JPH0453157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a system for configuring a subscriber circuit of a telephone exchange.

[Background of the invention]

In conventional subscriber circuits, the feedback circuit that determines the DC supply characteristics and AC termination characteristics was constructed from the part to which high voltage is applied, so the circuit elements had to withstand high voltages, were bulky and expensive, and had variable characteristics. It was also difficult to control. This will be explained using figures. FIG. 1 is an example of a block diagram of a conventional method of configuring a subscriber circuit. In Figure 1, 1 is the load resistance of the subscriber line, 2 is the voltage-current conversion circuit (conversion ratio gm), 3 is the voltage detection circuit (detection ratio k), and 4 is the DC feedback signal transmission circuit (transmission ratio G _DC ), 5 is a signal transmission circuit for AC feedback (transfer ratio G _AC ), and 6 is a DC or disconnection capacitor. In FIG. 1, the equivalent direct current resistance Z _DC and equivalent AC resistance Z _AC of the subscriber circuit are given by the following equations based on the conditions of the feedback circuit.

Z _DC = 1/(K·G _DC ·gm) ... Z _AC = 1/(K·G _AC ·gm) ... Therefore, the feedback characteristic can be determined by G _DC or G _AC .

Next, FIG. 2 shows an example of a conventional method of configuring a subscriber circuit. In FIG. 2, 101 is a subscriber line load resistance, 102 and 103 are current supply resistances,
104 and 105 are current supply transistors; 10
6,107,123 is an operational amplifier, 108-11
1, 120, 121 are resistors, 112 to 118 are current mirror circuits that output at a constant ratio to the input circled, 119 and 124 are transistors, 122 is a capacitor for AC removal, and 125 is for DC bias. Current source, 126 is a DC or disconnection capacitor, 127 is an AC impedance circuit, 12
8 is a low voltage power supply, and 129 is a high voltage power supply.

In Figure 2, the equivalent direct current resistance Z _DC and equivalent AC resistance Z _AC are expressed by the resistance value R as a subscript: Z _DC = 1/2 x (R ₁₀₈ + R ₁₀₉ ) x (1/2 R ₁₁₀ x R ₁₀₂ +
1/R ₁₁₁ × R ₁₀₃ )… Z _AC = 1/2 × (R ₁₀₈ + R ₁₀₉ ) × Z/R ₁₂₀ × (1/2R _1
10 ×R ₁₀₃ +1/R ₁₁₁ ×R ₁₀₃ )… R ₁₀₈ = R ₁₀₉ = R _A 2R ₁₁₀ = R ₁₁₁ = R _B R ₁₀₂ = R ₁₀₃ =
Assuming R _C , Z _DC = 2R _A・R _C /R _B … Z _AC = 2R _A・Z/R ₁₂₀・R _C /R _B … For example, R _A = 40kΩ R _B = 9.27kΩ R _C = 51Ω
If R ₁₂₀ = 13.3kΩ, then Z _DC = 440 (Ω) ... Z _AC = Z/30 ... Comparing with Figure 1, the following equation is obtained.

gm=1/R _C ... K=R _B /R _A ... G _DC = 1... G _AC = R ₁₂₀ /Z... In Fig. 2, current mirror circuits 115 to 118 are the circuits that determine G _DC and G _AC . Since the transistor 124 and the capacitor 122 are all circuits to which a high voltage level is applied, they are large in size and disadvantageous in terms of cost due to withstand voltage conditions. Furthermore, when adding a circuit for varying the characteristics, a high-voltage element is required, which cannot be easily realized.

In particular, it has been impossible to control the impedance of each subscriber line.

[Purpose of the invention]

The object of the present invention is to simplify the high voltage level circuit of the subscriber circuit, to provide a subscriber circuit configuration system that is inexpensive and easy to control variable characteristics, and in particular, to provide a subscriber circuit configuration method that is capable of controlling the impedance of each subscriber line one by one. The object of the present invention is to provide a subscriber circuit configuration system that allows

[Summary of the invention]

In the present invention, the feedback circuit that determines the direct current feeding characteristics and alternating current termination characteristics of the subscriber circuit is constructed entirely of low voltage level circuits, and it also makes it possible to control the impedance of each subscriber line.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained using figures. FIG. 3 is a block diagram of a subscriber circuit configuration method according to the present invention. In Fig. 3, the same parts as in Fig. 1 are given the same symbols, 2' to 6' are circuits that realize the same function, but the voltage conditions are different, and 7 and 8 are voltage levels. It is a conversion circuit. In FIG. 3, the entire area to the right of the line AA' divided by the voltage level conversion circuits 7 and 8 can be configured with low voltage level circuits.

FIG. 4 shows a reference diagram for explaining the present invention, in which the same parts as in FIG. Change the ratio to 10:1,
120' changes the resistance value to 1/10, current mirror circuits 115' to 118', transistor 124',
The capacitor 122' has relaxed voltage resistance conditions,
Resistor 121' was changed to 1/10, and capacitor 122' was
10 times the value, 130 is the current mirror circuit, 1
31 is a low voltage power supply. The DC equivalent resistance Z _DC and AC equivalent resistance Z _AC in FIG. 4 are exactly the same as the values found in FIG. 2. Everything to the right of the AA' line can be configured with low voltage level circuits.
Also, by lowering the values of R ₁₂₀ ′ and R ₁₂₁ ′,
This prevents the Dynamite Cleanse from running out.

Next, FIG. 5 shows an embodiment of the present invention. In FIG. 5, the same parts as in FIG. 2 or 4 are given the same reference numerals, 132 to 136 are current mirror circuits, 137 and 138 are current-voltage conversion resistors, and 139 and 140 are voltage-current conversion resistors. resistance, 14
1,142 is an analog-to-digital conversion (hereinafter referred to as A/D conversion) circuit; 143, 144 is a digital-to-analog conversion (hereinafter referred to as D/A conversion) circuit;
The circuit 145 is a digital arithmetic circuit. Fifth
The characteristics in the figure are A/D conversion circuits 141 and 14.
2 inputs V ₁ and V ₂ and D/A conversion circuits 143 and 14
It is determined by the relationship between the outputs V ₃ and V ₄ of No. 4.

For example, the conditions to obtain the same characteristics as in Figures 2 and 4 are R ₁₃₇ = R ₁₃₈ = R ₁₃₉ = R ₁₄₀ , and V ₁
~ Expressing the direct current component of V ₄ with the subscript DC and the alternating current component with the subscript AC, V _3DC = V _4DC = (V _1DC + V _2DC )・1/2 ... V _3AC = V _4AC = (V _1AC + V _2AC )・1 /2・R ₁₂₀ /Z... By multiplying the equation and the equation by a coefficient, it is easy to change the DC equivalent resistance and AC equivalent resistance proportionally.

Next, a case will be described in which the impedances of both wires are controlled separately.

If the impedance between the collector side of the current supply transistor 104 and the ground is ZB, and the impedance between the collector side of the current supply transistor 105 and the ground (the impedance of the high voltage power supply 129 is ignored as it is sufficiently small) is ZA, then ZB= R ₁₀₂ ×R ₁₀₈ /R ₁₁₀ ×R ₁₄₀ /R ₁₃₈ ×V ₂ /V ₄ … ZA＝R ₁₀₃ ×R ₁₀₉ /R ₁₁₁ ×R ₁₃₉ /R ₁₃₇ ×V ₁ /V ₃ … R ₁₄₀ =R ₁₃₈ , Assuming R ₁₃₉ = R ₁₃₇ , and defining GB = V ₄ /V ₂ ... GA = V ₃ /V ₁ ..., ZB = R ₁₀₂ × R ₁₀₈ / R ₁₁₀ × 1 / GB ... ZA = R ₁₀₃ × R ₁₀₉ / R ₁₁₁ × 1/GA... As an example of calculation, if the direct current component is expressed by the subscript DC and R ₁₀₂ = R ₁₀₃ = 51Ω, R ₁₀₈ = R ₁₀₉ = 40KΩ, R ₁₁₀ = R ₁₁₁ = 9.27KΩ, then ZB _DC = 220 × 1/GB _DC … ZA _DC = 220 × 1/GA _DC … As a control example, if GB _DC = 2 GA _DC = 2/3, ZB _DC = 110Ω, ZA _DC = 330Ω, and impedance control for each wire. becomes possible. Also, GB _DC
= 1 GA _DC = 0.001, ZB _DC = 220Ω ZA _DC = 22KΩ, and equivalently, one wire operation and one wire non-operation state can be realized, and since ZA _DC has a high resistance, the ZA side High resistance earth air detection can be easily performed. Next, the AC component is subscripted DC
Expressed as , and using the resistance value mentioned above, ZB _AC = 220 x 1/GB _AC ...〓〓 ZA _AC = 220 x 1/GA _AC ... As a control example, GB _AC = 220/200, GA _AC = 220/4
00, ZB _AC = 200Ω ZA _AC = 400Ω,
The AC equivalent resistance is expressed as differential impedance,
It becomes 600Ω. At this time, the common mode impedance is
Needless to say, the values of ZB _AC and ZA _AC are the same as above.

Furthermore, by providing GB _AC and GA _AC with complex impedance characteristics, it is possible to freely set AC impedance and perform sidetone prevention control on subscriber line telephones.

In the above explanation, the calculations are performed digitally, but it goes without saying that analog processing is also possible.

It is also obvious that the present invention can be applied to trunk circuits having similar functions as subscriber circuits.

〔Effect of the invention〕

According to the present invention, the high voltage level circuit of the subscriber circuit can be simplified to realize an inexpensive subscriber circuit, and the circuit for making the characteristics variable can also be configured with a low voltage level circuit. In particular, the impedance of each subscriber line can be controlled.
Furthermore, by using digital processing, there is an effect that variable control of characteristics can be made easier.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional subscriber circuit configuration method, FIG. 2 is a circuit diagram showing an example of a conventional subscriber circuit configuration method, and FIG. 3 is a subscriber circuit configuration method according to the present invention. FIG. 4 is a circuit diagram showing a reference example for explaining the present invention, and FIG. 5 is a circuit diagram showing an embodiment according to the present invention. DESCRIPTION OF SYMBOLS 1... Load resistance of subscriber line, 2... Voltage-current conversion circuit, 3... Voltage detection circuit, 4... Signal transmission circuit for direct current feedback, 5... Signal transmission circuit for alternating current feedback, 6... Capacitor for direct current or disconnection, 101 ...Load resistance of subscriber line, 102, 103...Resistance for current supply, 104,
105... Current supply transistor, 106, 10
7,123...Operational amplifier, 108-111,12
0,121...Resistor, 112-118...Current mirror circuit, 119,124...Transistor, 12
2...Capacitor for AC removal, 125...Current source for DC bias, 126...Capacitor for DC and disconnection,
127...AC impedance circuit, 128...Low voltage power supply, 129...High voltage power supply, 130...Current mirror circuit, 131...Low voltage power supply, 132-13
6... Current mirror circuit, 137, 138... Current-voltage conversion resistor, 139, 140... Voltage-current conversion resistor, 141, 142... A/D conversion circuit, 14
3,144...D/A conversion circuit, 145...digital calculation circuit.

Claims (1)

[Scope of Claims] 1. In an electronic subscriber circuit having means for supplying direct current to a terminal via a subscriber line and means for transmitting and receiving an alternating current signal to and from the terminal, the subscriber line and a low voltage level circuit which is a feedback circuit for the high voltage level, the high voltage level circuit detecting the voltage and current state of the subscriber line and converting it to the low voltage level. converting and transmitting separate voltage and current signals for both lines of the subscriber line to said low voltage level circuit; and converting separate drive signals for both lines from said low voltage level circuit from low voltage level direct current and alternating current; The low voltage level circuit has the function of converting to a high voltage level, transmitting it to the subscriber line, and driving the subscriber line, and the low voltage level circuit determines the DC supply characteristics and AC termination characteristics of the electronic subscriber circuit. It has a feedback characteristic, and by calculating the voltage and current signals of both subscriber lines,
In addition to the function that allows you to set the DC/AC feedback characteristics so that the differential signal and common-mode signal of the subscriber line are controlled separately, it is also possible to calculate the voltage and current signals for both subscriber lines separately. A subscriber circuit configuration system characterized by having a function of controlling the feedback characteristics of the subscriber line and controlling the impedance of both subscriber lines separately. 2 Analog on the input side of the low voltage level circuit,
A subscriber circuit configuration system according to claim 1, characterized in that by providing a digital conversion circuit and providing a digital/analog conversion circuit on the output side, the feedback characteristic can be calculated or controlled by a digital signal. .