JP3521307B2 - Splitter filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention mainly relates to xDSL.
(Digital subscriber line),
The present invention relates to a telephone line splitter filter suitable for separating and synthesizing an analog voice signal and a digital data signal.

[0002]

2. Description of the Related Art Conventional xDSL (digital subscriber)
The filter for the splitter used for the telephone line used for (line) will be described. Here, xDSL (x
Digital Subscriber Line (ADSL)
tric Digital Subscriber Line) and RADSL (Rate Adaptive AsymmetricD) derived from ADSL.
digital Subscriber Line) and HDSL (High
data rate DigitalSubscriber Line), VDSL
(Very High Speed Digital SubscriberLine),
SDSL (Symmetric Digital Subscriber Line)
This is a communication technology for performing high-speed data communication using an existing telephone line (copper twisted pair line).

[0003] The xDSL has attracted attention as a technology to compete with ISDN at present, as the demand for high-speed data communication is increasing due to the recent development of data communication networks represented by the Internet. Among them, ADSL is a DS that makes the downstream communication speed faster than the upstream communication speed.
L communication method, details of which are described in ANSI Recommendation T.
1-413.

[0004] Briefly describing ADSL, current analog telephone lines use only a voice band of about 0 to 4 kHz, whereas ADSL uses a higher frequency band. , Enabling high-speed digital data communication.

[0005] In ADSL communication, ADSL modems are provided at both ends of a subscriber line connecting a telephone station and a subscriber's home. This ADSL modem is a data modulation and demodulation device for performing ADSL communication, and is characterized by handling a higher frequency than an ordinary analog modem.

When an ADSL modem is connected to an existing subscriber line, a POTS (Plain Old Telepho) is used to separate and combine an analog voice signal and a digital data signal.
ne Service) A splitter is used. In addition, POTS
The term refers to a conventional analog telephone line service or a low frequency band of about 0 to 4 kHz used in analog communication.

[0007] The splitters are attached to both ends of a telephone line. One is connected as a voice signal to an existing telephone or exchange, and the other is connected to an ADSL modem. By making such a connection, data communication via the ADSL modem is always possible regardless of the communication state of the analog telephone.

FIG. 3 shows a circuit configuration of a conventional splitter filter. The splitter filter shown in FIG.
This is a circuit configuration described in 1-299399. The splitter filter of FIG. 3 is configured between the first and second signal lines, and the first inductor L ₁ installed on the first signal line in order from the input terminal side (line side). A second inductor L ₂ , a third inductor L ₃ connected in series , a fourth inductor L ₁ ′ installed on the second signal line,
_'And the inductor L ₃ of the _6' fifth inductor L ₂ and the inductor columns and which are connected in series, the first inductor L ₁ connected in the first signal line side, a second
The connection point of the inductor L _{2, 'the} fifth inductor L _2' fourth inductor L ₁ connected in the second signal line side to the first capacitor C ₁ that connects the connection point of
A third capacitor C _3, which is arranged between the terminals of the output terminal (telephone side or the exchange side), the second inductor L ₂ on the first signal line, a second capacitor C in parallel
₂ and the first damping resistor R ₁ are connected to form a resonance circuit, and the fourth capacitor C ₂ ′ and the fourth capacitor C ₂ ′ are connected in parallel with the fifth inductor L ₂ ′ on the second signal line. 2
Form a resonance circuit is a damping resistor R ₂ of connections.

[0009]

However, in the conventional circuit configuration described in Japanese Patent Application No. 11-299399, it is difficult (impossible) to reduce the number of components and to simplify the circuit configuration. There was a problem.

Therefore, the present invention is based on ITU-T standard G.
992.1 (G.dmt) AnnexEE.4Type4
It is another object of the present invention to provide a splitter filter having a high-performance filter characteristic, which satisfies the above conditions and realizes downsizing.

Accordingly, an object of the present invention is to provide a low-cost splitter filter having improved return loss characteristics, high-performance filter characteristics, and a small number of components.

[0012]

SUMMARY OF THE INVENTION A splitter filter according to the present invention has a cutoff frequency of an audio signal pass band (200 Hz to 4 kHz) for separating and synthesizing an audio analog signal and a digital data signal in xDSL.
, Around 4 kHz, to thereby provide a splitter filter with improved return loss characteristics.

Further, when the cutoff frequency is set to around 4 kHz, the frequency characteristic of the audio signal pass band is broken, but in order to improve this, a new series resonance circuit and a damping resistor are added to increase the gain. Compensated. Further, a series circuit of the series resonance circuit and the damping resistor is connected between lines on the input terminal side.

That is, the present invention relates to a splitter filter connected between a line and a telephone or a switch for separating an audio signal and a digital signal, wherein the cut-off frequency of the filter is 200 Hz to 4 kHz. And a line on the input terminal side connected to the line side of the splitter filter.
Between (w ₁ , w ₂ ) , a series resonance circuit (C ₃ , L ₃ ) that causes resonance in an audio signal pass band, and a damping resistor
A splitter filter comprising a series circuit with (R ₁ ) and compensating for the gain of a signal component that is lost on the high frequency side of the audio signal pass band.

[0015] For a splitter according to one embodiment of the present invention.
The filter includes first and second signal lines (w ₁ ,
w ₂ ) , and the first inductor (L ₁ ) and the second inductor (L ₂ ) installed on the first signal line (w ₁ ) are arranged in order from the input terminal side. A series of inductors connected in series, and a second signal line (w ₂ )
The third inductor (L ₁ ′) and the fourth inductor (L ₂ ′) installed above are arranged between an inductor row in which the fourth inductor (L ₂ ′) is connected in series and a connection point between both inductors in each of the inductor rows . the first and the capacitor _{(C 1),} said
The series circuit connected between a _second capacitor (C ₂ ) arranged in parallel on the output terminal side connected to a telephone or a switch and the line (w ₁ , w ₂ ) on the input terminal side
And the series circuit includes a third capacitor
(C ₃ ) and the fifth inductor (L ₃ )
It is composed of a column resonance circuit and a damping resistor (R ₁ ),
The resonance frequency of the series resonance circuit is set near the voice band, and the first inductor (L ₁ ) and the third inductor (L
₁ ′) and a second inductor (L ₂ ) and a fourth inductor
(L ₂ ′) is a splitter filter mutually forming a transformer structure.

According to an embodiment of the splitter filter,
If so , the first inductor (L ₁ ) and the third inductor (L ₁ ′) may be in the range of 9.45 mH to 11.55 mH.
, And the second inductor (L ₂ ) and the fourth inductor (L ₂ ′) have a constant of 7.
It has a constant in the range of 2 mH to 8.8 mH, and the first capacitor (C ₁ ) has a capacity of 73.8n.
Has a constant belonging to the range of F to 90.2 nF,
The second capacitor (C ₂ ) has a capacity of 73.8 nF to 9
The third capacitor (C ₃ ) has a constant belonging to the range of 0.2 nF, and constitutes the series resonance circuit.
It has a constant in the range of 1.2 nF to 74.8 nF, and the fifth inductor (L ₃ ) has a resistance of 423 mH.
To 517 mH, and the damping resistance (R ₁ ) is from 4.5 kΩ to 5.5 kΩ.
Wherein the resonance frequency of the series resonance circuit is set to around 1.5 kHz.
A splitter filter according to claim 2 is obtained.

Also,Another implementation of the splitter filter
According to the example, The first inductor(L ₁ )And the first
3 inductors(L ₁ ')Is from 11.7 mH to 14.
A constant belonging to the range of 3 mH,
Nacta(L ₂ )And fourth inductor(L ₂ ')
Is always in the range of 9.45 mH to 11.55 mH.
The first capacitor(C ₁ )
Is a constant belonging to the range of 73.8 nF to 90.2 nF.
And the second capacitor(C ₂ )Is 6
Has a constant in the range of 1.2 nF to 74.8 nF
And constitute the series resonance circuit.ThirdCapacitor
(C ₃ )Belongs to the range of 19.8 nF to 24.2 nF.
And the fifth inductor(L ₃ )
Has a constant in the range of 0.9H to 1.1H
And damping resistance(R ₁ )Is from 4.5kΩ
Has a constant belonging to the range of 5.5 kΩ,The series
Resonance circuitTo set the resonance frequency of the
Thus, a filter for the light source is obtained.

The splitter filter according to the second embodiment of the present invention is configured between first and second signal lines (w ₁ , w ₂ ), and is arranged in order from the input terminal side. On the first signal line (w ₁ ), a first inductor (L ₁ ) and a parallel circuit of a _second inductor (L ₂ ) and a fourth capacitor (C ₄ ) are connected in series. And a third signal line (w ₂ )
Is connected in series with a parallel circuit of a fourth inductor (L ₂ ′) and a fifth capacitor (C ₅ ), and the first and third inductors (L ₁ ′) are connected in series. ₁ , L ₁ ′) and each of the parallel circuits of the second and fourth inductors (L ₂ , L ₂ ′) and the fourth and fifth capacitors (C ₄ , C ₅ ). Is connected to a _first capacitor (C ₁ ), and a second capacitor (C ₂ ) is connected in parallel to an output terminal connected to the telephone or the exchange. w ₁ , w ₂ ), the series circuit is connected, the series circuit includes a series resonance circuit including a _third capacitor (C ₃ ) and a fifth inductor (L ₃ ), and a damping circuit. resistance consists de (R ₁₎ and, and, the series resonance The resonant frequency of the road and voiceband vicinity, also with the first inductor (L ₁₎ and the third inductor (L ₁ ') forms a trans configuration to each other,
The second inductor (L ₂ ) and the fourth inductor (L ₂ ′) are splitter filters forming a transformer structure with each other.

An embodiment of the splitter filter
According to a first inductor _(L 1) and the third inductor _{(L 1} ') has a constant within the scope of 8.8mH from 7.2MH, also a second inductor (L
₂ ) and the fourth inductor (L ₂ ′) are 2.7 mH
From 3.3 mH to 3.3 mH, and the first capacitor (C ₁ ) is from 42.3 nF to 51.3 nH.
Has a constant within the scope of 7NF, said second capacitor _(C 2) has a constant within the scope of 61.6nF from 50.4NF, also a fourth capacitor _{(C 4} ) And the fifth capacitor (C ₅ ) are 5.04
a third capacitor (C ) having a constant in the range of nF to 6.16 nF and constituting the series resonance circuit.
₃ ) has a constant in the range of 30.7 nF to 36.3 nF, and the fifth inductor (L ₃ )
Has a constant within the scope of 748mH from 612MH, also damping resistor _(R 1) has a constant within the scope of 6.82kΩ from 5.48Keiomega, the
A splitter filter characterized by setting the resonance frequency of the series resonance circuit to around 1.5 kHz is obtained.

The splitter filter according to the present invention is installed between a telephone line and a telephone so as to separate and synthesize a voice analog signal and a digital data signal in an xDSL telephone line. It is set to around 4 kHz on the high side of the signal pass band, and the characteristic attenuation of the filter generated in the cut-off frequency band and the polarity generated by the Chebyshev design method are used to adjust the mismatch attenuation (return loss) characteristics to the ITU-T standard. G. 9
92.1 (G. dmt) Annex EE. 4Type
The splitter filter according to any one of claims 1 to 6, which satisfies condition 4.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A splitter filter according to an embodiment of the present invention will be described below.

[0022] (Embodiment 1) FIG. 1 shows a circuit diagram of a splitter filter according to a first embodiment of the present invention. The splitter filter of FIG. 1 is installed between a telephone line and a telephone (or an exchange). The splitter filter of FIG.
L is a filter used as a POTS splitter for separating and synthesizing an audio analog signal and a digital data signal.

[0023] Splitter filter of the present embodiment 1, the passive filter 10, the resonance circuit section 11 are composed of the damping resistor R ₁ to adjust the sharpness of gradient of the attenuation of the resonant circuit.

In ADSL, a copper twisted pair wire composed of a pair of copper wires is used as a line. The two terminals on the right side of the splitter filter shown in FIG.
It is connected to each of the copper wires. Hereinafter, for convenience of explanation, the two copper wires and the signal lines connected thereto are respectively referred to as
These are called first and second signal lines.

The resonance circuit section 11 of the splitter filter according to the first embodiment has a configuration in which a series resonance circuit including an inductor L ₃ and a capacitor C ₃ is provided on the input terminal side connected to the line. The series resonance circuit has a damping resistor R for adjusting the sharpness of the slope of the resonance attenuation.
₁ is provided.

As described above, the splitter filter used for telephone lines according to the present invention is used for a splitter for separating and synthesizing a voice analog signal and a digital data signal in xDSL.

That is, the telephone line splitter filter according to the present invention is based on ITU-T standard G.992.1 (G.dmt).
Satisfies AnnexE E.4Type4, and
The number of parts was reduced and the size was reduced.

In the above, a more specific configuration will be described. In the splitter filter according to the present invention, the cutoff frequency is shifted to the vicinity of the audio signal pass band, the return loss characteristics are improved, and the cutoff frequency is shifted. The use of a resonance circuit and a damping resistor improves the frequency characteristic breakage due to the above.

The circuit configuration of the splitter filter shown in FIG. 1 will be described in more detail.

The splitter filter of FIG . 1 is configured between first and second signal lines w ₁ and w ₂ .
In order from the input terminal side, the first inductor L ₁ and the second inductor L ₂ and is an inductor columns which are connected in series which are placed on the first upper signal lines w _1, second signal line w ₂ An inductor row in which a third inductor L ₁ ′ and a fourth inductor L ₂ ′ installed on the upper side are connected in series, and a first inductor disposed between a connection point of both inductors in each of the inductor rows . a capacitor _{C 1,} the telephone
Or a second capacitor C _2, which are arranged in parallel to the output terminal side connected to the switch, the input terminal side line
and a series circuit connected between w ₁ and w _2.
Column circuit includes a third capacitor C ₃ fifth inductor L
₃ and a damping resistor R1
And the resonance frequency of the series resonance circuit is in the vicinity of the voice band, and the first inductor L ₁ and the third inductor L ₁ ′ mutually form a transformer structure,
The second inductor L ₂ and the fourth inductor
L ₂ ′ is a splitter filter forming a transformer structure with each other.

One embodiment of the splitter filter of FIG .
It is as follows . The first inductor L ₁ and the third inductor L ₁ ′ are between 9.45 mH and 11.5 mH.
The second inductor L ₂ and the fourth inductor L ₂ ′ have a constant belonging to a range of 5 mH, and
mH to 8.8 mH in a constant range,
The first capacitor _{C 1} from 73.8NF 9
A constant belonging to the range of 0.2 nF;
Capacitor _{C 2} of has a constant within the scope of 90.2nF from 73.8NF, third capacitor _{C 3} constituting the series resonant circuit, 7 61.2nF
It has a constant belonging to the range of 4.8 nF and the fifth
Inductor _{L 3} of has a constant within the scope of 517mH from 423MH, also damping resistor R
Reference numeral ₁ denotes a splitter filter having a constant in the range of 4.5 kΩ to 5.5 kΩ and having a resonance frequency of about 1.5 kHz.

[0032] Here, the reason the first range of the inductance of the inductor _{L 1} in the range of 11.55MH from 9.45mH is in the above 11.55MH, too low is the cutoff frequency, also blocked in 9.45mH or less This is because the frequency is too high.

Further, it had the second range of the inductance of the inductor _{L 2} in the range of 8.8MH from 7.5mH, in more 8.8MH, too low is the cutoff frequency, also cut-off frequency is 7.5mH below Is too high.

The reason why the range of the inductance of the third inductor L ₁ ′ is in the range of 9.45 mH to 11.55 mH is that the cut-off frequency is too low above 11.55 mH, and cut off below 9.45 mH. This is because the frequency is too high.

The reason why the range of the inductance of the fourth inductor L ₂ ′ is from 7.5 mH to 8.8 mH is that the cut-off frequency is too low above 8.8 mH, and cut off below 7.5 mH. This is because the frequency is too high.

Further, were the first capacitance of the capacitor _{C 1} in the range of 73.8~90.2nF is, 90.2NF
Above, the cutoff frequency is too low, and 73.8 nF
This is because the cutoff frequency is too high below.

Further, had the second capacitance of the capacitor _{C 2} in the range of 73.8~90.2nF is, 90.2NF
Above, the cutoff frequency is too low, and 73.8 nF
This is because the cutoff frequency is too high below.

Further, the capacitance of the third capacitor _{C 3} which constitutes a resonant circuit was in the range of 61.2~74.8nF is in the above 74.8NF, resonant frequency 1 set.
The frequency is too low for 5kHz and 61.2n
This is because the frequency becomes too high with respect to the set resonance frequency of 1.5 kHz below F.

[0039] Also the inductance of the fifth inductor _{L 3} constituting the resonant circuit was in the range of 517MH from 423mH, in more 517MH, too low a frequency relative to the resonance frequency 1.5kHz set, also 42
If the frequency is 3 mH or less, the frequency becomes too high with respect to the set resonance frequency of 1.5 kHz.

[0040] In addition, the damping resistor _{R 1, 4.5~5.}
The reason for setting the range to 5 kΩ is that if it is 5.5 kΩ or more, damping is too effective and the attenuation is large, and if it is 4.5 kΩ or less, the damping is not effective and the resonance circuit becomes unstable.

Next, another combination of circuit constants other than the above
A second embodiment will be described with reference to FIG. That is, the first inductor L ₁ and the third inductor L ₁ ′
Has a constant in the range of 11.7 mH to 14.3 mH, and the second inductor L ₂ and the fourth inductor L ₂ ′ have a constant of 9.45 mH to 11.55 mH.
It has a constant within the scope of, and the first capacitor _{C 1} has a constant within the scope of 90.2nF from 73.8NF, the second capacitor C
₂ has a constant belonging to the range of 61.2 nF to 74.8 nF, and the third capacitor C ₃ constituting the series resonance circuit has a constant belonging to the range of 19.8 nF to 24.2 nF. And the fifth inductor L ₃
Has a constant within the scope of 1.1H from 0.9H, also the damping resistor _{R 1} is 5 4.5Keiomega.
The splitter filter has a constant belonging to the range of 5 kΩ and has a resonance frequency near 1.5 kHz.

[0042] Here, the reason the first range of the inductance of the inductor _{L 1} in the range of 14.3MH from 11.7mH is in the above 14.3MH, too low is the cutoff frequency, also blocked in 11.7mH below This is because the frequency is too high.

[0043] Furthermore, had the second range of the inductance of the inductor _{L 2} in the range of 11.55MH from 9.45mH is in the above 11.55MH, too low is the cutoff frequency, also cut-off frequency is 9.45mH or less Is too high.

The reason why the range of the inductance of the third inductor L ₁ ′ is in the range from 11.7 mH to 14.3 mH is that the cut-off frequency is too low above 14.3 mH, and cut off below 11.7 mH. This is because the frequency is too high.

The reason why the range of the inductance of the fourth inductor L ₂ ′ is in the range of 7.5 mH to 8.8 mH is that the cut-off frequency is too low above 8.8 mH, and cut off below 7.5 mH. This is because the frequency is too high.

[0046] Furthermore, had the first capacitance of the capacitor _{C 1} in the range of 73.8~90.2nF is, 90.2NF
Above, the cutoff frequency is too low, and 73.8 nF
This is because the cutoff frequency is too high below.

Further, had the second capacitance of the capacitor _{C 2} in the range of 73.8~90.2nF is, 90.2NF
Above, the cutoff frequency is too low, and 73.8 nF
This is because the cutoff frequency is too high below.

[0048] Also the capacitance of the third capacitor _{C 3} which constitutes a resonant circuit was in the range of 61.2~74.8nF it is in the above 74.8NF, the resonance frequency was set 1.5
Frequency too low for kHz and 61.2 nF
This is because the frequency is too high with respect to the set resonance frequency of 1.5 kHz.

[0049] In addition, the damping resistor _{R 1, 4.5~5.}
The reason for setting the range to 5 kΩ is that if it is 5.5 kΩ or more, damping is too effective and the attenuation is large, and if it is 4.5 kΩ or less, the damping is not effective and the resonance circuit becomes unstable.

As described above, in the splitter filter according to the first embodiment , the cutoff frequency is shifted to the vicinity of the audio signal pass band (200 Hz to 4 kHz) to improve return loss characteristics. Since the resonance circuit and the damping resistor for causing resonance in the audio signal pass band are provided, it is possible to improve the frequency characteristic in the audio signal pass band.

The effect of this improvement will be described by comparing a conventional splitter filter ( FIG. 3 ) with the splitter filter according to the first embodiment (FIG. 1).

In the filter according to the first embodiment used for this comparison , L ₁ = 8 mH, L ₂ = 10.5 mH, L ₃
= 8 mH, L ₄ = 10.5 mH, L ₅ = 470 mH, C
₁ = 82 nF, C ₂ = 82 nF, C ₃ = 68 nF, R ₁
= 5 kΩ, and the measurement results are shown in Table 1 below.

[0053]

[Table 1]

As can be understood from Table 1, although some variation is allowed in the above circuit constants,
The variation was within ± 10%.

[0055] In the same manner, in the conventional example of a passive filter (3), the circuit constant of each component, the ratio of the
The splitter filter according to the first embodiment used for comparison .
Table 2 shows the results of comparison between the measurement results obtained when the same values as those of the components corresponding to the circuit components were used and the measurement results according to the present embodiment used for the above comparison .

[0056]

[Table 2]

As shown in Table 2, Embodiment 2 of the present invention
It can be understood that the improved circuit configuration using the splitter filter can obtain the same characteristics as those of the conventional circuit, and can reduce the number of parts and achieve downsizing. Note that the above combination of circuit constants is a representative example,
It is not limited to this. Therefore, a combination outside the above range is also possible.

Embodiment 2 FIG. 2 is a circuit diagram of a splitter filter according to Embodiment 2 of the present invention. This splitter filter is obtained by adding a capacitor to the basic circuit of the splitter filter according to the first embodiment. Specifically, a fourth capacitor C is connected in parallel with the _second inductor L2.
₄ Connect, also has the circuit configuration in which a capacitor C ₅ of the fifth parallel to the fourth inductor L 2 _'.

That is, the splitter filter according to the _second embodiment is configured between the first and second signal lines w ₁ and w ₂ , and the first signal line w _{1 is} arranged in order from the input terminal side. Above, a first inductor L ₁ and a parallel circuit of a _second inductor L ₂ and a fourth capacitor C ₄ are connected in series, and a second signal line w ₂
Above, a third inductor L ₁ ′ and a parallel circuit of a fourth inductor L ₂ ′ and a fifth capacitor C ₅ are connected in series, and the first and third inductors L ₁ ′ are connected in series. , L ₁ ′ and second and fourth inductors L ₂ ,
L ₂ ′ and the fourth and fifth capacitors C ₄ , C
₅ between the connection points with each of the _five parallel circuits.
₁ is connected, in parallel to the output terminal side and the second capacitor C ₂ are connected, the series circuit is connected between the line w _1, w ₂ of the input terminal side, the series circuit includes a third capacitor _{C 3} fifth inductor L
₃ and a damping resistor R
₁ and the resonance frequency of the series resonance circuit is in the vicinity of the audio band, and the first inductor L ₁ and the third inductor L ₁ ′ form a transformer structure with each other; the second inductor L ₂ and the fourth inductor L _{2 ',} a splitter filter that forms a transformer structure.

In the example of the splitter filter according to the second embodiment , the first inductor L ₁ and the third inductor L ₁ ′ have a capacitance of 7.2 mH to 8.8 mH.
And the second and fourth inductors L ₂ and L ₂ ′ have constants in a range from 2.7 mH to 3.3 mH, and capacitor _{C 1} is, 51.7nF from 42.3nF
Has a constant within the scope of, the second capacitor _{C 2} has a constant within the scope of 61.6nF from 50.4NF, also the fourth capacitor _{C 4} of the 5 the capacitor _{C 5, 6.16n} from 5.04nF
Has a constant within the scope of F, the third capacitor C ₃ constituting the series resonant circuit has a constant belonging from 30.7nF the range of 36.3NF, also the fifth inductor L ₃ has a constant within the scope of 748mH from 612MH, also the damping resistor _{R 1}
Has a constant belonging to the range of 5.48 kΩ to 6.82 kΩ, and the resonance frequency of the series resonance circuit is 1.5 kHz.
z is in the vicinity.

[0061] Here, the reason the first range of the inductance of the inductor _{L 1} in the range of 8.8MH from 7.2mH, in more 8.8MH, too low is the cutoff frequency, also blocked in 7.2mH below This is because the frequency is too high.

[0062] Furthermore, it had the second range of the inductance of the inductor _{L 2} in the range of 3.3MH from 2.7mH, in more 3.3MH, too low is the cutoff frequency, also cut-off frequency is 2.7mH below Is too high.

The reason why the range of the inductance of the third inductor L ₁ ′ is in the range from 7.2 mH to 8.8 mH is that the cut-off frequency is too low above 8.8 mH, and cut off below 7.2 mH. This is because the frequency is too high.

The reason why the range of the inductance of the fourth inductor L ₂ ′ is from 2.7 mH to 3.3 mH is that the cut-off frequency is too low above 3.3 mH, and cut off below 2.7 mH. This is because the frequency is too high.

[0065] Also the first capacitance of the capacitor _{C 1} has a range of 51.7nF from 42.3nF is 51.
Above 7 nF, the cutoff frequency is too low and 42.
This is because the cut-off frequency is too high at 3 nF or less.

[0066] Also a second capacitance of the capacitor _{C 2} and a range of 61.6nF from 50.4nF is 61.
Above 6 nF, the cutoff frequency is too low and 50.
This is because the cut-off frequency is too high at 4 nF or less.

The third and fourth capacitors C ₂
The capacitance is set in the range of 5.04 nF to 6.16 nF because the cut-off frequency is too low when it is 6.16 nF or more, and the cut-off frequency is too high when it is 5.04 nF or less.

[0068] Also the capacitance of the third capacitor _{C 3} which constitutes a resonant circuit was in the range of 30.7~36.3nF it is in the above 36.3NF, the resonance frequency was set 1.5
Frequency too low for kHz and 30.7 nF
This is because the frequency is too high with respect to the set resonance frequency of 1.5 kHz.

[0069] In addition, the damping resistor _{R 1, 5.48~}
The reason for setting the range to 6.82 kΩ is that if it is equal to or more than 6.82 kΩ, damping will be too effective, and the attenuation will increase.
If the resistance is less than 8 kΩ, damping does not work and the resonance circuit becomes unstable.

As described above, in the splitter filter according to the second embodiment , the cutoff frequency is shifted to the vicinity of the audio signal pass band (200 Hz to 4 kHz) to improve return loss characteristics. Since the resonance circuit and the damping resistor for causing resonance in the audio signal pass band are provided, it is possible to improve the frequency characteristic in the audio signal pass band.

The effect of this improvement will be described by comparing a conventional splitter filter ( FIG. 3 ) with the splitter filter according to the second embodiment ( FIG. 2 ).

As shown in Table 3, the second embodiment of the present invention
The improved circuit configuration using the splitter filter according to the present invention has characteristics similar to those of the conventional circuit (see the column of the conventional circuit configuration in Table 2).
2), and the number of parts was reduced to achieve downsizing.

[0073]

[Table 3]

The combination of the circuit constants described above is a typical example, and the present invention is not limited to this. Therefore, a combination outside the above range is also possible.

[0075]

As described above, according to the present invention, it is possible to provide a low-cost splitter filter having improved return loss characteristics, high-performance filter characteristics, and a small number of components.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a splitter filter according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a splitter filter according to a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a conventional splitter filter.

[Explanation of symbols]

10 Passive filter section 11 Resonance circuit section

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-303020 (JP, A) JP-A-4-104578 (JP, A) JP-A-50-115953 (JP, A) JP-A-11- 220336 (JP, A) JP-A-10-75144 (JP, A) JP-A-2000-165553 (JP, A) JP-A-11-122066 (JP, A) JP-A-57-178409 (JP, A) 55-100329 (JP, U) Table 9-509798 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H 5/00-7/12 H04B 3/02 H04M 11/06

Claims (6)

(57) [Claims] 1. A connection between a line and a telephone or exchange.
Split to separate the audio signal from the digital signal.
Filter having a cutoff frequency of 200
Around 4kHz for audio signal pass band of Hz to 4kHz
The splitter filter is set to
Between lines (w ₁ , w ₂ ) on the input terminal side connected to the line side
In addition, series resonance causing resonance in the audio signal pass band
Between the oscillation circuit (C ₃ , L ₃ ) and the damping resistor (R ₁ )
A row circuit is provided to prevent loss at the high frequency side of the audio signal pass band.
Filter for splitter that compensates for gain of lost signal component
A is installed, the splitter filter, the first and second signal lines (w _{1, w 2)} are constructed between, in order from the input terminal side, on the first signal line (w ₁₎ The first
Of the inductor (L ₁ ) and the second inductor (L ₂ ) are connected in series, and the third inductor (L ₁ ′) installed on the second signal line (w ₂ )
And a fourth inductor (L ₂ ′) connected in series, a first capacitor (C ₁ ) disposed between a connection point of both inductors in each of the inductor rows, A second capacitor (C ₂ ) arranged in parallel on the output terminal side connected to the exchange
And the series circuit connected between the lines (w ₁ , w ₂ ) on the input terminal side, the series circuit comprising a third capacitor (C ₃ ) and a fifth inductor (L ₃ ) , And a damping resistor (R ₁ ), the resonance frequency of the series resonance circuit is set near the voice band, and the first inductor (L ₁ ) and the third inductor (R ₁ ) L ₁ ′) form a transformer structure with each other, and the second inductor (L ₂ ) and the fourth inductor (L ₂ ′) form a transformer structure with each other. Luz splitter filter. 2. In the splitter filter, the first inductor (L ₁ ) and the third inductor (L ₁ ′) have constants belonging to a range from 9.45 mH to 11.55 mH, The second inductor (L
₂ ) and the fourth inductor (L ₂ ′) are 7.2 mH
8.8 mH, and the first capacitor (C ₁ ) has a constant of 73.8 nF to 9 mH.
A constant belonging to the range of 0.2 nF;
Capacitor (C ₂ ) ranges from 73.8 nF to 90.2 n
A third capacitor (C ₃ ) having a constant belonging to the range of F and constituting the series resonance circuit is 61.2 nF
To 74.8 nF, and the fifth inductor (L ₃ ) is from 423 mH to 517 mF.
mH, and the damping resistance (R ₁ ) has a constant ranging from 4.5 kΩ to 5.5 kΩ, and the resonance frequency of the series resonance circuit is 1.5 kHz. 2. The splitter filter according to claim 1 , wherein the filter is located near. 3. The splitter filter, wherein the first inductor (L ₁ ) and the third inductor (L ₁ ′) have constants belonging to a range from 11.7 mH to 14.3 mH, The second inductor (L ₂ ) and the fourth inductor (L ₂ ′) are 9.4
The first capacitor (C ₁ ) has a constant in the range of 5 mH to 11.55 mH, and the first capacitor (C ₁ ) has a capacity of 73.8.
The second capacitor (C ₂ ) has a constant belonging to a range of 61.2 nF to 74.8 nF, and the second capacitor (C ₂ ) has a constant belonging to a range of 61.2 nF to 74.8 nF. The third capacitor (C ₃ ) that constitutes
It has a constant in the range of 19.8 nF to 24.2 nF, and the fifth inductor (L ₃ ) is 0.9H
To 1.1H, and the damping resistance (R ₁ ) has a constant within a range of 4.5 kΩ to 5.5 kΩ, and the resonance frequency of the series resonance circuit is 請 characterized by the 1.5kHz vicinity
Splitter filter according to Motomeko 1. 4. A connection between a line and a telephone or exchange.
Split to separate the audio signal from the digital signal.
Filter having a cutoff frequency of 200
Around 4kHz for audio signal pass band of Hz to 4kHz
The splitter filter is set to
Between lines (w ₁ , w ₂ ) on the input terminal side connected to the line side
In addition, series resonance causing resonance in the audio signal pass band
Between the oscillation circuit (C ₃ , L ₃ ) and the damping resistor (R ₁ )
A row circuit is provided to prevent loss at the high frequency side of the audio signal pass band.
Filter for splitter that compensates for gain of lost signal component
The splitter filter is configured between the first and second signal lines (w ₁ , w ₂ ), and is arranged on the first signal line (w ₁ ) in order from the input terminal side. ,
A first inductor (L ₁ ) and a parallel circuit of a _second inductor (L ₂ ) and a fourth capacitor (C ₄ ) are connected in series, and are connected on a second signal line (w ₂ ). Has a third inductor (L ₁ ′) and a fourth inductor
And the inductor _{(L 2} ') and fifth and a parallel circuit of a capacitor _{(C 5)} are connected in series, the first and third each inductor _(L 1, _{L 1'),} the second
And a fourth capacitor (C ₁ ) between the connection point of each of the fourth inductors (L ₂ , L ₂ ′) and the parallel circuits of the fourth and fifth capacitors (C ₄ , C ₅ ). A second capacitor (C ₂ ) is connected in parallel to an output terminal connected to the telephone or the exchange, and the series capacitor is connected between the lines (w ₁ , w ₂ ) on the input terminal side. A circuit is connected, and the series circuit includes a series resonance circuit including a _third capacitor (C ₃ ) and a fifth inductor (L ₃ ), and a damping resistor (R ₁ ), In addition, the resonance frequency of the series resonance circuit is set near the voice band, and the first inductor (L ₁ ) and the third
And the second inductor (L ₂ ) and the fourth inductor (L ₁ ′) form a transformer structure with each other.
The inductor and (L ₂ '), the feature and be away splitter filter that forms a transformer structure. 5. In the splitter filter, the first inductor (L ₁ ) and the third inductor (L ₁ ′) have constants belonging to a range from 7.2 mH to 8.8 mH, and The second inductor (L ₂ ) and the fourth inductor (L ₂ ′) have constants in the range of 2.7 mH to 3.3 mH, and
Of the capacitor (C ₁ ) ranges from 42.3 nF to 51.7 nF.
H, the second capacitor (C ₂ ) has a constant in a range of 50.4 nF to 61.6 nF, and the fourth capacitor (C ₄₎ ) And the fifth capacitor (C ₅ ) are 5.04 n
Has a constant belonging to the range of F to 6.16 nF,
Third capacitor (C ₃ ) constituting the series resonance circuit
Has a constant in the range of 30.7 nF to 36.3 nF, and the fifth inductor (L ₃ )
The damping resistance (R ₁ ) has a constant in the range of 5.48 kΩ to 6.82 kΩ, and the resonance frequency of the series resonance circuit is 1 5. The splitter filter according to claim 4 , wherein the frequency is around 0.5 kHz. 6. The xDSL according to claim 1, wherein the splitter filter is an xDSL.
In order to separate and synthesize a voice analog signal and a digital data signal in a telephone line, the voice signal is installed between the telephone line and the telephone, and a cutoff frequency is set to around 4 kHz on a higher side of a voice signal pass band. Utilizing the variation of the characteristic impedance of the filter and the polarity generated by the Chebyshev design method, the mismatch attenuation (return loss) characteristic is defined by the ITU-T standard G. 992.1 (Gd
mt) Annex EE. The splitter filter according to any one of claims 1 to 5 , wherein 4 Type 4 is satisfied.