WO1998010582A1 - Electronic impedance supply circuit - Google Patents
Electronic impedance supply circuit Download PDFInfo
- Publication number
- WO1998010582A1 WO1998010582A1 PCT/IB1997/000889 IB9700889W WO9810582A1 WO 1998010582 A1 WO1998010582 A1 WO 1998010582A1 IB 9700889 W IB9700889 W IB 9700889W WO 9810582 A1 WO9810582 A1 WO 9810582A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- transistor
- electronic impedance
- coupled
- wire
- terminal
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/001—Current supply source at the exchanger providing current to substations
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M19/00—Current supply arrangements for telephone systems
- H04M19/001—Current supply source at the exchanger providing current to substations
- H04M19/005—Feeding arrangements without the use of line transformers
Definitions
- the present invention relates to a telecommunications system comprising a supply circuit for a telecommunications line comprising a first and a second wire, which supply circuit comprises a first electronic impedance circuit including a first transistor and a second electronic impedance circuit including a second transistor, the electronic impedance circuits being coupled between a first voltage reference terminal and the first wire and between a second voltage reference terminal and the second wire, respectively.
- a system can be a private automatic branch exchange coupled to a number of subscriber sets via twisted pairs, whereby the sets can be analog or digital sets and whereby the branch exchange can be coupled to the public switched telephone network, or any other suitable system wherein subscriber sets have to be fed via the telecommunications line.
- the present invention further relates to an automatic branch exchange, a line card, a supply circuit for a telecommunications line, and a telecommunications subscriber device.
- a telecommunications system of the above kind is known from the Belgium Patent No. 1007208A3, filed by the same applicant.
- This Belgium Patent discloses a telecommunications system comprising a supply circuit for feeding power to a twisted pair telecommunications line to another end of which a telecommunications subscriber device such as a telephone device or a facsimile apparatus or a data terminal, or the like, can be coupled.
- the telecommunications device is fed via a DC-voltage injected into the twisted pair by means of the supply circuit.
- the known supply circuit applies line voltage control so that the DC-line current is dependent on the supply needs of the subscriber device.
- the supply circuit In order to inject DC-power to the telecommunications line and at the same time to avoid that signal power is fed from the wired to the DC-supply, the known circuit applies electronic impedances symmetrically arranged between the wires and respective DC-power supply lines.
- the electronic impedances simulate large coils. This is because in modern branch exchanges, or the like, large coils should be avoided. Such coils are expensive and are bulky so that mounting is cumbersome.
- the electronic impedances comprise a FET (Field Effect Transistor) of which a control electrode is coupled to a DC- supply terminal and a wire via a junction of a series arrangement of a resistor and a capacitor, and further a resistor in the source lead of the FET. Due to the series arrangement of the resistor and the capacitor the gate voltage of the FET can only vary slowly so that a virtually constant voltage occurs across the source resistor of the FET. An AC-voltage at the drain of the FET is attenuated by a factor inversely proportional to the gain of the FET.
- FET Field Effect Transistor
- the electronic impedance behaves like a lump element coil, the equivalent impedance being equal to the value of the source resistor of the FET multiplied by the gain-factor of the FET, and the DC-resistance virtually being equal to the value of the source resistor.
- the resistor in the series arrangement preferably has a relatively high value, this resistor being connected parallel to the emulated coil.
- a diode-resistor series arrangement is provided between the control electrode of the FET and a DC-supply terminal or a wire, as the case may be.
- the known circuit comprises a resistor that is coupled between a source electrode and a wire or a DC-supply terminal, as the case may be.
- This resistor should be large enough so as to achieve that the impedance of the electronic circuit is as large as possible and small enough so as not to cause a too large voltage drop.
- the French Patent Application No. 2 254 168 discloses a supply circuit for a telecommunications line comprising a Darlington transistor pair instead of a FET.
- the Darling pair connected as an electronic impedance, has different electronic properties than a single FET, and has a higher amplification factor.
- a Darlington configuration could be applied for switching on/off relatively high currents but the Darlington pair would not perform well for linear applications or for putting digital data on the line having a relatively high frequency, such as in the order of 40-200 kHz.
- a Darlington is a current to current amplifier in which a main current is built up quickly after applying a control current to the Darlington, but this main current decreases very slowly if it is being switched off. I.e. , the Darlington quickly opens (high gain) but slowly closes. Due to the high loop gain, the Darlington pair will easily become instable, i.e. , the circuit will tend to oscillate or exhibit a phenomenon called 'motorboating' .
- the telecommunications system is characterized in that the supply circuit comprises a first electronic impedance multiplying circuit including a third transistor and a second electronic impedance multiplying circuit including a fourth transistor, a main current path of the first transistor being coupled in a series arrangement with a main current path of the third transistor between the first reference voltage terminal and the first wire and a main current path of the second transistor being coupled in a series arrangement with a main current path of the fourth transistor between the second reference voltage terminal and the second wire.
- impedance multiplication is done in a controlled way, namely in a least two separate stages, while at the same time a relatively low DC voltage drop is achieved across the multiplied electronic impedance.
- the AC-impedance can advantageously be increased by connecting more than two electronic impedance multiplying circuits in a cascode arrangement.
- the supply circuit comprises at least a reverse biased diode or a series arrangement of the reverse biased diode and a resistor coupled between a control electrode of at least one transistor of the electronic impedance circuit or the electronic impedance multiplying circuit and one of the voltage reference terminals or one of the wires, respectively.
- the AM-modulated disturbance signals such as strong radio channels which would otherwise become audible can be suppressed effectively.
- the bias voltage of the transistors can be made small. If the diode detects an AM-disturbance signal, the signal control swing of the transistors become larger dynamically.
- a main electrode of the first and/or the second transistor is coupled to the first voltage reference terminal and/ or to the second wire, respectively, via a series arrangement of at least one forward biased diode and a resistor.
- the DC voltage swing of the multiplied electronic impedance is decreased by at least one forward diode voltage so that power dissipation is reduced.
- a main electrode of the third and/or the fourth transistor is coupled to the first voltage reference terminal and/or to the second wire, respectively, and wherein a control electrode of the third and/or the fourth transistor is coupled to the main electrode via a series arrangement of a first resistor, a first forward biased diode, and a second forward biased diode, and a junction of the first resistor and the first diode is coupled to a third voltage reference terminal via a second resistor.
- the DC voltage swing of the multiplied electronic impedance is considerably decreased so that power dissipation is decreased. Then, a smaller transistor can be applied and thus a smaller heatsink or no heatsink at all.
- the first electronic impedance circuit and/or the second electronic impedance circuit comprise a control loop for controlling the voltage between main electrodes of the first and/or second transistor to a predetermined voltage value.
- a DC voltage between the main electrodes of the transistor of the electronic impedance circuit can be controlled to have the smallest possible value for achieving a proper operation for a given main electrode path resistance so that this transistor advantageously can be a small one.
- FIG. 1 schematically shows a telecommunications system according to the present invention
- Fig. 2 shows a blockdiagram of a telecommunications subscriber device according to the present invention
- Fig. 3 shows an embodiment of an electronic impedance circuit according to the present invention used in a supply circuit for a telecommunications line
- Fig. 4 shows another embodiment of an electronic impedance circuit according to the present invention
- Fig. 5 shows another embodiment of an electronic impedance circuit according to the present invention
- Fig. 6 shows another embodiment of an electronic impedance circuit according to the present invention.
- Fig. 7 shows a cascode arrangement of at least two electronic impedance multiplying circuits in a supply circuit according to the present invention.
- Fig. 1 schematically shows a telecommunications system 1 according to the present invention comprising an automatic branch exchange 2 which can be coupled to a public switched telecommunications network 3.
- the automatic branch exchange 2 comprises a number of line cards, a line card 4 being shown.
- a line card comprises a number of supply circuits for telecommunications lines.
- a supply circuit 5 is shown for supplying DC power to a telecommunications line 6, typically a twisted pair comprising a first wire a and a second wire b.
- the supply circuit 5 injects DC power into the line 6 to which further a useful signal such as a voice and/or data signal is injected via a transformer 7.
- a DC-blocking capacitor 8 is provided so as to avoid that the DC supply voltage is short- circuited by the transformer 7.
- the supply circuit comprises voltage generation means (not shown in detail) for generating a line voltage between a first voltage reference terminal 9 and a second voltage reference terminal 10, typically a voltage of -48 Volts.
- the supply circuit 5 comprises a first electronic impedance circuit 11 and a second electronic impedance circuit 12 emulating lump element coils, i.e. , the electronic impedances have a high impedance for signals to be transmitted and received via the telecommunications line 6 so as to avoid that signals do not flow into the DC supply lines, and the electronic impedances have a low impedance for DC signals so that DC power losses are as small as possible.
- the supply circuit 5 is arranged such that DC voltage control of the telecommunications line 6 is achieved.
- the line current is determined by the current required by a telecommunications subscriber device 13 coupled to the other end of the telecommunications line 6 via terminals a' and b ⁇ and furthermore, power losses in the line 6 are as small as possible.
- the line card 6 comprises other supply circuits, schematically indicated by further transformers 14 en 15 and dashed lines.
- Fig. 2 shows a blockdiagram of the telecommunications subscriber device 13 according to the present invention comprising a transformer 20 coupled to the terminals a' and b' of the telecommunications line 6 via a DC blocking capacitor 21. Via the transformer 20, signals to and from the telecommunications line 6 are exchanged with further circuitry and facilities 22 of the subscriber device 13, in a well-known way.
- the subscriber device 13 further comprises a supply circuit 23 for supplying DC power from the telecommunications line to the further circuitry and facilities 22.
- the supply circuit 23 comprises a diode bridge formed by diodes 24, 25, 26, and 27 and electronic impedance circuits 28 and 29 emulating lump element coils.
- the electronic impedance circuits 28 and 29 are coupled to the terminals a' and b', respectively, and at an other end to the diode bridge. Although it is preferable that both electronic impedance circuits 28 and 29 are present so as to obtain that common mode disturbance signals on the telecommunications line do not become audible, under certain circumstances one of the electronic impedance circuits could be replaced by a short-circuit.
- Fig. 3 shows an embodiment of the electronic impedance circuit 1 1 according to the present invention used in the supply circuit 5 for the telecommunications line 6.
- the electronic impedance circuits 12, 28, and 29 are similar in construction.
- the electronic impedance circuit 11 comprises a transistor 32 having a resistor 33 in its main current path.
- a resistor 34 is coupled between a terminal 35 of the electronic impedance circuit 11 and a control electrode of the transistor 32 and a capacitor 36 is coupled between the control electrode of the transistor 32 and a terminal 37 of the electronic impedance circuit 11.
- the electronic impedance circuit 11 further comprises a transistor 38 of which a main current path is coupled in a series arrangement with a main current path of the transistor 32, and of which a control electrode is coupled to a junction 39 of a series arrangement of a resistor 40 and a capacitor 41.
- a first electronic impedance circuit 31 is formed by the transistor 38, the resistors 33 and 40, and the capacitor 41, and an electronic impedance multiplying circuit is formed by the transistor 32, the resistor 34, and the capacitor 36.
- the electronic impedance circuit 11 only comprises the basic electronic impedance circuit 31, a value of the resistor 33 would have to be chosen such high that the AC impedance of the circuit would become high enough and such low that the DC voltage drop across the electronic impedance 11 would not be too high, i.e. , such a choice would be a compromise. Particulary with relatively high line currents, e.g. in the order of 200 mA, such a compromise is difficult to achieve.
- the resistor 40 is coupled to a junction 42 and the capacitor 41 is coupled to the terminal 37.
- a given reference voltage should be supplied to the junction 42.
- a voltage of one forward biased diode below a voltage on the terminal 35 is fed to the junction 42. This is done by coupling a forward biased diode 43 between the terminal 35 and the junction 42, the diode being biased by the resistor 44.
- the junction 42 may also be connected to the main path of the transistors 32 and 38, to a junction between the transistors 32 and 38.
- the component values of the components in the control circuits of the transistors 32 and 38 are chosen such that the voltage swing across the main electrodes of the transistor 32 is sufficient for dynamic behaviour and that the voltage swing across the main electrodes of the transistor 38 is as low as possible, virtually no signal being present on the main electrodes of the transistor 38.
- the power loss in the circuit according to the present invention is greatly reduced.
- One factor achieving this reduction is that the value of the resistor 33 can be chosen much smaller, typically in the order of 1 Ohm.
- the power loss is reduced to a value between 0.3W and 0.8W for a current of 200 mA.
- the electronic impedance circuit 11 may comprise series arrangements of a reverse biased diode and a resistor so as to better suppress common mode amplitude modulated disturbance signals.
- series arrangements of a diode 45 and a resistor 46 and of a diode 47 and a resistor 48 are coupled across the resistors 40 and 34, respectively.
- the transistors 32 and 38 may by bipolar transistors or Field Effect Transistors. With a combination of a Field Effect Transistor and a bipolar transistor, the transistor 32 preferably is a Field Effect Transistor.
- Fig. 4 shows another embodiment of the electronic impedance circuit 11 according to the present invention
- the junction 42 is coupled to a junction 49 of a resistor 50 which is coupled with its other end to the terminal 35 and to a series arrangement of at least one forward biased diode 51 which is coupled with its other end to a junction of main electrodes of the transistors 32 and 38. Shown is a further diode 52.
- the voltage across the main electrodes of the transistor 38 is typically reduced with 1.2 Volts if Silicium diodes are used.
- Fig. 5 shows another embodiment of the electronic impedance circuit 11 according to the present invention.
- the junction 42 is a junction between two forward biased diodes 55 and 56, the diode 56 being coupled with its other end to the terminal 35 and the diode 55 being coupled with its other end to a reference terminal 57 via a resistor 58.
- the reference potential at the terminal 57 is greater than the reference terminal at the terminal 35.
- the transistors 32 and 38 are Field Effect Transistors both having a gate-source-voltage of 2 Volts, for instance, in the embodiment given such relatively large gate-source voltages are partly compensated.
- the resistors 34 and 40 have a relatively great value so that, if the terminal 35 has ground potential, the gate of the transistor 32 has a voltage of 1.2 Volts and the gate of the transistor 38 has a voltage of 0.6 Volts.
- the dissipated power is typically reduced from 2W to 0.3W as compared to a basic electronic impedance circuit.
- Fig. 6 shows another embodiment of the electronic impedance circuit 1 1 according to the present invention. This embodiment differs from the above embodiments in that in the embodiments above compensation methods where applied for adjusting the voltage across the main electrodes of the transistor 38.
- the electronic impedance circuit comprises a control loop for controlling said voltage by means of a control circuit 60.
- the control circuit 60 comprises a first bipolar control transistor 61 of which the emitter is coupled to the source of the transistor 38 via a resistor 62 and of which the base is coupled to the drain of the transistor 38 via a resistor 63.
- the collector of the transistor 61 is coupled to ihe base of a second control transistor 64.
- the collector of the transistor 64 is coupled to the source of the transistor 38 via a resistor 65 and to the junction 42.
- the emitter of the transistor 64 is coupled to a terminal 66 via a resistor 67.
- the base of the transistor 64 is coupled to the terminal 66 via a resistor 68.
- the Field Effect Transistor can be controlled to have a low voltage across its main electrodes and thus can be small because of reduced dissipation. Operation is as follows. If the drain-source voltage of the transistor 38 gets above the base-emitter voltage of the transistor 61 , which is 0.6 Volts for a Silicium transistor, the transistor 61 becomes conductive. The current then flowing through the transistor 61 causes the transistor 64 to become conductive. The control loop is closed due to the fact that the collector of the transistor 64 is connected to the junction 42.
- the drain-source voltage across the Field Effect Transistor is controlled to a value equal to the base-emitter voltage of the transistor plus a small value in the order of some tenth of a volt, the small value being dependent on the loop gain. For stability reasons, the loop gain is kept relatively low.
- the drain-source voltage can even be made greater, namely 0.6 Volts plus a fraction equal to the quotient of the values of the resistors 63 and 69 times 0.6 Volts.
- a potentiometer (not shown in detail) can be applied of which the slider is coupled to the base of the transistor 61 and that further coupled between the drain and the source of the transistor 38.
- the drain-source voltage of the transistor can be easily adjusted to any desired value between 0.6 Volts and a higher voltage.
- Fig. 7 shows a cascode arrangement of at least two electronic impedance multiplying circuits 75 and 76 in a supply circuit according to the present invention in the electronic impedance circuit 11.
- the multiplying circuits 75 and 76 are similar in construction as the ones described.
- the AC impedance can be greatly increased without the risk of the circuit becoming instable. This is due to the fact that there are no loop gains exceeding the gain of a single stage while at the same time the impedance multiplication factor increases with the addition of further multiplication stages.
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- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Devices For Supply Of Signal Current (AREA)
- Direct Current Feeding And Distribution (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97929457A EP0858705A1 (en) | 1996-09-03 | 1997-07-17 | Electronic impedance supply circuit |
KR1019980703236A KR20000064316A (en) | 1996-09-03 | 1997-07-17 | Electronic impedance power circuit |
JP10512403A JPH11514828A (en) | 1996-09-03 | 1997-07-17 | Power circuit for electronic impedance |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP96202454.3 | 1996-09-03 | ||
EP96202454 | 1996-09-03 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998010582A1 true WO1998010582A1 (en) | 1998-03-12 |
Family
ID=8224347
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB1997/000889 WO1998010582A1 (en) | 1996-09-03 | 1997-07-17 | Electronic impedance supply circuit |
Country Status (6)
Country | Link |
---|---|
US (1) | US6134323A (en) |
EP (1) | EP0858705A1 (en) |
JP (1) | JPH11514828A (en) |
KR (1) | KR20000064316A (en) |
CN (1) | CN1164069C (en) |
WO (1) | WO1998010582A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003031215A1 (en) | 2001-10-08 | 2003-04-17 | Valeo Embrayages | Transmission assembly comprising two clutches and an electric machine, in particular for motor vehicle |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100805602B1 (en) * | 2001-12-31 | 2008-02-20 | 주식회사 케이티 | Device for automatically configuring impedance of balancing network in subscriber interfacing circuit of exchange |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2254168A1 (en) * | 1973-12-11 | 1975-07-04 | Ass Ouvriers Instr Precision | Telephone line supply device - is an active electronic device acting as resistance for direct current and high impedance for A.C. |
US3943432A (en) * | 1973-12-10 | 1976-03-09 | International Standard Electric Corporation | Electronic feeding bridge |
US4961220A (en) * | 1988-12-21 | 1990-10-02 | Spectrum Concepts, Inc. | Power management in a microprocessor-controlled battery-powered telephone device |
Family Cites Families (15)
Publication number | Priority date | Publication date | Assignee | Title |
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US4046968A (en) * | 1976-08-05 | 1977-09-06 | Bell Telephone Laboratories, Incorporated | Integrable line circuit for use with miniature line transformer |
FR2382810A1 (en) * | 1977-03-02 | 1978-09-29 | Labo Cent Telecommunicat | TELEPHONE LINE POWER CIRCUIT WITH PROTECTION |
US4181824A (en) * | 1978-10-10 | 1980-01-01 | Bell Telephone Laboratories, Incorporated | Balancing impedance circuit |
NL7903664A (en) * | 1979-05-10 | 1980-11-12 | Philips Nv | LINE CIRCUIT. |
US4554412A (en) * | 1984-07-23 | 1985-11-19 | At&T Information Systems Inc. | Resistive line circuit |
SE453240B (en) * | 1986-05-06 | 1988-01-18 | Ericsson Telefon Ab L M | DEVICE IN A TELECOMMUNICATION SYSTEM FOR POWERING A PHONE DEVICE |
AR240631A1 (en) * | 1986-06-06 | 1990-06-30 | Siemens Ag | Circuit for protecting an electronic subscriber line interface circuit |
US4767980A (en) * | 1987-10-22 | 1988-08-30 | Reliance Comm/Tec Corporation | Inductance multiplier circuit |
WO1992019062A1 (en) * | 1991-04-15 | 1992-10-29 | Northern Telecom Limited | Current limited circuit for subscriber interface |
US5359655A (en) * | 1991-06-06 | 1994-10-25 | U.S. Philips Corporation | Supply circuit for a telecommunication line, providing highly symmetrical and rapid response to line voltage disturbances |
US5274702A (en) * | 1992-04-16 | 1993-12-28 | Northern Telecom Limited | Wideband telephone line interface circuit |
BE1007208A3 (en) * | 1993-06-07 | 1995-04-25 | Philips Electronics Nv | Telecommunications system equipped with a supply switch for a telecommunication line and a supply switch for a telecommunication line suitable for application in the telecommunication system |
EP0651541B1 (en) * | 1993-10-29 | 2001-01-10 | STMicroelectronics S.r.l. | Telephone subscriber circuit with galvanic isolating element for driving the on/off states of a telephone line |
US5737411A (en) * | 1994-12-29 | 1998-04-07 | Advanced Micro Devices Inc. | Battery switching in a telephone subscriber line interface circuit |
US5867557A (en) * | 1996-05-17 | 1999-02-02 | Texas Instruments Incorporated | Remotely controlled communication line diagnostic apparatus and method |
-
1997
- 1997-07-17 EP EP97929457A patent/EP0858705A1/en not_active Withdrawn
- 1997-07-17 WO PCT/IB1997/000889 patent/WO1998010582A1/en active IP Right Grant
- 1997-07-17 JP JP10512403A patent/JPH11514828A/en not_active Abandoned
- 1997-07-17 CN CNB971911827A patent/CN1164069C/en not_active Expired - Fee Related
- 1997-07-17 KR KR1019980703236A patent/KR20000064316A/en active IP Right Grant
- 1997-08-28 US US08/919,973 patent/US6134323A/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3943432A (en) * | 1973-12-10 | 1976-03-09 | International Standard Electric Corporation | Electronic feeding bridge |
FR2254168A1 (en) * | 1973-12-11 | 1975-07-04 | Ass Ouvriers Instr Precision | Telephone line supply device - is an active electronic device acting as resistance for direct current and high impedance for A.C. |
US4961220A (en) * | 1988-12-21 | 1990-10-02 | Spectrum Concepts, Inc. | Power management in a microprocessor-controlled battery-powered telephone device |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN, Vol. 13, No. 34, E-708; & JP,A,63 232 742 (FUJITSU LTD), 28 Sept. 1988. * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2003031215A1 (en) | 2001-10-08 | 2003-04-17 | Valeo Embrayages | Transmission assembly comprising two clutches and an electric machine, in particular for motor vehicle |
Also Published As
Publication number | Publication date |
---|---|
CN1200218A (en) | 1998-11-25 |
CN1164069C (en) | 2004-08-25 |
KR20000064316A (en) | 2000-11-06 |
US6134323A (en) | 2000-10-17 |
EP0858705A1 (en) | 1998-08-19 |
JPH11514828A (en) | 1999-12-14 |
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