since it is a limiter, it effectively captures the peak occurrence of the multi-carrier signal that is approximately assumed when combining the baseband signals in the high frequency band, and effectively reduces the instantaneous power to average power ratio .
Moreover, there is an effect that the peak of the amplitude of each baseband signal can be efficiently suppressed.

According to the present invention, in a multi-carrier amplifier for amplifying a multi-carrier signal, a peak limiter inputs the base band signal of each carrier and approximately combines the base band signals in a high frequency band. Obtain the instantaneous power to average power ratio of the assumed multi-carrier signal, output each signal with the amplitude of each baseband signal suppressed based on the instantaneous power to average power ratio , and output the band-limiting filter from the peak limiter. Band limiting is performed on the baseband signal of each carrier whose peak is suppressed, the up-converter up-converts each band-limited signal to a high frequency band, and the combiner combines the signals of each carrier to output a multi-carrier signal. Since the amplifier is a multi-carrier amplifier that amplifies multi-carrier signals, each base band signal is After limited, captures the peak occurrence of approximately multicarrier signal is assumed when synthesized from converted into a high frequency band, effectively so as to reduce the instantaneous power to average power ratio, effectively the baseband The peak of the signal amplitude is suppressed, and as a result, the desired instantaneous power to average power ratio in the amplifier input signal can be accurately realized, and the power efficiency of the amplification system can be improved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a multicarrier amplifier according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a complex space representation of a plurality of carrier signals and a combined multi-carrier signal.

FIG. 3 is an internal block diagram of a peak limiter of the present invention.

FIG. 4 is a block diagram showing a configuration example of an average power detection unit of the present invention.

FIG. 5 is a block diagram showing a configuration example of an instantaneous power detection unit of the present invention.

FIG. 6 is an explanatory diagram illustrating characteristics of an amplifier and operation characteristics of each adjacent channel leakage power reduction method.

FIG. 7 is an explanatory diagram of a peak factor of a general amplifier.

FIG. 8 is a block diagram showing a configuration example of a conventional peak limiter.

FIG. 9 is a schematic block diagram of a conventional multicarrier amplifier.

[Explanation of Codes] 1, 1 '... Peak limiter, 2 ... Band limiting filter,
3 ... Up-converter, 4 ... Coupler, 5 ... Amplifier, 11, 11 '... Average power detection part, 12, 12'
... Instantaneous power detection unit, 13 ... Peak detection unit, 14, 1
4 '... Limiter unit, 21, 22, 23, 31, 32,
33 ... Complex operation part, 24, 34 ... Adder, 25, 3
5 ... Power calculation unit, 26 ... Average unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaki Sudo             3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Stocks             Hitachi Kokusai Electric Co., Ltd. (72) Inventor Masato Douguchi             3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Stocks             Hitachi Kokusai Electric Co., Ltd. (72) Inventor Toshio Takada             3-14-20 Higashi-Nakano, Nakano-ku, Tokyo Stocks             Hitachi Kokusai Electric Co., Ltd. F-term (reference) 5J030 CB03 CC01 CC11                 5K022 EE01 EE21 EE31                 5K067 AA33 BB04 BB21 CC10 GG08                       HH22

Claims (6)

[Claims] 1. A peak limiter used in a system for amplifying a multi-carrier signal, which is approximately assumed when a base band signal of each carrier is input and the base band signals are combined in a high frequency band. A peak limiter, characterized in that a peak factor of a multi-carrier signal is obtained, and each signal in which the amplitude of each of the baseband signals is suppressed is output based on the peak factor. 2. A peak limiter used in a system for amplifying a multi-carrier signal, which is approximately assumed when a base band signal of each carrier is input and the base band signals are combined in a high frequency band. An average power detection unit that calculates the average power of a multi-carrier signal and outputs average power information, and inputs the baseband signal of each carrier, and is approximately assumed when the baseband signals are combined in a high frequency band. An instantaneous power detector that determines the instantaneous power of the multi-carrier signal and outputs the instantaneous power information, and inputs the average power information and the instantaneous power information, determines the peak factor that is the ratio of the instantaneous power and the average power, and determines the peak. A peak detection unit that detects a peak by comparing a factor with a predetermined peak threshold value and outputs peak detection information; A baseband signal of each carrier and the peak detection information are input, and when a peak is detected from the peak detection information, a limiter unit that outputs each signal with the amplitude of the baseband signal of each carrier suppressed is provided. A characteristic peak limiter. 3. An average power detection unit for averaging the input baseband signals of the respective carriers by applying an offset of the frequency difference of the respective carriers and synthesizing the baseband signals, and obtaining an average power of the synthesized signals. The instantaneous power detection unit is an instantaneous power detection unit that calculates the instantaneous power of the combined signal by applying an offset of the frequency difference of each carrier to the input baseband signal of each carrier and combining the combined signals. 2. The method according to claim 2, wherein
The listed peak limiter. 4. The average power detection unit is an average power detection unit that performs a vector combining operation using a vector of a baseband signal of each carrier and obtains the average of the powers of the combined vectors as the average power. The peak limiter according to claim 2, which is characterized in that. 5. The instantaneous power detector is an instantaneous power detector that sums the powers of the baseband signals of the carriers at the timing when the carrier signals of the carriers are in phase to obtain the instantaneous power. The peak limiter according to claim 2 or 4. 6. A multi-carrier amplifying device for amplifying a multi-carrier signal, wherein the peak limiter according to claim 1 and a base band signal of each carrier in which a peak which is an output signal of the peak limiter is suppressed. A band limiting filter that performs limiting, an up converter that up-converts the band-limited signal to a high frequency band, and a combiner that combines signals of each carrier up-converted to the high frequency band and outputs a multi-carrier signal, A multi-carrier amplifying device, comprising: an amplifier for amplifying the multi-carrier signal.