JPH0983255A - Balanced type mixer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the balanced type mixer not susceptible to the effect of harmonics. SOLUTION: The mixer is made up of 1st and 2nd mixer diodes 14a, 14b connected in the same polarity, a 1/2 wavelength transmission line 17 connected between the two mixer diodes 14a, 14b, a 1st impedance matching circuit 13, and a 2nd impedance matching circuit 20. In the balanced type mixer extracting an output signal from a midpoint of the transmission line 17, a harmonic short- circuit stub 16b is connected at a position within a length of 1/4 wavelength with respect to a center frequency of a local oscillation signal from an electrode of the 2nd mixer diode 14b connecting to the transmission line 17.

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 the microwave or millimeter wave band.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional balanced mixer.
Will be described with reference to the configuration diagram of FIG.

An input terminal 31 receives an input signal. 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 to the input terminal 31. In addition, the microstrip line 32
b is a diode 34a, 34b connected in the same direction
Is connected to the connection point of. In addition, the diode 34a,
A microstrip line 35 having a length of ½ wavelength at the center frequency is connected to both ends of 34b1. Reference numeral 36 is a ground circuit for an output signal, which has a structure that does not act on the fundamental wave.

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

Then, the input signal input from the input terminal 31 and the local oscillator signal input from the local oscillator terminal 37 are mixed, and the mixed output signal of both signals is output to the output terminal 41 through the output signal circuit 40. It

[0006]

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

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a balanced mixer with less influence of harmonics.

[0008]

SUMMARY OF THE INVENTION According to the present invention, first and second mixer diodes connected in the same direction and 1/2 connected across the first and second mixer diodes are connected. A two-wavelength transmission line, a first impedance matching circuit connected to a connection point between the first and second mixer diodes, and an electrode of the second mixer diode on the side connected to the transmission line And a second impedance matching circuit through which a local oscillation signal passes, and in a balanced mixer for taking out an output signal from an intermediate point of the transmission line, the second mixer diode on the side connected to the transmission line A harmonic short-circuit stub is connected to a position up to a quarter wavelength at the center frequency of the local oscillation signal from the electrode.

Further, the first and second mixer diodes connected in the same direction, and the half-wavelength transmission line connected across the first and second mixer diodes so as to straddle the first and second mixer diodes, A first impedance matching circuit connected to a connection point of the first and second mixer diodes, and a first impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, through which a local oscillation signal passes. In a balanced mixer including an impedance matching circuit of 2 and extracting an output signal from an intermediate point of the transmission line, at a center frequency of a local oscillation signal from a connection point of the first mixer diode and the second mixer diode. Harmonic shorting stubs are connected at positions up to a quarter wavelength.

Further, the first and second mixer diodes connected in the same direction, and the half-wavelength transmission line connected across the first and second mixer diodes so as to straddle the first and second mixer diodes, A first impedance matching circuit connected to a connection point of the first and second mixer diodes, and a first impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, through which a local oscillation signal passes. And a center frequency of a local oscillation signal from an electrode of the second mixer diode on the side connected to the transmission line in a balanced mixer including an impedance matching circuit of No. 2 and an output signal from an intermediate point of the transmission line. At a position up to a quarter wavelength and at a connection point of the first mixer diode and the second mixer diode, a quarter wave at the center frequency of the local oscillation signal. Of each position to the length, harmonic shorting stub is connected. Further, instead of the stub for harmonic short circuit, a series resonant circuit for harmonic short circuit composed of a capacitor and an inductor is connected.

According to the above construction, the position from the electrode of the second mixer diode on the side connected to the transmission line to the length of ¼ wavelength at the center frequency of the local oscillation signal, and the first mixer diode. A harmonic short-circuit stub is connected to both or either of the connection point of the second mixer diode and the position up to the length of ¼ wavelength at the center frequency of the local oscillation signal.

Therefore, since the harmonic short-circuit stub is connected, the influence of the harmonic is reduced, and even if the mounting positions of the components such as the ground circuit for the output signal and the capacitor for the local oscillation signal vary, There is no need to recreate the matching circuit. It should be noted that from the electrode of the second mixer diode on the side connected to the transmission line, 1/4 at the center frequency of the local oscillation signal.
If both the position up to the wavelength length and the position from the connection point of the first mixer diode and the second mixer diode to the quarter wavelength length at the center frequency of the local oscillation signal are connected, The impact can be reduced.

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

[0014]

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

Reference numeral 11 is an input terminal to which an input signal is input. The input terminal 11 includes a microstrip line 12a for transmitting an input signal, an input signal matching circuit 13, and microstrip lines 12b, 1b for transmitting an input signal.
2c are connected in order. The microstrip line 12c is connected to the diode 14 connected in the same direction.
It is connected to the connection point of a and 14b. A ground circuit 15 for an output signal 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. Further, a microstrip transmission line 17 having a length of ½ wavelength at the center frequency is provided at both ends thereof so as to straddle the diodes 14a and 14b. Are connected. Reference numeral 18 is a local oscillator terminal to which a local oscillator signal is input. A microstrip line 19a for transmitting a local oscillation signal, a matching circuit 20 for a local oscillation signal, and microstrip lines 19b, 19c for transmitting a local oscillation signal are sequentially connected to the local oscillation terminal 18. The microstrip line 19c is connected to the microstrip line 17 and the diode 14
It is connected to the connection point of 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 oscillator terminal 18, and does not act on the fundamental wave. In addition, the microstrip line 19b,
A stub 16b that short-circuits harmonics is connected between 19c.

In the above structure, the input signal input from the input terminal 11 and the local oscillator signal input from the local oscillator terminal 18 are mixed, and the mixed output signal of both signals is output through the output signal circuit 22 to the output terminal. 23 is output.

According to the above structure, the stubs 16a and 16b for short-circuiting the higher 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 are variations in the positions where components such as the ground circuit 15 and the capacitor 21 of the output signal are mounted, variations in matching with harmonics are reduced. Therefore, even if the mounting positions of the output signal ground circuit 15 and the local signal capacitor 21 are varied, it is not necessary to remake the matching circuits 13 and 20.

Incidentally, the microstrip lines 12c, 1
As the length of 9c becomes longer, conductor loss increases, so
In order to reduce the effect of conductor loss, the center frequency of the local oscillation signal is set to ¼ 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 designated by the same reference numerals, and overlapping description will be omitted. In the embodiment of FIG. 2, in place of the stubs 16a and 16b for short-circuiting the harmonics in the embodiment of FIG.
1b is connected and harmonics are short-circuited. In this case also, the influence of harmonics can be eliminated, and the grounding circuit for the output signal 1
Even if the mounting positions of 5 and the capacitor 21 for the local oscillation signal are varied, it is not necessary to remake the matching circuits 13 and 20.

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

[0022]

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

[Brief description of drawings]

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

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

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

[Explanation of symbols]

 11 ... Input terminals 12a to 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 terminal 19a to 19c ... Microstrip line 20 ... Local signal matching circuit 21 ... Output signal blocking capacitor 22 ... Output signal circuit 23 ... Output terminals 31a, 31b ... Harmonic short-circuit series resonance circuit

Claims (4)

[Claims] 1. A first and a second mixer diode connected in the same direction, and a half-wavelength transmission line connected across the first and second mixer diodes so as to straddle the first and second mixer diodes, A first impedance matching circuit connected to a connection point of the first and second mixer diodes, and a first impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, through which a local oscillation signal passes. And a center frequency of a local oscillation signal from an electrode of the second mixer diode on the side connected to the transmission line in a balanced mixer including an impedance matching circuit of No. 2 and an output signal from an intermediate point of the transmission line. A balanced mixer characterized in that a stub for harmonic short circuit is connected to the position up to the length of 1/4 wavelength. 2. A first and second mixer diode connected in the same direction, and a half-wavelength transmission line connected across the first and second mixer diodes so as to straddle the first and second mixer diodes, A first impedance matching circuit connected to a connection point of the first and second mixer diodes, and a first impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, through which a local oscillation signal passes. A balanced mixer for extracting an output signal from an intermediate point of the transmission line.
A harmonic mixer stub is connected at a position from a connection point of the mixer diode and the second mixer diode to a length of ¼ wavelength at the center frequency of the local oscillation signal. 3. A first and a second mixer diode connected in the same direction, and a half-wavelength transmission line connected across the first and second mixer diodes so as to straddle the first and second mixer diodes, A first impedance matching circuit connected to a connection point of the first and second mixer diodes, and a first impedance matching circuit connected to an electrode of the second mixer diode on the side connected to the transmission line, through which a local oscillation signal passes. And a center frequency of a local oscillation signal from an electrode of the second mixer diode on the side connected to the transmission line in a balanced mixer including an impedance matching circuit of No. 2 and an output signal from an intermediate point of the transmission line. At a position up to a quarter wavelength, and from the connection point of the first mixer diode and the second mixer diode a quarter wavelength at the center frequency of the local oscillation signal. A balanced mixer characterized in that a stub for harmonic short circuit is connected to each of the positions so far. 4. The harmonic short-circuit series resonant circuit formed of a capacitor and an inductor is connected in place of the harmonic short-circuit stub, and the harmonic short-circuit stub is connected to the harmonic short-circuit stub. Balanced mixer.