JPH0744391B2 - Harmonic mixer circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic mixer circuit composed of a microwave circuit, and more particularly to a technique for attenuating unnecessary waves output from one output terminal.

[Conventional technology]

FIG. 4 shows a conventional harmonic mixer circuit which constitutes a frequency conversion circuit. In the figure, reference numeral 1 is a reference local oscillation signal, 2 is a capacitor, 3 is a high-impedance line with a short-circuited tip made of microstrip, and constitutes a high pass filter circuit 4 together with the capacitor 2. Reference numeral 5 is a microstrip line, 6 is a low-pass filter circuit including a microstrip circuit, 7 is a harmonic generation / mixing circuit (for example, antiparallel diode circuit), 8
Is an intermediate frequency output signal (IF output signal), 9 is a high frequency input signal (RF input signal), 10 is a band pass filter circuit, and 11 is
This is the IF output terminal.

In this configuration, the reference local oscillation signal 1 passes through the high pass filter circuit 4. This high pass filter circuit 4
This is a filter circuit that reflects the IF output signal 8. Therefore, the IF output signal 8 is a signal having a frequency lower than that of the reference local oscillation signal 1. The reference local oscillation signal 1 that has passed through the high-pass filter circuit 4 is branched into two, one of which passes through the low-pass filter circuit 6 and is injected into the harmonic generation / mixing circuit 7. The harmonic generation / mixing circuit 7 mixes the multiplied wave of the injected reference local oscillation signal 1 and the RF input signal 9 which has passed through the band pass filter circuit 10. Of this mixed wave, only the IF output signal 8 having a difference frequency between the multiplied wave and the RF signal passes through the low pass filter circuit 6, but the high pass filter circuit 4
Is reflected and output from the IF output terminal 11. The other branched local reference oscillation signal 1 is the IF signal output terminal 11
Sent out as an unwanted wave.

[Problems to be Solved by the Invention]

In the conventional configuration, a part of the reference local oscillation signal 1 is output from the IF output terminal 11 as an unnecessary wave.
There is a problem that it may have an adverse effect on the external circuit that uses the.

The present invention has been made to solve the above problems,
An object of the present invention is to provide a harmonic mixer circuit capable of significantly attenuating a reference local oscillation signal leaking to the outside as compared with a conventional one.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is configured such that the output section for outputting the intermediate frequency signal has an attenuating circuit for attenuating the reference local oscillation signal.

[Action]

In the present invention, since the output section that outputs the intermediate frequency signal has the attenuating circuit that attenuates the reference local oscillation signal, the reference local oscillation signal leaking from the intermediate frequency output terminal to the circulator is sufficiently attenuated. .

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 12 denotes a microstrip line, which is drawn from a position extremely close to the output side capacitor 4 of the high-pass filter circuit 4, and is a quarter wavelength of the reference local oscillation signal 1. It has an electric length of. Reference numeral 13 denotes a microstrip line having an open end, which has an electrical length of 1/4 wavelength of the wavelength of the reference local oscillation signal 1 and constitutes an attenuation circuit together with the microstrip line 12.
The other structure is the same as the structure shown in FIG.

In this configuration, the reference local oscillation signal 1 that has passed through the high pass filter circuit 4 is branched into two, and one of them passes through the low pass filter circuit 6 and is injected into the harmonic generation / mixing circuit 7. The harmonic generation / mixing circuit 7 mixes the multiplied wave of the injected reference local oscillation signal 1 and the RF input signal 9 which has passed through the band pass filter circuit 10. Of this mixed wave, only the IF output signal 8 passes through the low-pass filter circuit 6, but is reflected by the high-pass filter circuit 4 and output from the IF output terminal 11 through the microstrip line 12. The other branched local reference oscillation signal 1 is attenuated by the microstrip lines 12 and 13.

FIG. 2 shows an embodiment of the present invention. Instead of the open microstrip line 13 of FIG. 1, a short-circuited coaxial line using a dielectric having a high dielectric constant (see FIG. 14) is used. The coaxial line 14 has an electrical length of 1/2 wavelength of the reference local oscillation signal 1. In FIG. 3, reference numeral 15 is a cylindrical dielectric having a hole 17 formed at the center of a prism or a cylinder, and the outer surface and inner surface, except for the end surface 16, are plated with silver or the like. Since the permittivity is as high as 70 to 100, there is an advantage that the length is about 1/8 of that of a normal coaxial line. Since the coaxial line 14 is short-circuited at the tip, leakage of the reference local oscillation signal 1 from the IF output terminal 11 can be further reduced as compared with the case where the microstrip line 13 having an open tip is used.

The attenuation circuit may be configured by inserting the coaxial line 14 between the two microstrip lines 12 and connecting the microstrip line 13 to the output side of the microstrip line 12 in the subsequent stage, or both parallel lines 1 It may be a / 4 wavelength open microstrip line or a ½ wavelength shorted line.

〔The invention's effect〕

As described above, according to the present invention, the IF output terminal is drawn from the output side of the reference local oscillation signal input section through the attenuator circuit that attenuates the reference local oscillation signal. Can be reduced as compared with the conventional one.

[Brief description of drawings]

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 perspective view showing an example of the coaxial line in FIG. 2, and FIG. The figure is a circuit diagram of a conventional harmonic mixer circuit. 1 ... Reference local oscillation signal, 4 ... High-pass filter circuit, 6 ... Low-pass filter circuit, 7 ... Harmonic generation /
Mixed circuit, 9 ... RF signal, 11 ... Intermediate frequency signal output terminal, 12, 13 ... Microstrip line, 14 ... Coaxial line made of dielectric material. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first input section for introducing a reference local oscillation signal, a second input section for introducing a high-frequency signal, a harmonic generation / mixing circuit provided between both input sections, and the first input. A harmonic mixer circuit for extracting the intermediate frequency signal having a frequency difference between the multiplied signal of the reference local oscillation signal and the high frequency signal, the output section outputting the intermediate frequency signal extracted from the output side of the output section. Is a microstrip line having an electrical length of 1/4 wavelength of the reference local oscillation signal, and an open-ended microstrip line having an electrical length of 1/4 wavelength connected to one end of the microstrip line. Harmonic mixer circuit featuring.