JPS5944167A - Power supply system to subscriber circuit - Google Patents

Abstract

PURPOSE:To obtain a power supply circuit where the termination impedance is constituted optionally and which has resistance to AC induction, by using two operational amplifiers of voltage follower connection. CONSTITUTION:The AC output impedance of the power supply circuit is expressed as R1B(1+ZB/R2B)+R1A(1+ZA/R2A), where R2B>>R1B and R2A>> R1A. Thus, when R2B=N.R1B and R2A=N.R1A, the AC output impedance is equal to the termination impedance Z, and it means that the AC output impedance is selected freely. In regulating the cut-off frequency of the circuitry comprising a capacitor CB, a resistor R3B and a capacitor CA and a resistor R3A to 50-200Hz taking the AC induction into account, since the rsistors R3A, R3B are large amount then the capacitors CA, CB can be of small value.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a subscriber interfaced with a telephone Vζ etc. via an analog transmission line. J circuit KQ, especially city.

iI needed for the call after the talk! 1. The subscriber circuit supplying the current current and transmitting the audio signal to the telephone line is based on the ξ method. (8) Conventional technology and b; It is a diagram showing an example of a conventional electronic power supply circuit in the Kaikai Kaiki Department. In Fig. 1, the part corresponding to this time is the communication current supply circuit BSI and l3S.
2, we will supply 1U, disconnection device K communication, and communication communication In via teleprompted i times. π is converted into voice by the speaking device - 8 is transmitted to the 4 company type unbalanced circuit by the 2 side 4 gland conversion circuit 4W of the main 4 or 4 illusion part
, and BS must have a resistance of 4 Fft capable of supplying the required communication current IB to the telephone station, and must have a sufficiently high impedance so as to prevent the interference from the voice signal from being reduced as much as possible. Note that the talk current supply circuits BS+ and BSti have the same configuration and characteristics except for the differences in the transistors Tr and Trt due to the talk current polarity, so the following explanation will focus only on the talk current supply circuit BS. In the talking current supply circuit BSI, the talking current IB is mainly connected to the transistor Tr and the resistor R1.
is supplied through a series circuit consisting of The transistor Tr has a voltage divider circuit made up of resistors R+ and R2, a low-frequency r waveform generator made up of a resistor Rf and a capacitor Cf, and a loop loop composed of an arithmetic trench/width circuit A. Now, the voltage drop of the communication current supply circuit MESi due to the communication current IB is VB, the terminal IMJ tolerance voltage of the voltage dividing resistor R2 is V8, the negative phase input terminal voltage of the amplifier A is Vl, and the positive phase input terminal voltage is If VB, then the Ban equation is established according to the known characteristics of the operational amplifier A.

R7 Assuming R1 and R2 are large enough, Rs R
s R + 1 & Therefore, if the equivalent resistance of the talking current supply circuit BS is R1, then if the equivalent resistance of the transistor Trt is RT, then R
+ Rs RT f: RB - Rs:
(4)2 Therefore, if the power consumption of transistor Tr1 is WT, then R
, R8 WT: RT I B2 Knee ・I B2 (5) 2 For voice signals, the speech current supply circuit BS.

According to the known characteristics of operational amplifier A, where the terminal voltage of operational amplifier A is VB%, the negative phase input terminal voltage of operational amplifier A is vt, and the positive phase input terminal voltage is v3, V2 = Vs '': 0
(6) That is, almost no audio signal flows through the transistor Trl. Therefore, if the equivalent resistance of the speech current supply circuit BSs for the voice signal is rB, &+Rf As is clear from the above explanation, according to the conventional electronic power supply circuit, the values of the resistors R1 and R1 are set sufficiently large.
By appropriately determining the value of the resistor R3, it is possible to supply the required talking current IB while keeping the talking current supply circuits BSI and 1st for voice signals at sufficiently high impedance. However, the value of the termination impedance itself, for example 900Ω + 216μFX, is 600Ω + 2
μF is safe, but there are disadvantages in implementation, and
Since the AC impedance of the power supply circuit becomes high, it has the disadvantage of being vulnerable to father current conduction.

(2B) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the present invention is capable of configuring the terminal impedance as desired, and it is sufficient to prepare a value N times the terminal impedance, and the low frequency AC impedance of the power supply circuit ' (i: The purpose is to provide a power supply system that reduces the impedance to the level of DC impedance and is resistant to flow spinning.

(5) Structure and object of the invention According to the present invention, in a subscriber circuit for a digital electronic exchange, there is provided a first operational amplifier which is voltage-connected, and an output of the first operational amplifier. connected to one of the communication lines through a resistor, and the intersection of the first resistor and the communication line is connected via a second resistor to a complex impedance ZB and a second performance amplifier connected by voltage follow. , the other end of the double floor impedance ZB is connected to ground or a low impedance voltage source, and the output of the second operational amplifier is connected to a third resistor and the input of the first operational amplifier via a capacitor. and a communication current supply circuit formed by connecting the other end of the third resistor to the ground or the low impedance voltage source, and the above-mentioned communication current supply circuit connected to the other end of the communication line. This is achieved by providing a subscriber circuit power supply system characterized by comprising a communication current supply circuit having the same structure as the above.

(6) Embodiments of the invention Below, embodiments of the invention will be described in detail with reference to the drawings. Figure 2 is a circuit 7 showing an embodiment of the power supply circuit according to the invention.
), VAr V n Vi k source AIA r AHA
t AIB t A2B is the operator q-scaler, B+Ae'
fkhrRshrRsBe &n+Rsn is a resistor, C
A, CBi-J:′:lndensa, Z A p Z B
indicates the vibration isolation impedance. Amplifier AB.

AA'-"1m is the saturation pressure and B, A green caller number is input through resistor R2A+R2n, so consider the maximum amplitude of the input call number: J→J-. , VAeVg
comes next.

(0uit, J:VB=-2v*VA--46vkVC
Fa＞'spjru) CAIRIAmata r, l:CnRs
n is DC i (= @ (VA or V u )
and has the name of AC Tsukuda's adding plum. CA Rs A or CD&B is audio band A of amplifier A2A or AffiB.
In order to transmit the converted signal power to the terminals of the amplifiers A I or AIB without distortion, its rating must be sufficiently large. Generally 2001L or 1j220
oRtli and ZB or R2A and Z set to Ω
A constitutes a feedback circuit that determines the AC output impedance of this power supply circuit. For example, if an input signal of Vin is rarely applied to the BorA line, Ang AtB is also! R2H+ZB R2A q-Z).

CB R3H or CA R3A cutoff wave number is audio;
If the range and the range are sufficiently small, the signal to the amplifier AIB or AIA will be output. Therefore, R2B > B
+ B r Rz > B + A, the AC output impedance of this power supply circuit is as follows.

AC output impedance & B Rz h (assumption) R2Bmbe・R, B p R2 people=N
@RIAZ; If we set the termination impedance as AC output impedance = 2, then the above assumption (i.e., the ratio of RIE and R2n to R, B
ON times, RtA to Rz, <) RIA (7) N
If you put fig dor;';＞), the AC of this 9% circuit
Output impedance is 8, VCS selection - C'@, and &B+Z#1R2AZA is B
+B+B+A This can be achieved by preparing the number ``IZ'' or a value 8 times its value ・r.

For example, R1,\=R+r+=200Ω1Z=600Ω
+1 μF.

If N=500, &*=RtB=100000Ω=1
00KQ.

Zh=ZB=50000Q+Cr, 004μF.

Since the input interdance of amplifier A+ B p A4 A is extremely low, even if RsB*R3A is large, it will not affect the DC output of amplifier AIB + AHA. Also, even if the wave induction is set to 50 Hz to 200 Hz and the cutoff frequency number of CCBRsB and CA island A is set to 50Hz to 200Hz, 'RsA
+Ran can take a thick value, so C person + Cni
Is it a small value? Lr (, for example, Rsh”JLsn=2
If you press 00'lyΩ, Cut off the same waveform to 100H.
If you go to z, it becomes. As described above, it is possible to construct a flexible power supply circuit with a high resistance and a low capacitance.

(f) Effects of the Invention According to the present invention, if the desired terminal impedance is set to 2, the terminal impedance seen from A-Bm can be set to 2, and in fact, without using Z, N (--B+ x )
Zx is used to provide a subscriber circuit power supply system that is suitable for use in non-intrusive ICs.

[Brief explanation of drawings]

FIG. 1 shows a conventional electronic power supply circuit and a second electronic power supply circuit to which the input-saving circuit power supply system of the present invention is applied. In the drawing, the position is a telephone line, 4W is a 2-wire 4-wire changing circuit,
BSI, BS2 are call current supply circuits, VAIvB is a reference source, 4 AI AHA + A+ B 1-A2E arithmetic operation unit, A I R2A RIIA HR1B+R・
2D and ■ also show one resistor in 3B, C + CB + shows a capacitor, and ZA # ZB shows the adjustment impedance, respectively.

Claims (1)

[Claims] In the subscriber circuit for a digital electronic language exchanger, the voltage follow connection is performed. , an amplifier, and the output 't of the first operational ellipsoid - connected to one side of the communication line via a first resistor, and the first resistor and the father point of the communication line are connected to a second resistor. connected to the complex impedance ZB and voltage follow-connected second arithmetic amplifier J through the amplifier,
The other end of the complex impedance ZB is connected to a voltage source or a low impedance voltage source, and the output of the second operational amplifier is connected to a content? through the kite 3 resistor and the input of the first arithmetic amplifier, and the other end of the third resistor is connected to the ground or to the low impedance 1L voltage source. A system for subscriber circuit supply tb, characterized in that it comprises a communication current supply circuit of the same type as the above-mentioned communication current supply circuit and a communication current supply circuit connected to the other side of the communication line. .