JPH07183733A - Mixer circuit - Google Patents

Abstract

PURPOSE:To obtain a small mixer circuit used in a radio machine from a quasi- microwave band to a microwave band. CONSTITUTION:The mixer circuit is provided where a local oscillation signal and a high frequency signal are applied to first and second diodes connected between terminals A and B of a phase inverting rat-race circuit and a high-frequency short-circuit potential part. The high-frequency short-circuit potential part consists of a strip line 18d having a quarter wavelength, and a phase inverting coupling part consists of strip lines 251 and 252 coupled to each other with dielectric materials having a prescribed thickness and a prescribed specific dielectric constant between them, and a quarter-wave line consists of strip lines 11a, 11b, 12, and 16 having the multilayered structure. A local oscillation signal input terminal LO, a high frequency signal input/output terminal RF, and an intermediate frequency signal input/output terminal IF are provided on the side face of the multilayered substrate of substrates where the high-frequency short-circuit potential part, the phase inverting coupling part, and the quarter-wave line are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixer circuit for use in, for example, a quasi-microwave band to microwave band radio device.

For example, in a radio device used for mobile communication in the quasi-microwave band or multiplex wireless communication in the microwave band, a quasi-microwave band signal or a microwave band signal is converted into an intermediate frequency band signal. Alternatively, a mixer circuit that frequency-converts the signal in the intermediate frequency band into the signal in the quasi-microwave band or the microwave band is indispensable.

On the other hand, the above-mentioned radio equipment tends to be miniaturized, and accordingly, the mixer circuit is also required to be miniaturized.

[0004]

2. Description of the Related Art FIG. 5 is an explanatory view of a conventional example, (a) is a configuration diagram, and (b) is an equivalent circuit diagram. 6 is an explanatory view of another embodiment, (a) is a configuration diagram, (b) is an equivalent circuit of the phase inversion coupling part in (a), and (c) is a perspective view of the phase inversion circuit. .

Hereinafter, the drawings will be described by taking a receiving mixer circuit as an example. First, as shown in Fig. 5 (a), it has three terminals, a local oscillation signal input terminal (LO), a high frequency signal input terminal (RF), and an intermediate frequency signal output terminal (IF). Is 50Ω, impedance √2 × 50Ω
The (λ / 4) -long microstrip lines 11 to 16 are connected in a ring to form a rat race circuit.

Then, the line 17a and the line 17 are provided at the respective connection portions (isolation terminals, portions A and B in the figure) of the (λ / 4) length microstrip lines 11 and 12, 15 and 16.
Connect one end of b and provide open-ended line 18a, 18b of (λ / 4) length that becomes short-circuit potential in high frequency at local oscillation frequency and high-frequency signal frequency, and connect the other end of line 17a, 17b and open-ended line. Diodes D ₁ and D ₂ are connected so as to have opposite polarities between the high frequency short-circuit potential portions of 18a and 18b, as shown in the figure.

The high-frequency signal applied to the high-frequency input terminal RF of the mixer circuit connected as described above is divided into two parts, a part of which passes through the microstrip lines 12 and 17a, and a remaining part of which is a microstrip. Track 13, 14, 15,
17b through diode D ₁ and diode D ₂ respectively.
However, the phase of the signal reaching diode D ₂ is 2 × (λ / 4) more than the phase of the signal reaching diode D ₁ , that is,
180 degrees behind.

On the other hand, since the local oscillation signal applied to the local oscillation signal input terminal (LO) is reached diodes D _1, D ₂ in phase, by connecting with the polarity diodes D _1, D ₂ Conversely, an intermediate frequency An in-phase intermediate frequency signal is output from the signal output terminal (IF).

FIG. 5 (b) shows the configuration of FIG. 5 (a) in an equivalent circuit. The 180 degree distribution part 21 in the figure is the microstrip line 12, 13, 14, in FIG. 5 (a). In the 15 part, the in-phase distribution part 22 is the microstrip line 11, 17a, 16, 17b.
In the portion, the one end open portion 23 of (λ / 4) length corresponds to the microstrip lines 18a and 18b, respectively.

Next, FIG. 6A shows the (3λ / 4) line constituted by the microstrip lines 13, 14, 15 in FIG. 5A realized by the phase inversion circuit 25 by the coupled line. Then, as shown in FIGS. 6 (b) and 6 (c), the structure is such that conductor surfaces 25 are provided on both sides of the dielectric substrate.
1, 252 are provided, and different ends are grounded. The operation of the mixer circuit is the same as in FIG. The code in FIG. 6 (b) matches the code in (a).

[0011]

As described above, since the mixer circuit uses four or more (λ / 4) length microstrip lines, the size of the mixer circuit becomes large.

Further, there are a plurality of intermediate frequency signal output terminals (IF).
Since it is surrounded by a (λ / 4) -long microstrip line, the line for extracting the intermediate frequency signal must intersect the ring-shaped microstrip line in three dimensions. Therefore, when the intermediate frequency signal is taken out by the cable, there are two problems that the man-hours for processing and mounting the cable end are large. An object of the present invention is to provide a compact mixer circuit.

[0013]

[Means for Solving the Problems] As shown in FIG. 1, D ₁ , D ₂
Are first and second diodes, 251, 252 are phase inversion coupling coupling portions, 18d is high frequency short circuit potential portion, 11a, 11b, 12,
16 is a (λ / 4) long line.

In the first aspect of the present invention, the high-frequency short-circuit potential portion is a strip line having a length of (λ / 4), and the phase inversion coupling portion is provided with a dielectric material having a predetermined thickness and a predetermined relative dielectric constant. Strip lines (251, 252) coupled to each other, (λ / 4)
The long line is formed by a strip line having a multi-layer structure, and the high-frequency short-circuit potential part, the phase inversion coupling part, and the
(1/4) Multilayer the substrate on which the wavelength line is formed.

The local oscillation signal input terminal (LO), the high frequency signal input / output terminal (RF) and the intermediate frequency signal input / output terminal (IF) are provided on the side surface of the multilayer substrate. The second invention is
The relative permittivity of the dielectric material (333) in the phase inversion coupling part was made larger than the relative permittivity of the dielectric material (332) between the upper and lower ground conductors (321, 331) and the phase inversion coupling part.

In the third aspect of the present invention, the high-frequency short-circuit potential portion is composed of coils (L ₁ , L ₂ ) and capacitors (C ₁ , C ₂ ) that resonate in series at the local oscillation frequency and the high-frequency signal frequency. A fourth aspect of the present invention is a coil (L ₃ ) and a capacitor (C ₃ ) that resonate the high-frequency short-circuit potential portion in parallel at an intermediate frequency and have an impedance of a predetermined value or less at a local oscillation frequency and a high-frequency signal frequency. Configured.

The fifth aspect of the present invention is directed to first and second diodes.
A low-pass filter composed of a coil (L ₄ ) and capacitors (C ₄ , C ₅ ) is provided between the connection point of D ₁ and D ₂ and the intermediate frequency signal input / output terminal (IF). The oscillation frequency and the high frequency signal frequency are suppressed to a predetermined value or more, and the impedance as viewed from the intermediate frequency signal input / output terminal to the diode side has a substantially predetermined value.

In a sixth aspect of the present invention, the first and second diodes and coils (L _{1 to} L ₄ ) and capacitors (C _{1 to} C ₅ ) are formed on a multi-layer substrate which constitutes a phase inversion rat race circuit. I decided to do it.

[0019]

According to the first aspect of the present invention, as shown in FIG.
The first and second diodes D ₁ and D ₂ on top of the second layer 32
A short-circuited (λ / 4) long line 18d, which is almost short-circuited between the local oscillation frequency and the high-frequency signal frequency, the phase inversion coupling part in the third layer 33, the impedance in the fourth layer 34 and the fifth layer 35. Form (λ / 4) long lines of √2 × 50Ω respectively, but (λ / 4) long lines 11 are formed by dividing them into the 4th and 5th layers, and connect them with each other through holes. Therefore, the problem of crossing lines in the conventional planar structure does not occur.

Further, ground layers 311, 321, 331, 3 are provided between the layers.
41 and 351 are provided and each line has a strip line structure, the width of the center conductor of the strip line becomes smaller than that of the microstrip line, and when bending the center conductor, bend it as it is. It should be good (if the width of the center conductor is wide, processing such as cutting off some corners is required).

Further, a local oscillation signal input terminal (LO), a high frequency signal input / output terminal (RF), and an intermediate frequency signal input / output terminal (IF) are provided on the side surface of the multilayer substrate.
(IF) is connected to the common terminals of the first and second diodes.

According to the second aspect of the present invention, the relative dielectric constant of the dielectric material 333 of the phase inversion coupling portion is made larger than that of the dielectric material 332 forming the strip lines 251 and 252, so that the dielectric constant of the coupling portion is increased. It is possible to reduce the thickness of the body material, that is, the thickness of the second layer (see FIG. 2 (e)).

In the third and fourth aspects of the present invention, as means for making the connection point of the first and second diodes D ₁ and D ₂ high-frequency short-circuit potential, series resonance of a lumped constant coil and a lumped constant capacitor, Alternatively, by utilizing parallel resonance, the second layer of the multi-layer substrate becomes unnecessary and the number of etching layers is reduced (FIG. 3,
See Fig. 4 (a) and (b).

In the fifth aspect of the present invention, between the connection point of the first and second diodes and the intermediate frequency signal output terminal IF, for example,
A π-type low-pass filter is provided to make the impedance of the diode side from the terminal IF 50Ω and suppress the high frequency signal frequency and the local oscillation frequency. Therefore, connection with the next stage becomes easy (see Fig. 4 (c)).

That is, by constructing the line forming the rat race circuit in a plurality of layers, the local oscillation signal,
It can be configured without the three output terminals of the high frequency signal and the intermediate frequency signal intersecting the line. In addition, the line length and line width are reduced with a strip line configuration, and the high-frequency short-circuit potential part is configured with lumped constant elements instead of distributed constant elements.
Since it is mounted on the board, a small mixer circuit can be provided.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a constitutional view of the first and second embodiments of the present invention. (A) is a perspective view, (b) is a sectional view taken along line XX 'of (a), and FIG. 2 is each layer of FIG. 2A is an example of a pattern diagram of the phase inversion coupling portion of the third layer, and (b) is XX 'of the third layer.
Cross-sectional view, (c) is a pattern explanatory view of the fourth and fifth layers, (d)
[FIG. 4] is a cross-sectional view of the fourth layer taken along line XX ′, and (e) is an explanatory view when the relative permittivity of the dielectric material between the phase inversion coupling portions is changed.

FIG. 3 is a block diagram of the third and sixth embodiments of the present invention. (A) is a perspective view, (b) is the equivalent circuit of (a), and (c) is
FIG. 4 (b) is an explanatory diagram of frequency characteristics, FIG. 4 is a configuration diagram of the fourth and fifth embodiments of the present invention, (a) is an equivalent circuit of the fourth embodiment of the present invention, and (b) is (a). (B) is an equivalent circuit of the fifth embodiment of the present invention.

Here, the same reference numerals denote the same objects throughout the drawings. Hereinafter, taking a receiving mixer circuit as an example, FIG.
FIG. 4 will be described. As shown in Figs. 1 (a) and 1 (b), the receiving mixer circuit has a local oscillation signal input terminal (L
O), high frequency signal input terminal (RF), intermediate frequency signal output terminal (I
F), the ground terminals 40a and 40b are provided on the other two side surfaces, respectively, and the first and second diodes D ₁ and D ₂ have the characteristics of the high frequency band taken into consideration. The structure is provided near the intermediate frequency signal output terminal (IF). The first
Ground conductors 311, 321, 331, 341, 351 are the lower surfaces of layers 5 to 5.
Are provided, but these ground conductors are connected to the ground terminals on the side surface.

The second layer 32 has a through hole at one end.
High-frequency short-circuit potential portion composed of a strip line 18d of (λ / 4) length which is connected to the connection point of the first and second diodes D ₁ and D ₂ via 181 and has the other end in an open state. 3 layers 33
Is a phase inversion coupling portion composed of strip lines 251 and 252 coupled through an intermediate dielectric material, the fourth layer and the fifth layer.
The layers are (λ / 4) long stripline 11a ＋ 11b, 12, 16
It is a (λ / 4) long line composed of and extends over two layers through a through hole 111.

In FIG. 2, (a) to (d) show a strip line pattern which constitutes a rat race circuit. Now, when these lines are used in the 2 GHz band, if a dielectric material having a relative dielectric constant of 3.5 is used, the length of each pattern is λ / 4, which is about 20 mm. 2 (a) and 2 (b) are diagrams showing the configuration of the phase inversion coupling portion. The thickness of the dielectric material between the coupled strip lines 251 and 252 is 0.2 mm, and the spacing between the upper and lower ground conductors 321 and 331 is When the width is 1.0 mm, the width of the strip line is set to 0.22 mm (to set the line impedance to a specified value).

Further, in the √2 × 50Ω line of FIGS. 2 (c) and (d), the width of the strip line is set to 0.3 mm when the distance between the upper and lower ground conductors 331, 341 and 341, 351 is 0.8 mm. Strip line
Strip lines 11 and 12 are composed of different layers.
Is formed over the two layers in which the strip lines 12 and 16 are formed.

FIG. 2 (e) is an example in which the relative dielectric constants of the dielectric material 333 of the coupling portion forming the phase inversion coupling portion and the dielectric material 332 of the strip line are different. Since the permittivity ε _r2 is higher than the latter permittivity ε _r1 , it is possible to reduce the thickness of the dielectric material at the coupling portion or the thickness of the dielectric material between the ground conductors. It has the effect of reducing the height of the circuit (increasing ε _r2 increases the capacitance between lines. Therefore, to make the state between ground conductors the same as before ε _r2 was increased, , It is necessary to reduce the space between the ground conductors and increase the capacitance between them.

By adopting such a multi-layer structure, it is possible to realize the local oscillation signal input terminal, the high frequency signal input terminal and the intermediate frequency signal output terminal without intersecting each other and with the minimum number of layers. And by configuring the circuit with the above substrate constant, the mixer operation described above becomes possible,
The circuit can be configured in about 1/4 the area of the conventional example.

3 (a) and 3 (b), as means for short-circuiting the output sides of the first and second diodes D ₁ and D ₂ at the local oscillation frequency and the high frequency signal frequency, instead of the strip line, The lumped constant coils L ₁ and L _{2 with} external dimensions of 1.6 × 0.8 mm and the lumped constant capacitors C ₁ and C ₂ are short-circuited by using series resonance.

For example, using lumped constant capacitors C ₁ and C ₂ having a capacitance of 1.5 pF and lumped constant coils having inductances of 3.9 nH and 4.7 nH, a local oscillation frequency of 1.65 GHz and 1.9 GHz are used.
The high frequency signal frequency is short circuit. These lumped constant capacitors and lumped constant coils are provided on the surface of the first layer as shown in (a), and the other ends of the lumped constant capacitors C ₁ and C ₂ are grounded through through holes.

With this configuration, as shown in FIG. 3 (c), the impedance drops below a predetermined value at the local oscillation frequency f _LO and the high frequency signal frequency f _RF , but the intermediate frequency f _IF Since it is in a high impedance state, it is not necessary to provide a high frequency short-circuit potential portion in the inner layer of the multilayer substrate, and the number of layers can be reduced to reduce the number of manufacturing steps.

Further, in FIG. 4 (a), the impedance of the lumped constant capacitor C ₃ and the lumped constant coil L ₃ are set in order to reduce the impedance at the local oscillation frequency and the high frequency signal frequency while making the impedance at the intermediate frequency sufficiently high. This utilizes parallel resonance of the inductance of. By using a lumped-constant capacitor with a capacitance of 10 pF for realizing a short circuit at the above frequency and a lumped-constant coil with an inductance of 39 nH for realizing an opening at an intermediate frequency, it is possible to open at an intermediate frequency of 250 MHz.

FIG. 4 (b) shows the characteristics of impedance vs. frequency when the parallel resonant circuit side is viewed from point E of FIG. 4 (a). According to this embodiment, the number of parts can be further reduced. Figure 4 (c) shows the intermediate frequency output terminal (IF) and the first and second
The diode D _1, the capacity of the lumped constant capacitor C ₄ between the D _2, the inductance of the lumped constant coil L _4, by providing the π type low-pass filter with capacitance of the lumped constant capacitor C _5, a diode side This is an example in which impedance matching is observed.

According to this embodiment, the intermediate frequency output terminal (IF)
The impedance seen from the mixer circuit is 50Ω, and the output of the local oscillation frequency and the high frequency signal frequency can be suppressed by the low-pass filter configuration, which facilitates the connection with the next-stage circuit.

Here, it has been described above that the lumped constant capacitor and the lumped constant coil are mounted on the multilayer substrate constituting the rat race circuit. However, these are formed on the mother substrate on which the multilayer substrate is mounted. Needless to say, similar effects can be obtained.

That is, according to the present invention, in the quasi-microwave band and the microwave band, the strip line in the multilayer substrate and the lumped constant circuit element mounted on the upper surface of the substrate allow
It is possible to provide a small mixer circuit.

[0042]

As described in detail above, according to the present invention, it is possible to provide a small mixer circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the first and second embodiments of the present invention, in which (a)
Is a perspective view and (b) is a sectional view taken along line XX ′ of (a).

2 is a pattern explanatory view of each layer of FIG. 1, (a) is an example of a pattern diagram of a phase inversion coupling portion of the third layer, (b) is a XX ′ cross-sectional view of the third layer, (c) is the 4D, 5th layer pattern explanatory view, (d) is a XX 'cross-sectional view of the 4th layer, (e) is an explanatory view when the relative change rate of the dielectric layer between the phase inversion coupling parts is changed. is there.

FIG. 3 is a configuration diagram of the third and sixth embodiments of the present invention, (a)
Is a perspective view, (b) is an equivalent circuit of (a), and (c) is a frequency characteristic explanatory diagram of (b).

FIG. 4 is a configuration diagram of the fourth and fifth embodiments of the present invention, (a)
Is an equivalent circuit of the fourth embodiment of the present invention, (b) is an explanatory diagram of frequency characteristics of (a), and (c) is an equivalent circuit of the fifth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional example, (a) is a configuration diagram, and (b) is an equivalent circuit diagram.

FIG. 6 is an explanatory diagram of another conventional example, in which (a) is a configuration diagram and (b) is
FIG. 3A is an equivalent circuit of the phase inversion coupling part in FIG. 7A, and FIG. 7C is a perspective view of the phase inversion circuit.

[Explanation of symbols]

11a, 11b, 12, 16, 18d, 251, 252 Strip line 332, 333 Dielectric material 311, 321, 331, 341, 351 Ground layer D ₁ , D ₂ 1st, 2nd diode L ₁ ~ L ₄ concentrated Constant coil C _{1 to} C ₅ Lumped capacitor

Claims (6)

[Claims] 1. A (1/4) wavelength line and a phase inversion coupling part are connected to each other, and between the isolation terminals (A, B) of a phase inversion rat race circuit and a high frequency short-circuit potential part, In a mixer circuit in which first and second diodes (D ₁ , D ₂ ) are connected so as to have opposite polarities, and a local oscillation signal and a high frequency signal are added to the first and second diodes to extract an intermediate frequency signal , The high-frequency short-circuit potential part (1/4)
A strip line (18d) of wavelength, and a strip line (251, 252) in which the phase inversion coupling portions are mutually coupled through a dielectric material having a predetermined thickness and a predetermined relative dielectric constant.
The wavelength line is a strip line with a multilayer structure (11a, 11b, 12, 1
6), the local oscillation signal input terminal (LO) is formed on the side surface of the multilayer substrate which is formed by multilayering the substrate on which the high frequency short circuit potential portion, the phase inversion coupling portion and the (1/4) wavelength line are formed. , A high frequency signal input / output terminal (RF) and an intermediate frequency signal input / output terminal (IF). 2. The dielectric material of the phase inversion coupling portion (33
3. The mixer circuit according to claim 1, wherein the relative permittivity of 3) is made larger than the relative permittivity of the dielectric material (332) between the upper and lower ground conductors (321, 331) and the phase inversion coupling portion. 3. A coil (L ₁ , which resonates in series with the high frequency short circuit potential portion at a local oscillation frequency and a high frequency signal frequency).
The mixer circuit according to claim 1, wherein the mixer circuit comprises L ₂ ) and capacitors (C ₁ , C ₂ ). 4. A coil (L ₃ ) and a capacitor (C ₃ ) that resonate the high-frequency short-circuit potential portion in parallel at an intermediate frequency so that the impedance becomes a predetermined value or less at a local oscillation frequency and a high-frequency signal frequency. The mixer circuit according to claim 1, wherein: 5. A coil (L ₄ ) is provided between the connection point of the first and second diodes (D ₁ , D ₂ ) and the intermediate frequency signal input / output terminal (IF).
A low-pass filter composed of a capacitor and capacitors (C ₄ , C ₅ ) is provided.The low-pass filter suppresses the local oscillation frequency and the high frequency signal frequency to a predetermined value or more, and the intermediate frequency signal input / output terminal 2. The mixer circuit according to claim 1, wherein the mixer circuit is provided with a function such that the impedance viewed from the diode side becomes substantially a predetermined value. 6. The first and second diodes, the coil and the capacitor are formed on a multi-layer substrate which constitutes a phase inversion rat race circuit.
5 mixer circuits.