JP2003289229A - Agc circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AGC circuit, which can reduce the scale of a circuit and materialize ALC control and AGC control with high accuracy, by solving the problems, such as the deterioration of control accuracy caused by conventional circuit characteristics and the increase of the circuit. <P>SOLUTION: This AGC circuit controls the attenuation rate in a variable attenuator 2, by correcting the detected levels of an input signal and an output signal, by soft, using output characteristics correction data 21 and 31 and temperature characteristics correction data 22 and 32 set in advance, in a level corrector 20 and a level corrector 30, and conducting either an automatic gain control (AGC control) means or an automatic level control (ALC control) means in an AGC/ALC controller 40, according to the difference between the corrected input signal level and output signal level. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency (Radio Fr
amplifying device (AMPlif) for amplifying RF (equency: RF) signals, etc.
ier) Automatic Gain Control (Automatic Gain Cont)
rol: AGC) circuit, in particular, an AG capable of reducing the circuit scale and performing ALC and AGC control with high accuracy
Related to the C circuit. 2. Description of the Related Art A conventional amplifier using an AGC circuit will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of an amplifier using a conventional AGC circuit. An amplification device using a conventional AGC circuit includes a directional coupler 1,
Variable attenuator 2, amplifier 3, directional coupler 4, input level detection circuit 5, temperature characteristic correction circuit 6, output level detection circuit 7, temperature characteristic correction circuit 8, level difference detection circuit 9, a switching control unit 10, a switch 11, a switch 12, an AGC control circuit 13, and an ALC control circuit 1.
And 4. [0003] Each part of the conventional amplifying device using the AGC circuit will be described. The directional coupler 1 receives an input signal (RF
IN). The variable attenuator 2 is an attenuator capable of variably controlling an attenuation rate for variably controlling a gain as an amplifier. The amplifier 3 is a general amplifier. The directional coupler 4 separates the output signal (RF OUT) output from the amplifier 3. [0004] The input level detection circuit 5 includes a directional coupler 1.
This is a detection circuit that detects the input demultiplexed signal demultiplexed by the above, detects the level of the input signal and outputs the input signal level, and detects the level using a diode. The output characteristics of the analog detection circuit do not become primary output characteristics (not log-linear) due to the characteristics of the diode used, and even if the input level to the detection circuit is the same,
The output characteristics of the detection circuit often fluctuate due to the temperature characteristics of the circuit. The temperature characteristic correction circuit 6 applies a temperature change or the like to the input level detection circuit 5 because the output characteristic of the detection circuit fluctuates due to the temperature characteristic of the circuit even under the same input level to the input level detection circuit 5. This is a circuit (hardware) for correcting the fluctuation caused by the above. The output level detection circuit 7 includes a directional coupler 4
This is a detection circuit that detects the output demultiplexed signal demultiplexed by the above, detects the level of the output signal, and outputs the output signal level, and detects the level using a diode. Similarly to the input level detection circuit 5, the output characteristics of the analog detection circuit do not become primary output characteristics (not log-linear) due to the characteristics of the diode used, and the input level to the detection circuit is low. Even under the same conditions, the output characteristics of the detection circuit often fluctuate due to the temperature characteristics of the circuit. The temperature characteristic correction circuit 8 changes the output characteristics of the detection circuit 7 due to the temperature characteristics of the circuit even if the input level to the output level detection circuit 7 is under the same condition. This is a circuit (hardware) for correcting the fluctuation caused by the above. The level difference detection circuit 9 detects a difference between an input signal level from the input level detection circuit 5 and an output signal level from the output level detection circuit 7, and outputs a level difference signal. [0006] The AGC control circuit 13 is a circuit for outputting an attenuation rate to the variable attenuator 2 in order to perform automatic gain control of the amplifier as a whole. Even if there is a certain input, the attenuation rate of the variable attenuator 2 is controlled so that the output signal from the amplification unit 3 is always at a constant level. The ALC control circuit 14 is a circuit that outputs an attenuation rate to the variable attenuator 2 in order to perform automatic amplitude (level) control on the amplification unit 3, and supplies an input voltage of a certain level or more to the amplification unit 3. In order to prevent this phenomenon from occurring, the attenuation factor of the variable attenuator 2 is adjusted so that the level of the input signal to the amplifier 3 does not become excessive. Is controlled. The switch 11 inputs the difference output from the level difference detection circuit 9 to the AGC control circuit 13 or the ALC
A switch for switching to the control circuit 14. Switch 1
2 is a circuit for controlling the attenuation rate of the variable attenuator 2 by A
A switch for switching to the GC control circuit 13 or the ALC control circuit 14. The switching control unit 10 includes a level difference detection circuit 9
Switch 1 for switching the control of the variable attenuator 2 according to the level difference level according to the level difference signal from the
1 is a control unit that performs control for switching the switch 1 and the switch 12. Specifically, when the input level to the amplifier in the amplification unit 3 is a normal level, the AGC control is performed, and when the input level exceeds P1 dB which is the gain suppression of the amplifier (excessive input), It is necessary to switch to ALC control. On the other hand, the switching control unit 10 performs this switching control based on the magnitude of the level difference output between the input signal level output from the level difference detection circuit 9 and the output signal level, and determines that the level difference is larger than the threshold. In this case, it is determined that the normal amplification operation is
When the C control is performed and the level difference is smaller than the threshold value, the switch 11 and the switch 12 are switched to perform the ALC control on the assumption that a saturation state has occurred in the amplifier 3. The threshold value is determined in advance by the amplifying unit 3.
Are set in consideration of the input / output characteristics of Next, the operation of the conventional amplifying device using the AGC circuit will be described. In a conventional AGC circuit, for example, an input RF input signal is demultiplexed by a directional coupler 1, and an RF input signal for detection is detected by an input level detection circuit 5 to detect an input signal level. At this time, a variation such as a temperature change is corrected by the temperature characteristic correction circuit 6, and an input signal level is output. On the other hand, the main line RF input signal demultiplexed by the directional coupler 1 is attenuated by the variable attenuator 2 and amplified by the amplification unit 3 to become an RF output signal, and the RF output signal is split by the directional coupler 4. The output RF signal for detection is detected by an output level detection circuit 7 to detect an output signal level. At this time, a variation such as a temperature change is corrected by a temperature characteristic correction circuit 8 and the output signal is corrected. The level is output. At this time, the detection output signal from the input level detection circuit 5 does not become a log-linear output characteristic due to the characteristics of the diode in the input level detection circuit 5, and FIG.
As shown in (a), the curve is close to the direct proportion. Similarly, the detection output signal from the output level detection circuit 7 does not become a log-linear output characteristic due to the characteristics of the diode in the output level detection circuit 7, and is almost directly proportional as shown in FIG. It becomes a curve. FIG. 4 is a graph showing a detection output characteristic with respect to an input level of the input level detection circuit 5 and the output level detection circuit 7 in the amplifier using the conventional AGC circuit. The level difference detection circuit 9 detects a level difference between the input signal level from the input level detection circuit 5 and the output signal level from the output level detection circuit 7 and outputs a level difference signal. 10, the level difference is determined as a threshold value. If the level difference is larger than the threshold value, the switches 11 and 12 are switched to the AGC control circuit 1
The AGC control circuit 13 determines the attenuation rate of the variable attenuator 2 based on the level difference, and outputs the attenuation rate. The attenuation rate of the variable attenuator 2 is determined. On the other hand, if the level difference is smaller than the threshold in the threshold determination in the switching control unit 10, the switches 11 and 12
Switching to the control circuit 14 side, the ALC control circuit 14
, The attenuation rate of the variable attenuator 2 is specified and output from the level difference, and the attenuation rate of the variable attenuator 2 is determined. As a prior art of level control in an amplifier, Japanese Patent Application Laid-Open No. 11-1 published on July 9, 1999 is disclosed.
No. 86862, "Level control method" (applicant: NEC Saitama, inventor: Atsushi Inahashi). This prior art performs ALC control when the output level of a transmitter or the like is high, and performs ALC control when the output level of a transmitter or the like is low.
This is a level control method that performs GC control, calculates the correction gain in the transition period of both methods, and controls the variable attenuator, thereby achieving high precision gain stability over a wide dynamic range. is there. However, in the conventional AGC circuit, the output of the input level detection circuit 5 and the output of the output level detection circuit 7 do not have log-linear output characteristics due to the characteristics of the diodes used in the detection circuit. A
There is a problem that the control accuracy of GC or ALC is deteriorated. In addition, the variation of the output characteristic due to the temperature change of the detection circuit in the input level detection circuit 5 and the output level detection circuit 7 is corrected by using the temperature characteristic correction circuit 6 and the temperature characteristic correction circuit 8 of hardware. However, this has a problem that the circuit scale becomes large. In the conventional AGC circuit, the AGC control circuit 13 and the AGC control circuit 13 perform ALC control when the input level exceeds P1 dB, which is the gain suppression of the amplifier.
Since two hardware configurations with the C control circuit 14 are provided, and the control between the AGC control circuit 13 and the ALC control circuit 14 is switched by hardware based on the level difference between the input signal level and the output signal level, the circuit scale is also large here. There was a problem of becoming. [0015] The present invention has been made in view of the above circumstances, and the control accuracy is degraded due to the characteristics of the conventional detection circuit.
An object of the present invention is to provide an AGC circuit that solves the problem of an increase in circuit scale, reduces the circuit scale, and can realize ALC control or AGC control with high accuracy. According to the present invention, there is provided an AGC circuit for detecting a level of an input signal and outputting an input signal level in the AGC circuit. A circuit, a first level correction unit for correcting the input signal level, a variable attenuator for attenuating the input signal with a variable attenuation rate controlled from the outside, and amplifying the attenuated input signal to output an output signal Amplifying section, a second level detecting circuit for detecting the level of the output signal and outputting the output signal level, a second level correcting section for correcting the output signal level, and correcting the corrected input signal level. A level difference detection circuit for obtaining a difference from the output signal level, and a level difference detection circuit for outputting a level difference signal, and determining an attenuation rate for performing automatic gain control or automatic level control according to the level difference signal, An automatic gain / auto level control unit for outputting,
First and second level correction units correct output characteristic correction data for correcting input / output characteristics of the first and second level detection circuits to be linear, and temperature characteristics of the first and second level detection circuits. And a temperature correction unit for correcting the input or output signal level input from the first or second level detection circuit using the output characteristic correction data and the temperature characteristic correction data. An automatic gain / auto level control unit comprising: an automatic gain control means for outputting an attenuation rate based on the automatic gain control; and an automatic level control means for outputting an attenuation rate based on the automatic level control, and a level difference detection circuit. Is an automatic gain / automatic level control unit that executes either automatic gain control means or automatic level control means in accordance with the level difference signal from Hesi, and can be realized ALC control or AGC control with high accuracy. Embodiments of the present invention will be described with reference to the drawings. Note that the function realizing means described below may be any circuit or device as long as the function can be realized, and some or all of the functions may 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. [0018] In terms of the general concept, A according to the present invention
The GC circuit corrects the detected input signal level and output signal level using preset output characteristic correction data and temperature characteristic correction data, and calculates a difference between the corrected input signal level and output signal level. , Automatic gain control (A
(GC control) means or automatic level control (ALC control) means to control the attenuation rate in the variable attenuator by reducing the circuit scale and realize ALC control or AGC control with high accuracy. You can do it. Explained in terms of function realizing means, the AGC circuit according to the present invention detects a level of an input signal and outputs an input signal level, and a first level detection circuit for correcting the input signal level. A level corrector, a variable attenuator for attenuating the input signal with a variable attenuation rate controlled from the outside, an amplifier for amplifying the attenuated input signal and outputting an output signal, and detecting a level of the output signal A second level detection circuit for outputting an output signal level by using a second level detector, a second level correction unit for correcting the output signal level, and obtaining a difference between the corrected input signal level and the corrected output signal level. A level difference detection circuit that outputs a signal; and an automatic gain / auto level control unit that obtains an attenuation rate for performing automatic gain control or automatic level control according to the level difference signal and outputs the obtained attenuation factor to a variable attenuator. , Level correction unit of the first and second are
Output characteristic correction data for correcting the input / output characteristics of the first and second level detection circuits to be linear, and temperature characteristic correction data for correcting the temperature characteristics of the first and second level detection circuits are provided in advance. , A level correction unit that corrects an input or output signal level input from the first or second level detection circuit using output characteristic correction data and temperature characteristic correction data. Automatic gain control means for outputting an attenuation rate based on automatic gain control; and automatic level control means for outputting an attenuation rate based on automatic level control. The automatic gain control means according to a level difference signal from the level difference detection circuit. Alternatively, since it is an automatic gain / auto level control unit for executing any of the automatic level control means, the circuit scale can be reduced and ALC control or ALC control can be performed. Those capable of realizing C controlled with high precision. Incidentally, the correspondence between each means in the embodiment of the present invention and each unit in FIG. 1 will be described. The first level detection circuit corresponds to the input level detection circuit 5, and the first level correction unit is a level correction circuit. The second level detection circuit corresponds to the output level detection circuit 7, the second level correction section corresponds to the level correction section 30, and the automatic gain / auto level control section corresponds to AGC / ALC. It corresponds to the control unit 40. First, the configuration of an amplifier using an AGC circuit according to the present invention will be described with reference to FIG. FIG.
1 is a block diagram illustrating a configuration of an amplifier using an AGC circuit according to the present invention. Parts having the same configuration as in FIG. 3 are described with the same reference numerals. The amplifier using the AGC circuit of the present invention includes a directional coupler 1, a variable attenuator 2, an amplifying unit 3,
It comprises a directional coupler 4, an input level detection circuit 5, an output level detection circuit 7, and a level difference detection circuit 9, and as a feature of the present invention, a level correction unit 20
And a level correction unit 30 are provided, and instead of the conventional AGC control circuit 13 and ALC control circuit 14, AGC / A
An LC control unit 40 is provided. Next, each part of the amplifying device using the AGC circuit of the present invention will be described in detail, but the description of the same parts as the conventional one will be omitted, and the characteristic parts of the present invention will be described. The level correction unit 20 includes the input level detection circuit 5
The output signal level is corrected to a linear (linear) characteristic, and includes an output characteristic correction data table 21, a temperature characteristic correction data table 22, and a control unit 23 therein. The level correction section 30 corrects the output signal level output from the output level detection circuit 7 into a linear (linear) characteristic, and internally includes an output characteristic correction data table 31, a temperature characteristic correction data table 32, and a control circuit. A part 33. The level corrector 20 and the level corrector 30 have basically the same configuration, except that the input is different between the input signal level output and the output signal level output. Therefore, the insides of the level correction unit 20 and the level correction unit 30 will be described using the level correction unit 20 as an example.
The output characteristic correction data table 21 includes a level correction unit in consideration of the characteristics of the input signal level output from the input level detection circuit 5 being not log-linear (curved) due to the characteristics of the detection diode in the input level detection circuit 5. In order to correct the output from the input level detection circuit 5 so that a curve which is input to 20 and is close to a direct proportionality as shown in FIG. 2A, becomes a log-linear straight line as shown in FIG. Is a table in which the data of FIG.
FIG. 2 is a graph showing a detection output characteristic with respect to an input level of an input level detection circuit 5 and an output level detection circuit 7 in an amplifier using the AGC circuit of the present invention, and a detection output after correction. Note that the output characteristic correction data table 21 is
Since the output characteristic correction data table 31 is correction data corresponding to the input signal level and the output characteristic correction data table 31 is correction data corresponding to the output signal level, the data contents are different. The temperature characteristic correction data table 22 is a table in which data for correcting the output from the input level detection circuit 5 in accordance with the ambient temperature is stored in advance in consideration of the temperature characteristics of the input level detection circuit 5. . Here, the output characteristic correction data table 21
Alternatively, the data stored in the temperature characteristic correction data table 22 is held at an accuracy corresponding to the required correction accuracy. Further, the method of acquiring data to be actually stored is not limited in the present invention. For example, at the time of designing or manufacturing an apparatus, data may be obtained or manufactured based on prediction or simulation of a person in charge. A method of acquiring data based on actual measurement at the time is conceivable. The control unit 23 receives the input signal level from the input level detection circuit 5, corrects the detection level output using the output characteristic correction data table 21, detects the ambient temperature, and detects the ambient temperature. 22, the detection level output is corrected in accordance with the ambient temperature, and the corrected input signal level is output. In FIG. 1, the level correction unit 20 and the level correction unit 30 are shown as separate components. However, as a common configuration, the input signal level from the input level detection circuit 5 and the output level detection circuit 7 May be corrected and output to the level difference detection circuit 9. The AGC / ALC control section 40 receives the level difference from the level difference detection circuit 9 and controls the AGC and the ALC according to the level difference to control the attenuation rate in the variable attenuator 2. It is. A
In the GC / ALC control unit 40, the conventional AGC control circuit 1
3 or the ALC control circuit 14, instead of realizing each control by hardware, an AG that realizes AGC control
The C control means and the ALC control means for realizing the ALC control are each realized by software, and the magnitude of the level difference serving as a switching point for switching the control between the AGC and the ALC is stored as a threshold value. Is determined from the magnitude of the level difference output, and if the level difference is larger than the threshold value, the AGC control means is executed. If the level difference is smaller than the threshold value, the ALC control means is switched by software. It has become. This threshold value is set in advance by the amplifying unit 3 similarly to the conventional switching control unit 10.
Are set in consideration of the input / output characteristics of Next, the operation of the amplifier using the AGC circuit of the present invention will be described. In the AGC circuit of the present invention, for example, an input RF input signal is split by the directional coupler 1, and an RF input signal for detection is detected by the input level detection circuit 5, and is shown in FIG. An input signal level having such characteristics is detected, corrected by the level correction unit 20 to a linear characteristic as shown in FIG. 2B using the output characteristic correction data table 21, and further, using the temperature characteristic correction data table 22. The temperature characteristic is corrected, and a highly accurate corrected input signal level is output. On the other hand, the main line RF input signal demultiplexed by the directional coupler 1 is attenuated by the variable attenuator 2 and amplified by the amplifying unit 3 to become an RF output signal. 4, the detection RF output signal is detected by an output level detection circuit 7, an output signal level having a characteristic as shown in FIG. 2A is detected, and an output characteristic correction data is output by a level correction unit 30. The linear characteristic shown in FIG. 2B is corrected using the table 31, and the temperature characteristic is further corrected using the temperature characteristic correction data table 32, so that a corrected output signal level with high accuracy is output. . Then, the level difference detection circuit 9 detects a level difference between the corrected input signal level from the level correction section 20 and the corrected output signal level from the level correction section 30, and outputs a level difference signal. , AGC / AL
The C control unit 40 determines the level difference as a threshold value. If the level difference is larger than the threshold value, the AGC control unit is executed to specify and output the attenuation rate of the variable attenuator 2 and the attenuation rate of the variable attenuator 2 Is determined. On the other hand, if the AGC / ALC controller 40 determines that the level difference is smaller than the threshold, the ALC control means is executed to specify and output the attenuation rate of the variable attenuator 2, and the attenuation of the variable attenuator 2 is determined. The rate is to be determined. According to the AGC circuit according to the embodiment of the present invention, when the input signal and the output signal are detected by the input level detection circuit 5 and the output level detection circuit 7 using diodes, the detection output is determined by the characteristics of the diodes. Although the signal does not have a log-linear output characteristic, the level correction unit 20 and the level correction unit 30 output the output characteristic correction data table 31.
Is used to make a log-linear (linear) characteristic, so that the accuracy of the level difference is improved. As a result, AGC
Alternatively, there is an effect that the control accuracy of ALC can be improved. The AGC according to the embodiment of the present invention
According to the circuit, when the input signal and the output signal are detected by the input level detection circuit 5 and the output level detection circuit 7, the output characteristics fluctuate due to the temperature characteristics of the circuit. Since the correction is performed by software using the temperature characteristic correction data table 32, the accuracy of the level difference can be improved without increasing the circuit scale, and as a result, the control accuracy of AGC or ALC can be improved. The AGC according to the embodiment of the present invention
According to the circuit, the AGC / ALC control unit 40 determines AGC and ALC from the level difference detected by the level difference detection circuit 9.
Is switched to control the attenuation rate in the variable attenuator 2, but the AGC / ALC control unit 40 may not realize each control by hardware like the conventional AGC control circuit 13 or ALC control circuit 14. AGC control means for realizing AGC control and ALC control means for realizing ALC control are each realized by software, and a threshold is determined from the magnitude of the level difference output from the level difference detection circuit 9, and the AGC control means or Since the software is switched to execute any of the ALC control means,
There is an effect that AGC control or ALC control and switching between them can be realized without increasing the circuit scale. According to the present invention, the input signal level detected by the first level detection circuit and the output signal level detected by the second level detection circuit are respectively determined by the first level correction section and the first level correction section. A second level correction unit that corrects using preset output characteristic correction data and temperature characteristic correction data, and performs automatic gain / automatic level control according to the level difference between the corrected input signal level and output signal level. Since the AGC circuit controls the attenuation rate in the variable attenuator by executing either the automatic gain control (AGC control) means or the automatic level control (ALC control) means in the section, the circuit scale is reduced and the ALC control is performed. Alternatively, there is an effect that the AGC control can be realized with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an amplifier using an AGC circuit according to the present invention. FIG. 2 is a graph showing a detection output characteristic with respect to an input level of an input level detection circuit and an output level detection circuit in an amplifier using the AGC circuit of the present invention, and a detection output after correction. FIG. 3 is a block diagram illustrating a configuration of an amplification device using a conventional AGC circuit. FIG. 4 is a graph showing a detection output characteristic with respect to an input level of an input level detection circuit and an output level detection circuit in an amplifier using a conventional AGC circuit. [Explanation of Signs] 1 ... Directional coupler, 2 ... Variable attenuator, 3 ... Amplifier,
4 ... directional coupler, 5 ... input level detection circuit, 6 ...
Temperature characteristic correction circuit, 7 ... Output level detection circuit, 8 ...
Temperature characteristic correction circuit, 9 ... level difference detection circuit, 10
... Switching control unit, 11 ... Switch, 12 ... Switch,
13 ... AGC control circuit, 14 ... ALC control circuit,
20, 30: level correction section, 21, 31, output characteristic correction data table, 22, 32: temperature characteristic correction data table, 23, 33: control section

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masahiro Nishi             3-14-20 Higashinakano, Nakano-ku, Tokyo Stock             Hitachi Kokusai Electric Inc. F term (reference) 5J100 JA01 LA00 LA10 QA02

Claims (1)

1. A first level detection circuit for detecting a level of an input signal and outputting an input signal level, a first level correction unit for correcting the input signal level, A variable attenuator for attenuating a signal with a variable attenuation rate controlled from the outside; an amplifier for amplifying the attenuated input signal to output an output signal; and an output signal level for detecting a level of the output signal A second level detection circuit that outputs the output signal level, a second level correction unit that corrects the output signal level, a difference between the corrected input signal level and the corrected output signal level, and a level difference signal And an automatic gain / automatic level control for obtaining an attenuation factor for performing automatic gain control or automatic level control in accordance with the level difference signal and outputting the obtained attenuation factor to the variable attenuator. Has the door, the first and second level correction unit, the first and second
Output characteristic correction data for correcting the input / output characteristics of the level detection circuit to be linear, and temperature characteristic correction data for correcting the temperature characteristics of the first and second level detection circuits. Or a level correction unit that corrects an input or output signal level input from the second level detection circuit using the output characteristic correction data and the temperature characteristic correction data, wherein the automatic gain / automatic level control unit includes: Automatic gain control means for outputting an attenuation rate based on automatic gain control, and automatic level control means for outputting an attenuation rate based on automatic level control, wherein the automatic gain is controlled according to a level difference signal from the level difference detection circuit. An AGC circuit, which is an automatic gain / auto level control unit for executing either the control unit or the automatic level control unit.