JP2918477B2 - Balanced mixer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balanced mixer used in microwave and millimeter wave bands.

[0002]

2. Description of the Related Art FIG.
The configuration will be described with reference to FIG.

An input terminal 31 receives an input signal. To the input terminal 31, a microstrip line 32a for transmitting an input signal, an input signal matching circuit 33, and a microstrip line 32b for transmitting an input signal are sequentially connected. The microstrip line 32
b denotes diodes 34a, 34b connected in the same direction.
Connected to the connection point. Also, a diode 34a,
At both ends of the 34 b, a microstrip line 35 having a length of 1/2 wavelength at the center frequency are connected. Reference numeral 36 denotes a ground circuit for an output signal, which does not act on a fundamental wave.

Reference numeral 37 denotes a local oscillator terminal to which a local oscillator signal is input. To the local oscillator terminal 37, a microstrip line 38a for transmitting a local oscillator signal, a matching circuit 39 for a local oscillator signal, and a microstrip line 38b for transmitting a local oscillator signal are sequentially connected. The microstrip line 38b is
It is connected to a connection point between the microstrip line 35 and the diode 34b. Reference numeral 40 denotes a capacitor which blocks an output signal, prevents the output signal from leaking to the local oscillation terminal 37, and does not act on a fundamental wave.

[0005] The input signal input from the input terminal 31 and the local signal input from the local terminal 37 are mixed, and the mixed output signal is output to the output terminal 41 through the output signal circuit 40. You.

[0006]

When the conventional balanced mixer having the above-described structure is mass-produced, the positions where components such as the grounding circuit 36 for output signals and the capacitor 40 are mounted vary inevitably. Such a variation causes a variation in matching with respect to harmonics. Therefore, for example, when there is a variation in matching with respect to harmonics, it is necessary to recreate the matching circuits 33 and 39, for example.

An object of the present invention is to solve the above-mentioned disadvantages and to provide a balanced mixer which is less affected by harmonics.

[0008]

According to the present invention, there are provided first and second mixer diodes connected in the same direction, and a 1/2 connected between both ends so as to straddle the first and second mixer diodes. a transmission line of two wavelengths, and the first impedance matching circuit connected to the connection point of the first and second mixer diodes, the first impedance matching
A ground circuit for an output signal connected to a circuit, a second impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, and passing a local oscillation signal ; Connected to the impedance matching circuit
A balanced mixer comprising an output signal blocking capacitor for extracting an output signal from an intermediate point of the transmission line, wherein a local oscillation signal is output from an electrode of the second mixer diode connected to the transmission line. 1/4 at center frequency
Position up to the wavelength length , and said first mixer
From the node between the node and the second mixer diode.
Position up to 1/4 wavelength length at the center frequency of the emitted signal
A stub for harmonic short circuit is connected to each.

In addition, instead of the stub for harmonic shorting,
Series resonance for harmonic short-circuit consisting of a capacitor and an inductor
The circuit is connected.

[0010]

According to the above configuration, the position from the electrode of the second mixer diode connected to the transmission line to the center frequency of the local oscillation signal to a length of 1/4 wavelength, and the first mixer diode and a second position from the connection point of the mixer diode to a length of a quarter wavelength at the center frequency of the local oscillation signal, harmonic short stub to both the connected.

Therefore, the connection of the stub for harmonic short-circuit reduces the influence of harmonics. Even if the mounting positions of components such as the ground circuit for output signal and the capacitor for local oscillation signal vary, the stub is individually connected. There is no need to recreate the matching circuit .

The same effect can be obtained when a harmonic short-circuit series resonance circuit composed of a capacitor and an inductor is connected instead of the harmonic short-circuit stub.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

Reference numeral 11 denotes an input terminal to which an input signal is input. The input terminal 11 includes a microstrip line 12a for transmitting an input signal, a matching circuit 13 for an input signal, and a microstrip line 12b for transmitting an input signal.
2c are connected in order. The microstrip line 12c is connected to a diode 14 connected in the same direction.
a, 14b. An output signal grounding circuit 15 that does not act on the fundamental wave is connected between the input signal matching circuit 13 and the microstrip line 12b. And the microstrip line 12
A stub 16a for short-circuiting harmonics is connected between b and 12c. A microstrip transmission line 17 having a length of 1/2 wavelength at a center frequency is provided at both ends of the stub 16a so as to straddle the diodes 14a and 14b. Is connected. Reference numeral 18 denotes a local oscillator terminal to which a local oscillator signal is input. The local oscillation terminal 18 is connected to a microstrip line 19a for transmitting a local oscillation signal, a matching circuit 20 for a local oscillation signal, and microstrip lines 19b and 19c for transmitting a local oscillation signal. The microstrip line 19c is connected to the microstrip line 17 and the diode 14
b, that is, the cathode of the diode 14b.

A capacitor 21 is connected between the local signal matching circuit 20 and the microstrip line 19b. The capacitor 21 blocks the output signal and prevents the output signal from leaking to the local oscillation terminal 18, and does not act on the fundamental wave. Also, the microstrip line 19b,
A stub 16b for short-circuiting a harmonic is connected between 19c.

In the above configuration, the input signal input from the input terminal 11 and the local signal input from the local terminal 18 are mixed, and an output signal obtained by mixing the two signals is output through the output signal circuit 22 to the output terminal. 23.

According to the configuration described above, the stubs 16a and 16b for short-circuiting harmonics are connected between the microstrip lines 12b and 12c and at the connection point between the microstrip transmission line 17 and the diode 14b. For this reason, even if there is a variation in the position at which components such as the ground circuit 15 and the capacitor 21 of the output signal are mounted, the variation in the matching with respect to the harmonic is reduced. Therefore, even if the mounting positions of the ground circuit 15 for the output signal and the capacitor 21 for the local oscillation signal vary, it is not necessary to re-create the matching circuits 13 and 20.

The microstrip lines 12c, 1c
As the length of 9c becomes longer, conductor loss increases,
In order to reduce the effect of conductor loss, the center frequency of the local oscillation signal is set to 1/4 wavelength or less.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. In the embodiment of FIG. 2, instead of the stubs 16a and 16b for short-circuiting harmonics in the embodiment of FIG. 1, series resonance circuits 31a and 31
1b is connected to short-circuit harmonics. Also in this case, the influence of harmonics can be eliminated, and the grounding circuit 1 for the output signal can be used.
It is not necessary to re-create the matching circuits 13 and 20 even if the mounting position of the capacitor 5 and the local oscillation signal 21 varies.

In the above-described embodiment, the stub 16a for short-circuiting the harmonic is connected to both the connection point of the first and second diodes 14a and 14b and the connection point of the microstrip transmission line 17 and the diode 14b. 16
b or the series resonance circuits 31a and 31b are connected. By connecting to both in this way, the influence of harmonics can be further reduced .

[0022]

According to the present invention, it is possible to realize a balanced mixer which is less affected by harmonics.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Input terminal 12a-12c ... Microstrip line 13 ... Input signal matching circuit 14a, 14b ... Mixer diode 15 ... Output signal grounding circuit 16a, 16b ... Harmonic short circuit stub 17 ... Microstrip transmission line 18 ... Local oscillation terminal 19a to 19c: Microstrip line 20: Matching circuit for local oscillation signal 21: Capacitor for blocking output signal 22: Output signal circuit 23: Output terminal 31a, 31b: Series resonance circuit for harmonic short circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-11506 (JP, A) JP-A-2-53306 (JP, A) JP-A-64-65904 (JP, A) JP-A-2- 46009 (JP, A) JP-A-59-47815 (JP, A) JP-A-3-117105 (JP, A) JP-A 62-75618 (JP, U) JP-A 62-75619 (JP, U) Hikaru Sho 64-54411 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H03D 7/00-9/06

Claims (2)

(57) [Claims] 1. A first and second mixer diode connected in the same direction, a half-wavelength transmission line connected between both ends so as to straddle the first and second mixer diodes, and a first impedance matching circuit connected to the connection point of the first and second mixer diodes, this
Output signal connected to the first impedance matching circuit of
A ground circuit of use, which is connected to the electrode of the second mixer diode on the side connected to the transmission line, a second impedance matching circuit through the local oscillator signal, the second Inpi
Output signal blocking capacitor connected to the
And a balanced mixer for extracting an output signal from an intermediate point of the transmission line, wherein the center frequency of the local signal is 1/4 from the electrode of the second mixer diode connected to the transmission line. Position up to the wavelength length ,
And the first mixer diode and the second mixer
The center frequency of the local oscillation signal from the connection point of the
A balanced mixer wherein a stub for harmonic short circuit is connected to each of positions up to four wavelengths in length . 2. A capacitor instead of a stub for harmonic shorting.
Series resonant circuit composed of a resistor and an inductor
2. The rose according to claim 1, wherein
Type mixer.