JPH02283136A - Hybrid circuit - Google Patents

Abstract

PURPOSE:To evade a phase difference between a transmission signal inputted to a reception circuit via a noninverting amplifier and an inverted transmission signal via a transmission circuit together with a reception signal by providing a dummy circuit equivalent to a transformer and a transmission line. CONSTITUTION:A noninverting amplifier 7 in a hybrid circuit consists of an operational amplifier 21 and 3 resistors 22, 23, 24, and a dummy circuit 8 consists of a dummy transformer 25 of the same specification to that of a transformer 19 and of a dummy resistor 26 of the same resistance as a load resistor 20. One of transmission signal (a) inputs passes through an inverting amplifier 2, in which the signal is inverted and a phase shift is caused at the transformer 19, and the resulting signal is inputted to a summing amplifier 5. The other of the transmission signals (a) passes through a noninverting ampli fier 7, a phase shift is caused in a dummy transformer 25 and the resulting signal is inputted to one input of the summing amplifier 5. Thus, the summing amplifier 5 sums the inverting signals of the same phase difference with respect to the input of the transmission signal (a) to suppress the bypass of the transmis sion signal (a) to a reception signal output terminal 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application is a modulation/demodulation terminal device having a signal transmission/reception terminal capable of simultaneously transmitting and receiving signals in a data transmission system, and having a transmitter circuit and a receiver circuit inside. The signal from the transmitter circuit is transmitted from the above-mentioned transmitter/receiver terminal and is not input to the input terminal of the receiver circuit, while the signal received at the transmitter/receiver terminal is input to the input terminal of the receiver circuit and is not input to the input terminal of the receiver circuit. A function that does not input data is required. A circuit having such a function is called a hybrid circuit, and the present invention relates to a hybrid circuit having such a function.

Conventional technology hybrid circuits, as mentioned above, are circuits that combine and separate the transmission signal from the modulation/demodulation terminal equipment and the reception signal from the line when transmitting and receiving data. This will be explained based on FIG.

The transmission signal a inputted from the transmission signal input terminal 1 is inverted by the transmission inverting amplifier 2 and sent to the transmission line 4 via the transmission/reception terminal 3. The signal A is added to the sending signal a in the receiving summing amplifier 5 and outputted to the received signal output terminal 6. Since the transmitted signals are inverted from each other in five summing amplifiers and are added together, they do not appear at the received signal output terminal 6, and only the received signal from the transmission line 4 appears at the multiplied signal output terminal 6. , realizing the functionality of a hybrid circuit.

A specific circuit diagram of the hybrid circuit shown in FIG. 3 is shown in FIG. 4. The inverting amplifier 2 consists of an operational amplifier (hereinafter referred to as an operational amplifier) 11 and two resistors 12 and 13, and the summing amplifier 5 consists of an operational amplifier 14 and three resistors 15°16 and 17.
The output side of the operational amplifier 1 of the inverting amplifier 2 is connected to a transformer 19 for receiving and receiving signals from the transmission line 4 via a resistor 18 and a transmitting/receiving terminal 3 for providing a hybrid function. ing.

J represents the load resistance of the transmission line 4.

Problems to be Solved by the Invention In FIG. 4, the transformer 19 is a circuit having DC resistance and self-inductance, and the transmission signal N14 of the sending signal 3 is
For transmission, the transmission/reception terminal 3 side of the transformer I9 is connected to the primary side,
If the other side is the secondary side, this is done by passing an alternating current through the primary coil of the transformer 19.

The component of the sending signal C of the transmitting/receiving terminal 3 is 1 of the coil.
DC resistance molecule and self-inductance ωLi seen from the next side
It is generated by passing a ζ current. The current i flowing through the coil is an operational amplifier 1 that inverts and amplifies the input voltage V of the sending signal a.
is supplied through the resistor 18.

Here, to explain generally about 11 EEv generated in the coil of the transformer 19, as shown in FIG. 5, the voltage generated with respect to the flowing current i advances by 90'.

Let e be the back electromotive force generated in the coil by current i, then i = 13i1ωt II is a constant) ・=-
(1), and the rate of change of 5ina+t with respect to ωt is c
Since osωt, equation (2) can be expressed as e=ωLl cosωt −・−+31,
A back electromotive force e is induced by flowing a current i. Furthermore, since the coil also includes a DC resistance molecule, the voltage V generated by the current 11 is expressed by the vector shown in FIG. 6, and can be expressed by the following equation.

v=i(r+jωL)...(4) The magnitude of the generated voltage V is lvl =j, /; possible...(5) Phase angle θ of voltage V with respect to current i is -1ωL θ=tan □ ... t6J. Therefore, the sending signal C of the transmitting/receiving terminal 3 in FIG.
The received signal output terminal 6I is passed through the summing amplifier 5 formed by
However, there was a problem in that part of the sending signal a was output.

The voltage of the sending signal a output to the received signal output terminal 6 is V
l, the resistance value of resistor 12 is R12, the resistance value of resistor 13 is R11, the resistance value of resistor 15 is R16, the resistance value of resistor 6 is R1°, the resistance value of resistor 17 is R1? , the resistance value of the resistor 18 is R18, then the voltage V! is expressed by the following equation.

If the gain of the inverting amplification formed by the operational amplifier 11 is doubled, the voltage V in equation (7) becomes. If the impedance of the resistor 18 and the coil of the transformer 19 are the same, then R,, = qT, mountain... (9), and (82
The formula is: As is clear from Equation 00, v2-0 cannot be achieved without the R17/RI5 term ((r+jωL) JA).

The present invention solves the above-mentioned problem, and aims to provide a 7-hybrid circuit that can suppress the leakage of the transmitted signal to the output of the receiving circuit.

Means for Solving the Problems In order to solve the above problems, the hybrid circuit of the present invention has the following features:
A sending circuit that inputs a sending signal, inverts it, and sends it out to a transmission line via a transformer, and adds together the receiving signal input from the transmission line via the transformer and the sending signal input via a normal amplifier. a receiving circuit that outputs the
The dummy circuit is connected to the output side of the normal rotation amplifier and is equivalent to the transformer and transmission line.

Effect With the above configuration, by providing a dummy circuit equivalent to a transformer and a transmission line, a transmission signal is inputted to the reception circuit via a normal amplifier, and an inverted transmission signal is inputted together with the reception signal via the transmission circuit. The phase difference between the signals is eliminated, and the looping of the transmitted signal to the output of the receiving circuit is suppressed.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. Note that the same structures and parts as those in FIGS. 3 and 4 of the conventional example are denoted by the same reference numerals, and explanations thereof will be omitted.

FIG. 1 is a block diagram of a hybrid circuit showing one embodiment of the present invention. The hybrid circuit of the present invention inputs the sending signal a to the summing amplifier 5 via the non-rotating amplifier 7, and has a transformer 19 and a dummy equivalent to the transmission@4 (load resistor 20) on the output side of the non-rotating amplifier 7. It is constructed by connecting circuits 8.

A specific circuit diagram of the hybrid circuit shown in FIG. 1 is shown in FIG. 2. The normal rotation amplifier 7 is composed of an operational amplifier 21 and three resistors 22, 23, and 24, and a dummy circuit 8! - Consists of a dummy transformer 25 having the same specifications as the lance 19 and a dummy resistor 26 having the same resistance value as the load resistor 20.

The operation of the hybrid circuit with the above configuration will be explained.

One of the input signals a is inverted through an inverting amplifier 2,
A phase shift is generated in the transformer 19 and input to the summing amplifier 5. The other output signal a passes through the non-rotating amplifier 7, generates a phase shift in the dummy transformer 25, and is input to one side of the summing amplifier 5. Therefore, in the summing amplifier 5, the inverted signals having the same phase difference are added to the input of the sending signal a, thereby suppressing the loop-around of the sending signal a(D) to the received signal output terminal 6.

Effects of the Invention As described above, according to the present invention, by providing a dummy circuit equivalent to a transformer and a transmission line, a transmission signal inputted to a reception circuit via a normal amplifier and a reception signal inputted via a transmission circuit are It is possible to eliminate the phase difference of the inverted transmission signal that is input with the
! A hybrid circuit with improved performance can be provided by preventing detours to the circuit.

[Brief explanation of drawings]

FIG. 1 shows a hybrid circuit showing an embodiment of the present invention.
t Configuration diagram Fig. 2 is a circuit diagram of the hybrid circuit shown in Fig. 1;
Fig. 3 is a block diagram of a conventional hybrid circuit, Fig. 4 is a circuit diagram of a conventional hybrid circuit, Fig. 5 is a diagram of the phase relationship between the current flowing through the coil and the voltage generated, and Fig. 6 is a diagram of the relationship between the current flowing through the coil and the voltage generated. FIG. 2 is a vector relationship diagram between a DC resistance valve, self-inductance, and pressure generated by filling the tX flow. DESCRIPTION OF SYMBOLS 1... Sending signal input terminal, 2... Inverting amplifier (sending circuit), 3... Transmission/reception terminal, 4... Transmission line, 5...
- Summing amplifier (receiving circuit), 6... Received signal output terminal, 7... Normal rotation amplifier, 8... Dummy four terms, 19...
・(Signal reception is for passing) Transformer, 20... Load resistor, 25... Dummy transformer, 26... Dummy resistor,
a... Sending signal, b... Receiving signal.

Claims (1)

[Claims] 1. A sending circuit that inputs a sending signal, inverts it, and sends it to a transmission line via a transformer, and a receiving signal inputted from the transmission line via the transformer and the sending signal inputted via a normal amplifier. A hybrid circuit comprising a receiving circuit that adds the signals to each other and outputs the result, and a dummy circuit that is connected to the output side of the normal rotation amplifier and is equivalent to the transformer and the transmission line.