JPS6040029Y2 - High frequency mixer - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high-frequency mixing device that adds multiple high-frequency signals to a mixer via a variable attenuator and mixes them. The aim is to provide a device that does not require any connection.

What is shown in FIG. 1 is a block diagram of a conventional high frequency mixer, in which a high frequency signal is applied to a mixer 1 via a variable attenuator 2.3.

4 and 5 are input terminals, and 6 is an input signal source connected to the input terminal 4.

7 is a matching box connected to the input terminal 5.

When no input signal is applied to the input terminal 5, it is necessary to connect a matching device 7 to the input terminal for matching.

The present invention aims to provide a high frequency mixing device that eliminates the need to connect a matching box to the input terminal by adjusting a variable attenuator when no input signal is supplied. explain.

As shown in FIG.
High-frequency signal input terminals 11 and 12 are provided via 0.

13 is an input signal source connected to the input terminal 11.

Variable attenuators 9 and 10 are connected to input terminals 11.1 and 11.1, respectively.
2 and the input terminals 8a and Bb of the mixer 8 with a resistance of 14.15
and connect variable resistor 1 between input terminals 11 and 12 and ground.
6 and 17 and resistors 18 and 19 are connected in series, and the movable terminals of the variable resistors 16 and 17 are connected to the input terminals 8a and 8b of the mixer 8.

Now, let the input impedance of the mixer 8 be Za, zb, and the values of the resistors 14, 15, 16, 17, 18, 19 be R□
4. R15, R16, R17, R18, R□9.

The resistance value on the resistor 14 side from the movable terminal of the variable resistor 16 is rl
, the resistance value on the resistor 18 side is r2, the value on the resistor 15 side of the movable terminal of the variable resistor 17 is r3v, and the value on the resistor 19 side is r4.

The input impedance Zin looking from the input terminal 11 to the variable attenuator 9 side is as follows.

Zin=Kudan■r + R, Za rIR14r2+R18+Za Therefore, the output impedance of the input signal source 13 is this Z
It is set to a value close to in.

The same applies to the variable attenuator 10.

When an input signal source is not connected to the input terminal 12 like the variable attenuator 10, the movable terminal of the variable resistor 17 is moved to the resistor 19.

In this case, r3=R□7. r, = O, and the impedance Z1 of the variable attenuator 10 seen from the mixer 8 side
° is 210” R19.

This zlo is set to the same value as the input impedance of the mixer 8.

That is, as follows.

Zl o = Rls = Zb By satisfying this condition, variable attenuator 1
0 allows matching to be achieved and there is no need to connect a matching box to the terminal 12.

The same applies to the variable attenuator 9, R18=Za
You can set it to .

When the input impedance of the mixer 8 is 750, the values of the respective resistances of the variable attenuators 9 and 10 are set as follows, for example.

R14= R15= 1.2Ω, R16=R□7=
300Ω, R18=R19=75Ω.

Although the above embodiment has been described for the case where two signals are mixed, it can be applied to the case where a plurality of signals are mixed, and each variable attenuator may be set as described above.

As described above, according to the present invention, matching can be achieved by adjusting the variable attenuator without connecting a matching box to the input terminal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional high-frequency mixer, and FIG. 2 is a circuit diagram of a high-frequency mixer according to an embodiment of the present invention. 8...Mixer, 9,10...Variable attenuator, 11.12...Input terminal, 14.
15. 18.19...Resistance, 16,17...
...Variable resistance.

Claims (1)

[Scope of utility model registration request] A plurality of high-frequency signal input terminals are connected to each input terminal of the mixer via a resistor, and the high-frequency signal input terminal is connected to a series circuit of a variable resistor and a resistor, so that the variable resistor becomes the high-frequency signal input terminal side. The movable terminal of the variable resistor is connected to the input terminal of the mixer, and the value of the resistor connected in series with the variable resistor is set to be equal to the input impedance of the mixer. Device.