JP2001036365A - Agc amplifying circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the gain of an AGC amplifier by a single control signal by selecting an output, after processing output signals of AGC amplifiers amplifying an input signal by a gain corresponding to a gain control signal at plural signal processing circuits, according to the control signal and using it as gain control signals of the AGC amplifier. SOLUTION: An AGC amplifier 1 controls and amplifies the gain of an input signal according to a control signal from an AGC control circuit 2 and outputs it to a low-pass filter(LPF) 3, an A/D conversion circuit 4 and a digital signal processing circuit 5 in this order. The AGC control circuit 2 selects each output of either the LPF 3, the A/D conversion circuit 4 or the processing circuit 5 by a control signal from a main control circuit 6, and uses it as the control signal of the AGC amplifier 1. That is, an AGC control circuit 4 controls the selection, each inner characteristic or the like of AGC control loops L1 to L3 and controls the AGC amplifier 1. Thus, it is possible to control the gain of the AGC amplifier 1 and plural AGC control loops by a single control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AGC amplifier circuit, and more particularly, to an AGC (Automatic Gauge) circuit for amplifying input signals.
An AGC control circuit that adjusts the gain of an amplifier by adjusting the gain of a plurality of AGC control loops with a single control signal, so that it is suitable for use in communication devices and recording / reproducing devices. About.

[0002]

2. Description of the Related Art An AGC control circuit controls the gain of an AGC amplifier. Hereinafter, an example of a conventional AGC amplifier circuit including an AGC amplifier and an AGC control circuit will be described.

FIG. 7 shows a conventional AGC amplifier circuit, and FIG. 7 (a) shows an AGC amplifier circuit having an AGC control circuit for controlling gain using an analog circuit.
FIG. 7 (b) shows a case where the gain is controlled using a digital circuit.
1 shows an AGC amplifier circuit having a GC control circuit.

In FIG. 7A, reference numeral 1 denotes an AGC amplifier whose gain is controlled in accordance with a control voltage from a control voltage generating circuit 7, and 3 denotes a low-pass filter that passes only low-frequency components included in the output of the AGC amplifier 1. A band-pass filter (hereinafter referred to as LPF), 7 is a control voltage generating circuit for generating a control voltage for the AGC amplifier 1 in accordance with the output of the LPF 3, 6 is a control voltage generating circuit 7, and the AGC amplifier circuit is turned on. , OFF, and the like, and the LPF 3 and the control voltage generation circuit 7 constitute a conventional AGC control circuit 260.

In FIG. 7B, reference numeral 1 denotes an AG whose gain is controlled according to a control signal from a D / A conversion circuit 9.
C amplifier 4, 4 A / D conversion circuit for A / D converting the output of AGC amplifier 1, 8 a level detector for detecting the output level of A / D conversion circuit 4, and 9 the output of level detector 8 to D
/ A is converted and applied to the AGC amplifier 1 as a control signal.
A / D conversion circuit, the A / D conversion circuit 4, the level detector 8 and the D / A conversion circuit 9 enable other conventional A / D conversion circuits.
A GC control circuit 300 is configured.

The operation of the conventional AGC amplifier configured as described above will be described below. FIG. 7 (a)
Has an AGC control circuit 260 for controlling the gain using an analog circuit. The AGC control circuit 260 detects the level of the output of the LPF 3 by the control voltage generation circuit 7 and responds to the level. Generate control voltage. Then, by adjusting the gain of the AGC amplifier 1 in accordance with the control voltage output from the control voltage generating circuit 7, a desired value is obtained from the LPF 3 as an output signal of the present AGC amplifier circuit. In addition, the main control circuit 6
The AGC characteristic is controlled by controlling various characteristics such as turning on / off the operation of the AGC amplifier circuit and setting an initial value of an output signal of the control voltage circuit 7 by a control command from a CPU (not shown). Is controlled.

The AGC amplifier circuit shown in FIG. 7B has an AGC control circuit 300 for controlling the gain using a digital signal. , And compares the output level with a desired output value of the present AGC amplifier circuit, which is set in the level detector 8 in advance, and outputs a digital signal indicating the difference between the two. The output of this level detector 8 is D
A / A conversion circuit 9 converts a digital signal into an analog signal to generate a control voltage. The gain of the AGC amplifier 1 is adjusted by the control voltage output from the D / A conversion circuit 9, and the AGC amplifier is controlled so that a desired output signal is obtained.

[0008]

The conventional AGC amplifier circuit is configured as described above, and it is possible to obtain a desired output signal by controlling the gain of the AGC amplifier so as to be appropriately changed. However, in the AGC amplifier circuit, for example, selection of an AGC control loop using an analog signal or an AGC control loop using a plurality of digital signals is performed in accordance with the type of target signal processing. You need to select a control loop. In some cases, it may be necessary to switch loops during signal processing.

However, in the above-described conventional AGC amplifier circuit, the AGC control circuit only controls one AGC control loop including the AGC control circuit, and a single AGC control circuit uses a control loop using an analog signal or a digital signal. Control of multiple loops such as a control loop using
In addition, there is a problem that selection and switching of the control loop cannot be realized.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above. A plurality of loops can be controlled by a single AGC control circuit, and control loop selection and switching are also realized. It is an object of the present invention to obtain an AGC amplifier circuit that can be used.

[0011]

According to the first aspect of the present invention, there is provided A
The GC amplifier circuit includes a single AGC amplifier for amplifying an input signal with a gain corresponding to a gain control signal, a plurality of signal processing circuits for processing a signal output from the AGC amplifier, and a single control input terminal. And an AGC control circuit for selecting the outputs of the plurality of signal processing circuits according to the control signal and outputting the gain control signal to the AGC amplifier. A according to claim 1 of the present application
According to the GC amplifier circuit, since the AGC control circuit that adjusts the gain of the AGC amplifier with a single control signal is provided, it is possible to adjust the gain of the AGC amplifier with a single control signal.

An AGC amplifier circuit according to a second aspect of the present invention includes a single AGC amplifier for amplifying an input signal with a gain corresponding to a gain control signal, and a plurality of AGC amplifiers for processing a signal output from the AGC amplifier. A signal processing circuit; and an AGC control circuit for selecting outputs of the plurality of signal processing circuits according to an input signal of the AGC amplifier and outputting the gain control signal to the AGC amplifier. is there. According to the AGC amplifier circuit of the present invention, since the AGC control circuit for adjusting the gain of the AGC amplifier according to the input signal of the AGC amplifier is provided, the gain of the AGC amplifier can be adjusted with a single control signal. Is realized.

According to a third aspect of the present invention, there is provided the AGC amplifier circuit according to the first or second aspect, wherein the plurality of signal processing circuits are a low-pass filter and an A / D connected in series with each other. And a digital signal processing circuit.
The output of the GC amplifier is input, the output of the digital signal processing circuit becomes the output of the present AGC amplifier circuit, and
Each output of the low-pass filter, the A / D converter, and the digital signal processing circuit is input to the GC control circuit. According to the AGC amplifier circuit of the present invention, the plurality of signal processing circuits include a low-pass filter, an A / D converter, and a digital signal processing circuit, and the AGC control circuit includes a plurality of AGC control loops. Since the outputs of the low-pass filter, the A / D converter, and the digital signal processing circuit constituting the above are input, it is possible to control a plurality of AGC control loops with a single control signal.

The AGC amplifier circuit according to claim 4 of the present application is the AGC amplifier circuit according to claim 3, wherein
The GC control circuit receives the outputs of the A / D converter and the digital signal processing circuit as inputs, and detects the levels of the outputs of the A / D converter and the digital signal processing circuit, respectively.
The first and second level detectors performed before the output of the AGC control circuit is selected, and the respective characteristics of the first and second level detectors are input from a single control input terminal. And a level detection characteristic control circuit for controlling according to a control signal. According to the AGC amplifier circuit described in claim 4 of the present application, in the AGC control circuit for adjusting the gain of the AGC amplifier, the timing adjustment circuit is provided, so that the desired adjustment of the AGC control timing can be realized by a single control signal. You.

Further, the AGC amplifier circuit according to claim 5 of the present application is the AGC amplifier circuit according to claim 3,
The GC control circuit receives the output of the A / D converter and the digital signal processing circuit as an input, and adjusts the timing of AGC amplifier control by the output of the A / D converter and the digital signal processing circuit. The first and second timing adjustment circuits, which are performed before the output of the digital signal processing circuit is selected, and the characteristics of each of the first and second timing adjustment circuits are changed from a single control input terminal. And a timing adjustment characteristic control circuit for controlling according to the control signal. According to the AGC amplifier circuit of the present invention, since the D / A converter is provided in the AGC control circuit for adjusting the gain of the AGC amplifier, the gain of the D / A converter is adjusted with a single control signal. Is realized.

The AGC amplifier circuit according to claim 6 of the present application is the AGC amplifier circuit according to claim 3, wherein
The GC control circuit receives an output of the A / D converter and the digital signal processing circuit as an input, and converts a level value detected from an output of the A / D converter and the digital signal processing circuit into an analog value. A converter and a D / A conversion characteristic control circuit for controlling the characteristics of the D / A converter in accordance with a control signal input from a single control input terminal are provided. According to the AGC amplifier circuit described in claim 6 of the present application, in the AGC control circuit for adjusting the gain of the AGC amplifier, the control circuit for controlling the tracking speed is provided. Is achieved.

The AGC amplifier circuit according to claim 7 of the present application is the AGC amplifier circuit according to claim 3, wherein
The GC control circuit outputs the output of the low-pass filter and A /
An output of a D converter, a signal based on an output of a digital signal processing circuit as an input, a control filter that generates a gain control signal by performing a filter process, the control filter,
A tracking speed control circuit that controls a tracking speed of the gain control signal by controlling the control signal in accordance with a control signal input from a single control input terminal.
According to the AGC amplifier circuit described in claim 7 of the present application, AGC
In the AGC control circuit for adjusting the gain of the amplifier, a single control signal input terminal is provided.
Controlling the tracking speed of the GC control is realized.

An AGC amplifier circuit according to claim 8 of the present application is the AGC amplifier circuit according to claim 3, wherein
The GC control circuit receives the outputs of the A / D converter and the digital signal processing circuit as inputs, and performs first and second level detection for detecting the levels of the outputs of the A / D converter and the digital signal processing circuit, respectively. And first and second timing adjustments for inputting the outputs of the first and second level detectors and adjusting the AGC amplifier control timing by the outputs of the A / D converter and the digital signal processing circuit A first selection circuit for selecting one of the outputs of the first and second timing adjustment circuits, and a D / A converter for converting an output level value of the first selection circuit into an analog value. A second selection circuit for selecting one of the output of the low-pass filter and the output of the D / A converter, and performing a filtering process on the output of the second selection circuit to perform the gain control. A control filter for generating a signal, the first and second level detectors, a first and second timing adjustment circuit, a first selection circuit, a D / A converter, a second selection circuit, and a control filter. , And an internal control circuit for controlling according to a control signal input from a single control input terminal. According to the AGC control circuit of the present invention, since a single control signal input terminal is provided in the AGC control circuit for adjusting the gain of the AGC amplifier, a desired AGC control loop is selected by a single control signal. , The characteristics of the level detector, the adjustment of the timing of the AGC control, the adjustment of the gain of the D / A converter, and the control of the following speed of the AGC control are realized.

According to a ninth aspect of the present invention, there is provided the AGC amplifier circuit according to the eighth aspect, wherein the AGC control circuit holds an output of the control filter and outputs the held signal as the gain control signal. A circuit, wherein the internal control circuit also controls the hold circuit in accordance with a control signal input from the single control input terminal. AGC according to claim 9 of the present application
According to the amplifier circuit, the AG that adjusts the gain of the AGC amplifier
In the C control circuit, a hold determination circuit is provided.
Select a desired AGC control loop with a single control signal, adjust the characteristics of the level detector, adjust the timing of AGC control,
Adjustment of the gain of the A-converter, control of the tracking speed of the AGC control, and control of the gain holding of the AGC amplifier are realized.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) AGC according to Embodiment 1 of the present invention
The amplifier circuit will be described with reference to FIGS. FIG. 1 shows an AGC amplifier circuit according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an AGC amplifier whose gain is controlled in accordance with a control signal from an AGC control circuit 2;
Denotes an AGC control circuit according to the first embodiment, and an AGC amplifier 1 based on at least one output of a low-pass filter 3, an A / D conversion circuit 4, and a digital signal processing circuit 5.
Control. Reference numeral 3 denotes a low-pass filter (hereinafter, referred to as LPF) that passes a low-frequency component of the output of the AGC amplifier 1, 4 denotes an A / D conversion circuit that A / D-converts the output of the low-pass filter 3, and 5 denotes A And a digital signal processing circuit for performing digital signal processing on the output of the / D conversion circuit 4.
3, the A / D conversion circuit 4 and the digital signal processing circuit 5 constitute a plurality of signal processing circuits for processing the output of the AGC amplifier 1. Reference numeral 6 denotes a main control circuit that controls the AGC control circuit 2.

Next, the operation will be described. As shown in FIG. 1, the AGC amplifier 1 amplifies an input signal which is an analog signal, and removes a high frequency component from an output signal of the AGC amplifier 1 using a low-pass filter 3. The output of the low-pass filter 3 is converted into a digital signal using an A / D conversion circuit 4 and output to a digital signal processing circuit 5. The digital signal processing circuit 5 performs required digital signal processing, and outputs the digital signal after the signal processing to the outside. When the AGC amplifier circuit in FIG. 1 is, for example, a front-end circuit that processes a signal acquired by a head of a hard disk drive, the digital signal processing circuit 5 performs processing of a read channel or the like.

In the AGC amplifier circuit shown in FIG.
There are three AGC gain control loops, and the first is a first AGC control loop L1 that performs control using the output (analog signal) of the low-pass filter 3, which is an AG control loop.
It comprises a C amplifier 1, an LPF 3, and an AGC control circuit 2. The second system is a second AGC control loop L2 that performs control using the output (digital signal) of the A / D conversion circuit 4.
This comprises an AGC amplifier 1, an LPF 3, an A / D conversion circuit 4, and an AGC control circuit 2. The third system is a third AGC control loop L3 that performs control using the output (digital signal) of the signal processing of the digital signal processing circuit 5.
It comprises an AGC amplifier 1, an LPF 3, an A / D conversion circuit 4, a digital signal processing circuit 5, and an AGC control circuit 2.

The AGC control circuit 2 is controlled by one control signal line from the main control circuit 6, and the three A
It controls selection of the GC control loops L1, L2, and L3, and controls various characteristics inside the AGC control loop, and outputs a control signal for the AGC amplifier 1. The AGC control circuit 2 controls the three AGC control loops L1, L2, and A3 based on the AGC amplifier control signal so that a desired value is obtained at the output of the AGC amplifier circuit.
The AGC amplifier 1 is controlled by controlling L3.

FIG. 2 is a diagram showing the internal configuration of the AGC control circuit 2 of FIG. In the figure, reference numerals 8a and 8b denote level detectors for detecting the output levels of the A / D conversion circuit 4 and the digital signal processing circuit 5 in FIG. 1, respectively, and reference numerals 10a and 10b adjust the output timings of these level detectors 8a and 8b. 1b, a selection circuit for selecting one of the outputs of the timing adjustment circuits 10a and 10b, 9 a D / A conversion circuit for D / A conversion of the output of the selection circuit 13b, and 14 a FIG. A rectifier 13a rectifies the output of the LPF 3 of FIG.
A selection circuit for selecting one of the outputs of the A conversion circuit 9, a control filter 11 for performing a filtering process on an output of the selection circuit 13a, and a control filter 12 for the main control circuit 6 in FIG.
Encodes one control input (analog signal) input to the AGC control circuit 2 from the control filter 11,
A plurality of control signals (digital signals) to be output to the selection circuit 13a, the D / A conversion circuit 9, the rectifier 14, the selection circuit 13b, the timing adjustment circuit 10a, the timing adjustment circuit 10b, the level detector 8a, and the level detector 8b. Is an encoder that generates.

FIG. 3 shows an example of the configuration of the encoder of FIG.
FIG. 3 (a) shows a case where this is composed only of an A / D converter 12a, and FIG. 3 (b) shows a case where this is composed of an A / D converter 12a and a subsequent encoder main body 12b.
3C shows a case where the encoder body of FIG. 3B is configured by the ROM 12c.

Next, the operation will be described. Encoder 1
When the selecting circuit 13a selects the first AGC control loop L1 based on the output of the rectifier 2, the rectifier 14 rectifies the output of the LPF 3 of FIG. 1 and detects the level. The control filter 11 outputs an AGC amplifier control signal according to the output of the rectifier 14.

The selection circuits 13a and 13b are connected to the second
When the AGC control loop L2 is selected, the level detector 8a detects and outputs the level of the output of the A / D converter 4. The output of the level detector 8a is output to the timing adjustment circuit 1
0a is adjusted by the same circuit 10a and selected by the selection circuit 13b.
The signal is converted into an analog signal by the / A converter 9. The control filter 11 outputs an AGC amplifier control signal according to the output of the D / A converter 9.

Further, when the selection circuits 13a and 13b select the third AGC control loop L3, the level detector 8b detects and outputs the output level of the digital signal processing circuit 5. The timing at which the output of the level detector 8b is output from the timing adjustment circuit 10b is adjusted by the timing adjustment circuit 10b, selected by the selection circuit 13b, and then converted by the D / A converter 9 into an analog signal. The control filter 11 outputs an AGC amplifier control signal according to the output of the D / A converter 9.

The encoder 12 converts a control signal of the main control circuit 6 shown in FIG. 1 which is inputted as a single control signal (analog signal) to a control input terminal of the AGC control circuit 2 into a plurality of control signals based on the voltage. Encode into a signal (digital signal). Therefore, if a digital signal converted by a linear conversion characteristic with respect to a change in analog voltage can be used as a control signal as it is, the encoder 12
As shown in FIG. 3A, A having a linear conversion characteristic
It can be constituted only by the / D converter 12a. If non-linear characteristics are required as input / output characteristics of the encoder 12, as shown in FIG. 3 (b), the output of the encoder 12 is made non-linear at the subsequent stage of the A / D converter 12a having linear conversion characteristics. The encoder main body 12b may be provided, and when an A / D converter having a non-linear conversion characteristic is selected and used, the state shown in FIG. The encoder body is, for example, as shown in FIG.
It can be constituted by the ROM 12c.

The plurality of control signals encoded by the encoder 12 are represented by dashed arrows in FIG.
The characteristics of the level detectors 8a and 8b, the gain adjustment of the D / A converter 9, that is, the adjustment of the output dynamic range with respect to the change width of the input value, the timing adjustment circuit 10a,
10b timing adjustment circuit set value, control filter 11
The following speed of the AGC amplifier control signal, the selection circuit 13a,
The control of the selection of the signal 13b and the characteristics of the rectifier 14 are controlled so that the characteristics of each AGC control loop can obtain the optimum values of gain, timing, and following speed.

Therefore, the encoder 12 is connected to the level detector 8
a level detection characteristic control circuit for controlling the characteristics of a and 8b, a timing adjustment characteristic control circuit for controlling the characteristics of the timing adjustment circuits 10a and 10b, a D / A conversion characteristic control circuit for controlling the characteristics of the D / A converter 9, A tracking speed control circuit for controlling the tracking speed of the AGC amplifier control signal by controlling the control filter 11, and in addition to these controls, the selection circuits 13a and 13b also control the operation of selecting the signal, thereby performing AGC control. It corresponds to any of the internal control circuits that also control, select and switch the loop.

Here, the following speed of the AGC amplifier control signal is a speed at which the output signal of the AGC amplifier reaches a desired value by the AGC amplifier control signal. This following speed is
The optimum speed differs depending on various data modes (servo mode, data mode, etc.), data transfer speed, recording media, communication system, and the like. In the first embodiment, the following speed can be changed according to each state of the reproduction system.

The characteristic of the D / A conversion circuit 9 is one of the important factors for determining the AGC loop characteristic.
It is desirable to change the characteristics of the D / A conversion circuit 9 so that the characteristics of the control loop can obtain an optimum value. In the first embodiment, the characteristics of the D / A conversion circuit 9 can be changed according to each state of the reproduction system by appropriately setting the control signal from the main control circuit 6 in FIG. is there.

With such a configuration, the AGC amplifier circuit according to the first embodiment enables selection of a plurality of AGC control loops, and furthermore, the characteristics of each level detector,
It is possible to adjust the timing of the AGC control, adjust the gain of the D / A conversion circuit, and control the follow-up speed of the AGC control with a single control signal, and various control loops can be selected with a single AGC control circuit. Thus, the number of control input terminals can be reduced.

(Embodiment 2) Embodiment 2 of the present invention
Will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 shows an AGC amplifier circuit according to Embodiment 2 of the present invention. In FIG. 1, the AGC control circuit 2 receives a control signal from the main control circuit 6, but in FIG. Instead, the input to the AGC amplifier 1 is also used as a control signal for the AGC control circuit 2 and the main control circuit 6 is omitted.

FIG. 5 shows an AGC according to the second embodiment of the present invention.
FIG. 3 shows a configuration of a control circuit. In the figure, the same reference numerals as those in FIG. 2 denote the same components. Reference numeral 15 denotes an input signal determination circuit that determines the type of an input signal input to the AGC control circuit, and can be configured similarly to the encoder 12 shown in FIG. 5, the description of the same components as those shown in FIG. 2 is omitted.

The difference between the configuration of FIG. 5 and the first embodiment will be described. The input signal of AGC amplifier 1 is determined as a control signal instead of encoder 12 receiving a control signal from main control circuit 6 of FIG. That is, an input signal determination circuit 15 is used. The input signal of the AGC amplifier varies depending on the type of the recording medium, the communication method, the method of the recording method, and each mode of the input signal. For such various input signals, the AGC control loop requires a corresponding control loop. For this reason, the type of the desired input signal is determined using the input signal determination circuit 15 and the corresponding control signal is output. The control signal output by the input signal determination circuit 15 is
a, 8b characteristics, gain adjustment of D / A converter 9, timing adjustment circuit set values of timing adjustment circuits 10a, 10b, tracking speed of AGC amplifier control signal of control filter 11, selection of signals of selection circuits 13a, 13b Rectifier 14
Are controlled individually so that each AGC control loop has desired characteristics.

With such a configuration, the AGC
Selection of control loop, adjustment of characteristics of each level detector, adjustment of AGC control timing, adjustment of gain of D / A converter 9, AG
The follow-up speed of the C control can be controlled according to the input signal, so that external control such as a main control circuit is not required.

(Embodiment 3) Embodiment 3 of the present invention
Will be described with reference to FIG. FIG.
Denotes an AGC control circuit according to the third embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 2 and 5 denote the same components. Reference numeral 16 denotes a hold circuit that holds the output of the control filter 11. 6, FIG. 2 and FIG.
The description of the operation of the same components as those shown in FIG.

The difference of the third embodiment from the second embodiment is that the third embodiment is provided with a hold circuit 16 which receives an output of the control filter 11 and outputs an AGC amplifier control signal. Reference numeral 15 is a point at which a control signal for the hold circuit 16 is generated.

The input signal of the AGC amplifier varies depending on the type of the recording medium, the communication system, the method of the recording system, and each mode of the input signal. Sometimes it is better to keep the gain. Therefore, the type of the input signal is determined using the input signal determination circuit 15 and the AGC
And the gain control of the AGC.

With such a configuration, the AGC
Gain control and AGC gain hold can be controlled in accordance with an input signal, thereby preventing data reproduction errors that may occur when AGC gain control is performed on unnecessary data. Can be.

In the first embodiment, as in the third embodiment, a hold circuit may be provided. As in the third embodiment, AGC gain adjustment for unnecessary data is performed. , It is possible to prevent data from being erroneously reproduced when it is performed.

[0044]

As described above, according to the first aspect of the present invention, A
According to the GC amplifier circuit, a single AGC amplifier for amplifying an input signal with a gain corresponding to a gain control signal, a plurality of signal processing circuits for processing a signal output from the AGC amplifier, and a single control input Selecting outputs of the plurality of signal processing circuits in accordance with a control signal from a terminal;
An AGC control circuit for outputting the gain control signal to the C amplifier is provided.
There is an effect that the gain of the C amplifier can be adjusted.

According to the AGC amplifier circuit of the present invention, a single AGC amplifier for amplifying an input signal with a gain corresponding to a gain control signal and a signal output from the AGC amplifier are processed. A plurality of signal processing circuits;
An output of the plurality of signal processing circuits is selected according to an input signal of the C amplifier, and an AGC control circuit that outputs the gain control signal to the AGC amplifier is provided. There is an effect that the gain of the AGC amplifier can be adjusted.

According to the AGC amplifier circuit of the third aspect of the present invention, in the AGC amplifier circuit of the first or second aspect, the plurality of signal processing circuits include a low-pass filter, A, connected in series with each other. / D converter and a digital signal processing circuit, wherein the output of the AGC amplifier is input to the low-pass filter, the output of the digital signal processing circuit is the output of the AGC amplifier circuit, and the AGC control circuit , The respective outputs of the low-pass filter, the A / D converter, and the digital signal processing circuit are input, so that a single control signal can control a plurality of AGC control loops. There is an effect.

According to the AGC amplifier circuit of the fourth aspect of the present invention, in the AGC amplifier circuit of the third aspect,
The AGC control circuit receives the outputs of the A / D converter and the digital signal processing circuit as inputs, and detects the respective levels of the outputs of the A / D converter and the digital signal processing circuit. First and second level detectors which are performed before being selected;
And a level detection characteristic control circuit for controlling each characteristic of the level detector according to a control signal input from a single control input terminal, so that the AGC control circuit adjusts the gain of the AGC amplifier. Thus, there is an effect that the timing of desired AGC control can be adjusted with a single control signal.

According to the AGC amplifier circuit of the fifth aspect of the present invention, in the AGC amplifier circuit of the third aspect,
The AGC control circuit receives the outputs of the A / D converter and the digital signal processing circuit as inputs, and adjusts the timing of AGC amplifier control by the outputs of the A / D converter and the digital signal processing circuit. The first and second timing adjustment circuits, which are performed before the converter and the output of the digital signal processing circuit are selected, and the characteristics of each of the first and second timing adjustment circuits are determined by a single control input terminal. And a timing adjustment characteristic control circuit for controlling according to a control signal from the AGC.
In the AGC control circuit for adjusting the gain of the amplifier, there is an effect that the gain of the D / A converter can be adjusted with a single control signal.

According to the AGC amplifier circuit of the sixth aspect of the present invention, in the AGC amplifier circuit of the third aspect,
The AGC control circuit receives an output of the A / D converter and the digital signal processing circuit as an input, and converts a level value detected from an output of the A / D converter and the digital signal processing circuit into an analog value. A converter and the D / A
A D / A conversion characteristic control circuit for controlling the characteristics of the converter in accordance with a control signal input from a single control input terminal, so that the gain of the AGC amplifier is adjusted.
In the GC control circuit, a desired AGC
There is an effect that it is possible to obtain a control follow-up speed.

According to the AGC amplifier circuit of the present invention, in the AGC amplifier circuit of the third aspect,
The AGC control circuit receives an output of the low-pass filter, an output of an A / D converter, and a signal based on an output of a digital signal processing circuit, and performs a filtering process to generate the gain control signal. A control filter for controlling the tracking speed of the gain control signal by controlling the control filter in accordance with a control signal input from a single control input terminal; In the AGC control circuit for adjusting the gain of the amplifier, there is an effect that the following speed of the AGC control can be controlled by a single control signal.

According to the AGC amplifier circuit of the eighth aspect of the present invention, in the AGC amplifier circuit of the third aspect,
The AGC control circuit receives the outputs of the A / D converter and the digital signal processing circuit as inputs, and detects first and second levels of the outputs of the A / D converter and the digital signal processing circuit, respectively. A detector and the outputs of the first and second level detectors,
AGC by output of converter and digital signal processing circuit
First and second timing adjustment circuits for adjusting the timing of amplifier control, a first selection circuit for selecting one of the outputs of the first and second timing adjustment circuits, and the first selection circuit A D / A converter for converting the output level value of the signal to an analog value, a second selection circuit for selecting one of the output of the low-pass filter and the output of the D / A converter, A control filter for performing a filtering process on an output of the selection circuit to generate the gain control signal; a first and a second level detector; a first and a second timing adjustment circuit; a first selection circuit; A / A converter, a second selection circuit, and an internal control circuit that controls the control filter in accordance with a control signal input from a single control input terminal, so that the gain of the AGC amplifier is adjusted. AGC system Since a single control signal input terminal is provided in the circuit, a desired AGC control loop is selected with a single control signal, the characteristics of the level detector, the timing of AGC control are adjusted, and the gain of the D / A converter is adjusted. This has the effect that the following speed of the AGC control can be controlled.

According to the AGC amplifier circuit of the present invention, in the AGC control circuit of the present invention, the output of the control filter is held, and the held signal is output as the gain control signal. Since the internal control circuit also controls the hold circuit in accordance with a control signal input from the single control input terminal, the desired A
Selects a GC control loop, adjusts the characteristics of the level detector, adjusts the timing of AGC control, adjusts the gain of the D / A converter,
There is an effect that the following speed of the GC control can be controlled and the gain holding of the AGC amplifier can be controlled.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an internal configuration of the AGC control circuit of FIG.

FIG. 3 is a block diagram illustrating an internal configuration of the encoder of FIG. 2;

FIG. 4 is a block diagram showing a configuration of an AGC amplifier circuit according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing an internal configuration of the AGC control circuit of FIG. 4;

FIG. 6 is a block diagram showing an internal configuration of an AGC control circuit in an AGC amplifier circuit according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional AGC amplifier circuit.

[Explanation of symbols]

 Reference Signs List 1 AGC amplifier 2 AGC control circuit 3 Low-pass filter 4 A / D converter 5 Digital signal processing circuit 6 Main control circuit 7 Control voltage generation circuit 8, 8a, 8b Level detector 9 D / A conversion circuit 10a, 10b Timing Adjustment circuit 11 Control filter 12 Encoder 13a, 13b Selection circuit 14 Rectifier 15 Input signal judgment circuit 16 Hold circuit

Claims (9)

[Claims] 1. A single AGC amplifier for amplifying an input signal with a gain according to a gain control signal, a plurality of signal processing circuits for processing a signal output from the AGC amplifier, and a single control input terminal An AGC control circuit for selecting outputs of the plurality of signal processing circuits in accordance with the control signal of (a) and outputting the gain control signal to the AGC amplifier. 2. A single AGC amplifier for amplifying an input signal with a gain corresponding to a gain control signal; a plurality of signal processing circuits for processing a signal output from the AGC amplifier; An AGC control circuit for selecting outputs of the plurality of signal processing circuits in accordance with the AGC control circuit and outputting the gain control signal to the AGC amplifier. 3. The AGC amplifier circuit according to claim 1, wherein the plurality of signal processing circuits include a low-pass filter, an A / D converter, and a digital signal processing circuit connected in series with each other. The output of the AGC amplifier is input to the low-pass filter, the output of the digital signal processing circuit is the output of the AGC amplifier circuit, and the low-pass filter, A
An AGC amplifier circuit to which respective outputs of a / D converter and a digital signal processing circuit are inputted. 4. The AGC amplifier circuit according to claim 3, wherein the AGC control circuit receives an output of the A / D converter and the digital signal processing circuit as an input, and outputs the A / D converter and the digital signal processing circuit. A first and second level detector for detecting the level of each output before the output of the AGC control circuit is selected; and a characteristic of each of the first and second level detectors, And a level detection characteristic control circuit for controlling in accordance with a control signal input from a control input terminal of the AGC amplifier. 5. The AGC amplifier circuit according to claim 3, wherein the AGC control circuit receives an output of the A / D converter and the digital signal processing circuit as an input, and outputs the A / D converter and the digital signal processing circuit. First and second timing adjustment circuits for adjusting the timing of AGC amplifier control by the output before the output of the A / D converter and the digital signal processing circuit are selected; and the first and second timing adjustment circuits. An AGC amplifier circuit comprising: a timing adjustment characteristic control circuit that controls respective characteristics of the timing adjustment circuit according to a control signal from a single control input terminal. 6. The AGC amplifier circuit according to claim 3, wherein the AGC control circuit receives an output of the A / D converter and a digital signal processing circuit as an input, and outputs the A / D converter and the digital signal processing circuit. A D / A converter for converting a level value detected from an output into an analog value; and a D / A for controlling characteristics of the D / A converter in accordance with a control signal input from a single control input terminal. An AGC amplifier circuit comprising a conversion characteristic control circuit. 7. The AGC amplifier circuit according to claim 3, wherein the AGC control circuit inputs a signal based on an output of the low-pass filter, an output of the A / D converter, and an output of the digital signal processing circuit. And a control filter that performs a filtering process to generate the gain control signal, and controls the control filter according to a control signal input from a single control input terminal to thereby increase the following speed of the gain control signal. An AGC amplifier circuit comprising a tracking speed control circuit for controlling the AGC amplifier circuit. 8. The AGC amplifier circuit according to claim 3, wherein the AGC control circuit receives an output of the A / D converter and a digital signal processing circuit as an input, and outputs the A / D converter and the digital signal processing circuit. First and second detection of the level of each output
And the inputs of the first and second level detectors as inputs,
A first and a second timing adjustment circuit for adjusting the timing of the AGC amplifier control by the outputs of the A / D converter and the digital signal processing circuit; and one of the outputs of the first and the second timing adjustment circuits. A first selection circuit for selecting, a D / A converter for converting an output level value of the first selection circuit into an analog value, and an output of the low-pass filter or an output of the D / A converter A second selection circuit for selecting whether or not, a control filter for performing a filtering process on an output of the second selection circuit to generate the gain control signal, the first and second level detectors, And a second timing adjustment circuit, a first selection circuit, a D / A converter,
An AGC amplifier circuit comprising: a second selection circuit; and an internal control circuit that controls a control filter in accordance with a control signal input from a single control input terminal. 9. The AGC control circuit according to claim 8, further comprising: a hold circuit that holds an output of said control filter, and outputs the held signal as said gain control signal. An AGC amplifier circuit that also controls the hold circuit according to a control signal input from a control input terminal of the AGC.