JP3058092B2 - Single balance 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 frequency converter for a radio communication device, and more particularly to a single balance mixer for improving conversion loss and local signal suppression characteristics.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional mixer circuit of this kind.
This will be described with reference to FIG. Referring to FIG. 2, of the four ports of the hybrid circuit 1, two ports (for example, terminal 2) are used for local oscillation signal input and RF signal output, and the other two ports (for example, terminal 6) are provided with mixer diodes. 5 are connected to each other.
It is connected to an open stub 4 for short circuit, and this connection point is
It operates as a ground for RF signals, and
By drawing out the signal port 3, a single balance mixer is configured. In addition, this open stub 4
And the mixer diode 5 are arranged so as to be included inside the ring constituting the hybrid circuit 1.
As a result, the circuit scale and the circuit area of the mixer circuit can be reduced.

Further, in FIG. 2, an open stub 4
Is provided in order to obtain good short-circuit characteristics in the RF band and to eliminate the need to provide an IF and RF combining (separating) circuit outside the hybrid circuit 1. It has been downsized.

As another conventional example, Japanese Patent Application Laid-Open No. 63-212207 discloses a balanced mixer (balanced mixer) which is used in an S / U converter for receiving satellite broadcasting. As a configuration of the microwave circuit, the first and second stubs selected to have a length at which the mixer diode is short-circuited at the image frequency are provided at the mixer diode input terminals of the balanced mixer. A balanced mixer can be configured, improving the conversion efficiency of the balanced mixer and improving NF deterioration,
A microwave circuit having a high image suppression degree as a whole has been proposed.

As shown in FIG. 3, the microwave circuit comprises a hybrid ring 11 and a mixer diode 12.
A, 12B, and the hybrid ring 1
The first input terminal 11A1 received satellite broadcasting signal S _BS is input and the other input terminal 11A2 local oscillator signal S _L is input. Also, one output terminal 1 of the hybrid ring 11
1B1 is the first and second mixer diodes 12A,
Via a series circuit of 2B connected to the other output terminal 11B2, the first and second mixer diodes 12A, and is configured to output an intermediate frequency signal S _IF from the connection point of 12B. Further, in this circuit, the hybrid ring 1
First and second stubs 11 extending in the longitudinal direction from the tips of the first and second output ends 11B1, 11B2.
C1 and 11C2 are formed at the respective ends, and through holes 11D1 and 11D for grounding to the back surface ground conductor are provided.
D2 is provided, and the through holes 11D1 and 11D2 are provided.
The distance from the input to the diode input terminals 13A and 13B is selected to be a half wavelength of the image frequency.

[0006]

In the conventional single-balanced mixer shown in FIG. 2, in order to improve the local signal suppression characteristic and the conversion loss characteristic, the RF signal, the local signal input / output terminal 2, and The electrical length between the RF signal of each of the two mixer diodes 5 and the local signal input terminal is set to be 1 / the value of the RF signal (or the local signal or the intermediate frequency of both signals).
4 and 3/4 wavelengths, and the electrical length between the RF signal input / output terminals of the two mixer diodes 5 is set to 1 / (1) of the RF signal (or the local oscillation signal or the intermediate frequency of both signals).
While maintaining the two wavelengths and the one wavelength, the RF short-circuit side ends of the two mixer diodes 5 are grounded in terms of RF.

The problems in the conventional single balance mixer shown in FIG. 2 will be described below. That is, referring to FIG. 2, when the output terminal 6 of the hybrid circuit 1 is connected to the mixer diode 5, an absolute distance corresponding to the connection portion 7 is generated. RF applied to mixer diode 5 from end 6
A certain phase difference (180 deg in FIG. 2) that should be originally possessed by the signal and the local oscillation signal is shifted, which adversely affects various characteristics of the mixer circuit such as conversion loss and local oscillation signal suppression characteristics. Has the problem that

The reason is that the output terminal 6 of the hybrid circuit
And the open stub 4 for short-circuiting the RF are connected through the diode 5 for the mixer. However, as shown in FIG. Since the size of the diode 5 is determined, an absolute distance is required between the output terminal 6 of the hybrid circuit and the diode 5 for the mixer in terms of physical dimensions. It depends.

Next, FIG.
The problem of the microwave circuit described in Japanese Patent Publication No. 2207 will be described.

The first problem is the same as in the above-described conventional single balance mixer, as described in the above-mentioned Japanese Patent Application Laid-Open No. 63-212.
According to the description in Japanese Patent Application Publication No. 207/207, between the output terminals 11B1 and 11B2 of the hybrid ring and the diode input terminals 13A and 13B, as is apparent from FIG. Is necessary, in other words, the distance is generated. As a result, similarly to the above-described problem, conversion loss, and various characteristics of the mixer circuit, such as local signal suppression characteristics, are adversely affected. That's what it means.

The reason is almost the same as the above-mentioned reason.
In the microwave circuit shown in FIG. 3, a mixer diode 12 to the received satellite signal S _BS and the local oscillation signal S _L
Since the short circuit of A and 12B is realized by virtual grounding,
In order to improve the above-mentioned grounding effect, it is necessary to connect the mixer diodes 12A and 12B in series with each other in the shortest possible distance. As a side effect, the input ends 13A and And 1
3B to output terminals 11B1 and 1 of the hybrid ring
If attention is paid to the area up to 1B2, a physical distance will be generated there.

As a second problem, since the stubs 11C1 and 11C2 for suppressing the image frequency signal are connected to the output terminals 11B1 and 11B2 of the hybrid ring, there are adverse effects on the physical aspect of the mixer circuit, and This has a negative effect on the original electrical characteristics. In particular, the latter, for carrying out the suppression of side effects to the image signal generated in the mixer circuit, the frequency components to handle originally, i.e., the received satellite broadcasting signal S _BS according to the publication, and the station to the originating No. S _L As a result, the conversion loss characteristics of the mixer circuit deteriorate.

[0013] The reason is that first, regarding the physical aspect,
As is clear from the shape shown in FIG.
The fact that 1, 11C2 is connected increases the circuit area and circuit scale.

Next, regarding the electrical aspect, at the input terminals 13A and 13B of the mixer diode to which the stubs 11C1 and 11C2 for suppressing the image signal are connected, the image signal is short-circuited. while the signal level is attenuated significantly, the signal level of attenuation occurs with respect to the received satellite signal S _BS, and the local oscillation signal S _L. That is, as for the stub that is short-circuited to the image signal, as is apparent from the consideration of the relative band attenuation characteristic and the Q factor, as described in
No. 3-212207, a received satellite broadcast signal S
_BS, and station against oscillation signal S _L, operates as an element that indicates the attenuation characteristics.

For this reason, the reception satellite broadcast signal S _BS and the local oscillation signal S _L appearing at the output terminals 11B1 and 11B2 of the hybrid ring of the microwave circuit are input to the mixer diodes via the input terminals 13A and 13B of the mixer diode. When the signals are input to the diodes 12A and 12B, the levels of both signals are attenuated by the stub, and the conversion loss characteristics of the mixer circuit deteriorate accordingly.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and has as its object to realize a reduction in circuit size and circuit area, and to achieve better conversion loss and station quality. It is an object of the present invention to provide a single balance mixer capable of obtaining a signal suppression characteristic and the like.

[0017]

In order to achieve the above object, a single balanced mixer according to the present invention comprises a hybrid circuit, two mixer diodes, and the mixer for realizing an RF short circuit of the mixer diodes. An open stub for RF short-circuit connected to a diode for the mixer, wherein the diode for mixer and the open stub for RF short-circuit are arranged inside a ring constituting the hybrid circuit. Open stub for RF short circuit of diode,
It is characterized in that it is provided for each of the two mixer diodes.

That is, in the present invention, an RF short-circuit open stub connected to the mixer diode is provided for each of the two mixer diodes, and the other end of the mixer diode 5 is connected to the output terminal 6 of the hybrid circuit. The mixer diodes 5 can be connected directly underneath so that each mixer diode 5 can be independently grounded in terms of high frequency.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In a preferred embodiment of the present invention, an RF short-circuit open stub (4 in FIG. 1) connected to the mixer diode (5 in FIG. 1) is provided for each of the two mixer diodes. The other end of the diode is the output terminal of the hybrid circuit (6 in FIG. 1)
, And each mixer diode can be independently grounded in terms of high frequency.

As described above, in the single-balanced mixer according to the preferred embodiment of the present invention, the two short-circuit open stubs connected to the mixer diodes are provided for each of the two mixer diodes. RF ground terminal of each mixer diode and RF
Connecting the open stub for grounding and connecting the RF signal input (output) side terminal of each of the two mixer diodes to the output terminal of the hybrid circuit
There is no special restriction on the mutual installation position in terms of physical dimensions. That is, it can be connected to the RF signal input (output) side terminal of the mixer diode and directly below the output terminal of the hybrid circuit.

In order to describe the above-described embodiment of the present invention in more detail, examples of the present invention will be described below.

[0022]

Referring to FIG. 1, in the embodiment of the present invention, two ports (corresponding to 2 in FIG. 2) of the four ports of the hybrid circuit 1 are used for local oscillation signal input and RF signal input / output. Mixer diodes 5 are connected to the other two ports (corresponding to 6 in FIG. 2), respectively.
The other end of the mixer diode 5 is connected to an open stub 4 for RF short-circuiting with respect to each mixer diode 5.
By drawing out the signal port 3, a single balance mixer is configured.

The two open stubs 4 and the two mixer diodes 5 are arranged so as to be included inside the ring constituting the hybrid circuit 1, whereby an RF signal and a local oscillation signal are input. The electrical length between the output terminal 2 and the respective RF signal and local oscillation signal input terminals of the two mixer diodes 5 is set to be 1/4 wavelength of the RF signal (or the local oscillation signal or the intermediate frequency of both signals). , And ３ wavelength, and the electrical length between the RF signal input / output terminals of the two mixer diodes 5 is 波長 wavelength of the RF signal (or a local oscillation signal or an intermediate frequency of both signals). In addition, the RF short-circuit side ends of the two mixer diodes 5 can be grounded in an RF manner while maintaining the wavelength at one wavelength.

[0024]

As described above, according to the present invention,
Due to the absolute distance that has occurred in the connection between the output terminal of the hybrid circuit and the mixer diode, R added from the output terminal of the hybrid circuit to the mixer diode
The effect of being able to realize a single balance mixer that has improved the conversion loss and the adverse effect on the local oscillation signal suppression characteristics caused by the deviation from the phase difference that the F signal and the local oscillation signal should originally have. Play.

The reason is that, in the present invention, the open stub for short-circuiting the RF of the mixer diode is provided for each of the two mixer diodes.
Connecting the respective RF ground side terminals of the two mixer diodes to the RF grounding open stub, the respective RF signal input (output) side terminals of the two mixer diodes, and the output terminal of the hybrid circuit; Connecting is not limited in terms of physical dimensions with respect to the mutual installation position, thereby realizing the miniaturization of the circuit scale and the circuit area, etc., and the good conversion loss , And local oscillation signal suppression characteristics.

[Brief description of the drawings]

FIG. 1 is a plan view showing the configuration of an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a conventional single balance mixer.

FIG. 3 is a prior art (Japanese Patent Laid-Open No. 63-212207).
FIG. 3 is a plan view showing the configuration of the microwave circuit of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hybrid circuit 2 RF signal, local signal input / output terminal 3 IF signal terminal 4 RF short-circuit open stub 5 Mixer diode 6 Hybrid circuit output terminal 7 Mixer diode-hybrid circuit output terminal connection part 11 Hybrid ring 11A1, 11A2 Hybrid Ring input terminal 11B1, 11B2 Hybrid ring output terminal 11C1, 11C2 Stub 11D1, 11D2 Through hole 12A, 12B Mixer diode 13A, 13B Mixer diode input terminal S _BS received satellite broadcast signal S _L local oscillator signal S _IF intermediate frequency signal

Claims (3)

(57) [Claims] 1. A hybrid circuit, comprising: two mixer diodes; and an RF short-circuit open stub connected to the mixer diodes to realize an RF short-circuit of the mixer diodes. In a single balance mixer in which a diode and the RF short circuit open stub are arranged inside a ring forming the hybrid circuit, the mixer diode short circuit RF short open stub is provided for each of the two mixer diodes. A single-balanced mixer that is provided for a single balance mixer. 2. The single-balanced mixer according to claim 1, wherein an RF signal connection terminal of said mixer diode is connected immediately below an output terminal of said hybrid circuit. 3. A connection between two RF open short stubs.
IF signal terminal drawn from the continuation point and the hybrid
One of the RF short-circuit open
A tab and one set of the mixer diodes, and the other set of R
Open stub for short-circuiting F and other diodes for the mixer
Are arranged, respectively.
The single balance mixer according to claim 1.