JPS5846885B2 - Shuuhasuuhenkanki - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a frequency converter that employs a so-called image recovery method to reduce signal loss associated with frequency conversion, and in particular, the present invention relates to a frequency converter that employs a so-called image recovery method to reduce signal loss associated with frequency conversion. The reactance at the image frequency can be adjusted independently of the input signal supply circuit, thereby making the circuit reactance at the image frequency constant over a wide frequency band and reducing conversion loss.

In a down converter that mixes the frequency of an input signal with a local oscillation frequency to convert it to a lower frequency, an image recovery type frequency converter has conventionally been used in order to reduce loss associated with frequency conversion.

That is, when the input signal frequency is f and the local oscillation frequency is f, a component of intermediate frequency fi of ff is generated in the mixer diode constituting the down converter, but at the same time, an image having the relationship 2fp-fs-fm is generated. Since a frequency component is generated, if this fm component is absorbed by a loss resistance of the frequency converter, a portion of the input signal will be lost by the loss due to the resistance.

Therefore, we imagine a frequency converter in which the impedance seen from the mixer diode toward the circuit side is made reactive so that the fm image component generated in the mixer diode interacts with the f local oscillation component again to become the fi intermediate frequency component. It is called a one-sided recovery method.

In the conventional image recovery one-type frequency converter, as shown in FIG.
are inserted into each circuit, but since all of these band-passed transducers completely reflect the image frequency fm component, the impedance seen from the mixer diode D toward the circuit side becomes active.

The lumped constant equivalent circuit for the principle circuit configuration shown in Figure 1 is as shown in Figure 2. Regarding this lumped constant equivalent circuit, the frequency characteristics of the impedance seen from the mixer diode D to the circuit side are as shown in Figure 3. As shown in FIG. 3a, the impedance of the resistance valve R has a substantially constant value within the bands of the bandpass filters FS and F,
Outside those bands they have values close to zero.

On the other hand, the impedance and actance X is the third
As shown in the figure, near the input signal frequency f and local oscillation frequency f, it is a small value near zero, but near the image frequency fm it becomes a large value, and changes with frequency.

Moreover, the extent of the change is such that, assuming that the passband width of the input signal pass filter F5 is W, the intermediate frequency 0 ratio bandwidth piece increases by approximately 0°.

In addition, as another configuration of the conventional image recovery one-type frequency converter, as shown in FIG. However, even in such a configuration, the input impedance of the image frequency blocking p-wave device exhibits the same frequency characteristics as in the above-described configuration.

As mentioned above, in any conventional image recovery one-type frequency converter, the reactance changes in the image frequency band, so the frequency conversion loss also has characteristics that change depending on the frequency. However, it is difficult to obtain a frequency converter that exhibits uniform conversion characteristics over a wide frequency band.

In addition, in the conventional frequency converter, as is clear from the circuit configurations shown in FIGS. 1 and 4, the actance hole is a function of the characteristics of the input signal passing p-wavelength converter F, as seen from the mixer diode at the image frequency fm. Therefore, when trying to reduce the frequency conversion loss by adjusting the image frequency reactance Xm, the input signal frequency f5
Such adjustment becomes extremely difficult because the matching conditions for

The object of the present invention is to solve the above-mentioned problems and to reduce the reactance Xm at the image frequency seen from the mixer diode.
It has a configuration that makes it constant over a wide frequency band and can adjust the image frequency reactance ratio completely independently of the circuit corresponding to the input signal frequency f5, reducing frequency conversion loss and improving the signal-to-noise ratio. It is an object of the present invention to provide a frequency converter that can configure a receiver with excellent sensitivity.

That is, the frequency converter of the present invention has a circuit having a symmetrical structure in which two frequency converting elements are symmetrically coupled, and each of the two frequency converting elements has a 90°
Frequency conversion is performed by supplying local oscillation components having a phase difference of 100 degrees, and input signal components having the same phase or opposite phase through the symmetrical circuit. By guiding the image frequency component generated in the element to the reactance element through the circuit having the symmetrical structure, the mode excited by the generated image frequency component and the mode excited by the input signal component are separated into the symmetrical structure. The circuit is characterized in that the circuits are orthogonal to each other.

The present invention will be described in detail below with reference to the drawings.

In a down converter, when a local oscillation component is applied to the mixer diode, the conductance g of the mixer diode changes with time t, as shown in FIG. 5, and this can be expressed by the following equation.

The input signal frequency f5 to the mixer diode in such a state is
When the high frequency voltage ■5cos(ωst+θ3) is supplied, the diode current i becomes as follows.

Now, if a down converter is constructed using two mixer diodes D1 and D2, and the phases of the input signal component element 5 and the local oscillation component element applied to the diode D1 are their respective reference phases, the input applied to the diode D2 Let the phases of the signal component element s and the local oscillation component element be θ5 and θ, respectively.

Therefore, these two diodes D,. The mode of the input signal component element 5 that excites D2 and these two mixer diodes D1. By configuring the frequency conversion circuit so that the modes of the image frequency component element m generated from D2 are mutually orthogonal, the circuit corresponding to the input signal frequency and the circuit corresponding to the image frequency can be adjusted independently of each other. At the same time, since the image frequency circuit is not affected by the frequency characteristics of the input signal circuit, it is possible to obtain an image frequency circuit having wideband characteristics.

Furthermore, as shown in FIG. 6, in a frequency conversion circuit having mixer diodes D1 and D2, the diode D
1 and D2 are arranged symmetrically with respect to the plane of symmetry Sym, the eigenmodes of this frequency conversion circuit become an even mode and an odd mode.

Moreover, since these two modes are orthogonal to each other,
No energy is exchanged between these two modes.

Therefore, for example, if the circuit configuration is such that the component of the input signal frequency fS excites the mixer diodes D1 and D2 in an even mode as shown surrounded by dotted lines in FIG. Signal component element 5
The phase difference between is θs-0, and on the other hand, the image frequency component m generated from the mixer diodes D1 and D2 must be generated in an odd mode, as shown by the dotted line in FIG. become.

That is, the image frequency component m generated from the mixer diode D1 must have a phase difference of 180 degrees with respect to the image frequency component m generated from the mixer diode D2.

Therefore, in the above equation (2), since the phase difference of the image frequency component m is 20, specifically θ as described above, the following equation is obtained.

That is, the phase of the local oscillation component that excites mixer diode D2 must lead the phase of the local oscillation component that excites mixer diode D1 by 90 degrees.

In addition, in this case, the phase difference between the intermediate frequency component i generated in the mixer diode D2 and the intermediate frequency component i generated in the diode D1 is given by the above relationship in equation (2) above, and the mixer diode The intermediate frequency component i generated in D2 has a phase that is 90 degrees behind the intermediate frequency component i generated in mixer diode D1.

Therefore, both mixer diodes D1 and D2
In order to synthesize and extract the intermediate frequency component i generated by the above, a 90 degree phase shifter 4 is inserted into the intermediate frequency component extraction port from the diode D1, and then both intermediate frequency outputs are synthesized.

Next, two mixer diodes D1. In the frequency conversion circuit configured by symmetrically arranging the mixer diodes D2, two mixer diodes D1
and D2 are excited by an odd-mode input signal component, the phase difference of the input signal component s in equation (2) above becomes θ8=π, and therefore, the image generated by mixer diodes D1 and D2 The frequency component molecule m is
It must be in even mode, as shown surrounded by dotted lines in FIG.

That is, in the above equation (2), the above-mentioned particular θ8=
π, the phase difference of the image frequency component m is therefore the difference between the two mixer diodes D1 . Even when D2 is excited by the odd-mode input signal component 5, the phase of the local oscillation component that excites mixer diode D2 must be 90 degrees ahead of the phase of the local oscillation component that excites mixer diode D1. Must be.

In this case, the phase difference between the intermediate frequency component i generated by the mixer diode D2 and the intermediate frequency component i generated by the diode D2 is 90 degrees ahead of the phase of the intermediate frequency component i generated by the diode D1. Therefore, a 90 degree phase shifter 4 is added to the intermediate frequency output from the diode D2, and both intermediate frequency outputs are combined and extracted.

In the principle structure of the frequency converter of the present invention shown in FIGS. 6 and 7, the input signal components 8 are connected to the mixer diodes D1, . D2 is excited, while mixer diode D1. Image frequency component m generated in D2
is similarly led to the pure reactance element 2 via the symmetrical circuit 1, and by adjusting this pure reactance element,
Mixer diode D1. The system is designed to adjust the reactance at the image frequency seen from the terminal of D2 to the circuit side, and by adjusting the image frequency reactance through the symmetrical circuit 1, there is no effect on the circuit corresponding to the input signal frequency f8. Try not to give it.

In addition, the mixer diode D1. In order to excite D2 with local oscillation component elements having a phase difference of 90 degrees from each other, the local oscillation component elements are connected directly to one diode and through a 90 degree phase shifter 3 to the other diode, respectively. supply.

Next, for the respective circuit systems T and (2) in the Kinoe and open wave number converters shown in FIGS. 6 and 7 above, mixer diode D1. The phase aspect of each component supplied to D, , or generated from these mixer diodes is summarized in the following table.

FIG. 8 shows a specific example of the structure of the frequency converter of the present invention, the basic structure of which is shown in FIG. 7.

In the configuration example shown in FIG. 8, a ground conductor plate 6 is adhered to one surface of a dielectric substrate 5, and a microwave integrated circuit element is formed by adhering to the other surface. The local oscillation component input from input terminal P is connected to terminal T via hybrid ring H.
1 and T2 with a phase difference of 90 degrees from each other, and are applied to mixer diodes D1 and D2 via half-wavelength resonant stripped waveformers F, each resonating at the local oscillation frequency f.sub.1.

On the other hand, the input signal f5 supplied to the input terminal S is guided to the strip line via a band-pass waver consisting of TEo1δ mode dielectric oscillators R11R2 and R3 arranged so as to be electromagnetically coupled to each other. The signals are coupled to the mixer diodes D1 and D2 connected to both ends of the strip line and are applied in opposite phases to each other.

Therefore, the mixer diode D1. In D2, the image frequency components m are generated in the same phase, and by adjusting the length of the stub M connected to the midpoint of the strip line, the mixer diodes D1. The image frequency impedance seen from D2 can be adjusted independently of the input signal circuit.

Further, since the intermediate frequency component i generated by the mixer diode D2 has a phase 90 degrees ahead of the intermediate frequency component i generated by the mixer diode D1, At this point, it is brought into the same phase as the intermediate frequency component element i from the mixer diode D1, and an intermediate frequency output is taken out from the output terminal I.

Furthermore, the strip line N connected to the opposite side of the image frequency adjustment stub M at the midpoint of the strip line is a thin line having a length of T wavelength of the input signal component element 5, and the strip line N is a thin line having a length of T wavelength of the input signal component element 5. The other end E is connected to the ground conductor plate 6 on the back side through the dielectric substrate 5, and is connected to the mixer diode D1. Configure a DC circuit for D2.

Next, FIG. 9 shows an example of a specific circuit in which the frequency converter of the present invention according to circuit system I whose principle structure is shown in FIG. 6 is constructed by a waveguide circuit.

In the configuration example shown in FIG. 9, for example, a thin dielectric substrate 10 is inserted in contact with a ground conductor plate 9 provided perpendicularly to the direction of propagation of electromagnetic waves in a rectangular waveguide 8 in a TE product mode. Strip lines A1 and A2 are deposited on the surface of the waveguide 8 so as to be symmetrical within the cross section of the waveguide 8, and act as an antenna element that couples with the human input signal component 5 propagating within the waveguide 8. .

A mixer diode D1. D2 is connected, and the diode D1. A low-pass filter FLI t "L2 configured to take out only the intermediate frequency component i is formed by vapor deposition of a conductive film and connected to the other end QlIQ2 of D2, respectively. The other ends R1 and R2 of the transducer FLt1 FL2 are connected to a phase-shifting coupling circuit including an inductance L and a capacitor C, and an intermediate frequency output is synthesized and taken out.

In the circuit configuration as described above, since the input signal component s is coupled in the same phase to the strip lines A1 and A2 that act as antennas, the points R1 and R2 where the rain intermediate layer wave components are combined are as follows. As shown in the circuit configuration shown in FIG. 6, an intermediate frequency component element 1 having a phase difference of 90 degrees appears, and therefore, as described above, a 90 degree phase shift is formed by a π-shaped circuit consisting of an inductance L and a capacitor C. The circuit combines both intermediate frequency component elements in the same phase at the combination point R2.

Furthermore, since the image frequency components m generated in the mixer diodes D1 and D2 have opposite phases, the rectangular waveguide 8 is excited in the TE and % modes.

However, since this TE product mode excitation is in the cutoff region of the rectangular waveguide 8, the image frequency component m generated in the mixer diodes D1 and D2 does not propagate toward the input terminal of the input signal fs, and therefore, The image recovery operation described at the beginning will be performed.

In this case, to adjust the image frequency reactance Xm, adjust the length of the groove M formed in the center of the H-plane of the rectangular waveguide 8 parallel to the tube axis direction, as shown in FIG. By doing so, the image frequency reactance X□ can be adjusted regardless of the circuit operation with respect to the input signal f.

On the other hand, mixer diodes D1 and D2 each have a 90°
In order to supply the local oscillation component elements 1, f, and 2 having a phase difference of 1°, a hybrid ring H as shown in the configuration example shown in FIG. 8 may be used, or a hybrid ring H as shown in the configuration example shown in FIG. As shown in FIG. 10, a TE111 mode cylindrical resonator 12 was coupled onto the TE mode rectangular waveguide 8 in , and one end of this resonator 12 was terminated with a non-reflection termination element 13. A circularly polarized wave is excited by the local oscillation component propagated in the waveguide 11, and the local oscillation component of the circularly polarized wave is converted into a component having a phase difference of 90 degrees through the coupling holes S□ and S2. It can also be supplied into the rectangular waveguide 8.

In addition, the reference numeral 14 in FIG. 10 is a variable short-circuit plate for tuning of the input signal circuit.

As is clear from the above description, according to the present invention, the following remarkable effects can be obtained.

(1) In the frequency converter, the reactance at the image frequency seen from the mixer diode to the frequency conversion circuit can be adjusted independently of the input signal circuit.

(2) Therefore, the image frequency actance seen from the mixer diode can be made to have a nearly constant value over a wide frequency band, and the resistance to the image frequency becomes almost zero, so the frequency Conversion loss can be reduced.

(3) Therefore, it is possible to improve the performance of a 5HFHF receiving receiver by reducing the noise of a satellite broadcasting receiver over a wide frequency band.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of a conventional image recovery one-type frequency converter, Fig. 2 is a circuit diagram showing an equivalent circuit of the basic configuration shown in Fig. 1, and Figs. 3 a and b are Fig. 1 is a characteristic curve diagram showing the frequency characteristics of resistance and reactance in the frequency converter shown in Figure 1, Fig. 4 is a block diagram showing another principle configuration of the image recovery one-type frequency converter, and Fig. 5 is a mixer. FIG. 6 is a characteristic curve diagram showing temporal changes in the conductance of the mixer diode when a local oscillation signal is applied to the diode. FIG. 6 is a block diagram showing the principle configuration of the frequency converter of the present invention.
The figure is a block diagram showing another principle configuration of the frequency converter of the present invention, FIGS. 6. A perspective view showing a specific configuration example using a waveguide of the principle configuration of the frequency converter of the present invention shown in FIG. 10, FIGS. 10a and b.
FIG. 9 is a side view and a top view showing a schematic configuration example for supplying a local oscillation component to the configuration example shown in FIG. 9, respectively. 1... Symmetrical circuit, 2... Pure reactance element, 3.4... 90 degree phase shifter, 5...
...Dielectric substrate, 6... Ground conductor plate, 7...
... Conductive vapor deposited film, 8... Waveguide, 9...
...Ground conductor plate, 10...Dielectric substrate, 11
... Waveguide, 12 ... Resonator, 13.
...Non-reflection termination element, 14...Variable short-circuit plate, FS, F, ,Fi...Band-passed transducer,
Fm... Band-stop wave generator, D, Dl, D2...
...Mixer diode, Sym...Symmetry plane, P...Local oscillation input terminal, S...
Signal input terminal, ■・・・Intermediate frequency output terminal, H・
...Hybrid circuit, P construction...Intermediate frequency 90 degree phase shifter, R1, R2+ R3...Dielectric resonator, F□...Blocking filter, M...
... Image impedance adjustment stub, R...
...Absorption resistance, T1. T2...Terminal, L...
...Strip line, A,, A2...Strip line, FLt, FL2...Low pass filter.

Claims (1)

[Claims] It has a circuit having a symmetrical structure in which 12 frequency conversion elements are symmetrically coupled, and supplies a local oscillation component having a phase difference of 90 degrees to each of the two frequency conversion elements. A circuit having the symmetrical structure that performs frequency conversion by supplying input signal components in phase or opposite phases to each other through a circuit having a symmetrical structure, and converting image frequency components generated in the two frequency converting elements during the frequency conversion into the circuit having the symmetrical structure. The mode excited by the generated image frequency component and the mode excited by the input signal component are made to be orthogonal to each other in the circuit having the symmetrical structure by guiding the mode to the reactance element through the symmetrical structure. Features of frequency converter.