JP2646669B2 - Electronic hybrid circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic hybrid circuit for connecting a two-wire circuit and a four-wire circuit, and more particularly to switching a balanced network by an analog switch to achieve a balanced state. The present invention relates to a secure electronic hybrid circuit.

[Conventional technology]

In a conventional hybrid circuit, in order to suppress a signal from the input side to the output side of a four-wire circuit, a plurality of balanced networks are selectively switched by a strap line to maintain a balanced state. In the electronic hybrid circuit, such switching is performed by an analog switch.
Since the resistance of the analog switch cannot be neglected, in the case of the electronic type, a balanced network has been constructed in consideration of the resistance of the analog switch.

There is also a method of increasing the impedance of a circuit for suppressing a signal from the input side to the output side of a four-wire line and relatively reducing the impedance of a two-wire line.

[Problems to be solved by the invention]

However, in the conventional electronic hybrid circuit, the on-resistance of the analog switch varies, and the resistance of the analog switch tends to fluctuate depending on the operating conditions and the environmental temperature. Therefore, it has been difficult to maintain a sufficient equilibrium state.

Also, in the method of increasing the impedance of the signal suppression circuit, a large inductance is required to maintain a balance with a coil having a large inductance that hardly passes a frequency component of a voice band included in the signaling circuit. It is difficult to realize inductance.

An object of the present invention is to solve such a problem and provide an electronic hybrid circuit that can always maintain an equilibrium state without being affected by variations in the on-resistance of the analog switch, operating conditions of the resistance value, and fluctuations due to environmental temperature. To provide.

[Means for solving the problem]

The present invention provides a first transmission unit for transmitting an input signal from a four-wire line to a two-wire line, and a second transmission unit for transmitting an input signal from the two-wire line to the four-wire line. And a signal suppressing circuit for suppressing the input signal input from the first transmission unit to the second transmission unit from the four-wire line, wherein the first transmission unit is An input terminal connected to the four-wire line, and a first resistor connected between the output of the amplifier and the two-wire line, the second transmission unit, A first differential amplifier having one input terminal connected to the two-wire circuit, and a second resistor connected between an output terminal of the amplifier and the other input terminal of the first differential amplifier; The signal suppression circuit is configured to connect a second resistor to an input terminal of the first differential amplifier. A first network with one terminal connected to a point, a second network with one terminal connected to the other terminal of the network, and one terminal at the other terminal of the network. A third network connected, a fourth network having one terminal connected to the other terminal of the network, a common terminal connected to the other terminal of the network, An analog switch having a plurality of terminals that are selectively connected; a plurality of balanced networks each having one terminal connected to the plurality of terminals of the analog switch and the other terminal both grounded; An input terminal is connected to a connection point between the second resistor and the first network, and a negative input terminal is connected to a connection point between the second and third networks.
And a positive input terminal at a connection point between the fourth network and the common terminal of the analog switch, and a negative input terminal at a connection point between the second network and the third network. And a third differential amplifier connected thereto.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of an electronic hybrid circuit according to the present invention. The circuit includes a first transmission unit for transmitting an input signal from the four-wire line to the two-wire line, a second transmission unit for transmitting an input signal from the two-wire line to the four-wire line, 4 input from the first transmission unit to the second transmission unit
And a signal suppressing circuit for suppressing an input signal from the line type circuit.

The first transmission unit is connected between the amplifier 4 whose input terminal is connected to the input terminal 1 of the four-wire circuit and the output of the amplifier 4 and the input / output terminal 3 of the two-wire circuit. the first consists of resistors R ₁ Tokyo, the second transmission section, a positive input terminal connected to the output terminal 3 of the 2-wire circuit differential amplifier 5
When, and a second resistor R ₂ Metropolitan connected between the negative input terminal of the output terminal and the differential amplifier 5 of the amplifier 4.

Further, the signal suppression circuit includes a first circuit network 8 having one terminal connected to a connection point between the second resistor R ₂ and the input terminal of the differential amplifier 5, and a _second terminal connected to the other terminal of the circuit network. A second network 9 to which one terminal is connected, a third network 10 to which one terminal is connected to the other terminal of this network, and one terminal to the other terminal of this network. A fourth circuit network 11 connected thereto, an analog switch 12 having a common terminal connected to the other terminal of the network, and four terminals selectively connected to the common terminal; One terminal is connected to each of the four terminals, the other terminal is connected to four balanced networks 13 to 16 both grounded, and the positive input terminal is connected to the second resistor R ₂ and the first network 8. And the negative input terminal is connected to the connection point between the second network 9 and the third network 10, respectively. A differential amplifier 7, to the positive input terminal is the connection point between the common terminal of the fourth network 11 and the analog switch 12, a negative input terminal and the second network 9 3
And a differential amplifier 6 connected to a connection point with the circuit network 10 of FIG.

The differential amplifiers 6 and 7 and the networks 8 to 11 are described in the paper (A
ntoniou, A., “Realization of Gyrators Using Operati
onal Amplifiers and Their Use in RC−Active Networ
k Synthesis, "Proc. IEE, vol. 116, pp. 1838-1850, Nov. 19
It forms a circuit called GIC (Generalized Immitance Converter) in 69).

Next, the operation will be described. Each Z ₁ impedance of the network _{8~11, Z 2, Z 3,} Z 4, the internal resistance of the analog switch 12 R
₀ , the impedances of the balanced networks 13 to 16 are Z _L1 , Z _L2 , Z
_L3 , Z _L4, and a balanced network 13 by an analog switch 12.
There When selected, the impedance Z _i of GIC viewed from the resistor R ₂ side is expressed by the following equation.

Therefore, when the impedances Z _{1 to} Z ₄ of the networks 8 to 11 are set to Z ₁ = Z ₃ and Z ₂ = Z ₄ = 10Z ₁ , the combined impedance (R ₀ + Z _{0) of} the analog switch 12 and the balanced network 13 is set. _L1 ) will be multiplied by 1/100. To maintain the balance of the hybrid circuit in such a state, the impedance Z _L1 of the balanced network 13 may be increased, and the resistance R ₀ of the analog switch 12 is equivalently reduced to 1/100. Therefore, the effect of the resistance of the analog switch 12 is relatively reduced.

4-wire enters from the input terminal 1 of the circuit, the signal amplified by the amplifier 4, resistors R _1, R _2, 2-wire circuit of the impedance Z, and the input impedance Z _i of GIC the following formula R ₁ Z _i = When R ₂ Z is satisfied, the signal is not transmitted to the output terminal 2 of the 4-wire circuit. At this time, the power enters from the input terminal 1 of the four-wire system, and 1/2 of the signal amplified by the amplifier 4 is output to the input / output terminal 3 of the two-wire system. When the input terminal 1 of the 4-wire circuit is viewed from the input / output terminal 3 of the 2-wire circuit, the amplifier 4
Input-output terminal 3 and the output impedance is small it will be that terminate in a substantially resistance R _1, input-output terminal 3
Is not transmitted to the resistor R _2, but is output to the output terminal 2 via the differential amplifier 5.

By switching the balanced networks 13 to 16 by the analog switch 12 in accordance with the impedance of the two-wire line, the input terminal 1 to the output terminal 2 of the four-wire line are switched.
Signal, ie, the amount of sound attenuation can be increased.

〔The invention's effect〕

As described above, the present invention provides a first transmission unit for transmitting an input signal from a four-wire line to a two-wire line and a second transmission unit for transmitting an input signal from the two-wire line to a four-wire line. And a signal suppression circuit for suppressing an input signal from the first transmission unit to the second transmission unit from the four-wire line, and constituting a signal suppression circuit. The GIC is used to reduce the resistance value of an analog switch that switches a plurality of balanced networks according to the impedance of a two-wire circuit compared to the resistance value of a balanced network. It is possible to always maintain an equilibrium state without being affected by the operating conditions of the values and fluctuations due to the environmental temperature.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the electronic hybrid of the present invention. DESCRIPTION OF SYMBOLS 1 ... Input terminal of 4-wire type circuit 2 ... Output terminal of 4-wire type circuit 3 ... Input / output terminal of 2-wire type line 4 ... Amplifier 5-7 ... Differential amplifier 8-11 ... Circuit network 12 ...... analog switches 13 to 16 ...... balancing network R _1, R ₂ ...... resistance

Claims (1)

(57) [Claims] 1. A first transmission unit for transmitting an input signal from a four-wire line to a two-wire line, and a second transmission for transmitting an input signal from the two-wire line to the four-wire line. An electronic hybrid circuit comprising: a first transmission unit; and a signal suppression circuit that suppresses the input signal from the first transmission unit to the second transmission unit from the four-wire line. Comprises an amplifier having an input terminal connected to the four-wire circuit, and a first resistor connected between the output of the amplifier and the two-wire circuit. A first differential amplifier having one input terminal connected to the two-wire circuit, and a second differential amplifier connected between an output terminal of the amplifier and the other input terminal of the first differential amplifier. And a signal suppressing circuit, wherein the signal suppressing circuit is configured to connect a second resistor and an input terminal of the first differential amplifier. A first network having one terminal connected to the continuation point, a second network having one terminal connected to the other terminal of the network, and one terminal being connected to the other terminal of the network; , A fourth network having one terminal connected to the other terminal of the network, a common terminal connected to the other terminal of the network, and a common terminal connected to the other terminal of the network. An analog switch having a plurality of terminals selectively connected to the analog switch, a plurality of balanced circuits each having one terminal connected to the plurality of terminals of the analog switch, and the other terminal grounded together; Input terminal is connected to a connection point between the second resistor and the first circuit, and a negative input terminal is connected to a connection point between the second circuit and the third circuit. An amplifier having a positive input terminal connected to the fourth network and a common terminal of the analog switch; Point, electronic hybrid circuit characterized in that the negative input terminal is composed of a third differential amplifier which is connected to the connection point of the second network and the third network.