JPS62125747A - Signal reception circuit - Google Patents

Abstract

PURPOSE:To receive a signal of a subscriber line with good balance by using a beta compensation type current mirror circuit to convert in-phase noise into a current signal in a subscriber circuit, adding a collector of a beta compensation transistor (TR) to a current output of a signal reception circuit thereby eliminating the deviation of the ratio of the reception signals of subscriber lines A, B and using a semiconductor element. CONSTITUTION:A voltage signal at a subscriber line terminal A is inputted as a current signal in the beta compensation current mirror circuit Ac and a current signal is outputted from the collector of TRs Q2, Q3. A voltage signal at a subscriber line terminal B is inputted to a Darlington current mirror circuit Bc, a current output is given from the collector of the TR Q12 and a voltage is outputted from the emitter of the TR Q13. The collector of the beta compensation TR Q24 of the circuit Ac is connected to the collector of the Darlington TR Q23. Thus, the current signal is increased by the collector current of the TR Q24 to eliminate the deviation of the reception signals of the subscriber lines A, B thereby eliminating the noise due to the in-phase signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to signal reception and signal transmission in a subscriber circuit of a TD exchange.

(Prior art) Conventionally, subscriber circuits that supply current to subscriber terminals and receive signals from subscriber terminals are composed of electromagnetic components mainly consisting of letter coils, transformers, etc. Although it was difficult, it was excellent in receiving the signals generated on subscriber lines A and H in a well-balanced manner.

(Problems to be Solved by the Invention) On the other hand, due to advances in semiconductor technology in recent years, subscriber circuits mainly consisting of electromagnetic components are being made into semiconductor electronics. It was difficult to realize a well-balanced signal circuit.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional circuit and to realize a signal receiving circuit that can receive subscriber line signals with ease using semiconductor elements.

(Means for Solving the Problems) The present invention provides a subscriber circuit that uses a battery as a reference or has a pull filter circuit and a DC voltage correction circuit that corrects the DC voltage component generated by the ripple filter. , the original differential signal and common mode noise occur, but it is necessary to receive this signal, remove the common mode noise, and transmit only the differential signal. However, since the receiving characteristics of the A and B receiving circuits differ depending on the DC voltage correction circuit,
The common mode noise that should be removed is also transmitted, so in order to prevent this, the present invention converts it into a current signal using a β-compensated current mirror circuit, and further converts the output current into a voltage signal by connecting the collector of the β-compensating transistor. is connected to the current mirror output, the current signal is thickened by the collector current of the β complement 1 prize transistor, and the in-phase signal component is removed by eliminating the shift in the ratio of transmitting the AC signal. It is.

(Operation) According to the above-mentioned means, in the circuit that receives the signal generated on the subscriber line, the deviation in the ratio of the signals received by the receiving circuits of the A and B lines is removed, and It is possible to prevent the in-phase signal from being added as noise.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

In the figure, AC is a transistor Q21 with a common base.
'Q22' Q23 and each emitter resistor R21
゜R22'R25 and a β compensation transistor Q2 whose base and base and emitter are connected to the transistor Q2+.
The collector of the transistor Q21 is connected to the terminal A via the resistor R11.
The voltage signal to the terminal is inputted as a current signal, and is output as a current signal from the collectors of transistors Q22 and Q23.

R and A are a double emitter transistor Q26 whose collector is connected to the battery and whose emitter area is double that of the transistor Q25 which has a common base, the resistance R31 between the base of the transistor and the battery, and the capacitance C between the base and ground.
1, and the emitter of Q26 is the β-compensated current mirror circuit A. The emitter of transistor Q25 is connected to the other end of the emitter resistor of transistor Q21 and Q23, and the emitter of transistor Q25 is connected to the other end of the emitter resistor of transistor Q22 to prevent noise from the power supply from being mixed in as a signal component.

Bc is a Darlington transistor Q with a common base
11. The emitter resistor R24 connected to the emitter of Q1□ and each Darlington transistor is connected to the terminal B via the resistor R12 at the collector base of q1+ in the current mirror circuit, and the voltage signal of the terminal B is input, and the Q12
A current is output from the collector of Q10, and a voltage is output from the emitter of Q10.

P, Bc, transistor Q14゜Q with common base
10, and a resistor R3□ connecting the base of the transistor to the ground.
4. The emitter of Q15 is the Darlington current mirror circuit B. Q10. Emitter resistance R24 of Q10
, R25, and compensates for voltage with the ripple filters R and A.

The collector of the transistor Q22 is connected to the Goulington transistor Q12 and serves as an output terminal for the in-phase signal, and the collector of the transistor Q23 is connected to Q13 via a resistor R26 and is a terminal that outputs the differential signal as a voltage output. becomes.

In the circuit described above, in addition to the differential voltage that is the signal voltage, a common-mode signal is also generated at the terminals A and B due to external noise. Signal u o A l vD B, common mode signal vCA 1υ
. 8 occurs, and if the signal reception ratios of A and B lines are the same, the A line signal is received as shown in FIG. 2(b).

When a B line signal is received, the in-phase signal component is canceled at the voltage output terminal, leaving only the differential signal component. However, if the signal reception ratio is incorrect, the signal is received as shown in Figure 2 (c). death,
The in-phase component is not canceled out and remains, resulting in noise.

Let gm1 be the amplification factor β, then when AC signal voltage vB is generated at terminal B, resistor R1□
The current iB flowing through is, and when an AC signal voltage 1)A is generated at terminal A,
The current iA flowing through the resistor R1□ is as follows. In the formula, gm and β are determined by the transistor and cannot be changed.In order to reduce the difference between equations (1) and (2), R1 should be made large and R2 and R3 should be made small, but usually R1 =30, Q, R2=1okΩ, R
Since 5=15 is about Ω, we will consider this value from now on.Also, the transistor amplification factor β=501, and the DC bias current is assumed to be an average value, collector 'B= υ
B/4 (19K'j-A= vA740.5
, and the difference between i8 and iA is υi=υ8,
Furthermore, the voltage Vx[
If it is, it is! The collector of the compensation transistor Q24 is
When not connected to the collector of 23, the voltage ■ generated at the voltage output terminal by the current iA. is the first stage transistor of Darlington transistor Q13, and by substituting the numerical values, VXB = 1BX10.7K.

VXA = iAX 10. Assuming that I K zB and iA are equal, 10.7 K-10,1K V 8 and vXA are 10.7K × 100 Mai 6
The deviation will be % of the above. This is because the signal on the B line side is increased by the signal generated in the resistor R3□ of the DC voltage compensation circuit R, B. To correct this value, β compensation, which is a feature of the present invention, is required. transistor Q2
When the collector of 4 is connected to the collector of Darlington transistor Q23, if VxA, VXA = 'A (1
+ ) (R2+) −(5)β
gm, and by substituting the numerical values, VXA difference becomes 10
At 0#99, only a 1 inch deviation occurs.

In this way, by adding the collector of the β compensation transistor of the signal receiving circuit to the current output of the signal receiving circuit, the difference in the ratio of the received signals of subscriber lines A and B is removed.
Noise caused by common-mode signals can be removed.

(Effects of the Invention) As described in detail above, according to the present invention, the collector of the beta compensation transistor is connected to the current output terminal,
By increasing the current signal, it is possible to eliminate the difference in signal ratio when receiving signals that occur on subscriber lines A and B.

[Brief explanation of drawings]

FIG. 1 is a signal receiving circuit diagram of an embodiment of the present invention, and FIG. 2 (a
), Fig. 2(b) and Fig. 2(c) are explanations of signal waveforms. Bull emitter trannostar, C1...capacitance, ■o...
Constant current source. Patent Applicant: Oki Electric Industry Co., Ltd. Nippon Telegraph and Telephone Co., Ltd.

Claims (1)

[Claims] The bases are each connected to the emitters of a pair of transistors connected to ground through a common resistor and the emitters of a pair of Darlington transistors whose bases are connected in common through a resistor, respectively; The collector of the Darlington transistor is connected to the base of the Darlington transistor and connected to one of a pair of subscriber lines through a resistor, and the base is connected to the emitter of the Darlington transistor, and the collector is connected to the base of the Darlington transistor through a resistor. In the A line side signal receiving circuit paired with the B line side signal receiving circuit consisting of a Darlington transistor whose emitter is connected to the collector of one of the transistors connected to the ground and whose emitter is used as a signal output terminal, the collector is used as a power source and the base is A pair of transistors connected to a power source through a common resistor and at the same time connected to ground through a capacitor, one having twice the area of the other, with its emitter serving as the first output and the other transistor's The first output of a ripple filter circuit whose emitter is the second output is connected via a resistor to the emitters of two of the three transistors that share a common base, and the second output is connected to the emitter of one of the other transistors. connect to the emitter,
and the collector and base of one of the two transistors connected to the first output of the ripple filter via a resistor, and the collector of the beta compensation transistor whose emitter is connected to the base of the transistor; It is characterized in that it is connected to the collector of another transistor connected to the first output of the ripple filter, and at the same time is connected to the signal output terminal of the B line side signal receiving circuit via a resistor, and at the same time is configured as a voltage output terminal. signal receiving circuit.