JP2005244295A - Signal level controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize constant loop gain and constant detection characteristics in a signal level controller. <P>SOLUTION: At a forward processing section, a modulation means 21 modulates the synthesis result signal of a signal to be processed and the output signal from a feedback processing section, a variable attenuation means 22 performs attenuation, and amplification means 23 and 41 perform amplification. At the feedback processing section, a variable attenuation means 32 attenuates a part of output signal from the forward processing section, and demodulation means 33 and 25 perform demodulation. At a signal level detecting section, a variable attenuation means 26 attenuates a part of output signal from the forward processing section, and a signal level detecting means 27 detects the level. At a control section, a control means 28 controls attenuation of the variable attenuation means 26 and a control means 12 controls attenuation of the variable attenuation means 32 and the variable attenuation means 22 based on the output signal from the signal level detecting section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a signal level control device for controlling the level of a transmission signal by APC (Automatic Power Control) control in, for example, a Cartesian linearizer circuit, and in particular, a signal level that realizes constant loop gain and constant detection characteristics. The present invention relates to a control device.

For example, in a Cartesian linearizer circuit, the signal level is controlled by APC control and the distortion component generated in the circuit is reduced by using a forward part in the forward direction and a feedback part in the feedback direction. .
FIG. 2 shows a principle configuration example of a Cartesian linearizer circuit.
FIG. 3 shows a specific configuration example of the Cartesian linearizer circuit.
In FIG. 3, the same reference numerals are given to the processing units that are substantially the same as those shown in FIG. 1 according to the embodiment of the present invention. There is no intention to limit this.

JP 2002-31870 A JP 2002-171178 A JP 2000-13254 A

However, in the control method in the Cartesian linearizer circuit as shown in FIG. 3, only the feedback gain β of the feedback unit 24 is changed by the APC control by the APC control unit 12 and the forward gain A is constant. Since the improvement amount is determined by the loop gain (A · β), the distortion improvement amount of the loop varies due to the variation of the feedback gain β. At the same time, in the control method in the Cartesian / linearizer circuit as shown in FIG. 3, the detection characteristic of the detection unit 27 changes due to the change of the output level, and therefore the amount of change in the APC control by the APC control unit 12 (for example, The change rate of the detection voltage) fluctuates. As described above, in the control method in the Cartesian linearizer circuit as shown in FIG. 3, it is difficult to appropriately control the output level by securing both the constant loop gain and the constant detection characteristic. .
The present invention has been made to solve such a conventional problem. For example, when the level of a transmission signal is controlled by APC control in a Cartesian linearizer circuit, the loop gain is constant and the detection characteristic is constant. An object of the present invention is to provide a signal level control device capable of realizing the above.

In order to achieve the above object, in the signal level control device according to the present invention, in the configuration including the forward processing unit, the feedback processing unit, the signal level detection processing unit, and the control processing unit, as follows, Control the level of the signal.
That is, in the forward processing unit, the modulation unit modulates the signal obtained by combining the signal to be processed and the output signal from the feedback processing unit, and the forward variable attenuation unit modulates the modulated signal obtained by the modulation unit. Is attenuated by a variable attenuation amount, and the amplification means amplifies the signal attenuated by the forward variable attenuation means. The forward processing unit outputs the signal amplified by the amplification means.
In the feedback processing unit, the feedback variable attenuation unit attenuates a part of the output signal from the forward processing unit by a variable attenuation amount, and the demodulation unit demodulates the signal attenuated by the feedback variable attenuation unit. Then, the feedback processing unit outputs the demodulated signal obtained by the demodulating means.
In the signal level detection processing unit, the signal level detection variable attenuation unit attenuates a part of the output signal from the forward processing unit by a variable attenuation amount, and the signal level detection unit attenuates the signal level detection variable attenuation unit. The level of the received signal is detected. Then, the signal level detection processing unit outputs a signal as a result of detection by the signal level detection means.
Further, in the control processing unit, the feedback forward variable attenuation amount control means controls the attenuation amount of the feedback variable attenuation means of the feedback processing unit and the forward direction variable of the forward processing unit based on the output signal from the signal level detection processing unit. The amount of attenuation of the attenuation means is controlled.
Therefore, since each of the forward processing unit, the feedback processing unit, and the signal level detection processing unit is provided with variable attenuation means, it is possible to arbitrarily change the attenuation amount of the signal in each processing unit. For example, the level of the output signal from the forward processing unit can be adjusted to a desired value, and at this time, the gain of the loop composed of the forward processing unit and the feedback processing unit can be made constant. . For example, in a Cartesian linearizer circuit, when controlling the level of a transmission signal by APC control, it is possible to achieve constant loop gain and constant detection characteristics.

As one configuration example, the signal level control apparatus according to the present invention has the following configuration.
That is, in the control processing unit, the signal level detection variable attenuation amount control unit controls the attenuation amount of the signal level detection variable attenuation unit of the signal level detection processing unit.
And, by the control by the signal level detection variable attenuation amount control means of the control processing section, the level of the output signal from the forward processing section is adjusted, and by the control by the feedback forward variable attenuation amount control means of the control processing section, The gain of the loop composed of the forward processing unit and the feedback processing unit is made constant.
Therefore, for example, the level of the output signal from the forward processing unit can be adjusted while keeping the detection characteristic constant in the signal level detection processing unit, and the gain of the forward processing unit and the feedback processing unit can be adjusted along with this. The gain of the loop can be made constant by adjusting the gain.

Here, various signals may be used as a signal to be processed, for example, a transmission signal including an I component and a Q component is used.
Also, various levels may be used as the signal level. For example, a power level, an amplitude level, or the like can be used.
Further, as a signal resulting from the synthesis of the signal to be processed and the output signal from the feedback processing unit, for example, the signal to be processed is synthesized so that the output signal from the feedback processing unit is subtracted from the signal to be processed A signal is used.
Various schemes may be used as a modulation scheme and a demodulation scheme. For example, a digital modulation scheme such as 16QAM or π / 4 shift QPSK and a demodulation scheme thereof are used.
Further, each of the forward variable attenuation means, the feedback variable attenuation means, and the signal level detection variable attenuation means can be configured using, for example, a variable attenuator.
In addition, various configurations may be used as the amplifying unit, and for example, it may be configured using one or a plurality of amplifiers.
Further, as a part of the output signal from the forward processing unit used in the feedback processing unit and the part of the output signal from the forward processing unit used in the signal level detection processing unit, for example, forward processing They may be extracted together from the output side of the unit and then distributed to the feedback processing unit and the signal level detection processing unit, or may be individually extracted from the output side of the forward processing unit.
Various configurations may be used for the forward processing unit, the feedback processing unit, the signal level detection processing unit, and the control processing unit, respectively.
In addition, as each of the forward processing unit, the feedback processing unit, the signal level detection processing unit, and the control processing unit, it is not always necessary to have a configuration in which components (means for configuring) are integrated. A configuration in which one or more components (means for configuring) are arranged at spaced positions may be used.

  As described above, according to the signal level control device of the present invention, the forward processing unit modulates the signal resulting from the synthesis of the signal to be processed and the output signal from the feedback processing unit, and the modulation The signal is attenuated with a variable attenuation amount, the attenuated signal is amplified and output, and the feedback processing unit attenuates a part of the output signal from the forward processing unit with the variable attenuation amount, and the attenuation The signal level detection processing unit attenuates a part of the output signal from the forward processing unit with a variable attenuation amount, and detects the level of the attenuated signal. The detection result signal is output, and the control processing unit controls the attenuation amount in the feedback processing unit and the forward processing unit based on the output signal from the signal level detection processing unit.・ Lini In riser circuit, when controlling the level of the transmission signal by the APC control, it is possible to realize a constant of a certain size and the detection characteristics of the loop gain.

An embodiment according to the present invention will be described with reference to the drawings.
In this example, a case where the present invention is applied to a Cartesian linearizer circuit provided in a transmitter constituting a radio base station apparatus of a mobile communication system employing digital communication is shown. In the Cartesian linearizer circuit of this example, the level of the signal (transmission signal) to be transmitted is controlled by a negative feedback system using a loop composed of a forward unit and a feedback unit, and nonlinear distortion generated by the power amplifier, etc. To compensate for distortion components. Also, an antenna is connected to the output side of the Cartesian / linearizer circuit of this example, and a transmission signal whose level is controlled by the Cartesian / linearizer circuit of this example is transmitted wirelessly from the antenna to a mobile station apparatus or the like. In the Cartesian linearizer circuit of this example, as a modulation method, for example, a method such as 16QAM or π / 4 shift QPSK is used.

FIG. 1 shows a configuration example of the Cartesian linearizer circuit of this example.
The Cartesian / linearizer circuit of this example controls the linearizer phase and gain, and so on, and modulates a baseband signal into a modulated signal of a predetermined frequency in the forward direction and demodulates in the feedback direction. And a power amplifying unit (PA unit) 3 for amplifying the modulated signal to a signal of a predetermined level.
The control unit 1 includes a modulation signal generation unit 11 and an APC control unit 12.
The transmitter 2 includes a modulator 21, a forward variable ATT 22 that is a forward variable attenuator (variable ATT), a preamplifier 23, a feedback unit 24, a demodulator 25, and a variable detector input level. A detector input variable ATT 26 that is an attenuator (variable ATT), a detector 27, and an adjustment volume unit 28 are provided.
The feedback unit 24 includes a distributor 31, a feedback variable ATT 32 that is a variable attenuator (variable ATT) in the feedback direction, and a feedback IF (Intermediate Frequency) unit 33. Here, the feedback unit 24 constitutes a circuit on the feedback side of the linearizer circuit.
The power amplifier 3 includes a power amplifier (PA) 41 and a directional coupler 42.

An example of a schematic operation performed by the Cartesian linearizer circuit of this example is shown.
The modulation signal generator 11 generates a baseband signal composed of an I component and a Q component as a signal to be transmitted (transmission signal), and outputs the baseband signal to the modulator 21. The output signal is combined with the feedback signal from the demodulator 25 and input to the modulator 21.
The modulator 21 synthesizes the input I component and Q component signals and outputs them to the forward variable ATT 22 as a modulated signal (modulated wave).
The forward variable ATT 22 attenuates the level of the modulation signal input from the modulator 21 by the amount of attenuation controlled by the APC control unit 12 and outputs the attenuated modulation signal to the preamplifier unit 23.
The preamplifier unit 23 amplifies the modulation signal input from the forward variable ATT 22 and outputs the amplified signal to the power amplifier 41. Here, the preamplifier unit 23 is an amplifier that amplifies the modulation signal level to some extent by the unit of the transmission unit 2 in order to amplify the modulation signal to a signal of a predetermined power level by the power amplifier 41. .
The power amplifier 41 is a main amplifier, and amplifies the modulation signal input from the preamplifier unit 23 to a signal having a predetermined power level and outputs the amplified signal. Here, the amplified signal output from the power amplifier 41 is wirelessly transmitted via an antenna (not shown) in this example.

The directional coupler 42 extracts a part of the amplified signal output from the power amplifier 41 and outputs it to the distributor 31.
The distributor 31 distributes the signal (feedback signal) input from the directional coupler 42 into two, outputs one distribution signal to the feedback variable ATT 32, and outputs the other distribution signal to the detector input variable ATT 26. Output.
The feedback variable ATT 32 attenuates the level of the signal input from the distributor 31 by the amount of attenuation controlled by the APC control unit 12, and outputs the attenuated signal to the feedback IF unit 33.
The feedback IF unit 33 converts the frequency of the signal input from the feedback variable ATT 32 from the transmission frequency to the intermediate frequency (IF), adjusts the input level to the demodulator 25, and performs the frequency conversion and the The level-adjusted signal is output to the demodulator 25.
The demodulator 25 demodulates the signal (modulated signal) input from the feedback IF unit 33 into a baseband signal composed of an I component and a Q component and outputs the demodulated signal to the input side of the modulator 21.
In this example, the I component signal output from the modulation signal generator 11 and the I component signal output from the demodulator 25 are combined and input to the modulator 21 and output from the modulation signal generator 11. The Q component signal and the Q component signal output from the demodulator 25 are combined and input to the modulator 21. In this example, such synthesis is performed in a phase relationship in which the output signal from the demodulator 25 is subtracted from the output signal from the modulation signal generator 11.

The detection unit input variable ATT 26 attenuates the level of the signal input from the distributor 31 by the attenuation amount controlled by the adjustment volume unit 28, and outputs the attenuated signal to the detection unit 27.
The detection unit 27 detects the output level from the power amplifier 41 by detecting the signal input from the detection unit input variable ATT 26, and outputs the detection voltage as the detection result to the APC control unit 12.
The adjustment volume unit 28 has a function of controlling the attenuation amount of the detection unit input variable ATT 26, thereby adjusting the input level to the detection unit 27 and adjusting the output level from the power amplifier 41. Is possible. As an example, the adjustment volume unit 28 is configured in a form that can be operated by a person (user), and changes the attenuation amount of the detection unit input variable ATT 26 according to the operation by the user. As another example, the adjustment volume unit 28 can be controlled from a device inside or outside the linearizer circuit, and changes the attenuation amount of the detection unit input variable ATT 26 according to the control.
The APC control unit 12 takes in the detection voltage input from the detection unit 27 and controls the control signal for controlling the attenuation amount of the feedback variable ATT 26 and the attenuation amount of the forward variable ATT 22 based on the detection voltage. Control signal for output.
In this example, the APC control unit 12 averages the detection voltage by the detection unit 27 in terms of time, and adjusts the attenuation amount of the feedback variable ATT 32 based on the averaged value, thereby adjusting the feedback gain of the feedback direction. The value is adjusted, and the forward gain value in the forward direction is adjusted by adjusting the attenuation amount of the forward variable ATT 22 to make the loop gain constant.

As described above, in the Cartesian linearizer circuit of this example, when changing the output level, for example, the reference voltage of the detection unit is not changed, but the attenuation amount of the detection unit input variable ATT 26 is adjusted by the adjustment volume unit 28. Thus, the input power to the detector 27 is adjusted.
In the Cartesian linearizer circuit of this example, when performing APC control based on the detection voltage by the detection unit 27, the attenuation amount of the feedback variable ATT 32 is controlled by the control signal from the APC control unit 12, and the APC control unit 12, the amount of attenuation of the forward variable ATT 22 is controlled. This control is performed so that the value of the loop gain (A · β) composed of the forward gain value A and the feedback gain value β is constant. For example, when the attenuation of the feedback variable ATT 32 increases by 1 dB. Control is performed to decrease the attenuation of the forward variable ATT 22 by 1 dB.

Next, a specific example of processing performed by the Cartesian linearizer circuit of this example is shown.
For example, when the adjustment volume unit 28 is set so that the attenuation amount of the detection unit input variable ATT 26 has a predetermined value, the output level from the power amplification unit 3 is 40 dBm and the feedback power level is 10 dBm. To consider. Further, APC control based on the detection voltage detected by the detection unit 27 is considered, and the loop gain (A · β) at this time is assumed to be 30 dB.
In the APC control of this example, the feedback variable ATT 32 is controlled by the APC control unit 12 so that the detection voltage by the detection unit 27 matches the reference voltage, and accordingly, the APC control unit 12 so that the loop gain becomes constant. Thus, the forward variable ATT 22 is controlled.

  As an example, when the attenuation of the detection unit input variable ATT 26 is increased by 1 dB by the adjustment volume unit 28 in order to increase the output from the power amplification unit 3 by 1 dB, the input power to the detection unit 27 decreases by 1 dB, and the detection unit 27 The detection voltage due to is also reduced. Then, the APC control unit 12 controls the feedback variable ATT 32 so that the detection voltage is returned by 1 dB, and the gain (feedback gain) of the feedback unit 24 increases by 1 dB. At the same time, in order to keep the loop gain constant, the APC control unit 12 controls the forward variable ATT 22 to decrease the forward gain (forward gain) by 1 dB. As a result, the output from the power amplifying unit 3 increases by 1 dB to 41 dBm. The level of the feedback power is also increased by 1 dB to 11 dBm. Here, since the attenuation of the detection unit input variable ATT 26 is increased by 1 dB, the input power to the detection unit 27 converges to the same level as before the change, and the detection voltage by the detection unit 27 becomes the same voltage as before the change. Converge. Further, since the forward gain (forward gain) changes by −1 dB and the feedback gain (feedback gain) changes by +1 dB, the loop gain remains unchanged at 30 dB, and therefore, the distortion improvement amount of the loop does not change. Without being stable.

As described above, in the Cartesian linearizer circuit of this example, a part of the feedback power is distributed and detected, and the feedback section gain is controlled by the feedback variable ATT 32. In the configuration of the APC control circuit, the forward section is forwarded. In addition to the direction variable ATT 22, the detection input unit includes the detection input variable ATT 26, the detection unit input power is controlled by the detection input variable ATT 26, the feedback unit gain is controlled by the feedback variable ATT 32, and the forward gain by the forward direction variable ATT 22. To control.
Specifically, in the APC control system including the Cartesian linearizer circuit of this example, for example, the detection input unit to the detection unit 27 and the variable ATTs 22 and 26 are provided in the forward direction unit, and the detection unit input power and the forward direction are included. The gain is controlled, and when this control is performed, balance control by the feedback variable ATT 32 and the forward variable ATT 22 is performed, thereby controlling the loop gain and the detection characteristics to be constant. In this case, adjustment by the adjustment volume unit 28 is performed on the detection unit input variable ATT 26 that varies the level of the feedback signal to the detection unit 27 so that an arbitrarily defined reference voltage is input to the detection unit 27. . The loop gain (A · β) is controlled by a feedback variable ATT 32 that varies the level of the feedback signal and a forward variable ATT 22 that varies the level of the forward signal.
Therefore, in the Cartesian linearizer circuit of this example, it is possible to realize APC control in which the loop gain and the detection characteristics are kept constant.

In this example, the signal level control device according to the present invention is applied to the Cartesian linearizer circuit.
Further, in the Cartesian linearizer circuit of this example, the function of the modulator 21 that constitutes the modulation means, the function of the forward variable ATT 22 that constitutes the forward variable attenuation means, the preamplifier unit 23 and the power amplifier that constitute the amplification means The forward processing unit is configured by 41 functions.
In the Cartesian linearizer circuit of this example, the function of the directional coupler 42 that extracts a part of the output signal from the forward processing unit, the function of the distributor 31 that distributes the extracted signal, and the variable feedback A feedback processing unit is configured by the function of the feedback variable ATT 32 constituting the attenuation unit and the function of the feedback IF unit 33 and the demodulator 25 constituting the demodulation unit.
In the Cartesian linearizer circuit of this example, the signal level detection processing unit is configured by the function of the detection unit input variable ATT 26 constituting the signal level detection variable attenuation unit and the function of the detection unit 27 constituting the signal level detection unit. Has been.
Further, in the Cartesian linearizer circuit of this example, control is performed by the function of the APC control unit 12 constituting the feedback forward variable attenuation amount control means and the function of the adjustment volume unit 28 constituting the signal level detection variable attenuation amount control means. A processing unit is configured.
In addition, the Cartesian / linearizer circuit of this example includes a modulation signal generator 11 that generates and outputs a signal to be processed.
The forward processing unit, the feedback processing unit, the signal level detection processing unit, and the control processing unit do not necessarily have to be clearly divided into functional units of the target device. For example, if the functional means of the target apparatus has substantially the same function as each of these processing units, it corresponds to the implementation of each of these processing units.

The background of the technology related to the present invention will be described below. Note that the matters described here are not necessarily limited to the conventional technology.
FIG. 2 shows a principle configuration example of a Cartesian linearizer circuit.
In the example of FIG. 2, between the input terminal 51 and the output terminal 52, a first adder (subtractor as a function) 61, a forward gain 62 that is a forward gain (gain), and a circuit A second adder 63 to which a distortion component input terminal 53 to which a generated distortion component (model) is input is connected in series. A feedback gain 64 that is a gain in the feedback direction is connected to the output terminal of the second adder 63, and an output from the feedback gain 64 is input to the first adder 61.

Here, the input signal input to the input terminal 51 is x (t), the distortion component input to the distortion component input terminal 53 is D (t), and the output signal output from the output terminal 52 is y (t). ), The value of the forward gain 62 of the forward unit is A, and the value of the feedback gain 64 of the feedback unit is β, Equation 1 is established. Note that t represents time. Further, the gain of the loop composed of the forward portion and the feedback portion is (A · β).
Further, when Formula 1 is approximated, it is expressed as Formula 2.
Further, under the condition of (A · β) >> 1, Expression 2 is expressed as Expression 3.
As shown in Equation 2, the distortion component D (t) is reduced by the loop gain (A · β).
Further, as shown in Expression 3, the level of the transmission output is determined only by the value β of the feedback gain 64.

FIG. 3 shows a specific configuration example of the Cartesian linearizer circuit.
In FIG. 3, the same reference numerals are given to the processing units that are substantially the same as those shown in FIG. 1 according to the embodiment of the present invention. There is no intention to limit this.
An outline of the operation performed by the Cartesian linearizer circuit shown in FIG. 3 will be described.
As described above, the transmission output level is determined only by the feedback gain value β. Therefore, in order to always adjust the transmission output to a specified level, the feedback signal from the power amplification unit (PA unit) 3 is distributed by the distributor 31, the output level is detected by the detection unit 27, and the detection result (detection) Voltage) to the APC controller 12 of the controller 1.
Here, for example, in a radio device using a digital modulation method, the output level is constantly fluctuating, so that the detection voltage captured by the APC control unit 12 is averaged in order to detect the average power of the transmission output. To do. Then, the variable attenuator (variable ATT) 32 of the feedback unit 24 is controlled by the control voltage based on the average value, and the feedback gain β of the feedback unit 24 is changed, whereby the output from the linearizer circuit is always at a specified level. Control is performed so as to be constant.
In the circuit shown in FIG. 3, the output level is changed by changing the detection output voltage of the detection unit 27 by the adjustment volume unit 28 and changing the detection characteristic (detection output value with respect to the input power to the detection unit 27). Is done.

Here, the configuration of the signal level control device and the like according to the present invention is not necessarily limited to the above-described configuration, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various devices and systems.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
In addition, as various processes performed in the signal level control device according to the present invention, for example, the processor executes a control program stored in a ROM (Read Only Memory) in a hardware resource including a processor, a memory, and the like. May be used, and for example, each functional unit for executing the processing may be configured as an independent hardware circuit.
Further, the present invention can also be grasped as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the above control program, or the program (itself). The processing according to the present invention can be performed by inputting a program from the recording medium to a computer and causing the processor to execute the program.

It is a figure which shows the structural example of the linearizer circuit which concerns on one Example of this invention. It is a figure which shows the example of a fundamental structure of a linearizer circuit. It is a figure which shows the structural example of a linearizer circuit.

Explanation of symbols

1 ·· Control unit 2 ·· Transmission unit 3 ·· Power amplification unit (PA unit) 11 ·· Modulation signal generation unit 12 ·· APC control unit 21 ·· Modulator 22, 26, 32 ·・ Variable attenuator (variable ATT) 23 ・ ・ Preamplifier unit 24 ・ ・ Feedback unit 25 ・ ・ Demodulator 27 ・ ・ Detection unit 28 ・ ・ Adjusting volume unit 31 ・ ・ Distributor 33 ・ ・ Feedback IF unit 41... Power amplifier 42.. Directional coupler 51.. Input end 52. Output end 53. Distortion component input 61 61 63 Adder 62 Forward gain 64 ・ Feedback gain,

Claims (2)

In a signal level control device for controlling the level of a signal,
It has a forward processing unit, a feedback processing unit, a signal level detection processing unit, and a control processing unit,
The forward processing unit modulates the signal resulting from the synthesis of the signal to be processed and the output signal from the feedback processing unit, and attenuates the modulation signal obtained by the modulating unit with a variable attenuation amount. A forward variable attenuation means, and an amplification means for amplifying the signal attenuated by the forward variable attenuation means, and outputs the signal amplified by the amplification means,
The feedback processing unit includes a feedback variable attenuation unit that attenuates a part of the output signal from the forward processing unit with a variable attenuation amount, and a demodulation unit that demodulates the signal attenuated by the feedback variable attenuation unit, Output the demodulated signal obtained by the demodulation means,
The signal level detection processing unit detects a level of the signal attenuated by the signal level detection variable attenuation unit and a signal level detection variable attenuation unit that attenuates a part of the output signal from the forward processing unit by a variable attenuation amount. A signal level detection means for outputting a signal of a detection result by the signal level detection means,
The control processing unit is configured to control the feedback forward variable attenuation that controls the attenuation of the feedback variable attenuation unit of the feedback processing unit and the forward variable attenuation unit of the forward processing unit based on the output signal from the signal level detection processing unit. With quantity control means,
A signal level control device. The signal level control apparatus according to claim 1, wherein
The control processing unit includes signal level detection variable attenuation amount control means for controlling the attenuation amount of the signal level detection variable attenuation means of the signal level detection processing unit,
By the control by the signal level detection variable attenuation amount control means of the control processing unit, the level of the output signal from the forward processing unit is adjusted,
By the control by the feedback forward variable attenuation control means of the control processing unit, the gain of the loop composed of the forward processing unit and the feedback processing unit is made constant,
A signal level control device.

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