JPS61133712A - Two-way amplifier - Google Patents

Abstract

PURPOSE:To eliminate oscillation due to detour signal and to attain high gain by constituting the titled amplifier that a sound band signal of two systems of a 4-wire circuit is switched in time division and is amplified by an amplifier. CONSTITUTION:The sound band signal fed to a terminal 9 is given to a hybrid (HYB)11 and an impedance matching device (PD)13, switched by an analog switch 15 and fed to an amplifier 16. The switched sound band signal is amplified by the amplifier 16 by the amplification factor decided by a gain limit resistor 18 selected by an analog switch 17, fed to an LPF26 through an analog switch 21, a PD22 and an (HYB)25, a switching frequency component generated by the switches 15, 17, 21 is eliminated and the result is outputted. A control signal from an analog switch control circuit 20 is an ON/OFF signal having a frequency being over the Nyquist frequency of the cut-off frequency of the LPF. This is the same as to the sound band signal fed to a terminal 27. Thus, the signal detour is eliminated and the two-way sound band signal is amplified stably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bidirectional amplification device for amplifying voice band signals in both directions with one amplifier circuit in a voice band two-wire line.

(Prior Art) 'Revised edition of Wired Communication Engineering J P131-132, published by Corona Publishing, December 10, 1962 For example, as described in the above document, conventionally this type of device was Insert a hybrid transformer 2 into the wire line to convert it to a four-wire line, insert amplifier circuits 4 and 5 for each line, perform amplification, and then use the hybrid transformer 6 again to convert the four-wire line into a two-wire line. It was converted to a formal line.

(Problem to be Solved by the Invention) However, in the device with the above configuration, there is a problem that oscillation occurs when the gain of the amplifier circuit is set to 0. There was a point.

(Means for Solving the Problems) The present invention provides a bidirectional amplification device that converts a 2-wire line into a 4-wire line, amplifies the signal for each line, and then converts the signal into a 2-wire line again. Hypuri transformers 11 and 25 that reversibly convert between the hybrid transformer 11 and the 4-wire line, and an analog switch 15 that time-divisionally switches the inputs of the 4-wire line of the hybrid transformers 11 and 25. an amplifier 16 for amplifying the input input;
The output of the hybrid transformer 11 and 25-4
An analog switch 21 for time-divisionally switching to the output on the wire line side, an analog switch control circuit 20 for controlling the analog switches 15 and 21, and an analog switch control circuit 20 provided on the two-wire line side of the hybrid transformers 11 and 25, respectively. Low Gus Filter 10. and 26.

(Function) The function of the above means will be explained. Hybrid transformer 1
The four-wire line side inputs 1 and 25 are time-divisionally switched by an analog switch 15 and input to an amplifier 16 where they are amplified. The output of the amplifier 16 is also time-divisionally switched by the analog switch 21 to the output of the four-wire line of the hybrid transformers 11 and 25. That is, when the analog switch 15 is switched to the input side of the hybrid transformer 11, the analog switch control circuit 20 switches the analog switch 21 to the output side of the hybrid transformer 25, and the analog switch 15 switches to the input side of the hybrid transformer 25. When it is switched to , the analog switch 21 is switched to the output side of the hybrid transformer 11, and the above combination is performed at high speed.

Therefore, at some point, the hybrid transformer 11 to 2
The signal only flows in one direction, either toward 5 or the opposite direction, and no signal looping occurs.

Note that the low-pass filters 10 and 26 are only for removing switching frequency components caused by the analog switches 15 and 21.

(Example) Hereinafter, it will be explained in detail using examples.

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

The audio band signal applied to the terminal 9 passes through the low frequency filter 10 and is applied to the PD 13 by the hybrid 11. Here, PD stands for a transformer impedance matching device, and is usually a resistance attenuator.

The audio band signal passed through PD 13 is sent to analog switch 1.
5 and applied to the amplifier 16.

The switched audio band signal is amplified by 1 times the amplification degree A determined by the gain limiting resistor 18 selected by the analog switch 17 in the amplifier 16, and then the analog switch 21
, PD 22, and hybrid transformer 25 are added to the low-pass filter 26. The low-pass filter 26 removes the switching frequency components generated by the analog switches 15, 17, and 21 and outputs the audio band signal to the terminal 2.
It is output from 7. Analog switch 15.17°21
is controlled by a control signal from the analog switch control circuit 20. This control signal is naturally a 0N10FF signal that is higher than the Nyquist frequency (zxfc) of the cutoff frequency (fc) of the low-pass filter, and usually has a Nyquist speed (4
A value equal to or greater than XJ'c) is taken. The audio band signal applied to terminal 27 is Rono J? The analog switch 15 passes through the filter 26, the hybrid transformer 25, and the PD 23.
is applied to the amplifier 16, switched and applied to the amplifier 16. The switched audio band signal is amplified by 2 times the amplification degree A determined by the gain limiting resistor 19 selected by the analog switch 17, and then the analog switch 21 and the PD 14
, and are applied to the low/'Ps filter 10 through the hybrid transformer 11. Then, the low-pass filter 10 removes the switching frequency components generated by the analog switches 15, 17, and 21, and outputs the voice band signal to the terminal 9.
It will be outputted.

As explained above, by switching the input/output circuit of one amplifier at a speed higher than the Nyquist frequency, it is possible to eliminate signal interference and stably amplify voice band signals from both directions. .

(Effects of the Invention) As described above in detail, according to the present invention, the audio band signals of two systems of the 4-wire line are switched in a time-sharing manner,
Since amplification can be performed with one amplifier, there is no problem of oscillation due to signal interference, and there is an advantage that a high gain bidirectional amplifier device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a bidirectional amplifier according to the prior art. 9.27...Terminal, 10,26...Low noise filter, 11.25...Hybrid transformer, 12゜24...Neutralization resistor, 13,14,22,23...Impedance matching 15, 17, 21... Analog switch, 18, 19... Gain limiting resistor, 20...
Analog switch control circuit. Figure 1 Figure 2 4.5-. 59@n

Claims (1)

[Claims] After converting a 2-wire line to a 4-wire line, the signal is amplified for each line and then converted back to a 2-wire line.A bidirectional amplifier that reversibly converts between a 2-wire line and a 4-wire line. a first means and a second means for switching the four-wire line side inputs of the first means and the second means in a time-sharing manner; amplifying means; and an output of the amplifying means to the first means and the second means.
a second switching means for time-divisionally switching to the output on the four-wire line side of the means;
and means for selectively passing necessary signals, provided on the two-wire line side of the first means and the second means, respectively.