JPS58114516A - Mixing circuit - Google Patents

Abstract

PURPOSE:To prevent mutual interference, by supplying the 1st input signal to an output terminal via a BPF and a series resonance circuit and supplying the 2nd input signal to the output terminal via a band rejecting filter. CONSTITUTION:A signal inputted to the 1st input terminal 1 passes through a BPF9 defining specific frequencies as a pass band, and passes through a series circuit 20 and is applied to an output terminal 6. A signal inputted to the 2nd input terminal 2 is applied to the output terminal 6 via a band rejecting filter 10 where frequencies other than specific frequencies are defined as pass band. The signal through the filter 10 is blocked at the series circuit 20 and not detoured to the BPF9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixing circuit used for mixing multiple types of signals having different frequency bands, such as a television signal of a specific channel and a television signal of a channel other than the specific channel.

The drawings showing the embodiments of the present application will be described below.

Figure 1 is a wiring diagram of a mixed circuit, where 1 indicates the first input terminal, which can be connected to either an unbalanced feed line (e.g. coaxial cable) or a balanced feed line (e.g. feeder). used.

When connecting a coaxial cable, connect the center conductor to terminal 2,
Further, an external conductor is connected to the terminal 3. When connecting a feeder, the conductive wires of the feeder are connected to the terminals 2 and 4, respectively. Reference numeral 5 indicates a second input terminal, and reference numeral 6 indicates an output terminal, to which an unbalanced power supply line (for example, a coaxial cable) can be connected. The center conductor of the coaxial cable is connected to terminal 7, and the outer conductor is connected to terminal 8.

Reference numeral 9 denotes a band pass filter, in which, for example, a specific TV channel or a specific frequency is set as a pass band, and other TV channels or frequencies are set as a stop band. 9
a is the input end, 9b is the output end, and the number is the passband,
The above-mentioned specific channel or frequency is considered to be a stop band. 10a shows its input end, and 10b shows its output end. 1],
A is a first resonant element, which is composed of an inductor element 12a and a capacitor element 13a. Inductor element 12a
is composed of various distributed constant lines, one end of which is grounded and the other end connected to one end of the capacitor element 13a. The other end of capacitor element 13a is grounded. Reference numeral 11b denotes a second resonant element, which is configured in the same manner as the first resonant element 11a, including an intertarter element 12b and a capacitor element 13b. 14a is an input side coupling element, which connects the input end 9a and the first resonant element 11a.
and one end is provided for electromagnetically coupling the input end 9.
It consists of a distributed constant line connected to a and the other end grounded. The input side impedance of the bandpass filter 9 in the pass band is set to a value that can be matched with the impedance of the external circuit by adjusting the length and characteristic impedance of the input side coupling element 14a. 14b is an output side coupling element,
It is provided to electromagnetically couple the output end 9b and the second resonant element 11b, and consists of a distributed constant line having one end connected to the output end 9b and the other end grounded. Note that the output side impedance of the bandpass filter 9 in the passband is set to a value that can be matched with the impedance of the external circuit by adjusting the length and characteristic impedance of the output side coupling element 14b. 15 is a resonant coupling element, the first resonant element 1];
It is used to electromagnetically couple the second resonant element 11b and the second resonant element 11b, and consists of a distributed constant line whose both ends are grounded.

Next, in the band elimination filter 10, 1.6a, 1
7a, 18a are inductor elements, 16b, 17b,
18b and 19 indicate capacitor elements, respectively. 20 is a series circuit, which is interposed between the output terminal 9b of the band-pass filter 9 and the output terminal 6, and the signal passing through the band-pass filter 9 is passed through without loss, and other signals and interference waves are blocked. (However, excluding frequency components described later), the inductor element 21 and capacitor element 22
It is composed of. Reference numeral 23 denotes an impedance transformation circuit interposed between the input end 9a of the bandpass filter and the first input terminal 1, and includes an inductor element 24 and a capacitor element 25. Furthermore, impedance transformation circuit 2
3 is the second input terminal 5 and the input terminal 10 of the band-stop filter.
It can also be provided between a. In this case, if a second input terminal 5 having the same configuration as the first input terminal 1 is used, either an unbalanced feed line or a balanced feed line can be connected.

Next, in the mixed circuit having the above configuration, the inductor element 21
The element values of the capacitor element 22 and the capacitor element 22 will be explained in detail. However, in this case, the inductance of the output side coupling element 14b is set to L (H), and the center frequency of the pass band (for example, a specific TV channel) of the band pass filter 9 is set to fo (Hz).
). Here, the inductance of the interpolator element 21 is n times the inductance of the output side coupling element 14b, which is nL.
(H), and the capacitance of the capacitor element 22 is C
(F).

At this time, since one end of the output side coupling element 14b is grounded, there is a large attenuation part in the pass band due to the characteristics of the band elimination filter 10, but this is outside the frequency band used (for example, TV VHF low band). and VHF high band, or between TV VHF high band and TV UHF
(between the band, etc.). If the center frequency of the above-mentioned portion with large attenuation is fl, n is found from equation (1) and equation (2) and equation (3) as described above, and the inductance of the inductor element 21 is found. Further, when C is determined using equation (1), the capacitance of the capacitor element 22 is determined.

Next, in the above configuration, the operation will be described when a television signal of a specific channel is applied to the first input terminal 1 and a television signal of a channel other than the specific channel is applied to the second input terminal 5. First, a television signal of a specific channel passes through a bandpass filter 9, then a series circuit 20, and is sent out from an output terminal 6. In this case, since the band-elimination filter 9 has a very high impedance for the signal of a specific channel (particularly the parallel circuit of the inductor element 16a and the capacitor element 16b), the TV signal of the specific channel passed through the series circuit 20 is the bandstop filter 10
Most of the signal is sent out from the output terminal 6 without going around. On the other hand, television signals other than the specific channel are transmitted from the second input terminal 5 through the band elimination filter 10 and sent out from the output terminal 6. In this case, since the impedance of the series circuit 20 is very high for TV signals other than the specific channel, the TV signals other than the specific channel that have passed through the band-elimination filter 10 will not go around to the band-pass filter 9. Most of the output is sent from the output terminal 6. For the above reasons, the mixing circuit has a small passing loss for the signals to be mixed.

Note that even if a TV signal other than the specific channel enters the first input terminal 1, it will be blocked by the blocking characteristics of the bandpass filter 9 and the series circuit 20 and will not be output to the output terminal 6. Needless to say, even if a television signal of a specific channel is mixed in from the filter 5, it will be blocked by the rejection characteristics of the band-elimination filter 10 and will not be output to the output terminal 6.

Next, Figures 2 and 3 show examples of the circuit shown in Figure 1 being implemented (assembled) on a board. Figure 2 is a perspective view from the front side of the board, and Figure 3 is a perspective view from the back side of the board. It is a perspective view seen from
Components in both figures that correspond to those in FIG. 1 are designated by the same reference numerals. Reference numeral 26 denotes a circuit board, which is composed of an insulating member 27 and a copper foil member 28 attached thereto. The first input terminal 1 consists of a pair of connection terminals 2 and 4 and an external conductor connection part 3, and the external conductor connection part 3 and the copper foil member 28 are made electrically conductive by soldering or the like, and are connected to a feeder. It is configured as a well-known connection terminal that can also be used for coaxial cable connection. In addition, in the case of feeder connection, a pair of connection terminals 2 and 4
In the case of coaxial cable connection, the center conductor may be connected to the connection terminal 2 and the outer conductor may be connected to the outer conductor connection portion 3. Second input terminal5. Output terminal 6
each consists of a connecting terminal 7 for connecting the center conductor and an outer conductor connecting part 8, and the outer conductor connecting part 8 and the copper foil member 28 are made electrically conductive by soldering, etc., and are made of a well-known coaxial cable connecting terminal. It is configured as a terminal. The impedance transformation circuit 23 is composed of an inductor element 24 with a printed pattern, a capacitor element 25, and a jumper wire 33 using a tin-plated copper wire. Note that the jumper wire 33 connects the connection terminal 4 and one end of the printed coil 24. Inductor element 12a, 1
．． 2b, input side coupling element 14a, output side coupling element 14b
, the resonant coupling elements 15 are each formed of a printed pattern having a predetermined width and length, and are distributed constant lines having a required characteristic impedance. Capacitor element 13a
, 13b are used as ceramic capacitors and are attached to the circuit board 26 from the front side of the board, but any of various known capacitors may be used, such as a well-known gap capacitor made of printed circuits. still,
29 is a capacitor correction element, which is formed by a printed pattern and is used to supplement the minute capacitance lacking in the capacitor element 13a; 30 is a coupling degree variable element made of tin-plated copper wire, which connects the first resonance element 11a and the first resonance element 11a; It is used to change the degree of coupling with the resonance element 11b of 2 according to its inclination angle, and is connected in parallel with the resonance coupling element 15. Both ends of the coupling element are connected to the copper foil member 28 by soldering or the like. It is. Next, inductor elements 16a, 17a, 18
A coil formed with a printed pattern is used for a. Ceramic capacitors are used for capacitor elements 16b, 17b, 18b, and 19. 31a, 31b.

31c is a jumper wire connecting each element, and a tin-plated copper wire is used, and 3]a is the input terminal 9a of the bandpass filter.
and the connecting terminal 2 are electrically connected. 31b electrically connects one end of the printed coil 18a and one end of the ceramic capacitor 18b. 31c is printed coil 16
a, one end of a parallel circuit consisting of ceramic capacitor 16b, and printed coil 17a, ! : Electrically connects to one end of a parallel circuit consisting of the ceramic capacitor 17b. Next, the inductor element 21 includes a portion 21a made of a printed coil formed with a printed pattern;
The jumper wire portion 21b is made of tin-plated copper wire. Jumper wire 21b electrically connects one end of printed coil 21a and one end of ceramic capacitor 22. A ceramic capacitor is used as the capacitor element 22. Furthermore, 32.32. . . . indicates the soldered portion between the lead of each element or the end of the tin-plated copper wire and each printed pattern.

In the above configuration, for example, the specified TV channel is Ch19 (506 to 512 MHz), and the width of TV channels other than the specified channel is 2 m as a modulus.
m, length 23 mm, and the printed coil 21a is a coil with a width of 1 mm and a pattern of approximately 2 turns (effective length is 58 mm), and the jumper wire 21b is a tin-plated copper wire with a wire diameter of 0.5 mm and a length of 15 mm. using
A 2 pF ceramic capacitor is used as the capacitor 22, and the capacitors 13a and 13b.

16b, 17b, 18b, 19 each have 4 pF,
5T)F.

FIG. 5 is a chart showing the attenuation characteristics between the input terminal and the output terminal of ceramic conductors of 12 pF, 12 pF, 2.5 pF, and 2 pF, and the VSWR characteristic on the first input terminal side. FIG. 6 is a chart showing the attenuation characteristic between the second input terminal and the output terminal, and FIG. 7 is a chart showing the VSWR characteristic on the second input terminal side.

In each figure, the bandpass filter output end 9b and one end of the capacitor 22 (the end not connected to the output terminal 6) are directly connected with a tin-plated copper wire with a wire diameter of 0.6 mm and a length of 10 mm. TV channel Ch
28 or higher (560MHz or higher), the loss is particularly small.
It turns out that it is excellent.

Also, a printed coil 21a and a jumper wire 21b.

All capacitors 22 are removed and the output terminal 6
In the case where the band-pass filter output terminal 9b is directly connected to the band-pass filter output terminal 9b, the pass band loss of the band-elimination filter 10 is large in the TV VHF band (the mixing circuit is shown in combination with the mixing circuit, but the band-pass filter and the low pass filter,
Alternatively, a mixing circuit using a combination of a band-pass filter and a high-pass filter can also be configured. In this case, it goes without saying that the series circuit 20 is provided, but the output side of the low-pass filter or the high-pass filter is provided with a circuit that has high impedance with respect to a signal having a frequency in the pass band of the band-pass filter. (for example, a parallel circuit of an inductor element and a capacitor element).

As described above, the present invention has the advantage that even if a plurality of types of signals with different frequency bands are mixed, all the signals can be mixed with low loss and little mutual interference.

[Brief explanation of the drawing]

The drawings relate to embodiments. Figure 1 is a wiring diagram of a mixing circuit, Figure 2 is a perspective view of an example of an assembled mixing circuit viewed from the front side of the board, and Figure 3 is a wiring diagram of the mixing circuit in Figure 2. FIG. 4 is a perspective view seen from the back side. Figures 5, 6, and 7 are characteristic diagrams. 1...First input terminal, 5...Second input terminal, 6
...Output terminal, 9...Band pass filter, 10...
・Band elimination filter, 20...Series circuit, 21...
Inductor element, 22... Capacitor element. Patent applicant Maspro Electric Works Co., Ltd. Representative Takashi Hatayama 11 Kaimei 58-114516 (5) (Y) - ('J no 1 (gp) ￥愼 - aMs△ = (U) Brush method 96 - dMsA

Claims (1)

[Claims] In a mixing circuit including a first input terminal, a second input terminal, and an output terminal, a bandpass filter is provided between the first input terminal and the output terminal to pass a signal of a specific frequency. A filter is interposed between the second input terminal and the output terminal to allow signals other than a specific frequency to pass, and a filter is interposed between the output terminal of the band-pass filter and the output terminal. is a mixed circuit characterized by interposing a series circuit consisting of an inductor element and a capacitor element.