JPH06350344A - High frequency double balance mixer - Google Patents

Abstract

PURPOSE:To make the frequency band broad by providing two conductors onto a plane circuit compensate balun via a dielectric material and inserting a center conductor between the two conductors and two ground conductors, thereby widening the impedance variable range. CONSTITUTION:Center conductors 26, 27 are inserted between two ground conductors 2, 3 and two ground conductors 28, 29 of a plane circuit compensate balun 21. A signal received from a port (a) is excited between the conductor 2 and the conductors 26, 28 and between the conductor 3 and the conductors 27, 29. The conductors 26, 27 are coupled with the conductors 2, 3 and the conductors 28, 29 through the provision of the conductors 2, 3 to decrease the coupling between the conductors 26, 27 and the case to be negligibly small. Since the impedance of the conductor 27 with respect to the conductors 29, 3 is decreased by the conductor 3, the impedance matching range is extended. Thus, the frequency is made broad.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency double balance mixer for microwaves and millimeter waves equipped with a planar circuit compensating balun.

[0002]

2. Description of the Related Art Conventionally, as a high frequency double balance mixer of this type, for example, there is one as shown in FIG.

A conventional high frequency double balance mixer 20 shown in FIG. 6 has a local oscillation signal (hereinafter, L) from a port a.
A planar circuit compensating balun 21 to which an O signal is input and a high frequency signal (hereinafter, RF) from the port b.
Coupled line balun 22 to which a signal) is input,
The low-pass filter circuits 23a and 23b connected to the output side of the coupled line balun 22 and the low-pass filter circuit 23
a and 23b, and a mixing circuit 24 connected between the output sides of the planar circuit compensating balun 21.

These planar circuit compensating baluns 2
1 and the coupled line balun 22 are both composed of a balanced mode transmission circuit board, and the planar circuit compensating balun 21 is composed of a dielectric substrate 25 made of a dielectric material and a surface 2 of the dielectric substrate 25.
5a, conductors 26 and 27, and dielectric substrate 25
Conductors (ground conductors) 28, 2 formed on the back surface 25b of the
9 (see FIGS. 6 and 7), the coupled line balun 22 includes a conductor 31 formed on the front surface 25a of the dielectric substrate 25 and a conductor formed on the back surface 25b of the dielectric substrate 25 ( Ground conductor) 32.

The low-pass filter circuits 23a and 23b are respectively composed of capacitors 32a and 32b and coils 33a and 33b, and the mixing circuit 24 is provided on the front surface 25a and the rear surface 25b of the dielectric substrate 25, respectively.
A total of four mixer diodes 34a, 3 arranged one by one
4b, 34c and 34d (or transistors or the like), and the low-pass filter circuit 23a,
The output side of 23b is provided with a port c for outputting an intermediate frequency signal (hereinafter referred to as an IF signal).

More specifically, the two mixer diodes 34a and 34b are arranged on the surface 25a of the dielectric substrate 25.
And the other two mixer diodes 3
4c and 34d are arranged on the back surface 25b side of the dielectric substrate 25. The LO signal input from the port a is transferred to the mixer diode 34 on the surface 25a side of the dielectric substrate 25.
a, 34b and conductors 35, 36 and through holes 37, 38 on the surface 25a of the dielectric substrate 25 in order to be added.
Is provided.

Thus, when the LO signal is input to the port a and the RF signal is input to the port b, the LO signal and the RF signal are balanced by the planar circuit compensating balun 21 and the coupling line balun 22, respectively. It is converted into a mode and supplied to the mixing circuit 24 at the same time.

As described above, each of the mixer diodes 34a, 34b, 34c and 34d of the mixing circuit 24 has the L
When the O signal and the RF signal are simultaneously applied, the IF signal is generated due to the switching and non-linearity of the mixer diodes 34a, 34b, 34c and 34d.

Then, the I generated in the mixing circuit 24
The F signal component is taken out from the port c through the low-pass filter circuits 23a and 23b having a high impedance with respect to the RF signal. In this case, the conductors 28 and 29 also serve as the return path of the IF signal.

Contrary to the above case, the port a has an R
Even if the F signal is input and the LO signal is input to the port b, the IF signal is obtained from the port c as in the case described above.

[0011]

However, the conventional high-frequency double balance mixer 20 as described above has the following problems.

That is, the frequency range that can be handled as an IF signal is limited by the frequencies of the LO signal and the RF signal.

Further, the mixer diodes 34a, 34b,
Considering the attachment of 34c and 34d, as described above, two are provided on the front surface 25a and the back surface 25b of the dielectric substrate 25, respectively.
It is desirable to arrange them individually. However, in the case of such a configuration, the LO signal input from the port a is transferred to the mixer diode 34a on the surface 25a of the dielectric substrate 25,
The conductors 35 and 36 and the through holes 37 and 38 are required to be added to 34b, resulting in discontinuity in the signal path. For this reason, when the frequency becomes high, the influence of the discontinuous portion cannot be ignored and the characteristics are deteriorated.

Further, the use band of the compensate balun is limited by the reflection characteristic. In order to improve the reflection characteristics, it is desirable to reduce the impedance between the conductor 26 and the conductor 28 and increase the impedance between the conductor 28 and the case ground. However, in the case of the planar circuit compensating balun as shown in FIG. 6, it is the actual situation that it is difficult to adopt a configuration that simultaneously satisfies the above conditions in a limited space.

The present invention has been made in view of the above problems, and its object is to widen the frequency range in which impedance matching is possible without degrading the mode conversion characteristics, and further to mix signals. Another object of the present invention is to provide a high-frequency double balance mixer that can realize a high frequency by using a structure that does not require a conductor or a through hole to be added to the mixer.

[0016]

In order to achieve the above object, the present invention comprises a planar circuit compensating balun, another arbitrary balun, and a mixing circuit connected between the two baluns. In the high-frequency double balance mixer, two conductors are attached on the above-mentioned planar circuit compensating balun via a dielectric, and the two conductors and two ground conductors of the planar circuit compensating balun provide the planar circuit compensating balun with The center conductor is sandwiched so that the mixing circuit is connected between these two conductors and the two ground conductors of the planar circuit compensating balun.

Further, according to the present invention, two conductors are provided on the planar circuit compensating balun via a dielectric, and the two conductors and two ground conductors of the planar circuit compensating balun are used to form the planar circuit compensating balun. The two central conductors are sandwiched between these two conductors and the two ground conductors of the planar circuit compensating balun at the same time to form two transmission lines, and a mixing circuit is connected between the respective transmission lines, and at the same time, each transmission line is connected. The other end is used as a local oscillation signal and high frequency signal input port to take out an intermediate frequency signal from the center conductor of the planar circuit compensating balun.

[0018]

By providing two conductors on the planar circuit compensating balun via the dielectric substrate, it is possible to reduce the coupling between the conductors forming the planar circuit compensating balun and the case to a negligible level, and Since the variable impedance range is widened, it is possible to achieve high isolation and a wide frequency band. Moreover, by connecting a mixing circuit component such as a diode to the newly attached conductor, it is not necessary to use a conductor or a through hole for adding a signal to the mixing element, and it is possible to avoid discontinuity of the signal path, which leads to high frequency. It is possible to sufficiently cope with the above, and it becomes possible to increase the frequency.

Further, since the signal is inputted between the newly attached conductor and the two conductors of the planar circuit compensating balun, the planar circuit compensating balun, the conductor attached to the planar balun and the mixing are provided. The high frequency double balance mixer can be configured only by the circuit, and the frequency of the intermediate frequency signal can be selected regardless of the frequencies of the local oscillation signal and the high frequency signal.

[0020]

Embodiments of the present invention will be described below with reference to FIGS.

FIGS. 1 and 2 show a first embodiment of a high frequency double balance mixer according to the present invention. The high frequency double balance mixer 1 of this example has conductors 2, 3 in addition to the conventional structure. Is newly added. In FIGS. 1 and 2, the same parts as those in FIGS. 6 and 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

More specifically, in this example, as shown in FIGS. 1 and 2, the conductor (center conductor) 2
Conductors (ground conductors) 2 and 3 are disposed on the dielectric substrates 6 and 27 via a dielectric substrate 4. That is, the conductors 2, 26
And 28 are arranged in the vertical direction with the dielectric substrates 4 and 25 overlapped with each other, and the conductors 3, 27 and 29 are vertically overlapped with each other via the dielectric substrates 4 and 25, respectively. Correspondingly arranged in a state. Thus, the central conductor 2 of the planar circuit compensating balun 21 is formed by the two grounding conductors 2 and 3 and the two grounding conductors 28 and 29 of the planar circuit compensating balun 21.
6 and 27 are sandwiched.

A mixing circuit 24 is connected between the two ground conductors 2 and 3 and the two ground conductors 28 and 29 of the planar circuit compensating balun 21. That is, the mixer diodes 34a and 34b are connected between the ends 2a and 3a of the conductors 2 and 3, and the mixer diodes 34c and 34 are connected between the ends 28a and 29a of the conductors 28 and 29.
d is connected. Then, the mixer diode 34
The intermediate point between a and 34b is connected to the low pass filter circuit 23a, and the intermediate point between the mixer diodes 34c and 34d is connected to the low pass filter circuit 23b.

According to the high frequency double balance mixer 1 having such a configuration, the conductors 2 and 3 are connected to the dielectric substrate 4 as described above.
Since the conductors 26 and 27 existing in the middle are almost not coupled to the case 5 (see FIGS. 3 and 4), as a result, between the ports a and b and c. The isolation characteristic will be improved.

That is, in the high frequency double balance mixer 1 of this example, the signal (LO
Signal or RF signal) is excited between conductor 2 and conductors 26, 28 and between conductor 3 and conductors 27, 29. At this time, if the conductors 2 and 3 do not exist, the conductor 26,
In addition to connecting with the conductors 28 and 29, 27 is also connected with the case 5 as shown in FIG.

On the other hand, when the conductors 2 and 3 are provided as in this example, the case 5 and the conductors 26 and 27 are provided as shown in FIG.
By placing the conductors 2 and 3 between the conductor 2 and
6, 27 are coupled with the conductors 2, 3 and the conductors 28, 29, and the coupling between the conductors 26, 27 and the case 5 is cut off. The conductors 26 and 27 are coupled to the side portions 5a and 5b of the case 5, but the coupling amount is extremely small and can be ignored.

Further, according to the high frequency double balance mixer 1 of this example, the presence of the conductor 3 causes the conductor 2 of the conductor 27 to be separated.
Since the impedances for 9 and 3 are lowered, the impedance matching range is widened and the frequency band can be widened.

That is, the operation is theoretically explained as follows. First, the impedance Z of the transmission circuit is inversely proportional to the square root of the capacitance C of the transmission circuit per unit length. On the other hand, since the conductor 3 and the conductor 29 have the same potential, the capacitance value is approximately twice different between the case where the conductor 3 is provided and the case where the conductor 3 is not provided. Therefore, when the conductor 3 is present, the impedance between the conductor 27 and the conductors 29 and 3 is
It is about 1/2 of the impedance between the conductor 27 and the conductor 29 without the conductor 3. Therefore, with a simple circuit configuration in which the conductor 3 is provided, the impedance can be reduced in a limited space, and the wide band of the compete balun can be achieved.

Further, in this embodiment, it is not necessary to provide conductors or through holes for applying a signal to the mixer diode in the dielectric substrates 4 and 25, so that the discontinuity of the signal path can be reduced. With such a configuration, even if the frequency is increased, the characteristics are less likely to be adversely affected, and the frequency can be increased.

FIG. 5 shows a second embodiment of the high frequency double balance mixer according to the present invention, in which the high frequency double balance mixer 10 of this embodiment is provided with a dielectric substrate (not shown). A signal source is connected between the newly attached conductor 2 and the conductor 26, and between the newly attached conductor 3 and the conductor 27 via the dielectric substrate. In FIG. 5, the same parts as those in FIG. 1 are designated by common reference numerals, and detailed description thereof will be omitted.

More specifically, the conductor 3 is provided with a port a, the conductor 2 is provided with a port b, and the conductor 26 is provided with a port c, respectively.
₁ , A ₂ and one end 3a of conductor 3, 29, terminal B on the 29a side
₁ , ₁ and B ₂ are connected to the mixing circuit 24 as shown in FIG. Thus, by applying the local oscillation signal and the high frequency signal between the conductors 2 and 3 and the conductors 28 and 29, respectively, the high frequency double balance mixer 1 is composed of only the conductors 26 to 29, the conductors 2 and 3 and the mixing circuit 24.
0 is configured.

Although not shown in FIG. 5,
As in the case of the above-described first embodiment, a dielectric substrate is interposed between the conductors 26 and 27 and the conductors 28 and 29, and between the conductors 26 and 27 and the conductors 2 and 3. There is.

When the LO signal source is connected to the port a of the high frequency double balance mixer 10 of this embodiment and the RF signal source is connected to the port b, the respective signals are transmitted to the conductor 28.
And baluns 2 and 3 and baluns 29 and 3 respectively convert to a balanced mode, and terminals A ₁ and A
₂ and terminals B ₁ and B ₂ are added to the mixer diode of the mixing circuit 24.

In this case, the IF signal has terminals A ₁ and A ₂ ,
And the terminals B ₁ and B ₂ are in phase with each other,
The terminal A ₁ (A ₂ ) and the terminal B ₁ (B ₂ ) have opposite phases to each other, and the above circuit as seen from the IF signal serves as a compete balun having the port c as an output terminal.

Therefore, in addition to the features of the high frequency double balance mixer 1 of the first embodiment shown in FIG. 1, the high frequency double balance mixer 10 of this embodiment has an IF frequency band of LO,
It has a feature that cannot be realized by the conventional high-frequency double balance mixer, which can be selected regardless of the RF frequency. Specifically, the IF frequency band similar to that of the triple balance mixer can be realized.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the above-described first and second embodiments, port a
The LO signal is input to the port b and the RF signal is input to the port b to output the IF signal from the port c.
Any of the ports a, b, and c may be selected as the O signal port, the RF signal port, and the IF signal port, and the same circuit operation is performed in any case.

[0037]

As described above, according to the present invention, two conductors are provided on the planar circuit compensating balun via the dielectric,
The center conductor of the planar circuit compensating balun is sandwiched by the two conductors and the two grounding conductors of the planar circuit compensating balun, and these two conductors and the two grounding conductors of the planar circuit compensating balun are connected. Since the mixing circuit is connected between them, the presence of the conductor can reduce the coupling between the conductor forming the planar circuit compensate balun and the case to a negligible level, thus providing high isolation. Can be realized. Therefore, the generation of the unbalanced mode can be suppressed, and the impedance between the two conductors forming the planar circuit compensating balun can be changed without deteriorating the mode conversion characteristics, and the frequency band can be widened. You can

Further, according to the high frequency double balance mixer of the present invention, a conductor or a through hole for adding a signal to the mixing element is formed by connecting a constituent element of the mixing circuit (for example, a mixer diode or the like) to the conductor. It is not necessary to provide it on the dielectric substrate. Therefore, the number of discontinuous portions of the signal path is reduced, and therefore, even at a high frequency, it is possible to prevent the characteristics from being adversely affected, and it is possible to increase the frequency.

Furthermore, by providing a simple circuit configuration in which one end of each of the conductors is provided as a signal input port with three unbalanced input terminals, there is no relation to the frequencies of the local oscillation signal and the high frequency signal. Instead, the frequency of the intermediate frequency signal can be selected, and the intermediate frequency band equivalent to that of the triple balance mixer can be realized.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a high frequency double balance mixer according to the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is an explanatory diagram for conceptually explaining coupling between a conductor and a case in the case of a conventional high frequency double balance mixer.

FIG. 4 is an explanatory diagram for conceptually explaining the coupling between the conductor and the case in the case of the high-frequency double balance mixer according to the present invention.

FIG. 5 is a circuit configuration diagram showing a second embodiment of the high frequency double balance mixer according to the present invention.

FIG. 6 is a circuit configuration diagram of a conventional high frequency double balance mixer.

7 is a cross-sectional view taken along the line YY in FIG.

[Explanation of symbols]

 1,10 High frequency double balance mixer 2,3 Conductor (ground conductor) 2a, 3a One end 4,25 Dielectric substrate 5 Case 21 Planar circuit Compensate balun 22 Coupling line balun 23a, 23b Low pass filter circuit 24a, 24b Mixing circuit 26 , 27 conductor (center conductor) 28, 29 conductor (ground conductor) a, b, c port

Claims (2)

[Claims] 1. A planar circuit compensating balun and another
In a high-frequency double balance mixer composed of two arbitrary baluns and a mixing circuit connected between the two baluns, two conductors are attached to the planar circuit compensating balun via a dielectric, and the two conductors are attached. And the two ground conductors of the planar circuit compensating balun so as to sandwich the center conductor of the planar circuit compensating balun, and the mixing between the two conductors and the two grounding conductors of the planar circuit compensating balun. A high-frequency double balance mixer characterized by connecting a circuit. 2. A planar circuit compensating balun is provided with two conductors via a dielectric, and the two conductors and two grounding conductors of the planar circuit compensating balun form a central conductor of the planar circuit compensating balun. At the same time, two transmission lines are formed by these two conductors and two ground conductors of the planar circuit compensating balun, and a mixing circuit is connected between each transmission line, and the other end of each transmission line is connected. A high-frequency double balance mixer characterized in that an intermediate-frequency signal is extracted from the center conductor of a planar circuit compensating balun as a local oscillation signal and high-frequency signal input port.