JPH08107326A - Mixer and branching filter - Google Patents

Abstract

PURPOSE: To realize a mixer that is able to mix signals of frequency bands close to each other by providing a BPF and an impedance compensation circuit in series in a filter. CONSTITUTION: A 1st signal received by a 1st terminal 1 whose frequency band is set to a low frequency is outputted to a 3rd terminal 10 via an LPF 2, and a 2nd signal received by a 2nd terminal 5 whose frequency band is set to a high frequency is mixed with the 1st signal via a series circuit comprising an HPF 6, a BPF 7, and an impedance compensation circuit 8 and the mixed signal is outputted to a 3rd terminal 10. Thus, the LPF 2 and the HPF 6 whose block band width is made narrow are realized by the BPF 7 and the impedance compensation circuit 8, and the frequency band width of the 1st signal is made close to that of the 2nd signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixer for mixing signals having a wide frequency band which are very close to each other, such as a CS-IF channel signal and a BS-IF channel signal, and a wide frequency band which is very close to each other. The present invention relates to a demultiplexer capable of demultiplexing into a signal having, and is particularly suitable for application to a co-listening system.

[0002]

2. Description of the Related Art At present, satellite broadcasting includes BS broadcasting and CS broadcasting, and television broadcasting and audio broadcasting are performed respectively. These broadcasts are received by installing receiving antennas individually, but in a housing complex, CS broadcasts and B broadcasts are received.
A joint reception system has been proposed in which an antenna system for receiving S broadcasts is installed and both broadcasts can be transmitted by a single coaxial cable.

FIG. 10A shows this joint reception system device.
Shown in In this figure, the orthogonal polarized wave composed of the vertical polarized wave and the horizontal polarized wave transmitted from the communication satellite of JCSAT2 is received by the CS antenna 101, and the signal is CS.
-Intermediate frequency input to the IF converter 103 (CS-I
F) is converted to a signal. Further, the orthogonally polarized wave composed of the vertically polarized wave and the horizontally polarized wave transmitted from the communication satellite of Super Bird B is received by the CS antenna 102, and the signal thereof is input to the CS-IF converter 103 and the intermediate frequency (C
S-IF) signal.

On the other hand, a BS antenna 1 for receiving BS broadcasting
The signal received by 04 and converted to the intermediate frequency (BS-IF) is input to one of the BS / U / V amplifiers 108 and amplified to a predetermined level. Then, the UHF television signal received by the UHF antenna 105 and V
The VHF television signal received by the HF antenna 106 is mixed by the U / V mixer 107 to produce BS · U /
The signal is input to the other side of the V amplifier 108, amplified to a predetermined level, mixed with the BS-IF signal, and BS · U / V.
It is output from the amplifier 108.

Further, the CS-IF signal output from the CS-IF converter 103 and the signal output from the BS / U / V amplifier 108 are mixed by a CS / BS / UV mixer 109 to form a coaxial cable. The mixed signal is output and transmitted through the coaxial cable, and is branched into, for example, each house of an apartment house. In each home, by inputting the branched signal to the tuner, a desired broadcast can be received.

By the way, the U / V mixer 107 and the CS
A mixer such as the BS / BS / UV mixer 109 is usually shown in FIG.
It has the structure shown in FIG. In this mixer, the input signal having the lower frequency band is input to the input terminal 111, and the input signal having the higher frequency band is input to the input terminal 112. The low frequency band signal input to the input terminal 111 is a low pass filter (LPF).
A high frequency band signal input to the input terminal 112 via the high-pass filter (HPF) 1
It is mixed via 14 and outputted from the output terminal 115.

By the way, the LPF 113 and the HPF 11
4 causes impedance interference with each other, and LPF1
Since the characteristics of 13 and the HPF 114 are deteriorated, it is possible to obtain a mixer having a wide stop band, but it is difficult to obtain a mixer having a narrow stop band as compared with the specific band. Further, the above-mentioned mixer has reversibility, and a low frequency band component of a signal input to the terminal 115 can be demultiplexed to the terminal 111 and a high frequency component can be demultiplexed to the terminal 112. it can. Therefore, although the above-mentioned mixer can be used as a demultiplexer, it is difficult to obtain a demultiplexer in which the stop band is extremely narrower than the ratio band, like the mixer. Therefore, the conventional C
In the S / BS / UV mixer (demultiplexer), the stop band is 45 MHz, and the signal in the frequency band of 10 to 1335 MHz and the signal in the frequency band of 1380 to 1770 MHz are mixed (demultiplexed). .

By the way, the IF assigned to the BS broadcast
The configurations of the frequencies and channel arrangements of the channels and the frequencies and channel arrangements of the CS broadcast IF channels are as shown in FIG. The frequency band of the lowest frequency J1 channel (ch) of the CS-IF channels shown in this figure is 1309.75 to 1336.75 MHz, and the highest frequency channel of the BS-IF channels BS-15 channel. Frequency band is 103
It is set to 4.50 to 1331.50 MHz. Since the frequency bands of the J1 channel and the BS15 channel overlap in this way, if the CS / BS / UV mixer 109 continues to mix them, the signals will overlap and interfere with each other. Therefore, the CS-IF channel is set to CS so that the frequency bands do not overlap.
-It is relocated to the extension channel by the IF converter 103.

An example of this rearrangement configuration is shown in FIG. 12. As a television broadcasting channel for CS broadcasting, JCS
Since 6 channels are assigned to AT2 and 6 channels are assigned to Super Bird B, a total of 12 channels are assigned. Therefore, in FIG. 12, one system CS is used when the 12 channels assigned as CS broadcasting and BS-IF channels are mixed.
The television arrangement is shown. That is, BS-IF
The J1 channel that overlaps with the channel is relocated to the extension channel JC20, and the J5 channel is also changed to JC22
, J7 channel to JC24, J9 channel to J
The C11, J11 channel, and J13 channel are relocated to JC28 and JC30, respectively. Also, the S1 channel of Super Bird B is relocated to the extension channel SC13.

[0010]

As described above, in the conventional mixer, a signal in the frequency band of 10 to 1335 MHz and a signal in the frequency band of 1380 to 1770 MHz can be mixed. The CS-IF channels arranged as follows are 1335 to 1771.7.
Since it is set to 5 MHz, the S3 channel cannot be mixed and transmitted. That is, in the conventional mixer, since the stop band is about 45 MHz, C
The S-IF channel has a problem that only 11 channels can be transmitted.

In order to solve this, a signal having a frequency of 1331.5 MHz or less which is a frequency band of BS · U / V and a signal having a frequency band of 1355 MHz or more which is a frequency band of CS broadcasting are provided in FIG. 10 (b). If it is attempted to mix them with the circuit shown in (1), it is theoretically possible to realize the LPF 113 and the HPF 114 with a 7th-order elliptic function (Chebyshev type) filter. However, in this case, the quality factor (Q) of the capacitor C and the coil L that form the filter must be infinite, which is not practically possible. Further, even if it can be realized, when two filters are connected, impedance interference occurs between the filters at the connection point and the characteristics are deteriorated, so that the desired function as a mixer or a demultiplexer is exerted. I can't.

Therefore, according to the present invention, the width of the stop band is made extremely small so that the frequency band of the first signal and the frequency band of the second signal can be mixed or demultiplexed even if they are close to each other. It is an object of the present invention to provide a mixer and a demultiplexer that can be used.

[0013]

In order to achieve the above object, the mixer or the duplexer of the present invention has a first terminal for inputting or outputting a first signal whose frequency band is low. And a second terminal for inputting or outputting a second signal having a high frequency band, and outputting a signal in which the first signal and the second signal are mixed, or the first signal Signal and a third terminal to which a signal split into the second signal is input, one end of a low-pass filter is connected to the first terminal, and one end of a high-pass filter is connected to the second terminal. Is connected, the other end of the low-pass filter and the other end of the high-pass filter are connected to form a connection part, and the connection part is connected to the third terminal, Filter and before The or between the high-pass filter and the connection portion with the connection portion, in which band-pass filter and impedance compensation circuit is as is interposed are connected in series.

When the ratio band of the first signal is smaller than the ratio band of the second signal, the band pass filter and the impedance compensating circuit are arranged between the low pass filter and the connection portion. If the ratio band of the first signal is larger than the ratio band of the second signal, the band pass filter and the impedance compensation circuit are connected to the high pass filter and the high pass filter. It is arranged so as to be interposed between the connection part and the connection part.

[0015]

According to the present invention, mutual impedance interference between the high pass filter and the low pass filter can be prevented by the impedance compensation circuit. In a conventional mixer or demultiplexer, adjusting one filter affects the setting of the other filter, and it is necessary to alternately readjust the filter. If you set
Mutual influence can be prevented and adjustment work becomes easy. And
By providing the impedance compensating circuit and the bandpass filter in this way, even if the low frequency band and the high frequency band are close to each other,
A mixer or demultiplexer capable of mixing or demultiplexing can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the mixer of the present invention is shown in FIGS.
However, since the mixer according to the present invention has reversibility and operates as a demultiplexer with the same configuration, the mixer and the demultiplexer according to the present invention will be described below. Wave instrument). FIG. 1 is a block diagram of an embodiment of the mixer (branching filter) of the present invention. In this figure, the first terminal 1 to which the first signal in the lower frequency band is input (output)
A low-pass filter (LPF) 2 is connected to the high-pass filter (HPF) 6, a band-pass filter (BPF) 7, and a second terminal 5 to which the second signal in the higher frequency band is input (output). The impedance compensation circuit 8 is connected in series. Then, the LPF 2 and the impedance compensating circuit 8 are connected to each other to form a connection portion (branching portion).
9 is formed, and a signal obtained by mixing the first signal and the second signal is output to this connection portion 9 (the signal that is divided into the first signal and the second signal is input). The third terminal 10 is connected.

Such a mixer (branching filter) is shown in FIG.
Used as the CS / BS / UV mixer 109 indicated by 0, the BS / U / V signal, which is a low frequency band signal, is input to the first terminal 1 and is a high frequency band signal. The signal of the CS-IF channel is input to the second terminal 5. Then, a signal obtained by mixing these signals is the third terminal 1
It is output from 0. In this case, the mixed frequency band on the LPF2 side is set to 10 to 1332 MHz, and the passage loss is 4
dB or less, stopband attenuation is 18 dB or more, voltage standing wave ratio (VSWR) is 2.2 or less, the mixed frequency band on the HPF6 side is 1355 to 1880 MHz, its pass loss is 5 dB or less, stopband attenuation The amount is 20 dB or more,
The voltage standing wave ratio (VSWR) is set to 2.0 or less.

A concrete circuit diagram of this mixer (demultiplexer) is shown in FIG. 2. In this circuit diagram, the LPF is connected to the first terminal 1.
The four coils L1 to L4 that form part 2 are connected in series, and the connecting portions between these coils L are each 1
One coil L5 to L7 and one capacitor C1
It is grounded through the series circuit of C3. The coils L1 to L7 and the capacitors C1 to C3 form a Chebyshev type LPF2. Further, the second terminal 5 has four capacitors C4 to
C7 are connected in series, and the connection between these capacitors C is grounded via a series circuit of one coil L8 to L10 and one capacitor C8 to C10, respectively. Chebyshev type HP by these coils L8 to L10 and capacitors C4 to C10
F6 is configured.

At one end of the HPF 6, a condenser C11, a coil L11 and a coil L12 which constitute the BPF 7 are provided.
And the capacitor C12 are connected in series, and the connection between the coil L11 and the coil L12 is grounded via the capacitor C13. The coils L11 to L12 and the capacitors C11 to C13 form a BPF 7 having broad frequency characteristics.
At one end of the BPF 7, two capacitors C14 and C15 forming the impedance compensation circuit 8 are connected in series, and the connecting portion between the capacitor C14 and the capacitor C12 of the bandpass filter 7 is a coil. It is grounded via L13, and the connecting portion between the condenser C14 and the condenser C15 is a coil L.
It is grounded through 14. These coils L13,
The impedance compensating circuit 8 is composed of a circuit including L14 and capacitors C14 and C15.

As described above, the mixer (branching filter) inputs a signal of 10 to 1332 MHz to the first terminal 1 and a signal of 1355 to 1880 MHz to the second terminal 5 to mix them. You can That is, this stop band is 1355 to 1332 = 23 MHz, which is a much narrower bandwidth than the conventional 45 MHz shown in FIG. Therefore, in the past, one CS-IF channel was used.
Although only one channel could be transmitted, the S3 channel can be newly transmitted due to the use of the band of 1355 to 1380 MHz which could not be used conventionally.
It is possible to increase the number of channels and transmit 12 channels.

By the way, in the conventional mixer (demultiplexer) shown in FIG. 10B, the LPF 113 and the HPF 114 are directly connected to each other, and impedance interference occurs at the connection point, so that the stop band is reduced. If it is made smaller, the characteristics required for the mixer (branching filter) cannot be obtained. Therefore, in this embodiment, the impedance compensation circuit 8 is inserted in order to eliminate the impedance interference between the HPF 6 and the LPF 2.

Further, the impedance compensating circuit 8 prevents mutual impedance interference, and good filter characteristics can be obtained for each, but still L
When PF2 is adjusted, the effect appears on HPF6 and HP
Adjustment of F6 goes wrong. On the contrary, even if the HPF6 is adjusted, the adjustment of the LPF2 is wrong and the LPF2 and the HPF6 influence each other. The BPF 7 is provided to prevent the mutual influence. Since the capacitance value of the capacitor C15 in the impedance compensation circuit 8 can be made extremely small by inserting the BPF 7, the mutual interference between the LPF 2 and the HPF 6 can be further reduced.

By the way, CS- input to the second terminal 5
Since the ratio band in the frequency band of the IF channel signal is significantly smaller than the ratio band in the frequency band of the BS / U / V signal input to the first terminal 1, the frequency that is broad after the HPF 6 on the smaller ratio band side. By inserting the characteristic BPF 7 and the impedance compensation circuit 8,
The interference between the LPF 2 and the HPF 6 is reduced. That is, BPF7 functions as a kind of buffer. By inserting this BPF7, even if the HPF6 is adjusted, the adjustment of the LPF2 can be prevented from being directly affected.

Next, the frequency characteristics of the mixer (branching filter) of this embodiment are shown in FIGS. In these figures, A shows the position of 1332 MHz which is the upper limit frequency of the low band, B shows the position of 1355 MHz which is the lower limit frequency of the high band, and C shows the position of 1880 MHz which is the upper limit frequency of the high band. . When a signal is input to the second terminal 5 of the mixer (branching filter), that is, the characteristics of the passband loss and the voltage standing wave ratio (VSWR) on the HPF 6 side are shown in FIGS. 3 and 4. Note that FIG. 4 shows the characteristics in the vicinity of the stop band narrower than that in FIG. In this figure, (a) shows the pass band loss characteristic, and (b) shows the reflection loss characteristic. Then, as shown in FIG.
It is sufficiently attenuated at 20 dB or more at 2 MHz or less, and has a pass band loss of 5 dB or less at 1355 to 1880 MHz shown as B to C. Further, as shown in (b) of this figure, the reflection loss is 1355 to 1880.
Since it is 9.54 dB or less at MHz, the VSWR is about 2.0 or less, and good characteristics are obtained.

FIGS. 5 and 6 show the characteristics of the passband loss and VSWR when a signal is input to the first terminal 1 of the mixer (branching filter), that is, on the LPF 2 side. Note that FIG. 6 shows the characteristics in the stop band narrower than that in FIG. In this figure, (a) shows the pass band loss characteristic, and (b) shows the reflection loss characteristic. Then, as shown in (a) of this figure, at 1355 MHz or higher shown as B, it is sufficiently attenuated at 18 dB or higher.
At 32 MHz, the amount of attenuation is 4 dB or less. Further, as shown in (b) of this figure, the reflection loss is 10 to 1
Since it is 8.52 dB or less at 332 MHz, its VSWR is approximately 2.2 or less, which is a good characteristic.

Further, the combined characteristics of these are shown in FIGS. Note that FIG. 8 shows the characteristics in the vicinity of the stop band as described above. In this figure, (a) shows the pass band loss characteristic, and (b) shows the reflection loss characteristic. Then, as shown in (a), the pass band loss characteristic is 10 to
It has good characteristics over the entire frequency band of 1880 MHz. By inserting the impedance compensating circuit 8, as shown in (a) of FIG. 7 and FIG. 8, the shoulder characteristic of the passband loss characteristic, that is, the passband loss in the vicinity of the frequencies shown in A and B is balanced. I was able to.
Further, as shown in (b), since the reflection loss is 8.52 dB or less at 10 to 1880 MHz, its VSWR is approximately 2.2 or less, which shows good characteristics. Further, as shown in FIG.
At 55 MHz, the reflection loss does not show the deteriorated characteristics as in the conventional mixer (demultiplexer) shown by the broken line. This is due to the action of the impedance compensation circuit 8.

Incidentally, in FIG. 2, LPF2 and HPF6
In order to eliminate mutual interference with the impedance of the HPF6 side viewed from the LPF2 side (HP viewed from the LPF2 side
It is necessary to increase the impedance of the F side), that is, the impedance of the impedance compensation circuit 8.
Since the BPF 7 is provided between the impedance compensation circuit 6 and the impedance compensation circuit 8, the capacitance of the capacitor C15 of the impedance compensation circuit 8 can be made extremely small.
Therefore, the impedance of the impedance compensating circuit 8 can be increased, so that the mutual interference can be almost eliminated.

Further, in the LPF2 and the HPF6, since the inductor is large and the capacitance is small to increase the Q of the filter, the capacitors C1 and C2 of the LPF2 and the capacitor C9 of the HPF6 are small and the filter is cut off. The characteristics are sharp. In this way, when the capacitors C1, C2, C9 have a very small capacitance, the capacitors may be formed by distributed constants instead of discrete components. That is, the capacitors are formed by using the copper foils on both sides of the printed circuit board. The circuit diagram of the mixer (branching filter) in this case is shown in FIG. 9, and the capacitor formed by the distributed constant using the printed circuit board is shown by the broken line.

As described above, HPF6 and BPF7 are added.
By connecting the impedance compensation circuit 8 and the impedance compensation circuit 8 in series, signals of 10 to 1332 MHz and 1355 to 18
80 MHz signals can be mixed (split) without affecting each other. That is, only 2 stopbands
A mixer (demultiplexer) having a frequency of 3 MHz can be realized, and the width of the stop band can be significantly narrowed as compared with the conventional case. Therefore, 1355-1 which could not be used conventionally
Since the 380 MHz band can be used, CS-I
It becomes possible to transmit S3 channel of F channel, and conventionally only 11 channels could be transmitted, but it becomes possible to transmit 12 channels by adding 1 channel.

Since the BPF 7 and the impedance compensation circuit 8 are not connected in series to the LPF 2 but the coils are connected in series, the first terminal 1 and the third terminal 1 are connected.
DC current can pass between 0 and
Power can be transmitted to the antenna 104. In the above description, the impedance compensating circuit 8 and the BPF 7 are connected to the HPF 6 in series because the ratio band on the high frequency side for transmitting the CS-IF channel is small.
When the specific band on the low frequency side is small, it is connected to the LPF 2 in series. Although the mixer (branching filter) is described as a mixer in the above-mentioned embodiment, the mixer in the embodiment has reversibility, and thus the third terminal 10
Can be used as a demultiplexer for demultiplexing the signal into the first terminal 1 and the second terminal 5.

[0031]

According to the present invention, since the bandpass filter and the impedance compensation circuit are provided in series with either filter, the stop band width of the mixer (branching filter) can be narrowed with a simple structure. it can. As a result, it is possible to mix signals having close frequency bands or to split signals into signals having close frequency bands. Also, CS
When this mixer (branching filter) is used in a joint reception system that transmits broadcasting and BS broadcasting by a single coaxial cable,
Since the band of 1355 to 1380 MHz, which cannot be used conventionally, can be used, it is possible to increase the number of channels by one and transmit 12 channels of CS-IF channels.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a mixer (branching filter) of the present invention.

FIG. 2 is a circuit of a mixer (branching filter).

FIG. 3 is a characteristic diagram of a passband loss characteristic and a voltage standing wave ratio (VSWR) on the HPF side of a mixer (demultiplexer), (a)
Shows the pass band loss characteristic, and (b) shows the reflection loss characteristic.

FIG. 4 is a characteristic diagram in the vicinity of the stop band of FIG.

5A and 5B are characteristic diagrams of a passband loss characteristic and a VSWR on the LPF side of a mixer (demultiplexer), (a) showing a passband loss characteristic, and (b) showing a reflection loss characteristic.

FIG. 6 is a characteristic diagram in the vicinity of the stop band of FIG.

7 is a characteristic diagram in which the characteristics shown in FIG. 3 and the characteristics shown in FIG. 5 are combined, (a) shows pass band loss characteristics, and (b) shows reflection loss characteristics.

FIG. 8 is a characteristic diagram in the vicinity of the stop band in FIG.

FIG. 9 is a modification of the mixer (branching filter).

10A and 10B are explanatory views of a conventional mixer, FIG. 10A is a diagram showing a joint reception system device, and FIG. 10B is a block diagram of the conventional mixer.

FIG. 11 is a diagram showing a frequency array of BS-IF channels and CS-IF channels.

FIG. 12 is a diagram showing a 1-system CS television broadcast arrangement.

[Explanation of symbols]

 1 1st terminal 2 Lowpass filter (LPF) 5 2nd terminal 6 Highpass filter (HPF) 7 Bandpass filter (BPF) 8 Impedance compensation circuit 9 Connection part 10 3rd terminal

Claims (4)

[Claims] 1. A first terminal to which a first signal having a low frequency band is input, a second terminal to which a second signal having a high frequency band is input, and A third terminal for outputting a signal obtained by mixing the first signal and the second signal is provided, one end of a low-pass filter is connected to the first terminal, and one end of a high-pass filter is connected to the second terminal. Is connected, the other end of the low-pass filter and the other end of the high-pass filter are connected to form a wire connection portion, and the wire connection portion is connected to the third terminal, wherein the low-pass filter and the wire connection are connected. A mixer, wherein a bandpass filter and an impedance compensation circuit are connected in series and interposed between the high-pass filter and the connection portion. 2. When the ratio band of the first signal is smaller than the ratio band of the second signal, the band pass filter and the impedance compensating circuit are arranged between the low pass filter and the wire connection part. Is intervened in
On the contrary, when the ratio band of the first signal is larger than the ratio band of the second signal, the band pass filter and the impedance compensation circuit are provided between the high pass filter and the connection part. The mixer according to claim 1, wherein the mixer is interposed. 3. A first terminal for outputting a first signal having a low frequency band, a second terminal for outputting a second signal having a high frequency band, and A first terminal and a second terminal to which a signal for demultiplexing the second signal is input are provided, one end of a low-pass filter is connected to the first terminal, and a second terminal of the high-pass filter is connected to the second terminal. In the duplexer in which one end is connected, the other end of the low-pass filter and the other end of the high-pass filter are connected to form a connection part, and the connection part is connected to the third terminal, the low-pass filter and A duplexer, in which a bandpass filter and an impedance compensation circuit are connected in series and interposed between the connection section or between the high-pass filter and the connection section. 4. The bandpass filter and the impedance compensating circuit are arranged between the low-pass filter and the connection part when the ratio band of the first signal is smaller than the ratio band of the second signal. Is intervened in
On the contrary, when the ratio band of the first signal is larger than the ratio band of the second signal, the band pass filter and the impedance compensation circuit are provided between the high pass filter and the connection part. The duplexer according to claim 3, wherein the duplexer is interposed.