JP2006013989A - High frequency circuit device and high frequency module for use in same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency circuit device capable of obtaining a high C/N characteristic as well as low profile. <P>SOLUTION: This high frequency module A is constituted of a multilayer substrate that has first and second dielectric layers 2 and 1 vertically across a line electrode 4 and a ground electrode 5 facing the line electrode 4 on the upper side of the first dielectric layer 2 and no ground electrode at a part facing at least the line electrode 4 of the lower side of the second dielectric layer 1, wherein the second dielectric layer is thinner than the first dielectric layer 2 and the lower side 1a of the second dielectric layer 1 is a mounting face. The high frequency module A is mounted on the upper side of a mounting substrate 10, which faces the line electrode 4 and has no ground electrode, and a ground electrode 12 facing the line electrode 4 is provided on the lower side of the mounting substrate 10. A stripline resonator of a triplate structure is composed of the line electrode 4, the ground electrode 5 on the upper side of the first dielectric layer 2 and the ground electrode 12 on the lower side of the mounting substrate 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a high-frequency circuit device used for a mobile phone, and more particularly to a high-frequency circuit device in which a high-frequency module is mounted on a mounting substrate.

Conventionally, in a high-frequency oscillator such as a voltage controlled oscillator (hereinafter referred to as a VCO), a stripline resonator is formed inside a multilayer substrate, an active element is mounted on the upper portion of the multilayer substrate, and these are connected. A structure that constitutes an oscillation circuit is generally known. A stripline resonator is a resonator having a triplate structure in which a ground electrode exists above and below a line electrode via a dielectric layer, and is formed inside a multilayer substrate.

FIG. 4 shows an example of a VCO module B having a general dielectric three-layer structure, and FIG. 5 shows a state in which the VCO module B is mounted on a mounting substrate 30.
In FIG. 4, the VCO module B is formed by laminating dielectric layers 23, 24, and 25 in order from the bottom. A lower ground electrode 21 is disposed below the dielectric layer 23, and a dielectric layer 24 is disposed on the dielectric layer 24. A line electrode 20 is provided between the upper ground electrode 22 and the dielectric layers 23 and 24. The line electrode 20, the upper ground electrode 22, and the lower ground electrode 21 constitute a stripline resonator having a triplate structure. A circuit electrode 26 is provided on the dielectric layer 25, and a plurality of elements 27 such as active elements are mounted on the circuit electrode 26. As shown in FIG. 5, ground electrodes 31 and 32 are provided on the upper and lower surfaces of the mounting substrate 30, respectively, and the lower ground electrode 21 of the VCO module B is connected to the ground electrode 31 on the upper surface of the mounting substrate 30. .

In recent years, a VCO module using a multilayer substrate incorporating a stripline resonator has been required to have a low profile and a high C / N characteristic. In order to realize a low profile, it is necessary to further reduce the product height H ₀ . Therefore, when the thickness of the multilayer substrate constituting the VCO module is reduced, the triplate interlayer thicknesses d ₄ and d ₅ are also reduced, and the capacitance value between the line electrode 20 and the ground electrodes 21 and 22 is increased. As a result, the Q of the device becomes low, and the C / N characteristics deteriorate.

In Patent Document 1, a triplate-type stripline resonator having a line electrode and two ground electrodes sandwiching the line electrode is formed inside the multilayer substrate, and the stripline resonator and the electrical circuit are electrically connected to the surface of the multilayer substrate. A circuit pattern connected to the first electrode is provided, and one of the two ground electrodes is provided with a region in which a conductor is not formed corresponding to the shape of the line electrode. A VCO module having a shape that reduces the capacitance value between the two has been proposed. In the VCO module having this structure, the resonator Q is increased by lowering the capacitance value, and the C / N characteristics are improved.
However, when the module height H ₀ is lowered for the purpose of reducing the height, the triplate interlayer thickness is also reduced, and the capacitance value between the line electrode and the other ground electrode is increased. Since the C / N characteristics depend on the thinner layer thickness between the line electrode and the upper and lower ground electrodes, that is, the layer thickness between the line electrode and the other ground electrode, high C / N characteristics can be obtained in the end. Have difficulty.
Japanese Patent No. 3100036

Accordingly, an object of the present invention is to provide a high-frequency circuit device capable of obtaining a high C / N characteristic with a low profile and a high-frequency module used in the high-frequency circuit device.

In order to achieve the above object, the invention according to claim 1 has first and second dielectric layers above and below the line electrode, and the upper surface of the first dielectric layer faces the line electrode. A ground electrode is provided, and at least a portion of the lower surface of the second dielectric layer facing the line electrode is not provided with a ground electrode, and the thickness of the second dielectric layer is smaller than the thickness of the first dielectric layer. The high frequency module is formed of a multilayer substrate having a lower surface of the second dielectric layer as a mounting surface, and the high frequency module is mounted on an upper surface having no ground electrode facing the line electrode, and the lower surface is opposed to the line electrode. A strip substrate having a ground plate, and a strip plate resonator having a triplate structure is configured by the ground electrode on the upper surface of the first dielectric layer and the ground electrode on the lower surface of the mounting substrate. Features To provide a high frequency circuit device.

The invention according to claim 4 has first and second dielectric layers above and below the line electrode, and has a ground electrode facing the line electrode on the upper surface of the first dielectric layer. At least a portion of the lower surface of the dielectric layer facing the line electrode does not have a ground electrode, the second dielectric layer is thinner than the first dielectric layer, and the second dielectric layer Provided is a high-frequency module comprising a multilayer substrate whose lower surface is a mounting surface.

In a high-frequency module composed of a multilayer substrate incorporating a stripline resonator, it is necessary to increase the Q of the resonator in order to realize high C / N characteristics. Here, the Q of the resonator is related to the capacitance value between the line electrode and the upper and lower ground electrodes, that is, the triplate interlayer thickness, and the resonator Q is increased by increasing the interlayer thickness. However, simply increasing the thickness of the triplate layer impairs the reduction in the height of the module.
Therefore, in the present invention, the ground electrode provided on the lower surface of the second dielectric layer constituting the lower layer of the line electrode of the high-frequency module, that is, the ground electrode provided on the mounting surface is removed, and the line electrode and the mounting surface are separated. The second dielectric layer therebetween is made thinner than the first dielectric layer between the line electrode and the upper ground electrode. And this high frequency module is mounted in the area | region which does not provide the ground electrode of the upper surface of a mounting substrate. A ground electrode is provided on the lower surface of the mounting substrate. As a result, one ground electrode is provided on the upper layer of the line electrode of the high-frequency module via the first dielectric layer, and the other ground electrode is provided on the lower layer via the second dielectric layer and the mounting substrate. These three electrodes constitute a stripline resonator having a triplate structure. That is, the stripline resonator is formed not by a single high-frequency module but by a combined structure including the mounting substrate. Therefore, even if the height of the module is the same as before, the triplate interlayer thickness can be made larger than the triplate interlayer thickness of the conventional high-frequency module, and the resonator Q can be increased. That is, high C / N characteristics can be realized. Conversely, if the triplate interlayer thickness (C / N characteristics) is the same as before, the height of the module can be lowered by the thickness of the second dielectric layer, and a further reduction in height can be realized.

As a material for the dielectric layer constituting the high-frequency module, a material having a dielectric constant substantially equal to that of the material constituting the mounting substrate is preferable. The reason is that if the dielectric constants of the two are greatly different, even if the upper and lower triplate interlayer thicknesses of the line electrodes are made equal, the capacitance values differ greatly between the upper and lower sides, so there is no point in increasing the interlayer thickness. The high frequency module is preferably mounted in close contact with the upper surface of the mounting substrate. This is because the capacitance value greatly fluctuates if there is a gap between the high-frequency module and the mounting substrate.

As in claim 2, it is preferable that the thickness of the first dielectric layer and the sum of the thicknesses of the second dielectric layer and the mounting substrate are set to be approximately equal.
In this case, the triplate interlayer thickness can be increased, and the capacitance values between the line electrode and the upper and lower ground electrodes are equal, so that higher C / N characteristics can be obtained.

According to a third aspect of the present invention, the thickness of the first dielectric layer may be set thinner than the sum of the thicknesses of the second dielectric layer and the mounting substrate.
The C / N characteristic depends on the thinner layer thickness between the line electrode and the upper and lower ground electrodes, that is, the layer thickness between the line electrode and the upper ground electrode. Does not affect.

When the high-frequency module according to claim 4 is mounted on a mounting substrate having no ground electrode at the mounting position on the upper surface and having a ground electrode on the lower surface, the line electrode of the high-frequency module and the ground electrode on the upper surface of the first dielectric layer And a ground electrode on the lower surface of the mounting substrate constitute a stripline resonator having a triplate structure.

As described above, according to the present invention, the ground electrode provided on the lower surface of the second dielectric layer that constitutes the lower layer of the line electrode of the high-frequency module is removed, and the second dielectric layer is removed from the line electrode and the upper ground electrode. Is thinner than the first dielectric layer between them. And by mounting this high frequency module on the area where the ground electrode on the upper surface of the mounting substrate is not provided, the line electrode of the high frequency module, the ground electrode on the upper surface of the first dielectric layer, and the ground electrode on the lower surface of the mounting substrate A stripline resonator having a triplate structure is formed. Therefore, the overall height can be reduced as compared with the conventional technique while the triplate interlayer thickness is increased, and a high-frequency circuit device that achieves both low profile and high C / N characteristics can be realized.

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

FIG. 1 shows a first embodiment of a multilayer high-frequency module A according to the present invention, and FIG. 2 shows a state in which the high-frequency module A is mounted on a mounting substrate 10. Here, an example is shown in which a voltage controlled oscillator module (hereinafter referred to as a VCO module) is used as the high frequency module.

The VCO module A includes a multilayer substrate composed of three dielectric layers 1 to 3. Here, as the dielectric layers 1 to 3, a resin having a dielectric constant substantially equal to that of the material of the mounting substrate 10 is used, but a ceramic material may be used. A line electrode 4 constituting a stripline resonator is provided between the lowermost dielectric layer 1 and the intermediate dielectric layer 2, and the intermediate dielectric layer 2 and the uppermost dielectric layer 3 are connected to each other. A ground electrode 5 is provided therebetween. The ground electrode 5 is provided on almost the entire surface so as to include a portion facing the line electrode 4, but it is not necessary to be the entire surface. A circuit electrode 6 is provided on the upper surface of the uppermost layer 3, and a plurality of elements 7 such as transistors and capacitors are mounted on the circuit electrode 6. Although not shown in FIG. 1, the circuit electrode 6, the line electrode 4, and the ground electrode 5 are connected to each other via a via conductor or an end face electrode.
The lower surface 1a of the lowermost layer 1 is a mounting surface, and no ground electrode is provided at a position facing the line electrode 4 at least. Note that a terminal electrode (not shown) for external connection connected to the line electrode 4, the ground electrode 5, or the circuit electrode 6 is provided at a position not facing the line electrode 4 on the mounting surface 1 a or on the side surface of the VCO module A. ing.

When the thickness of the lowermost dielectric layer 1 is d ₁ and the thickness of the middle dielectric layer 2 is d ₂ ,
d ₁ <d ₂ (1)
Is set to

The mounting substrate 10 is a known printed circuit board, and a circuit pattern 11 is formed on the upper surface thereof, and a ground electrode 12 is formed on the entire lower surface thereof. The VCO module A is mounted on the upper surface of the mounting substrate 10 where no ground electrode is provided. That is, the terminal electrode of the VCO module A is connected and fixed to the circuit pattern 11 by soldering or the like. At this time, it is preferable that the mounting surface 1a of the VCO module A is fixed so as to be in close contact with the upper surface of the mounting substrate 10. In a state where the VCO module A is mounted on the mounting substrate 10, the ground electrode 5 is provided on the upper layer of the line electrode 4 via the dielectric layer 2, and the ground electrode is provided on the lower layer via the dielectric layer 1 and the mounting substrate 10. 12, a stripline resonator having a triplate structure is constituted by these three electrodes 4, 5 and 12.

The thickness d ₁ of the dielectric layer 1, the thickness d ₂ of the dielectric layer 2, the thickness d ₃ of the mounting substrate 10 is set as follows.
d ₁ + d ₃ ≈d ₂ (2)
That is, the upper layer ground electrode 5 and the lower layer ground electrode 12 are provided at substantially the same distance across the line electrode 4. Moreover, since the mounting substrate 10 and the dielectric layers 1 and 2 have substantially the same dielectric constant, the capacitance value between the line electrode 4 and the ground electrode 5 and the capacitance between the line electrode 4 and the ground electrode 12 are the same. The value is almost equal.

Here, the VCO module A according to the present invention (see FIG. 1) is compared with the conventional VCO module B (see FIG. 4).
Assume that the total height of the VCO module A according to the present invention is H ₁ , the total height of the conventional VCO module is H _0, and the heights of both are equal (H ₁ = H ₀ ). Both modules have a three-layer structure, and it is assumed that the uppermost dielectric layers 3 and 25 have the same thickness. In this case, if the thicknesses of the lowermost and intermediate dielectric layers in the conventional VCO module are d ₄ and d ₅ , the following relational expression is established.
d ₁ + d ₂ = d ₄ + d ₅ (3)
Here, d ₄ = d ₅ in general.

In a stripline resonator having a triplate structure, in order to increase the C / N value, it is necessary to reduce the loss of the resonator. Here, the smaller the capacitance between the line electrode and the upper and lower ground electrodes, the smaller the loss of the resonator. Therefore, the dielectric layer between the line electrode and the upper and lower ground electrodes is If the thickness is increased, the capacitance value C can be reduced.
The capacitance value is obtained by the following equation.
C = ε ₀ εS / d
Here, S is the electrode area, d is the distance between the electrodes, ε is the dielectric constant of the dielectric layer, and ε ₀ is the dielectric constant of the vacuum.

In the conventional VCO module, when the capacitance values between the line electrode and the upper and lower ground electrodes are C ₁ and C ₂ , the combined capacitance value C is expressed by the following equation.
C = 1 / {(1 / C ₁ ) + (1 / C ₂ )}
= Ε ₀ εS / (d ₄ + d ₅ ) (4)
On the other hand, the combined capacity value C ′ of the VCO module of the present invention is expressed by the following equation.
C ′ = ε ₀ εS / (d ₁ + d ₂ + d ₃ ) (5)
Here, since d ₄ + d ₅ <d ₁ + d ₂ + d ₃ , the following equation is established.
C> C '
Thus, the VCO module of the present invention has a smaller capacitance value between the line electrode and the upper and lower ground electrodes and a smaller loss of the resonator than the conventional VCO module. That is, the Q of the resonator is increased, and a high C / N characteristic is obtained.

In the above embodiment, the sum of the thickness d ₃ of the thickness d ₁ and the mounting substrate 10 of the dielectric layer 1 as shown in Equation (2), has been set substantially equal to the thickness d ₂ of the dielectric layer 2 When the thickness d ₃ of the mounting substrate 10 is thick, the following occurs.
d ₁ + d ₃ > d ₂ (6)
Also in this case, assuming that the height H _{1 of the} module is the same as that of the conventional H ₀ , the combined capacity value C ′ is smaller than the combined capacity value C of the conventional VCO module, as in equations (3) to (5). As a result, the Q of the resonator becomes high and high C / N characteristics can be obtained.
Note that the Q of the resonator strongly depends on the thinner interlayer thickness with respect to the ground electrode, that is, the thickness d _2. Therefore, even if the thickness d ₃ of the mounting substrate 10 varies, the C / N characteristics are hardly affected.

FIG. 3 shows a state in which the VCO module A ′ of the second embodiment is mounted on the mounting substrate 10.
In the first embodiment, the thickness d ₂ of the upper dielectric layer 2 of the line electrode 4 has been thicker than the dielectric layer 24 of a conventional VCO module B, VCO module A in this example 'is the line electrode 4, the thickness d ₂ of the upper dielectric layer 2 is equivalent to the thickness of the dielectric layer 24 of the conventional VCO module B.
d ₂ = d ₅
However, it is assumed that d ₁ and d ₃ are determined so that d ₁ + d ₃ > d ₂ .
Since the thickness d ₁ of the lower dielectric layer 1 of the line electrode 4 is thinner than the thickness d ₂ of the upper dielectric layer 2, the height H ₁ ′ of the module A ′ is increased accordingly by the conventional height H. Can be lower than ₀ and can be lowered.
The Q of the resonator depends on the thinner layer d ₂ with the ground electrode, and this thickness d ₂ is equivalent to the interlayer thickness d ₅ of the conventional module. Can be obtained.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
Although the case where the dielectric layers 1 to 3 are made of a resin has been described in the above description, when the mounting substrate 10 is made of a ceramic material, the dielectric layers 1 to 3 can also be made of a ceramic material.
Although the module having the three dielectric layers 1 to 3 has been described in FIGS. 1 to 3, by increasing the number of dielectric layers located above the stripline resonator having the triplate structure, four or more layers are provided. Of course, it is good also as a structure. In this case, an internal electrode may be provided as appropriate between the dielectric layers above the stripline resonator having the triplate structure to form a capacitor portion, or chip components such as a chip resistor and a chip capacitor may be embedded. Good.
2 and 3 show an example in which the mounting surface 1a, which is the bottom surface of the module A, is in close contact with the upper surface of the mounting substrate 10. However, when the terminal electrode is provided on the mounting surface 1a of the module A, FIG. A gap is generated between the mounting surface 1 a of the module A and the upper surface of the mounting substrate 10 because the terminal electrode is connected to the pattern electrode on the upper surface of the mounting substrate 10. However, since the dielectric constant of the gap is low, the Q of the resonator depends on the thickness d ₂ of the thinner interlayer with the ground electrode, and this gap can be ignored in terms of C / N characteristics. .

It is sectional drawing of 1st Example of the high frequency module concerning this invention. It is sectional drawing of the high frequency circuit apparatus which mounted the high frequency module shown in FIG. 1 on the mounting board | substrate. It is sectional drawing of the high frequency circuit apparatus which mounted 2nd Example of the high frequency module concerning this invention on the mounting board | substrate. It is sectional drawing of an example of the conventional high frequency module. It is sectional drawing of the high frequency circuit apparatus which mounted the high frequency module shown in FIG. 4 on the mounting board | substrate.

Explanation of symbols

A VCO module
1 Dielectric layer (second dielectric layer)
1a Mounting surface 2 Dielectric layer (first dielectric layer)
4 Line electrode 5 Ground electrode 6 Circuit electrode 7 Element 10 Mounting substrate 11 Circuit pattern 12 Ground electrode

Claims (4)

First and second dielectric layers are provided above and below the line electrode, and a ground electrode facing the line electrode is provided on the upper surface of the first dielectric layer, and at least a lower surface of the second dielectric layer is provided. A multi-layer in which the portion facing the line electrode does not have a ground electrode, the thickness of the second dielectric layer is thinner than the thickness of the first dielectric layer, and the lower surface of the second dielectric layer is the mounting surface A high-frequency module comprising a substrate;
The high-frequency module is mounted on an upper surface that does not have a ground electrode facing the line electrode, and includes a mounting substrate having a ground electrode facing the line electrode on the lower surface,
A high-frequency circuit device comprising: a stripline resonator having a triplate structure constituted by the ground electrode on the upper surface of the first dielectric layer and the ground electrode on the lower surface of the mounting substrate. 2. The high-frequency circuit device according to claim 1, wherein a thickness of the first dielectric layer is set to be substantially equal to a sum of thicknesses of the second dielectric layer and the mounting substrate. 2. The high-frequency circuit device according to claim 1, wherein a thickness of the first dielectric layer is set to be thinner than a sum of thicknesses of the second dielectric layer and the mounting substrate. First and second dielectric layers are provided above and below the line electrode, and a ground electrode facing the line electrode is provided on the upper surface of the first dielectric layer, and at least a lower surface of the second dielectric layer is provided. A multi-layer in which the portion facing the line electrode does not have a ground electrode, the thickness of the second dielectric layer is thinner than the thickness of the first dielectric layer, and the lower surface of the second dielectric layer is the mounting surface A high-frequency module consisting of a substrate.

Images