JP2000059158A - Automatic digital gain control method and device and radio communication equipment provided with automatic gain control function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically control gain by loop gain optimum for the fluctuation width or fluctuation cycle of an input signal level and to perform high-speed pull-in to the target value of automatic gain control. SOLUTION: Based on the level of output signals for which input signals are amplified, gain variable amplification is controlled and fixed output signals are obtained. The output signals are detected (S20) and converted to digital signals first (S21). The change amount of the detection voltage of the output signals is obtained by latching and adding the detection voltage (S22) and the difference value of a detection voltage value and a target convergence value is generated (S23). Further, the difference value is variably multiplied by the change amount of the detection voltage (S24), the change value of the difference value is obtained by latching and adding the variable multiplication value (S25) and automatic gain control signals are generated by conversion from the difference change value (S26). The automatic gain control signals are converted to analog signals and supplied to a gain variable amplifier (S27), the loop gain to the fluctuation of the input signals is made appropriate and the gain variable amplification is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital automatic gain control for stabilizing an output signal with respect to an input signal having a fluctuation such as a received signal in which fading has occurred in a mobile communication device by a closed loop automatic gain control. AG
C), in particular, a digital automatic gain control method and apparatus for automatically setting an optimum loop gain for a fluctuation width or a fluctuation period of an input signal level and performing a high-speed pull-in operation, and a radio having an automatic gain control function Related to a communication device.

[0002]

2. Description of the Related Art Conventionally, in various signal processing apparatuses, for example, a wireless communication apparatus, a fluctuation of a signal level of a received signal caused by a fluctuation of a received electric field intensity in a radio wave propagation path such as a radio line is fixed to reduce a demodulation error. Digital automatic gain control for reduction is performed. Such digital automatic gain control detects an input signal level fluctuation and controls the gain of a variable amplifier or the like in a subsequent stage by an automatic gain control signal generated by detecting the level fluctuation of the input signal. There is known a closed loop control method for controlling a gain of a variable amplifier or the like in a preceding stage by using a generated automatic gain control signal.

In such digital automatic gain control, for example, when the fluctuation of the input signal is large and a high-speed periodic fluctuation occurs, it is desirable to perform real-time automatic gain control for the fluctuation state. In particular, in the closed-loop control method, high-speed processing (high-speed pull-in) for a case where the loop delay or the fluctuation of the input signal is fast and large is a problem.
For example, when a digital AGC circuit is provided in an automobile telephone, a signal having large fluctuations in signal level due to multiple radio wave propagation (multipath) during high-speed running or running in a building street and having a fast fading cycle. Automatic gain control capable of high-speed pull-in is required for signals.

As an example of such a digital AGC device, Japanese Patent Application Laid-Open No. 9-83276 entitled "AGC Amplifier Control Circuit" is well known. In this publication, at the start of the pull-in, the gain at the time when the previous pull-in was completed is held, the held gain is set as an initial value in the AGC amplifier, and the pull-in error is controlled using a digital AGC loop. As a result, primary pull-in by analog is eliminated, and high-speed amplitude pull-in control is enabled.

In this publication, an optimum loop gain cannot be set for the variation width and the variation speed of the input signal level, and high-speed pull-in is performed for an input signal whose signal level changes rapidly with time. May be difficult. For example, in a mobile phone or the like, the signal level fluctuates greatly and a high-speed fading period cannot be received at a high speed with respect to a received signal. In some cases, switching (handover) of a cell base station due to location registration at the time of turning on or movement between zones (cells) cannot be performed instantaneously.

[0006]

As described above, in the above conventional example, when the signal level of the input signal changes at a high speed, the optimum loop gain can be set for the fluctuation state of the input signal level. There was a problem that it was sometimes difficult.

The present invention is to solve such a problem in the prior art, and automatically sets a loop gain corresponding to a fluctuation width or a fluctuation period of an input signal level, and performs automatic gain control at an optimum loop gain. Can do
It is an object of the present invention to provide an excellent digital automatic gain control method and apparatus capable of performing a high-speed pull-in operation that converges to a target value of automatic gain control at high speed, and a wireless communication apparatus having an automatic gain control function.

[0008]

According to a first aspect of the present invention, there is provided a digital automatic gain control method according to the first aspect of the present invention, wherein the input signal is adjusted based on a level of an output signal amplified by a variable gain amplifier. The amplifier is controlled to obtain a constant output signal by optimizing the loop gain of the amplification system with respect to the fluctuation of the input signal, and a detection step of detecting the amplified output signal and a variation of the detection voltage are obtained. A change amount calculation step, a difference value generation step of generating a difference value between the digital value of the detection voltage and a target convergence value, and a variable multiplication step of variably multiplying the difference value according to the change amount of the detection voltage, A difference change value calculating step of obtaining a change value of the variably multiplied difference value; and a control signal for generating an automatic gain control signal by performing conversion of the difference change value by a predetermined conversion method. And having a generating step.

A digital automatic gain control method according to a second aspect of the present invention controls the variable gain amplifier based on the level of the output signal obtained by amplifying the input signal by the variable gain amplifier, and controls the amplification system in response to a change in the input signal. A detection step for detecting the amplified output signal, a fading cycle detection step for detecting a fading cycle indicating a fluctuation cycle of the input signal, and the detection voltage. A difference value generating step of generating a difference value between the digital value and the target convergence value, a variable multiplying step of variably multiplying the difference value according to the fading cycle, and a difference for obtaining a change value of the variably multiplied difference value. A change value calculating step, and control signal generation for generating an automatic gain control signal by converting the difference change value by a predetermined conversion method. And having a step.

A digital automatic gain control method according to a third aspect of the present invention controls the variable gain amplifier based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier, and controls the amplification system in response to a change in the input signal. A detection step of detecting the amplified output signal, a change amount calculating step of obtaining a change amount of the detection voltage, a digital value of the detection voltage and a target value. A difference value generating step of generating a difference value between the convergence value, a difference change value calculating step of obtaining a change value of the difference value, and a plurality of conversion methods for converting the difference change value in accordance with the change amount of the detection voltage. And a control signal generation step of performing conversion of the difference change value by the selected conversion method to generate an automatic gain control signal. Characterized in that it has and.

A digital automatic gain control method according to a fourth aspect of the present invention controls the variable gain amplifier based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier, and controls the amplification system in response to a change in the input signal. A detection step for detecting the amplified output signal, a fading cycle detection step for detecting a fading cycle indicating a fluctuation cycle of the input signal, and the detection voltage. A difference value generating step of generating a difference value between the digital value and the target convergence value, a difference change value calculating step of obtaining a change value of the difference value, and a conversion method of converting the difference change value according to the fading cycle. Selecting a conversion method from a plurality of conversion methods, and converting the difference change value by the selected conversion method to obtain an automatic gain. And having a control signal generating step of generating a control signal.

In the digital automatic gain control method according to the present invention, as a method of converting the difference change value for generating the automatic gain control signal, a table reference process using a conversion table or an arithmetic process using a conversion formula is used. Things.

According to a sixth aspect of the present invention, there is provided a digital automatic gain control device for controlling a variable gain amplifier based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier. A detection means for detecting the amplified output signal, a change amount calculation means for obtaining a change amount of the detection voltage, a digital value of the detection voltage and a target value. Difference value generation means for generating a difference value from the convergence value; variable multiplication means for variably multiplying the difference value according to the amount of change in the detection voltage; and a difference change value for obtaining a change value of the variably multiplied difference value. It is characterized by comprising calculating means, and control signal generating means for converting the difference change value by a predetermined conversion method to generate an automatic gain control signal.

According to a seventh aspect of the present invention, there is provided a digital automatic gain control device for controlling a variable gain amplifier based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier. A detecting means for detecting the amplified output signal, a fading cycle detecting means for detecting a fading cycle indicating a fluctuation cycle of the input signal, and a detecting voltage for detecting the amplified output signal. A difference value generating means for generating a difference value between the digital value and the target convergence value, a variable multiplying means for variably multiplying the difference value according to the fading cycle, and a difference for obtaining a change value of the variably multiplied difference value. Change value calculating means, and control signal generating means for performing conversion by a predetermined conversion method on the difference change value to generate an automatic gain control signal. And butterflies.

The digital automatic gain control device according to the present invention controls the variable gain amplifier based on the level of the output signal obtained by amplifying the input signal by the variable gain amplifier, and controls the amplification system in response to the fluctuation of the input signal. A detection means for detecting the amplified output signal, a change amount calculation means for obtaining a change amount of the detection voltage, a digital value of the detection voltage and a target value. Difference value generating means for generating a difference value from the convergence value; difference change value calculating means for obtaining a change value of the difference value; and a plurality of conversion methods for converting the difference change value in accordance with the amount of change in the detection voltage. A conversion method selecting means for selecting from the conversion methods, and a control signal generating means for generating an automatic gain control signal by converting the difference change value by the selected conversion method. That.

According to a ninth aspect of the present invention, there is provided a digital automatic gain control apparatus for controlling a variable gain amplifier based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier. A detecting means for detecting the amplified output signal, a fading cycle detecting means for detecting a fading cycle indicating a fluctuation cycle of the input signal, and a detecting voltage for detecting the amplified output signal. A difference value generating means for generating a difference value between the digital value and the target convergence value, a difference change value calculating means for obtaining a change value of the difference value, and a conversion method for converting the difference change value according to the fading cycle. A conversion method selecting means for selecting from a plurality of conversion methods, and a control for generating the automatic gain control signal by converting the difference change value by the selected conversion method. Characterized by comprising a signal generating means.

The digital automatic gain control device according to the present invention is provided with a conversion table or a memory means for storing a conversion expression representing a conversion method of a difference change value for generating the automatic gain control signal. is there.

A wireless communication device having an automatic gain control function according to the present invention is provided with a configuration of the digital automatic gain control device according to any one of claims 6 to 9 in a receiving system. The gain control device performs automatic gain control for stabilizing an output signal related to a received signal in the receiving system.

The digital automatic gain control method and apparatus of the present invention generate an automatic gain control signal in accordance with the amount of change in the detection voltage of the output signal corresponding to the input signal level or the fading cycle detected from the input signal. By automatically setting the loop gain and performing automatic gain control with an optimum loop gain, a high-speed pull-in operation that converges to a target value of the automatic gain control at high speed becomes possible.

At this time, the difference value between the digital value of the detection voltage and the target convergence value is set in accordance with the amount of change of the detection voltage or the fading cycle, for example, so that when these values are large, the automatic gain control signal becomes large. By performing variable multiplication or selecting a conversion method for converting the change value of the difference value into an automatic gain control signal from among a plurality of methods, the gain variable amplification is performed with a gain suitable for the fluctuation state of the input signal level. It is possible to do.

Further, the digital automatic gain control method and apparatus of the present invention generate an automatic gain control signal using a conversion table or conversion formula stored in a memory means or the like. In this case, an automatic gain control signal according to the fluctuation state of the input signal is easily generated. When a conversion formula is used, the central processing unit (CP
When the processing is performed in U), the configuration is simplified as compared with the case where a conversion table or a conversion formula is stored in a memory or the like. In addition, since the automatic gain control signal can be generated by either the conversion table or the conversion formula, the degree of freedom of the circuit configuration can be obtained.

Further, in the radio communication device of the present invention, the configuration of the digital automatic gain control device is provided in a reception system of the radio communication device, and performs, for example, automatic gain control for stabilizing the output signal of the demodulation means. As a result, for example, when this configuration is provided in a receiving system such as an automobile telephone, an input intermediate frequency signal is automatically set to a loop gain according to a change amount of a detection voltage or a fading cycle, and an optimum loop is set. Automatic gain control with gain is performed. That is, a high-speed pull-in operation that converges to the target value of the automatic gain control at a high speed becomes possible. In this case, suitable automatic gain control is performed to quickly follow a received signal having a large fluctuation due to multiple radio wave propagation (multipath) during high-speed running or a building street and a fast fading cycle. This also reduces demodulation errors.

[0023]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. [First Embodiment] FIG. 1 is a block diagram showing a configuration of a digital automatic gain control method and apparatus according to a first embodiment of the present invention. This example is provided, for example, in a receiving system of a wireless communication device such as a mobile phone or a mobile phone, and performs automatic gain control on an intermediate frequency (IF) signal (input signal S1) from a high frequency processing unit (amplification / frequency conversion). (AGC) Variable gain amplifier 1 as variable amplifying means for amplifying and outputting a signal level at a constant level, and an output signal obtained by demodulating an intermediate frequency (IF) signal (input signal S1) from variable gain amplifier 1 A demodulator 2 for transmitting S3;
And an AGC controller 3A for automatically controlling the gain of the variable gain amplifier 1 based on the level of the output signal S3 to stabilize the output signal S3.

The AGC control section 3A includes a detection circuit 12 as a detection means for outputting a detection voltage obtained by detecting the envelope (level) of the output signal S3, and an adder 13 for calculating and outputting a difference between the detection voltage and the latch value. A latch circuit 14 for latching the detection voltage from the detection circuit 12; and a variable multiplier 18 for changing the optimum gain based on the change amount of the detection voltage obtained by the change amount calculation means by the latch circuit 14 and the adder 13.
And a CPU 15a for controlling the setting of the detection signal, and converting the detection voltage from the detection circuit 12 to a digital signal to
3. A / D output to latch circuit 14 and adder 17
It has a converter 16 and an adder 17 as a difference value generating means for calculating a difference between the detection voltage from the A / D converter 16 and a preset target convergence value S2.

Further, the AGC control unit 3A has a CPU 15
a variable multiplier 18 that variably multiplies the output signal from the adder 17 under the control of a, an adder 19 that calculates the difference between the output signal from the variable multiplier 18 and the latch signal, and a A latch circuit 20 for latching and feeding back an output signal, a memory 21 storing a conversion table for converting an output signal from the latch circuit 20 into an automatic gain control signal and outputting the same, and an automatic gain control signal from the memory 21 To an analog signal to convert the
And a D / A converter 22 for outputting to the gain control terminal. Here, the CPU 15a and the variable multiplier 18
Constitutes a variable multiplication means. The adder 19 and the latch circuit 20 constitute a difference change value calculating unit. The memory 21 constituting the control signal generating means stores table data in which a predetermined conversion method for generating an automatic gain control signal is defined as a conversion table.

Next, the AGC operation of the first embodiment will be described. FIG. 2 is a flowchart showing a processing procedure in the AGC operation of the first embodiment. 1 and 2, a variable gain amplifier 1 variably amplifies an input signal S1 based on an analog automatic gain control signal from a D / A converter 22, and outputs a constant output signal S3 by the automatic gain control. Send out. This output signal S3 is supplied to the detection circuit 12
Then, the envelope (level) detection is performed (step S20: detection step), and the digital signal is converted by the A / D converter 16 (step S21).

At this time, the detection voltage value output from the A / D converter 16 and the previous detection voltage value latched by the latch circuit 14 are added by the adder 13 to obtain a difference value, and based on this difference value, The amount of change in the detection voltage is calculated, and the CPU 15a
(Step S22: change amount calculating step).

Further, the detection voltage value output from the A / D converter 16 and the target convergence value S2 are added by the adder 17 to generate a difference value (step S23: difference value generation step). Then, the CPU 15a controls the variable multiplier 18 based on the detected voltage change amount, and
In step 8, variable multiplication of the difference value is performed (step S24: variable multiplication step). The variable multiplication value is input to the adder 19, and the value latched in the latch circuit 20 is fed back to calculate a change value of the difference value in the adder 19 (step S25: difference change value calculation step). After this difference change value is latched by the latch circuit 20, it is input to the memory (conversion table) 21 and converted into an automatic gain control signal (step S26: control signal generation step). Then, the converted automatic gain control signal is converted into an analog signal by the D / A converter 22 (step S27), and this automatic gain control signal is supplied to the gain control terminal of the variable gain amplifier 1. As a result, variable gain amplification based on the gain based on the automatic gain control signal is performed (variable amplification step).

The variable gain amplifier 1 amplifies the input signal S1 while controlling the gain according to the automatic gain control signal. At this time, the CPU 15a controls the amount of multiplication by the variable multiplier 18 based on the amount of change in the detection voltage calculated by the latch circuit 14 and the adder 13 so that the optimum gain of the variable gain amplifier 1 can be set. By repeating the closed loop operation of feeding back the automatic gain control signal so that the output signal S3 has a constant value, the output signal S3 is stabilized.

Next, the main part of the AGC operation in the first embodiment will be described in detail. In the initial state of the AGC operation, the values latched by the latch circuits 14 and 20 are 0.
It is. Therefore, in the variable gain amplifier 1, an automatic gain control signal of a certain value is stored in the memory (conversion table) 21 by the
Input through the / A converter 22. As a result, the amplification gain in the variable gain amplifier 1 changes, and the level of the output signal S3 changes due to the change in the gain amplification. further,
The level of the detection voltage output from the detection circuit 12 changes, and the difference value from the target convergence value S2 changes. The difference between the difference value and the value latched by the latch circuit 20 is added to the adder 19.
The change value of the difference value from the target convergence value S2 is sent to the memory (conversion table) 21.

By inputting an automatic gain control signal corresponding to the change value to the variable gain amplifier 1, the amplification gain of the variable gain amplifier 1 changes. This closed loop operation is repeated, and when the difference between the detection voltage value and the target convergence value S2 becomes 0, the value latched in the latch circuit 20 becomes constant, and the automatic gain control signal input to the variable gain amplifier 1 becomes Since the level also becomes constant, the detection voltage value becomes the target convergence value S2
Converges to As a result, the level of the output signal S3 also converges to a constant value.

In this AGC operation, the CPU 15a
Sets the multiplication amount of the variable multiplier 18 according to the change amount of the detection voltage obtained by the latch circuit 14 and the adder 13 so that the optimum gain can be obtained in the variable gain amplifier 1. For example, when the change amount of the detection voltage is large (CPU
(When the input value of 15a is large), the multiplication amount of the variable multiplier 18 is increased so that the amplification gain of the variable gain amplifier 1 is increased. Thereby, the loop gain is automatically optimized, and the high-speed pull-in operation is performed. As a specific example of the high-speed pull-in operation, for example, when one step of latching by the latch circuit is set to about 600 nsec, the multiplication amount of the variable multiplier 18 is set so that a loop gain value that can perform the pull-in operation in several μsec is obtained. Control.

As described above, according to the first embodiment, the amplification gain of the variable gain amplifier can be set to an appropriate value in accordance with the amount of change in the detection voltage value, and the loop gain in the AGC operation can be changed by changing the input signal level. It can be automatically set to the optimal value for the state. As a result, automatic gain control can be performed with an optimum loop gain, and even when the input signal level fluctuates at high speed, a high-speed pull-in operation that converges to the target value of automatic gain control at high speed becomes possible. .

[Second Embodiment] FIG. 3 is a block diagram showing a configuration according to a second embodiment of the present invention. The second embodiment has a variable gain amplifier 1, a demodulator 2, and an AGC control unit 3B that receive the same input signal S1 as the first embodiment and transmit an output signal S3. The AGC control unit 3B includes a detection circuit 12, an A / D
Converter 16, adder 17, variable multiplier 18, adder 1
9, a latch circuit 20, a memory (conversion table) 21, and a D / A converter 22. Further, the AGC control unit 3B has a fading cycle detection unit 25,
In the fading cycle detecting section 25, the input signal S1
CPU 15b based on the fading cycle detected from
Is used to control the variable multiplier 18.

The fading cycle detecting section 25 constituting the fading cycle detecting means is a circuit generally provided in a mobile communication device such as a cellular type cellular phone, and can detect the cycle of the level fluctuation (fading) of the received signal. Any material can be used. By this fading detection, it is possible to determine whether or not the base station of the cell is far from the mobile station, and it is possible to appropriately control the operation of receiving radio waves from the base stations of surrounding cells to be performed in preparation for handover. In this embodiment, this fading cycle detection is applied to the setting of the loop gain in the AGC operation.

Next, the AGC operation of the second embodiment will be described. FIG. 4 is a flowchart showing a processing procedure in the AGC operation of the second embodiment. 3 and 4, the operations of the variable gain amplifier 1 and the demodulator 2 are the same as those of the first embodiment shown in FIG. Further, the operation from the detection circuit 12 to the D / A converter 22 in the AGC control unit 3B (steps S40 and S41) is the same as in the first embodiment shown in FIG. That is, the detection voltage from the detection circuit 12 is converted into a digital signal by the A / D converter 16 and then input to the adder 17. At this time, the fading cycle detector 25 detects the fading cycle from the input signal S1 and sends it to the CPU 15b (step S5).
42: Fading cycle detection step).

The adder 17 includes an A / D converter 16
A difference value is generated by adding the detection voltage value output from the above and the target convergence value S2 (step S43). And CP
U15b controls the variable multiplier 18 based on the fading cycle, and performs variable multiplication of the difference value by the variable multiplier 18 (step S44: variable multiplication step). The variable multiplication value is input to the adder 19, and the value latched in the latch circuit 20 is fed back to calculate a change value of the difference value in the adder 19 (step S4).
5). After this difference change value is latched by the latch circuit 20, it is input to the memory (conversion table) 21 and converted into an automatic gain control signal (step S46). Then, the converted automatic gain control signal is converted into an analog signal by the D / A converter 22 (step S47), and this automatic gain control signal is supplied to the gain control terminal of the variable gain amplifier 1. The variable gain amplifier 1 amplifies the input signal S1 while controlling the gain according to the automatic gain control signal.

In the second embodiment, the fading cycle detector 25 detects a fading cycle from the input signal S1 and sends it to the CPU 15b. The CPU 15b sets the amount of multiplication of the variable multiplier 18 according to the fading cycle from the fading cycle detection unit 25 so that the optimal gain can be obtained in the variable gain amplifier 1. Under the control of the variable multiplier 18, the loop gain is automatically optimized with respect to the fading cycle, and a high-speed pull-in operation is performed.

As described above, according to the second embodiment, the amplification gain of the variable gain amplifier can be set to an appropriate value in accordance with the fading period detected from the input signal S1, and the loop gain in the AGC operation is set to the input signal level. Can be automatically set to an optimum value for the fluctuation state of As a result, automatic gain control can be performed with an optimum loop gain, and even when the input signal level fluctuates at high speed, a high-speed pull-in operation that converges to the target value of automatic gain control at high speed becomes possible. .

[Third Embodiment] FIG. 5 is a block diagram showing a configuration according to a third embodiment of the present invention. The third embodiment has a variable gain amplifier 1, a demodulator 2, and an AGC controller 3C that receive an input signal S1 similar to that of the first embodiment and transmit an output signal S3. The AGC control unit 3C includes a detection circuit 12, an adder 13, a latch circuit 14, an A / D converter 16, and an adder 1 as in the first embodiment.
7, adder 19, latch circuit 20, and D / A converter 2
Two. Further, the AGC control unit 3C has a memory 21a having a plurality of conversion tables,
The configuration is such that U15c controls the memory (conversion table) 21a based on the output signals (changes in the detection voltage) of the adder 13 and the latch circuit 14. The memory (conversion table) 21a stores a plurality of conversion tables each defining a plurality of conversion methods corresponding to the amount of change in the detection voltage.
It can be selected by the control of c. The CPU 15c and the memory (conversion table) 21a constitute a conversion method selecting unit. Note that the variable multiplier 18 of the first embodiment is not provided.

Next, the AGC operation of the third embodiment will be described. FIG. 6 is a flowchart showing a processing procedure in the AGC operation of the third embodiment. 5 and 6, the operations of the variable gain amplifier 1 and the demodulator 2 are the same as those of the first embodiment shown in FIG. Further, the operation (steps S60 and S61) from the detection circuit 12 to the D / A converter 22 in the AGC control unit 3C is the same as in the first embodiment shown in FIG. That is, the detection voltage from the detection circuit 12 is converted into a digital signal by the A / D converter 16 and then input to the adder 17. At this time, the change amount of the detection voltage is calculated by the adder 13 and the latch circuit 14 and transmitted to the CPU 15c (step S62).

The adder 17 includes an A / D converter 16
A difference value is generated by adding the detection voltage value output from the step S1 and the target convergence value S2 (step S63). Then, the difference value is input to the adder 19 and the latch circuit 20
Is fed back to the adder 19.
In step S64, a change value of the difference value is calculated (step S64:
Difference change value calculation step). After the difference change value is latched by the latch circuit 20, the difference change value is input to the memory (conversion table) 21a.

At this time, the CPU 15c controls the memory (conversion table) 21a based on the detected voltage change amount, and selects an optimal conversion table in the memory (conversion table) 21a (step S65: conversion method). Selection step). Then, the difference change value is converted into an automatic gain control signal by the selected conversion table (step S66: control signal generation step). Further, the converted automatic gain control signal is converted into an analog signal by the D / A converter 22 (step S67), and this automatic gain control signal is supplied to the gain control terminal of the variable gain amplifier 1. The variable gain amplifier 1 amplifies the input signal S1 while controlling the gain according to the automatic gain control signal.

In the third embodiment, the CPU 15c operates the memory (conversion table) 21a so that the optimum gain can be obtained in the variable gain amplifier 1 in accordance with the amount of change in the detection voltage obtained by the latch circuit 14 and the adder 13. Select the optimal conversion table in. Thereby, the first
As in the embodiment, the loop gain is automatically optimized for the amount of change in the detection voltage, and the high-speed pull-in operation is performed. In this case, the automatic gain control operation can be performed with a simple configuration without using the variable multiplier 18 in the first embodiment.

As described above, according to the third embodiment, the amplification gain of the variable gain amplifier can be set to an appropriate value by selecting the conversion table according to the amount of change in the detection voltage value, and the loop in the AGC operation can be set. The gain can be automatically set to an optimum value for the fluctuation state of the input signal level. As a result, automatic gain control can be performed with an optimum loop gain, and even when the input signal level fluctuates at high speed, a high-speed pull-in operation that converges to the target value of automatic gain control at high speed becomes possible. .

[Fourth Embodiment] FIG. 7 is a block diagram showing a configuration according to a fourth embodiment of the present invention. The fourth embodiment includes a variable gain amplifier 1, a demodulator 2, and an AGC control unit 3D that receive an input signal S1 similar to that of the second embodiment and transmit an output signal S3. The AGC control unit 3D includes a detection circuit 12, an A / D
Converter 16, adder 17, adder 19, latch circuit 2
0, D / A converter 22 and fading period detecting section 2
Five. Further, the AGC control unit 3D stores a memory 21 having a plurality of conversion tables similar to the third embodiment.
b, so that the CPU 15d controls the memory (conversion table) 21b based on the output signal (fading cycle) of the fading cycle detecting unit 25.

Next, the AGC operation of the fourth embodiment will be described. FIG. 8 is a flowchart showing a processing procedure in the AGC operation of the fourth embodiment. 7 and 8, the operations of the variable gain amplifier 1 and the demodulator 2 are the same as in the second embodiment shown in FIG. Further, the operations (steps S80 and S81) from the detection circuit 12 to the D / A converter 22 in the AGC control unit 3D are the same as in the second embodiment shown in FIG. That is, the detection voltage from the detection circuit 12 is converted into a digital signal by the A / D converter 16 and then input to the adder 17. At this time, the fading cycle detector 25 detects the fading cycle from the input signal S1 and sends it to the CPU 15d (step S5).
82: Fading cycle detection step).

The adder 17 includes an A / D converter 16
Then, the difference value is generated by adding the detection voltage value output from and the target convergence value S2 (step S83). Then, the difference value is input to the adder 19 and the latch circuit 20
Is fed back to the adder 19.
In step S8, a change value of the difference value is calculated (step S8).
4). After the difference change value is latched by the latch circuit 20, the difference change value is input to the memory (conversion table) 21a.

At this time, the CPU 15d controls the memory (conversion table) 21b based on the fading cycle, and selects an optimum conversion table in the memory (conversion table) 21b (step S85: conversion method selection step). . Then, the difference change value is converted into an automatic gain control signal by the selected conversion table (step S86: control signal generation step). Further, the converted automatic gain control signal is converted into an analog signal by the D / A converter 22 (step S87), and this automatic gain control signal is supplied to the gain control terminal of the variable gain amplifier 1. The variable gain amplifier 1 amplifies the input signal S1 while controlling the gain according to the automatic gain control signal.

In the fourth embodiment, the CPU 15d selects an optimum conversion table in the memory (conversion table) 21b in accordance with the fading cycle from the fading cycle detector 25 so that the optimum gain can be obtained in the variable gain amplifier 1. I do. As a result, the loop gain is automatically optimized for the fading cycle as in the second embodiment, and the high-speed pull-in operation is performed.

In the above description, the automatic gain control signal for the variable gain amplifier 1 is obtained from the difference between the detection voltage and the target convergence value S2 by a table reference process using the memory (conversion table) 21. It can also be obtained by an arithmetic process using a conversion formula as shown in the following fifth embodiment.

[Fifth Embodiment] FIG. 9 is a block diagram showing a configuration according to a fifth embodiment of the present invention. This fifth embodiment is a modification of the first embodiment shown in FIG.
In the GC control unit 3E, a memory 27 storing a conversion formula is provided instead of a conversion table. The configuration of other parts is the same as that of the first embodiment, and the description is omitted here.

The conversion equation is obtained by expressing the above-mentioned conversion table by an equation. For example, an arithmetic circuit corresponding to the following equation expressing the gain control characteristic of the variable gain amplifier 1 is formed in the memory 27. V = aG + b (1) where V is an output signal voltage, G is a gain, and a and b are predetermined constants.

In the fifth embodiment, as in the first embodiment, the change amount of the detection voltage is calculated by the adder 13 and the latch circuit 14 and sent to the CPU 15a.
a controls the variable multiplier 18 based on the change amount of the detection voltage, and the variable multiplier 18 performs variable multiplication of the difference value. Then, the change value of the difference value is calculated by the adder 19 and the latch circuit 20 and input to the memory (conversion formula) 27, where the calculation is performed by the conversion formula of the above equation (1) to convert it into an automatic gain control signal. This automatic gain control signal is referred to as D / A
The signal is converted into an analog signal by the converter 22 and the variable gain amplifier 1 is
, The gain of the variable gain amplifier 1 is controlled in accordance with the automatic gain control signal, and the output signal S3 is stabilized.

When the automatic gain control signal is determined by the conversion formula, this conversion operation is performed by the CPU 15 or
This can be performed by a CPU of a mobile phone or the like (not shown). In this case, the memory (conversion type) 27 becomes unnecessary, and the device configuration can be simplified. In addition, a configuration using a conversion formula instead of the conversion table in the second to fourth embodiments is also possible.

According to the fifth embodiment, similarly to the first embodiment, the amplification gain of the variable gain amplifier can be set to an appropriate value according to the amount of change in the detection voltage value, and the loop gain in the AGC operation is changed to the input signal level. Can be automatically set to an optimum value for the fluctuation state of Further, since the conversion formula can reduce the amount of data, the same effect as in the first embodiment can be obtained with a memory having a smaller capacity than the memory capacity for storing the conversion table.

[0057]

As is apparent from the above description, according to the digital automatic gain control method and apparatus of the present invention, the amount of change in the detected signal obtained by detecting the amplified output signal or the fluctuation period detected from the input signal is indicated. An automatic gain control signal is generated in accordance with the fading cycle, and the gain is changed in accordance with the automatic gain control signal to perform variable gain amplification, so that the loop gain corresponding to the fluctuation width of the input signal level or the fluctuation cycle is automatically adjusted. The automatic gain control can be performed at an optimum loop gain by setting, and a high-speed pull-in operation that converges at a high speed to a target value of the automatic gain control can be performed.

Further, according to the digital automatic gain control method and apparatus of the present invention, a table reference process using a conversion table or an arithmetic process using a conversion formula is used as a conversion method of a difference change value for generating an automatic gain control signal. Thereby, it is possible to easily generate an automatic gain control signal according to the fluctuation state of the input signal. Further, it is possible to provide a digital automatic gain control unit having a degree of freedom in a circuit configuration and capable of simplifying the configuration.

Further, according to the wireless communication apparatus of the present invention,
The configuration of the digital automatic gain control device is provided in the receiving system of the wireless communication device, and the digital automatic gain control device performs automatic gain control to stabilize an output signal related to a received signal in the receiving system, thereby changing the detection voltage. Or automatically set the loop gain according to the fading cycle,
It is possible to perform automatic gain control with an optimum loop gain, perform suitable automatic gain control that quickly follows a received signal having a large fluctuation range and a high-speed fading cycle, and reduce demodulation errors.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a processing procedure in an AGC operation according to the first embodiment.

FIG. 3 is a block diagram illustrating a configuration according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure in an AGC operation of the second embodiment.

FIG. 5 is a block diagram showing a configuration according to a third embodiment of the present invention.

FIG. 6 is a flowchart showing a processing procedure in an AGC operation of the third embodiment.

FIG. 7 is a block diagram showing a configuration according to a fourth embodiment of the present invention.

FIG. 8 is a flowchart illustrating a processing procedure in an AGC operation according to a fourth embodiment.

FIG. 9 is a block diagram showing a configuration according to a fifth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 gain variable amplifier 2 demodulator 3A to 3E AGC control unit 12 detection circuit 13, 17, 19 adder 14, 20 latch circuit 15a to 15d CPU 16 A / D converter 17 adder 18 variable multiplier 21, 21a memory ( Conversion table) 22 D / A converter 25 Fading period detection unit 27 Memory (conversion formula) S1 input signal S2 target convergence value S3 output signal

Claims (11)

[Claims] 1. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control method for obtaining a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection step of detecting the amplified output signal, and obtaining a change amount of the detection voltage A change amount calculation step, a difference value generation step of generating a difference value between the digital value of the detection voltage and a target convergence value, and a variable multiplication step of variably multiplying the difference value according to the change amount of the detection voltage. A difference change value calculating step of obtaining a change value of the variable value obtained by variably multiplying, and a control signal generating step of generating an automatic gain control signal by performing conversion according to a predetermined conversion method on the difference change value. Digital automatic gain control method. 2. A variable gain amplifier is controlled based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control method for obtaining a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection step of detecting the amplified output signal; and indicating a fluctuation cycle of the input signal. A fading period detecting step of detecting a fading period, a difference value generating step of generating a difference value between a digital value of the detection voltage and a target convergence value, and a variable multiplying step of variably multiplying the difference value according to the fading period. And a control signal generation step of performing a conversion according to a predetermined conversion method on the difference change value to generate an automatic gain control signal. A digital automatic gain control method. 3. A variable gain amplifier is controlled based on the level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control method for obtaining a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection step of detecting the amplified output signal, and obtaining a change amount of the detection voltage A change amount calculation step, a difference value generation step of generating a difference value between the digital value of the detection voltage and a target convergence value, a difference change value calculation step of obtaining a change value of the difference value, and converting the difference change value A conversion method for selecting a conversion method to be performed from a plurality of conversion methods in accordance with the amount of change in the detection voltage, and a control signal for converting the difference change value by the selected conversion method to generate an automatic gain control signal. A digital automatic gain control method, comprising: 4. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control method for obtaining a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection step of detecting the amplified output signal; and indicating a fluctuation cycle of the input signal. A fading cycle detecting step of detecting a fading cycle, a difference value generating step of generating a difference value between a digital value of the detection voltage and a target convergence value, a difference change value calculating step of obtaining a change value of the difference value, A conversion method selecting step of selecting a conversion method for converting a difference change value from a plurality of conversion methods in accordance with the fading cycle; and converting the difference change value by the selected conversion method to generate an automatic gain control signal. A digital automatic gain control method, comprising: a control signal generating step. 5. The method according to claim 1, wherein a conversion process of the difference change value for generating the automatic gain control signal is performed by a table reference process using a conversion table or an arithmetic process using a conversion formula. A digital automatic gain control method according to any one of claims 1 to 3. 6. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control device that obtains a constant output signal by optimizing a loop gain of an amplification system with respect to a change in an input signal, a detection unit that detects the amplified output signal, and obtains a change amount of the detection voltage. Change amount calculation means, difference value generation means for generating a difference value between the digital value of the detection voltage and a target convergence value, and variable multiplication means for variably multiplying the difference value according to the change amount of the detection voltage. A differential change value calculating unit that obtains a change value of the variable value that is variably multiplied; and a control signal generating unit that generates an automatic gain control signal by performing conversion according to a predetermined conversion method on the differential change value. A digital automatic gain control device. 7. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control device that obtains a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection unit that detects the amplified output signal, and a fluctuation cycle of the input signal. Fading cycle detecting means for detecting a fading cycle, difference value generating means for generating a difference value between the digital value of the detection voltage and a target convergence value, and variable multiplying means for variably multiplying the difference value according to the fading cycle. And a control signal generating means for performing a conversion according to a predetermined conversion method on the differential change value to generate an automatic gain control signal. Digital automatic gain control device. 8. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control device that obtains a constant output signal by optimizing a loop gain of an amplification system with respect to a change in an input signal, a detection unit that detects the amplified output signal, and obtains a change amount of the detection voltage. Change amount calculation means, difference value generation means for generating a difference value between the digital value of the detection voltage and a target convergence value, difference change value calculation means for obtaining a change value of the difference value, and converting the difference change value Conversion method selecting means for selecting a conversion method to be performed from a plurality of conversion methods according to the amount of change in the detection voltage, and a control signal for converting the difference change value by the selected conversion method to generate an automatic gain control signal. A digital automatic gain control device, comprising: generating means. 9. A variable gain amplifier is controlled based on a level of an output signal obtained by amplifying an input signal by the variable gain amplifier,
In a digital automatic gain control device that obtains a constant output signal by optimizing a loop gain of an amplification system with respect to a fluctuation of an input signal, a detection unit that detects the amplified output signal, and a fluctuation cycle of the input signal. A fading period detecting unit that detects a fading period, a difference value generating unit that generates a difference value between a digital value of the detection voltage and a target convergence value, a difference change value calculating unit that obtains a change value of the difference value, A conversion method selecting means for selecting a conversion method for converting a difference change value from a plurality of conversion methods in accordance with the fading cycle; and converting the difference change value by the selected conversion method to generate an automatic gain control signal. A digital automatic gain control device, comprising: control signal generation means. 10. The apparatus according to claim 6, further comprising a conversion table indicating a conversion method of a difference change value for generating the automatic gain control signal, or a memory unit for storing the conversion equation. A digital automatic gain control device according to claim 1. 11. A receiving system comprising a configuration of the digital automatic gain control device according to any one of claims 6 to 9,
A wireless communication device having an automatic gain control function, wherein the digital automatic gain control device performs automatic gain control for stabilizing an output signal relating to a received signal in the receiving system.