JPS601993B2 - current supply circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit that connects a subscriber terminal such as a telephone to a subscriber line via a subscriber line in a telephone exchange.

FIG. 1 is an example of a conventional fin-ryu kousondai circuit for a conventional Kiwawa exchange toll machine.

The prior art will be explained with reference to FIG. 1. In an S-talk switching machine, as shown in FIG.
At the same time, a sufficiently high impedance is provided on the subscriber line 4 so as not to be a loss for AC signals such as voice from the subscriber terminal 5. On the contrary, it is necessary to have a sufficiently low impedance against the induced storm phase noise. At this point, the choke coil 2 supplies DC to the subscriber terminal 5 via the subscriber line 4, and at the same time has sufficient quotient impedance for AC signals such as voice, with little loss, and the AC signal passes through the DC blocking capacitor 6. While being relayed to the terminals c and d, the choke coil 2 has a sufficiently low impedance due to only the winding resistance against common mode noise induced on the subscriber line 4, and is hardly relayed to the terminals c and d. As described above, the current supply circuit using the choke coil has sufficient functionality for the above-mentioned telephone exchange, but
In order to improve the transmission characteristics, the number of windings in the choke coil increases, and a shield is required to prevent crosstalk due to electromagnetic induction, which limits the size and weight reduction.

The present invention was made in order to eliminate these drawbacks, and the current supply circuit is made entirely of fins, making it smaller, lighter, and more efficient.
The present invention provides a current supply circuit that enables C conversion and has excellent transmission characteristics.

This will be explained in detail below. FIG. 2 is a diagram of the principle of the present invention, where Qo is a transistor for amplifying the torrent current, Q is a transistor for controlling it, and Q2 is a transistor for amplifying the emitter voltage of transistor Q with resistors R4 and R5. This is a transistor for amplifying the voltage transmitted to the base of transistor Q.

Also shown are resistances Ro, R, and capacitance C. The circuit network consisting of the collector fin pressure of the transistor Qo is
, is the circuit network that transmits the signal to the emitter of . Here, resistance R
It is assumed that the fin current passing through IX is lx, the DC amplification factor of transistor Q2 is 82, the base emitter current is V882, and the base current of transistor Q is negligible compared to IX.

Then, if the base voltage of transistor Q is VB, then
VB=V, 10IXR5 ...(1-1)V, 10,XR
53; R6 0, is possible, and by approximating equation (1-3) under this condition, V8 Gotsu V. 10VE-VB
E2 -...--(1-4>).

On the other hand, current IB flows into the base of transistor Qo.

is 18, assuming that the emitter current of transistor Q is IE, and the common base amplification factor is Q.

=Q, 18, ...(1-5)'. Also, the emitter current IE, is the base of the transistor Q.
If the emitter voltage is VB, then vB-vBE, -V
c... (1-6) IE・= ~ 10R, becomes.

Therefore, the emitter potential VE of the transistor Qo has a common emitter DC amplification factor of 3. Then, from equations (1-5) and (1-6), V8=[(a.

11) IB. 1IX〕R3. ．． ．． ．． ．． ．． (1-7a), and here the conditions for deriving equations (1-2) and (1-4) are ancient; Ear 1 V, -VB Ear 2) ... is approximated as (1-7b), and therefore (1-7a), (1-7b)
From the formula, V8 (・- climb) = [(8.

11) IB. 10 degrees VB ear 20V・)〕R3----
--- becomes. 8oIB here.

If the resistance ~+R is sufficiently large compared to the load, then
This is the current supplied to the load via the transistor Qo, and by appropriately selecting R5 compared to this, it can be reduced to 1/R5.
(V8820V,)《8.18.

It is possible to do this, and if R3《R4*, then (
1-7c) From equations (1-5) and (1-6), VE=(
801) 180R3=(3011)R3Q・-V8-
Mugi empty sleep; VC---...--(・-7). From equations (1-7) and (1-4), evening (3.11) Q black 3 (
Vine V・10VE-V882-VB8・-VC〉……(1
-8) V ear = ~ 10R, from this VC-V8 Fgi 藷;;) = turtle V'V iso - V cape side skin -
(1-9) Here, for example, if Qgo1, R3go1500, FujuR, Go1plateQ,8goloo0 (use Q2 as a Darlington transistor etc. as necessary), R RainbowjyuR
I scream (3.

10,) R3 = Both in advance. Goo-o7《・ ＊,
Here, R uniform ten RI 1》Q, (8.

10,)R3...If you select (1-10), VCE:V
G-V83 Tortoise V'V882-V881--...-(1-1
1) Therefore, the collector-emitter fin pressure of transistor Qo can be kept constant regardless of the load, and if this fin pressure is set to the minimum voltage that takes into account the maximum audio level and AC induced noise, the voltage of transistor Qo can be kept constant regardless of the load. Collector loss can be made extremely small, and IC implementation becomes possible.

Also, the AC signal voltage of the collector of the transistor Q is Ve,
When the AC signal current is i8 and the AC signal current flowing through the resistor is i, the impedance Zo seen from the load side is Z.

= Otorod; ...(2-1) Here, transistors Q,,Q
Assuming that the AC amplification factor of 2 is sufficiently large, and as described later, the capacitance C is sufficiently large and the transistor Q is equivalent to grounding the base in terms of AC, the AC signal fin grain at the base of the transistor Q is connected to v8 and the emitter passing AC. If the signal current is iT, and the AC potential at the connection point between capacitance Co and resistors Ro and R is v, then (ZC=1/i■Co), . , T=V drop=Sokushu 10 or 8 total/(Kotsu Toru).・．． …(
2-3) The most turtle side.・・・． ...(2-4) Also, if the AC amplification factor of transistor Qo is hre, then small re=
i8 suna covered・i. = Agriculture, and by substituting it into equation (2-5), we get [(Mi projection - mother) - point) ie = table... (2-6).

If the amplification factor of the transistor Qo is sufficiently large and by choosing an appropriate constant, the formula (2-6) becomes c of i.

R. )・Vessel 3. ．． ．． ．． ．． ．． (2-7) 1e* Next, when calculating for i, the equations (2-2), (2-4), (2-7
)Than·. Husband (...T) sealing character) Ve needle/Saku poison〕 = arc + Toru) Ve-sha - taking i8) / Haji) Vesu [hase) V
e-R. (Book thigh) I walk... Here, for example, Co = 5〃F, ~GoIqK, R, GoIK, ■ = 2 × stroke ×
If it is 300Hz, the COR is 1.

》1・Miss《1, Table《1, Harm《. Therefore, the formula (2
-9), from equations (2-1), (2-7), and (2-10), the impedance seen from the load side is a parallel connection of the impedances shown by equations (2-7) and 2-10). , Co, Ro, R3, R4, and R5 are selected as constants as described above, and the insertion loss, which is one of the transmission characteristics, can be extremely reduced.

Furthermore, with respect to the noise generated at point A, if the AC impedance seen from the collector of transistor Q is sufficiently high, then the AC impedance seen from the emitter of transistor Qo appears to be sufficient. On the other hand, the capacity C,
If the value of is selected to be sufficiently large compared to the resistor &, the same mother pressure as the noise voltage generated between the base and emitter of the transistor Q2 will be generated, and the collector current of the transistor Q will not change. Therefore, the collector of transistor Q2 v
o does not change, and the influence of noise on the load can be minimized. An embodiment of the present invention is such that the transistors in the circuit shown in FIG. 2 are each made up of complementary transistors and inserted into the earth side and the power supply side to form a stream supply circuit, as shown in FIG. 3. .

In FIG. 3, 30 is a control transistor Qo. ,Q
、． The capacitance CO and resistance connected to o,o,,R,o,
R,. It is a rewax network consisting of transistors Qoo,Q
, o are transistors for amplifying the fly current that supply the fly current to the subscriber terminal 5 via the subscriber line. 31, 32 are transistor Q side Q, 2 and resistor ~4, R hawk. R ground R, 5
The emitter voltage of the mother current amplification transistors Qoo, Q, o is amplified by the control transistors Q, Q, .
This is a circuit that transmits data to the base of the fins.

Here, the capacitance CO for reducing the AC impedance seen from terminals a and b, and the voltage between the collectors and emitters of transistors Qoo, Q, and o are defined as constant voltages regardless of the subscriber line length. For example, by using a diode DO in both the ground side circuit and the source side circuit, the impedance to ground of the current supply fin circuit can be lowered against common mode noise generated on the subscriber line, and It can be used as a foundation that is strong against source noise. In addition,
In the above description of the circuit, a diode DO is used, but the present invention is not limited to this in any way, and other devices may be used as long as they have the same structure as the device. As explained above, according to this invention, since the structure is made up of transistors, resistors, and capacitors, the Z flow supply circuit can be made entirely of fins, making it possible to make it smaller, lighter, and integrated into ICs, and to improve transmission characteristics. It has the advantage of being easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a current supply circuit for a secondary telephone exchange, FIG. 2 shows a principle of the present invention, and FIG. 3 shows an embodiment of a once-through supply circuit according to the present invention.

1...Power supply, 2...Choke coil,
3...Fin flow supply circuit, 4...Subscriber line, 6...DC blocking capacitor, 30...
...Circuit network, 31, 32...Military pressure amplifier circuit, C
o,C,,COO,C,o...Customer! , D0...
Zener diode, ~~to, ~o~obon6, R, o~R,
6...Resistance, Qo~Q, Qoo, Q,, Q's, Q, o,
Q. , Q, 2...Transistor, VC...
·power supply.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a current supply circuit for supplying direct current to subscriber terminals such as telephones via subscriber lines, the current that supplies current to subscriber terminals via subscriber lines connected to the earth or a power source through a resistor. Transistor Q_0 for amplification, transistor Q_1 for its control, and transistor Q_0
Voltage amplification transistor Q that amplifies the emitter voltage of
Two sets of _2 are used as the ground side and the power supply side, and the emitter of transistor Q_1 is connected to the collector of transistor Q_0 via two resistors connected in series, the base is connected to the collector of transistor Q_2, and the collector is connected to the collector of transistor Q_0. The emitter of the transistor Q_2 is connected to the emitter of the transistor Q_0 via a resistor, and the base is connected to its own collector via a resistor and connected to the ground or a power source via a capacitor.
Furthermore, the collectors of the transistor Q_2 on the power supply side and the earth side are connected through a constant voltage element with low impedance that has a resistance at both ends, and the two series-connected resistors on the power supply side and the earth side Each of the connection points between them is connected via a capacitor, and the collectors of the transistors Q_0 on the earth side and the power supply side are connected to the subscriber line, respectively, so that the circuit configured above is connected in parallel to the subscriber line. Current supply circuit.