JPH0548500A - Amplitude equalizer - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of an output signal level due to a change in amplitude equalization or ambient temperature in the amplitude variable equalizer. CONSTITUTION:The equalizer is provided with a memory 7 fetching amplitude equalization information and ambient temperature information and outputting a data, a D/A converter 6 converting the data in the memory into a control current, an amplitude variable equalizer 1 varying the amplitude equalization quantity by the control current and a gain variable section whose gain is controlled based on each information, and the gain variable section consists of a 2nd memory 9 fetching each information and outputting a data, a 2nd D/A converter 8 converting the data into a control current and a gain variable amplifier 5 controlling the gain of an output signal level of the amplitude variable equalizer 1 based on the control current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplitude equalizer for correcting the slope of the amplitude frequency characteristic caused by a transmission cable.

[0002]

2. Description of the Related Art A conventional amplitude equalizer is shown in FIG. The variable amplitude equalizer 1 has a pin diode 4 at one end.
Has a transmission line 3 terminated with a buffer amplifier 2 for impedance matching and input / output level setting before and after the transmission line 3.
Has been inserted. By changing the current flowing through the pin diode 4, the terminating resistance value of the transmission line 3 is changed, and the reflection of the signal there is used to give the output signal an amplitude-frequency characteristic with a first-order slope to perform amplitude equalization. ing.

The memory 6 fetches the amplitude equalization amount information and the environmental temperature information to be set as an address, and changes the amplitude equalization amount depending on the temperature so that the amplitude equalization amount given corresponding to this address is obtained. Output the data with minute correction.
This data is converted into a control current by the D / A converter 5 and supplied to the pin diode 4 of the amplitude variable equalizer 1 to change its high frequency resistance and control the amplitude equalization amount.

[0004]

Since such a conventional amplitude equalizer uses the reflection in the transmission line 3,
As shown in FIG. 3, when the amplitude equalization amount is changed, there is a problem that the slope of the amplitude frequency characteristic is changed and the output signal level of the amplitude variable equalizer 1 is changed accordingly. or,
The fluctuation of the output signal level due to the ambient temperature also differs depending on the amount of amplitude equalization. Therefore, it is difficult to keep the output signal level of the amplitude equalizer constant.
An object of the present invention is to provide an amplitude equalizer that prevents fluctuations in the output signal level due to changes in the amplitude equalization amount or the environmental temperature in the amplitude variable equalizer.

[0005]

The amplitude equalizer of the present invention comprises:
A memory that takes in amplitude equalization amount information and environmental temperature information and outputs data corresponding to these information, a D / A converter that converts this data into a control current, and the amplitude equalization amount can be changed by this control current The variable amplitude equalizer, and the gain variable unit that controls the gain of the output signal level of the variable amplitude equalizer according to the amplitude equalization amount information and the environmental temperature information. Here, the gain varying unit receives the amplitude equalization amount information and the environmental temperature information and outputs data corresponding to these information, and a second memory that converts this data into a control current.
And a variable gain amplifier whose gain is controlled by the control current from the second D / A converter and which is connected to the output side of the variable amplitude equalizer.

[0006]

According to the present invention, by controlling the gain of the variable gain section according to the amplitude equalization amount and the temperature change, the fluctuation of the output signal level generated in the variable amplitude equalizer is eliminated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.
The amplitude variable equalizer 1 is configured in the same manner as the conventional one, and one end of the transmission line 3 is terminated by a pin diode 4, and a buffer amplifier 2 for impedance matching and input / output level setting is inserted before and after the pin diode 4. There is. Further, the memory 7 outputs data corresponding to the inputted amplitude equalization amount information and environmental temperature information, and the D / A converter 6 outputs a control current based on the data output from the memory 7. Then, the termination resistance value is changed by supplying the control current obtained on the basis of each of the above information to the pin diode 4, and the reflection frequency of the signal there is used to provide the output signal with the amplitude frequency characteristic of the primary slope. Then, the amplitude equalization is performed based on this amplitude frequency characteristic.

Further, in this configuration, the second memory is arranged in parallel with the memory 7.
The memory 9 is connected, and the second D / is connected to the output side of the second memory.
The A converter 8 is connected. On the other hand, a variable gain amplifier 5 is connected to the output of the variable amplitude equalizer 1, and the output of the second D / A converter 8 is supplied to the gain control terminal of the variable gain amplifier 5. ..

According to this configuration, the memory 7 outputs data corresponding to the amplitude equalization amount information and the environmental temperature information, and D /
The A converter 6 outputs a control current based on this data,
Applying this control current to the pin diode 4 changes the termination resistance value of the transmission line 3 and performs amplitude equalization according to the obtained amplitude frequency characteristic, as in the past. At the same time, the second memory 9 corrects the change in the amplitude equalization amount generated in the amplitude variable equalizer 1 and the change in the output signal level due to the temperature change, corresponding to the amplitude equalization amount information and the environmental temperature information. Output data for the second D / A
The converter 8 outputs a control current based on this data, and the gain of the variable gain amplifier 5 is controlled by this control current.
Therefore, fluctuations in the output signal level caused by changes in the amplitude equalization amount and changes in temperature in the amplitude variable equalizer 1 are eliminated by the gain variable amplifier 5 whose gain is controlled by the control current obtained by following these changes. Will be.

[0010]

As described above, the present invention is provided with the gain variable section whose gain is changed based on the amplitude equalization amount information and the environmental temperature information, and the output signal of the amplitude variable equalizer is provided by this gain variable section. Since the gain of the level is controlled, the fluctuation of the signal level due to the amount of amplitude equalization in the variable amplitude equalizer or the temperature can be corrected. As a result, the amplitude variable equalizer can pursue the amplitude equalization function without being particularly limited by the fluctuation of the signal level.
This has the effect of enabling highly accurate amplitude equalization and improving stability against temperature changes.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an amplitude equalizer of the present invention.

FIG. 2 is a block diagram of a conventional amplitude equalizer.

FIG. 3 is an amplitude frequency characteristic diagram in the variable amplitude equalizer.

[Explanation of symbols]

 1 Amplitude Variable Equalizer 3 Transmission Line 4 Pin Diode 5 Gain Variable Amplifier 6 D / A Converter 7 Memory 8 Second D / A Converter 9 Second Memory

Claims (2)

[Claims] 1. A memory for taking in amplitude equalization amount information and environmental temperature information and outputting data corresponding to these information, and a D / A converter for converting this data into a control current.
An amplitude variable equalizer for varying the amplitude equalization amount by the control current, and a gain variable unit for controlling the gain of the output signal level of the amplitude variable equalizer according to the amplitude equalization amount information and the environmental temperature information. An amplitude equalizer, comprising: 2. The variable gain section includes a second memory which takes in the amplitude equalization amount information and the environmental temperature information and outputs data corresponding to these information, and a second D which converts the data into a control current. The A / A converter and a variable gain amplifier connected to the output side of the amplitude variable equalizer and having a gain controlled by a control current from the second D / A converter. Amplitude equalizer.