JPS5818840B2 - Tatyan Nershiyuhasubunkatsufilta - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-channel frequency division filter, which has a flat frequency amplitude characteristic after synthesis by cascading a two-divided frequency division filter and a phase shift circuit that have a flat frequency amplitude characteristic after synthesis. It is an object of the present invention to provide a frequency division filter capable of obtaining characteristic multi-channel signals.

In general audio, the audio signal frequency is divided into several parts according to the band used and then supplied to speakers for each band, and the listener acoustically synthesizes the signals extracted from each speaker. listening to things.

In addition, there are several other examples, such as limiters and noise reduction systems, in which the frequency is divided once, transmitted through each transmission system, and then added again.

Therefore, in such cases, the characteristics after recombining (adding) the once frequency-divided signals become a problem. In particular,
As a frequency division filter, important conditions are sharp cutoff characteristics and flat frequency amplitude characteristics after synthesis (hereinafter simply referred to as amplitude characteristics).

The following table shows an example of the transfer characteristic of a two-division (two-channel) frequency division filter having a flat amplitude characteristic after synthesis, and the transfer characteristic after synthesis.

Moreover, FIGS. 1A to 1H show a low-pass filter, a high-pass filter, and the amplitude characteristics and phase characteristics after combining them.

Note that a to h shown in the characteristics column of the table correspond to A to H in Fig. 1, respectively, and in each figure, ■ indicates the amplitude characteristic and ■ indicates the phase characteristic. Middle and H are high-pass filters,
L indicates a low pass filter.

FIGS. 2A to 2E show circuit diagrams of one example of a specific circuit for obtaining the transfer characteristics shown in the table.

Moreover, in each figure, the frequency scale is shown as a magnification with the crossover frequency as 1.

Here, conventionally, when two frequency division filters having characteristic a (FIG. 1A) are synthesized with the same polarity, both the phase characteristic and the amplitude characteristic are flat, as shown in FIG. 1E. A multi-channel frequency division filter can be obtained by simply cascading these filters, but as is clear from Figure 1A, the cut-off characteristics of the low-pass filter and high-pass filter themselves are poor, making them impractical. There were drawbacks.

Conventionally, a two-part frequency division filter with relatively good cutoff characteristics as shown in FIG. 1C or DI is used as shown in FIG. 3A.
As shown in FIG. 3B (in the case of 3 channels) or as shown in FIG. 3B (in the case of 4 channels), there are multi-channel frequency division filters that are combined.

In Figure 3 A and B, 1 is an input terminal, 2 to 4, 7 are output terminals, 5□, 5□, 53 are high-pass filters, 6□, 6□, 6
3 indicates a low pass filter.

Note that the same subscripts attached to the numbers of the high filter and the low-pass filter indicate a set of two-divided frequency division filters having a flat amplitude characteristic after synthesis.

However, this conventional multi-channel frequency division filter has a drawback that the amplitude characteristic after synthesis is not flat, as shown in FIG. 5 (in the case of three channels), for example.

Note that the amplitude characteristics of the filter shown in FIG. 5 are as shown in FIG.
Amplitude of a three-channel frequency division filter configured as shown in Figure 3A by combining two two-part frequency division filters with flat amplitude characteristics after synthesis as shown in F, G, and H. It is a characteristic.

The crossover frequencies of this 3-channel frequency division filter are 1 kHz and 5 kHz, and the cutoff characteristic of the 2-divided frequency division filter constituting this 3-channel frequency division filter is 18 dBloc.

Furthermore, either a high-pass filter or a low-pass filter called the Yamanaka method or the subtraction method is prepared, and the input and filter output are subtracted to obtain the other filter characteristics, or after equivalent synthesis. A multi-channel frequency division filter can be obtained by cascading two frequency division filters with flat amplitude and phase characteristics as shown in FIG. 4, but as is clear from FIG.
The splitting filter itself has drawbacks such as having a large peak in amplitude characteristics and poor cut-off characteristics, making it impractical.

Note that the characteristics shown in Figure 6 are based on a high-pass filter of 18 dBl.
oct Butterworth filter is used, and in the same figure, ■ indicates the amplitude characteristic, ■ indicates the phase characteristic, H indicates the high-pass filter, and L indicates the low-pass filter.

As mentioned above, there are conventional frequency division filters with two divisions that have good cut-off characteristics and amplitude characteristics after synthesis, but there are multichannel filters with three or more divisions that have good cut-off characteristics and amplitude characteristics after synthesis as a division filter. There was no frequency division filter.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described with reference to FIG. 7 and subsequent figures.

FIG. 7 shows a block system diagram of an embodiment in which the multi-channel frequency division filter according to the present invention is applied to three channels.

In the figure, an audio signal input from an input terminal 8 is supplied to a high-pass filter 9□ and a low-pass filter 102, where it is separated into respective predetermined frequencies.

The signal taken out from the high-pass filter 9□ is supplied to the high-pass filter 9 and the low-pass filter 101, where it is again separated into respective predetermined frequencies, and then output to the output terminals 11 and 12.
These signals are extracted as a high frequency signal and a medium frequency signal, respectively.

On the other hand, the signal taken out from the low-pass filter 10□ is supplied to a phase shift circuit 131, where the phase is changed by a predetermined amount, and then taken out from the output terminal 14 as a low-pass frequency signal.

In addition, in the figure, the same subscripts attached to the numbers of the high-pass filter and the low-pass filter indicate a set of two-divided frequency division filters whose amplitude characteristics are flat after synthesis.

Here, high-pass filters 9□, 92, low-pass filter 10□
, 10° and the characteristics of the phase shift circuit 131 are set as follows.

Characteristics of high-pass filter 9□ Characteristics of phase shift circuit 13□ -Ts PS・-1+T,s (5) (1) ~ (4
) and the table above, the high-pass filter 91
and the low-pass filter 10 are a set of two-divided frequency 1+T1s number-divided filters that have a flat amplitude characteristic, that is, ± after synthesis, and the high-pass filter 92 and the low-pass filter 10□ have a flat amplitude characteristic, that is, 1- after synthesis. This is a set of 2-divided frequency division filter 1+T2s having T path.

Further, the characteristics of the phase shift circuit 13° are the same as the characteristics after synthesis of the two-divided frequency division filter by the high-pass filter 9 and the low-pass filter 10□.

Next, consider the amplitude characteristics of this multi-channel frequency division filter after synthesis.

FIG. 8 shows a block system diagram of a configuration in which the signals of a predetermined frequency taken out from the output terminals 1L12 and 14 shown in FIG.

As mentioned above, the characteristics after the synthesis of the two-part frequency division filter by the high-pass filter 9□ and the low-pass filter 10□ are as follows.
As shown in columns f and g after synthesis in the table on page 1 and F and G in FIG. 1, the amplitude characteristic (■) is flat but the phase characteristic (■) is not.
The phase characteristic after combining the outputs of the divided frequency division filters can be considered to be equivalent to the phase characteristic of the output of one phase shift circuit.

As a result, the frequency division filter divided into two by the high-pass filter 91 and the low-pass filter 101 shown in FIG. Phase circuit 13□'
, and FIG. 8 is equivalent to FIG. 9.

Further, the phase shift circuit 13 shown in FIG. The phase characteristic of the phase shift circuit 131 is equal to the phase characteristic after combining the outputs of the frequency division filter divided into two by the high-pass filter 9□ and the low-pass filter 101, and the phase characteristic of the phase shift circuit 131 is It is equal to the phase characteristic after combining the outputs of the frequency division filter divided into two by the filter 10.

The amplitude characteristic after combining the outputs of the two frequency division filters by the high-pass filter 9□ and the low-pass filter 102 is flat, and the high-pass filter 92 and the low-pass filter 1
Since the phase shift circuits 131 and 131 are connected in cascade to the two outputs of the frequency division filter divided into two by 0□, the outputs of the frequency division filter divided into two by the high-pass filter 9° and the low-pass filter 102 are synthesized. The output obtained by synthesizing the phase characteristics obtained when the output after the above is input to the phase shift circuit 13' and the output of the frequency division filter divided into two by the high-pass filter 92 and the low-pass filter 102 is input to the phase shift circuit 13. Since the phase characteristics in both cases can be said to be the same, FIG. 9 is equivalent to FIG. 10.

Furthermore, in FIG. 10, the two-part frequency division filter formed by the high-pass filter 9□ and the low-pass filter 102 is a phase shifter having a phase characteristic equal to the phase characteristic after combining the outputs of the two-part frequency division filter. It can be replaced with the circuit 13□, and FIG. 10 is equivalent to FIG. 11.

Therefore, the amplitude characteristics after synthesis of the three-channel frequency division filter shown in FIG. 7 are as shown in FIG. and 132 are connected in cascade, and therefore, by using a filter circuit with a sharp cutoff characteristic, the amplitude characteristic after synthesis becomes flat.

The above-mentioned embodiment of the multi-channel frequency division filter according to the present invention uses a 18 dBloc Butterworth filter, and this cutoff % = 18 dBloct is used.
It is not limited to multi-channel frequency division filters that combine two-way frequency division filters made up of dBloct's Butterworth filters.
dBloct's two-part frequency division filter also uses the first
As shown in Figures E, F, G, and H, the amplitude characteristics after combining the outputs of the two frequency division filters are flat, so these filters can be used instead of the example using the 18 dBloc Butterworth filter. 6, l 2, 24
A dBloct two-part frequency division filter can be used in the multi-channel frequency filter embodiment of the present invention.

That is, as is clear from the above description of the embodiment of the multi-channel frequency division filter according to the present invention using the 18 dBloc Butterworth filter, the frequency division into two is such that the amplitude characteristic after synthesis is flat. When the outputs of channels that have passed through this filter are combined, it is equivalent to passing through one phase shift circuit, and the channels that do not pass through this two-part frequency division filter are subjected to phase shift with the same constraints as above. By providing a phase shift circuit that has the same phase characteristics as the circuit, it is possible to correct the phase shift that occurs between the channel that passes through the two-way frequency division filter and the channel that does not pass through the two-way frequency division filter. Become.

. The above embodiment is an example in which a frequency division filter of 18 dBloct is used, but when using a 6 dBloct filter, high-pass filters 9□, 92, low-pass filters 01, 10□, and a phase shift circuit are used. The characteristics of 13□'s husband are set as follows.

Characteristics of high-pass filter 9□ -T, s HP・-1+T1・Characteristics of low-pass filter 0□ LP・−1+T1・Characteristics of high-pass filter 9° 2s HP・=l +T2 s Characteristics of low-pass filter 02 LP・-1+T2s phase shift circuit 13. Characteristics 1-T,s P8・-1+T1s When using a 12 dBloc filter, the characteristics of the high-pass filters 90 and 92, the low-pass filters 00 and 102, and the phase shift circuit 131 are set as follows. do.

Characteristics of high-pass filter 9m - (Tls) 2 HP・=(1+T,8)・Characteristics of low-pass filter 0, LP・=(1+1.8)・Characteristics of high-pass filter 9□Hp=-(Tpa) ' 2(l+T2S)2 Characteristics of low-pass filter 02 LP = 1 2(1+T2s)2 Characteristics of phase shift circuit 13□ - T1s PSl-1+T1s Also, when using a 24 dBloct filter, high-pass filters 91, 9□ , low pass filter 0. ．． 102
and the characteristics of the phase shift circuit 131 are set as follows.

Characteristics of high-pass filter 9□ ('rts)' HP,=i.

+ρ18 engineering. ,,)2). Low pass filter 0. Characteristics LP, -i1+Koi T1・+("t・)・)・Characteristics of high-pass filter 92 (T2s) 4 fat"' (t+, /'N T, S engineering.

2. )2) Characteristics of 2 low-pass filter 02■ LP・-(1+sJ"i:'T2syo (T2S)2)"
Characteristics 1 of phase shift circuit 13□ sl”E T2 s + (T2 s )2P8'
=t+c'r,,S+(T2S)" With this configuration, an equinodal circuit similar to the case using the 18 dB 10 ct filter described above is established, and the amplitude characteristic after synthesis becomes flat.

Therefore, it is clear that when the signals of both channels are combined, the amplitude characteristic after the combination becomes flat, regardless of the cutoff characteristic or phase characteristic of each of the two frequency division filters.

FIG. 12 shows a block system diagram of an embodiment I in which the multi-channel frequency division filter according to the present invention is applied to four channels.

In the figure, 17 is an input terminal, 18 to 21 are output terminals, and 22
1, 222, 223 are high-pass filters, 23□, 232,
233 is a low-pass filter, and 240 and 242 are phase shift circuits.

In the figure, the same subscripts attached to the numbers of the high-pass filter and low-pass filter indicate a set of two-divided frequency division filters with flat amplitude characteristics after synthesis, and the subscripts attached to the numbers of the phase shift circuit indicate A phase shift circuit having the same characteristics as a combination of a set of two frequency division filters with the same subscript is shown.

Here, as in the case of the embodiment shown in FIG. 1, the characteristics of the high-pass filters 22□ to 223, the low-pass filters 231 to 233, and the phase shift circuits 24□ and 24□ are set as follows. has been done.

Characteristics of the high-pass filter 221 HP-”・”' (6) ' (1+T15)(, l+T, s+, (Tls)2
) Characteristics LP1 of the low-pass filter 23 = (7) (1
+T15) (1+T1s+(Tls)") Characteristics of high-pass filter 22□ - (T2s) 3 HP2-(8) (1+T2s) (1+T2s+(T2s)2) Characteristics of low-pass filter 232 LP - (9) 2 (1+T2S ) (1+T2S +(T2S)2)
Characteristics of the high-pass filter 223 - (T3S) 3 HP - (10) '' (1 + T3s) (l + T3s + (T3s) 2) Characteristics of the low-pass filter 233 LP3 - □ circle (1 + Ts s ) (' 1 T3s + (T3s
)2) Characteristics 1-Tls of the phase shift circuit 24□.

P8・−1+1.5 Characteristics of the phase shift circuit 242 ps l−T・” (13) 1+T2s (6) ~As is clear from the round equation and the table above, the high-pass filter 22□ and the low-pass filter 231 are -Ts is a set of two-divided 1+T1s frequency division filters having a flat amplitude characteristic, that is, □, and the high-pass filter 222 and the low-pass filter 232 have a flat amplitude characteristic, that is, l after synthesis.
It is a set of two frequency division 1+T2s filters having −T, s, and the high-pass filter 22 and the low-pass filter 233 have a flat amplitude characteristic after synthesis, that is, −Ts The wave number is 10% 71″, which is 0 pairs.

Further, the characteristics of the phase shift circuit 241 are the same as the characteristics after synthesis of the two-part frequency division filter by the high-pass filter 221 and the low-pass filter 23□, and the characteristics of the phase-shift circuit 24□ are the same as those of the high-pass filter 221 and the low-pass filter 23□. A two-part frequency division filter using a low-pass filter 232.

The properties are the same as those after synthesis.

Now, if we consider the amplitude characteristics of this multi-channel frequency division filter after synthesis, we will see that, just as explained in FIG. 7, FIG. two phase shift circuits.

This is equivalent to cascading 241, 24□, and 243.

Therefore, the amplitude characteristic of this filter after synthesis becomes flat.

The above embodiment is an example in which a 18 dBloct frequency division filter is used, but when a 6 dBloct filter is used, the high-pass filters 22□ to 223,
Low-pass filters 23□ to 233 and phase shift circuits 24□, 24
The characteristics of each of 2 are set as follows.

Characteristics of high-pass filter 22□ T15 HP・-1+1.5 Characteristics of low-pass filter 231! LP・-1+T1s Characteristics of high-pass filter 222 -T, 5 HP2-1+T28 Characteristics of low-pass filter 232 LP・-I+T2・Characteristics of high-pass filter 223 ss Skin-1+T3s Low-pass filter 2ηp characteristics! LP・-1+T3 s Characteristics of phase shift circuit 24□-T1s P8・-1+1.8 Characteristics of phase shift circuit 24□-T2s P8・-1+T,s Also, when using a 12 dBloct filter,
High-pass filters 22□~223, low-pass filters 231~2
33 and the phase shift circuits 241 and 242 are set to have their respective characteristics as if they were missing.

Characteristics of high-pass filter 221 -(Tls)2 HP・-(1+T1・)・ Characteristics of low-pass filter 231 LP-□ 1 (I+T15)2 Characteristics of high-pass filter 222 -(T2s)2 Fat = (1+T.

8)・Characteristics of low-pass filter 232 LP・=(1+T,s)・Characteristics of high-pass filter 223Characteristics of low-pass filter 233Also, when using a filter of 24 dBloct, high-pass filters 22□, 223, low Range filter 23□~23
The characteristics of each of the phase shift circuits 24□ and 24□ are set as follows.

Characteristics of the high-pass filter 221 By configuring in this way, the above-mentioned 18 dB10c
An equivalent circuit similar to that when using a filter of t is established,
The amplitude characteristics after synthesis become flat.

FIG. 14 shows a block diagram of another embodiment in which the multi-channel frequency division filter of the present invention is applied to four channels.

In the same figure, the same components as in FIG. 12 are given the same reference numerals.
Since its operation can be easily understood from the embodiments shown in FIGS. 7 and 12, its explanation will be omitted.

FIG. 15 shows a block diagram of still another embodiment in which the filter of the present invention is applied to four channels.

In the same figure, the same components as in FIG. 12 are given the same reference numerals.
The explanation will be omitted.

Here, considering the amplitude characteristics after synthesis in the same way as in the case of the filter shown in FIG. The characteristics are the same as those of the circuit 243,
The characteristics after synthesis of the two-part frequency division filter by the high-pass filter 221 and the low-pass filter 231 are the characteristics of the phase shift circuit 24.
The characteristics are the same as □.

Therefore, FIG. 15 is equivalent to cascade-connecting phase shift circuits 24□, 243 with flat amplitude characteristics to the high-pass filter 222 and the low-pass filter 232, respectively, as shown in FIG. is further equivalent to FIG.

Therefore, the amplitude characteristic of this filter after synthesis becomes flat.

Note that this embodiment can be configured with one less phase shift circuit than the embodiments shown in FIGS. 12 and 14.

Note that the configurations of the filter circuit and phase shift circuit of the multi-channel frequency division filter of the present invention are not limited to the above embodiments.

That is, the 2-split frequency division filter circuit used in the multi-channel frequency division filter of the present invention is not limited to the 18 dB 10 ct Butterworth filter as in the above embodiment, but can be modified depending on the cutoff characteristics and phase of the filter. There are no limitations on the characteristics or the circuit configuration of the filter, as long as it is a two-part frequency division filter circuit that has a flat frequency and amplitude characteristic after synthesis.

The phase shift circuit used in the multi-channel frequency division filter according to the present invention may be any phase shift circuit that can correct the frequency amplitude characteristic after combining the outputs of the two-part frequency division filter as described above to be flat. Good.

Moreover, it is not limited to 3 channels and 4 channels as in the above embodiments, and can be similarly applied to a larger number of channels, by configuring a filter circuit and a phase shift circuit as appropriate according to the number of channels. good.

As described above, the multi-channel frequency division filter according to the present invention is a multi-channel frequency division filter that divides a signal input from an input terminal into at least three or more channels of frequency signals using a plurality of frequency division filter circuits having predetermined transfer characteristics. In the channel frequency division filter, a first two-way frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and the first two-way frequency division filter circuit is combined into one output of the first two-way frequency division filter circuit. After that, a second two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic is connected in cascade, and the second two-part frequency division filter circuit is connected to the other output of the first two-part frequency division filter circuit. It consists of cascade-connected phase shift circuits having transfer characteristics that are approximately equal to the transfer characteristics after synthesis of the filter circuits, and a signal input from an input terminal is processed by at least a plurality of frequency division filter circuits having predetermined transfer characteristics. In a multi-channel frequency division filter that divides and extracts frequency signals of four or more channels, a first two-division frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and the first A second two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is cascade-connected to one output of the first two-part frequency division filter circuit, and the other output of the first two-part frequency division filter circuit is connected in series. A third 2-split frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is cascade-connected to the output, and one output of the first 2-split frequency division filter circuit and the second 2-split frequency division filter circuit are connected in cascade to the output. A first phase shift circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the third frequency division filter circuit is inserted and connected between the frequency division filter circuit of the third frequency division filter circuit, and between the other output of the frequency division filter circuit and the third frequency division filter circuit, which has a transfer characteristic substantially equal to the combined transfer characteristic of the second frequency division filter circuit; 2
A multi-channel system configured by inserting and connecting phase shift circuits of In the frequency division filter, a first two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and one output of the first two-part frequency division filter circuit has a substantially flat frequency amplitude characteristic after synthesis. A second frequency division filter circuit having a flat frequency amplitude characteristic is connected in cascade, and a third frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to one output of the second frequency division filter circuit having a flat frequency amplitude characteristic. In addition to connecting two frequency division filter circuits in cascade,
The transfer characteristic after combination of the second frequency division filter circuit with two divisions and the transmission after combination of the third frequency division filter circuit with two divisions to the other output of the first frequency division filter circuit with two divisions. A first phase shift circuit having a transfer characteristic substantially equal to the sum of the transfer characteristics and the second phase shift circuit is connected in cascade, and
A second phase shift circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the third two-part frequency division filter circuit is connected in cascade to the other output of the third two-part frequency division filter circuit. Therefore, the amplitude characteristic of the entire filter after synthesis is equivalent to cascading multiple phase shift circuits with flat amplitude characteristics. It has the advantage of being able to obtain multi-channel signals with amplitude characteristics, and being relatively inexpensive to construct since it is only necessary to cascade a simple phase shift circuit and a filter circuit.

[Brief explanation of drawings]

Figures 1A-H are amplitude characteristic diagrams and phase characteristic diagrams of general high-pass filters and low-pass filters, Figures 2A-E are circuit diagrams of an example of a specific circuit for obtaining predetermined transfer characteristics, Figure 3A,
B and FIG. 4 are block diagrams on each side of a conventional multi-channel frequency division filter, FIG. 5 is an amplitude characteristic diagram of an example of the filter shown in FIG. 3 X, and FIG. 6 is a conventional multi-channel frequency division filter. An amplitude characteristic diagram and a phase characteristic diagram of another example of the filter, FIG. 7 is a block system diagram of one embodiment of the multi-channel frequency division filter according to the present invention, and FIGS. 8 to 11 are diagrams of the filter shown in FIG. 7. FIGS. 12 and 13 are block diagrams for explaining the amplitude characteristics after synthesis, respectively, and FIGS. Figures 14 and 15 are block diagrams of still other examples of the multi-channel frequency division filter of the present invention, and Figures 16 and 17 are block diagrams of the filters shown in Figure 15 after synthesis. FIG. 3 is a block diagram for explaining amplitude characteristics. 8.1T...Input terminal, 91, 92, 22□,
22□. 223...High-pass filter, 101, 102, 2
3. 232.233...Low pass filter, 11, 12
゜14.16,18~21.25~28...Output terminal, 130.13', 132,241,242
, 243... Phase shift circuit, 15... Adder.

Claims (1)

[Claims] 1. A signal input from an input terminal is divided into at least three frequency division filter circuits having predetermined transfer characteristics.
In a multi-channel frequency division filter that divides and extracts frequency signals of more than one channel, a first two-division frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and A second two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is cascade-connected to one output of the two-part frequency division filter circuit, and the other of the first two-part frequency division filter circuit. A multi-channel frequency division filter characterized in that a phase shift circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the second two-part frequency division filter circuit is connected in cascade to the output of the second frequency division filter circuit. 2 The signal coming from the input terminal is divided into at least 4
In a multi-channel frequency division filter that divides and extracts frequency signals of more than one channel, a first two-division frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and A second two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is cascade-connected to one output of the two-part frequency division filter circuit, and the other output of the first two-part frequency division filter circuit is connected in cascade. A third 2-split frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected in cascade, and one output of the first 2-split frequency division filter circuit and the second 2-split frequency division filter circuit are A first phase shift circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the frequency division filter circuit divided into two by three is inserted and connected between the frequency division filter circuit, and the frequency of the first two division filter circuit is inserted and connected. A second frequency dividing filter circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the second frequency dividing filter circuit is connected between the other output of the dividing filter circuit and the third frequency dividing filter circuit. A multi-channel frequency division filter characterized by having a phase shift circuit inserted and connected. 3 The signal coming from the input terminal is divided into at least 4
In a multi-channel frequency division filter that divides and extracts frequency signals of more than one channel, a first two-division frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected to the input terminal, and A second two-part frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is cascade-connected to one output of the second two-part frequency division filter circuit, and one output of the second two-part frequency division filter circuit. A third 2-split frequency division filter circuit having a substantially flat frequency amplitude characteristic after synthesis is connected in cascade, and the second 2-split frequency is connected to the other output of the first 2-split frequency division filter circuit. A first phase shift circuit having a transfer characteristic substantially equal to a transfer characteristic obtained by adding the transfer characteristic after the synthesis of the divided filter circuit and the transfer characteristic after the synthesis of the third two-divided frequency division filter circuit is connected in cascade. and a second phase shift circuit having a transfer characteristic substantially equal to the combined transfer characteristic of the third two-way frequency division filter circuit is cascaded to the other output of the second two-way frequency division filter circuit. A multi-channel frequency division filter characterized in that: