JPH09294040A - Thin film lc filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the LC filter which is furthermore miniaturized. SOLUTION: Inductors L1-L3 and capacitors C1-C3 are arranged in parallel alternately, a plurality of inductors 12 (L-L3) connected in series to form a signal wire 14, conductors of the signal wire 14 interconnecting the inductors 12 (L1-L3), a conductor interconnecting a ground wire 15 to the capacitors C1-C3 are located close to each other so as to be 10μm-100μm thereby forming prescribed stray capacitance. Furthermore, the inductors 12 (L1-L3) and the capacitors C1-C3 are arranged closely so as to have prescribed stray capacitance between the signal wire 14 making up of the inductors 12 and the capacitor 13 and between electrodes above and under a dielectric layer of the capacitor 13 and the adjacent inductor 12 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film LC filter configured in a lumped constant type by a thin film inductor using a thin film soft magnetic material and a thin film capacitor using a thin film dielectric, and more particularly to further miniaturization. Thin film L
Regarding the C filter.

Further, this thin film LC filter is an electronic device including a thin film inductor and a thin film capacitor, and is used in an oscillating section of a high frequency circuit, a radio wave receiving section, and an electronic circuit which needs to prevent noise oscillating in the high frequency circuit. , Is used to adjust the inductance of the thin film inductor and the capacitance of the thin film capacitor appropriately to obtain a desired filter characteristic or a predetermined characteristic in an incorporated circuit.

[0003]

2. Description of the Related Art In a conventional thin film LC filter, an air core inductor is used, and a spiral coil and a meander coil are used in combination with a chip capacitor and a thin film capacitor. These thin film LC components need to be miniaturized with the integration of the system used, and the chip inductor or chip capacitor components are miniaturized to 3025 type, 2012 type, 1608 type or 1005 type. In addition, thin film inductors or thin film capacitors have been required to be downsized.

Further, in the conventional thin film LC filter, since the inductance value and the capacitance value are produced in advance in accordance with the designed values, each individual characteristic is "±.
Even if the accuracy is within 2.5% ", deviations from the prescribed value were always present in the finished product incorporating these. In the case of chip parts, the conductor pattern was sintered to form an insulator or magnetic material. Therefore, it is impossible to finely adjust the characteristics for changing the inductance value or the capacitance value.

On the other hand, the air core inductor requires an area ten times as large as that of the magnetic core inductor in order to obtain the same inductance value as that of the magnetic core inductor. As a result, in the thin film LC filter using the air core inductor, the whole is large,
It cannot be accommodated in the 3025 type and 2012 type larger shapes as well as the 8 type and the 1005 type.

Therefore, air core inductors are being replaced by magnetic core inductors, and thin film LC components are required to be further miniaturized.

For the purpose of miniaturization, chip inductor and chip capacitor elements are formed on a substrate or a resin insulating layer using SMT (surface mounting technology) by a thin film technology. Since this SMT (Surface Mount Technology) is used, the shapes of the chip inductor and chip capacitor elements are constant.

Next, with reference to FIGS. 11 and 12, a conventional triple-layer thin film LC filter formed using SMT (Surface Mount Technology) will be described.

As shown in FIG. 11, the electrical equivalent circuit of a triple LC filter has three chip inductors (L19 = 150n) connected in series to form a signal line.
H, L29 = 149 nH, L39 = 157 nH) and three chip capacitors (C19 = 31.9 pF, C29 = 1) that connect the output side of each chip inductor to the ground line.
2.9 pF, C39 = 14 pF).

In this case, as shown in FIG.
The 2012 type chip inductor elements are connected and arranged in series to form the signal line 29, and these three chip inductor elements 49 (L19, L29, L39) are provided.
Adjacent to each other, three 1608 type chip capacitor elements 39 (C19, C29, C39) are arranged adjacent to each other like chip inductor element 49, and each chip capacitor element 39 (C19, C29, C39) is connected to chip inductor element 49. (L19, L29, L39) are connected and arranged between the respective output sides and the ground line 19.

In such an arrangement of elements, one of the single elements is
It is difficult to reduce the size to approach the size of a single 608 type or 2012 type.

Further, when designing an LC filter that cannot be finely adjusted after manufacturing, a circuit is designed according to the inductance value or capacitance value of the element whose error is fixed so that stray capacitance with an unstable fixed value does not occur. The thin film inductor and the thin film capacitor are arranged with a space between them,
For this reason also, it was difficult to downsize the LC filter.

[0013]

DISCLOSURE OF THE INVENTION Conventional thin film L described above
In the C filter, the elements of the chip inductor and the chip capacitor are formed by using SMT (Surface Mount Technology) on the substrate or the resin insulating layer for the purpose of downsizing, so the shape of the element is constant. However, the reality is that it is still far from miniaturization.

An object of the present invention is to provide a thin film LC filter in which a large number of LC elements which can be further miniaturized are continuously arranged.

That is, the target thin film LC filter has a shape called “3025 type” having a size of “3.0 mm × 2.5 mm” or a size of “2.0 mm × 1.2 m”.
It is a chip element produced by film formation by integration so that the element is arranged in a shape called 2012 type of m ″.

[0016]

According to the thin film LC filter of the present invention, in the thin film LC filter composed of a thin film inductor and a thin film capacitor, the thin film inductors and the thin film capacitors are alternately and adjacently arranged at a predetermined narrow interval. Further, the thin film capacitor is arranged so as to have a predetermined stray capacitance between a ground line connected to the thin film capacitor and a signal line formed by connecting the thin film inductors in series.

In the thin film LC filter according to the present invention, the thin film inductor and the thin film capacitor are
There is a narrow space between the signal line formed by connecting the thin film inductors in series and the thin film capacitor, and the electrodes above and below the dielectric layer of the thin film capacitor (signal line and ground line). Any one of them is connected) and an adjacent inductor (forming a signal line) are alternately arranged in parallel so as to have a predetermined stray capacitance.

The capacitance value of the stray capacitance generated by this closely arranged structure is added to the capacitance value of the thin film capacitor. As a result, the capacitor becomes small with a small capacitance value.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing an embodiment of the present invention. The thin film LC filter shown in FIG. 1 includes an inductor 12 composed of three inductors L1 to L3 that are formed by connecting signal lines 14 in series, and a signal line 14 and a ground line 15 that connect the inductors L1 to L3. Three capacitors C1 to be inserted and connected between
3 formed by the capacitor 13 composed of C3
It is a continuous three-pole type filter and has good filter characteristics as shown in FIG.

First, a typical structure of each of the inductors L1 to L3 is a thin film coil having a conductor coil 6 in which a magnetic material 5 is inserted inside a surface of a substrate 7 as shown in FIG. For this, a solenoid (spiral) type, a spiral type, a meander type or the like is adopted according to the inductance value.

A typical structure of each of the capacitors C1 to C3 is a dielectric layer 9 of a thin film dielectric in which a lower electrode 10, a dielectric layer 9 and an upper electrode 8 are sequentially stacked on the upper surface of a substrate 11 as shown in FIG. Is sandwiched between a lower electrode 10 and an upper electrode 8 of a thin film conductor.

As shown in FIG. 1, the inductors L1 to L3 and the capacitors C1 to C3 of the thin film LC filter are arranged alternately adjacent to each other in the vertical direction with respect to the linear ground line 15, and the inductors L1 to L3 are respectively arranged. Are arranged such that their central axes are parallel to each other and the winding directions of the coils are the same.

The signal line 14 is connected from the input side electrode to one end of the inductor L1 opposite to the ground line 15, and the signal line 14 connecting between the inductors L1 and L2 is connected to the ground line 15 side of the inductor L1. Inductor L1, between the inductor L1 and L2 from the other end
Ground wire 1 of inductor L2 parallel to L2 respectively
It shall be connected to one end on the side opposite to 5. Also,
One end of the ground line 15 of the inductor L2 is the signal line 1
4 is connected to the output side electrode.

On the other hand, the capacitor C1 is the inductor L1,
It is arranged below the conductor of the signal line 14 connecting between L2, and the conductor of this signal line 14 and this signal line 14
Is connected in parallel with the conductor of the ground line 15 which is arranged in parallel with and is connected to the capacitor C1. Capacitor C2
Similarly, the inductor L2 and L3 are inserted and connected between the conductor of the signal line 14 and the conductor of the ground line 15, and the conductor connecting the inductors L2 and L3 forms a capacitor. The capacitor C3 is the inductor L
It is inserted and connected between a conductor connecting 3 and the electrode of the signal line 14 and a conductor connected to the electrode of the ground line 15.

Further, capacitors C1 to C of the LC filter
The stray capacitance that supplements the capacitance value of 3 is the result of the conductors of the signal line 14 connecting the electrodes and the inductors L1 to L3 connected in series and the conductor connecting the capacitors C1 to C3 to the ground line 15 arranged close to the inductors L1 to L3. ,
It is supplemented by stray capacitance generated between the conductors of the signal line 14 and the ground line 15.

When the capacitors C1 to C3 and the inductors L1 to L3 are alternately arranged in parallel, the respective intervals, that is, the signal line 1 including the inductors L1 to L3.
4 and the ground line 15 connected to the capacitors C1 to C3
A predetermined stray capacitance value is obtained by setting the distance between and to 10 μm to 100 μm. Further, the stray capacitance between the inductor 12 and the capacitor 13 is due to the capacitors C1 to C1.
3 Electrodes 8 and 9 above and below the dielectric layer 9 and signal line 1 respectively
By adding the stray capacitance generated between 4 and 4, the capacitance value is increased more reliably.

In FIG. 2, the distance between the inductors L1 to L3 and the capacitors C1 to C3 is 10 μm to 100 μm.
The thin film triple LC filter characteristics are shown when they are closely arranged so as to have a thickness of μm. As shown in the figure, since the interval between the inductors L1 to L3 and the capacitors C1 to C3 is narrow, a sufficient stray capacitance of 10 pF is obtained, the agility is sufficient, and the attenuation amount is -60 dB.

On the other hand, in the example shown in FIG. 3, the inductors L1 to L3 and the capacitors C1 to C3 are sufficiently separated from each other so that no stray capacitance is generated, and a stray capacitance of 0.1 pF is generated. The thin film triple LC filter characteristics in the open state are shown. The characteristics obtained in this case have sufficient agility and attenuation as a filter, but the frequency band is shifted to the high frequency side. A major problem is that they are placed so far apart from each other that they cannot accommodate the size of the 1608 type as well as the large 3025 type.

Further, a wide attenuation bandwidth and a steep attenuation characteristic, which are necessary as a characteristic of the low-pass filter for transmitting a signal in a necessary frequency band and blocking a signal in an unnecessary frequency band, are provided. In order to make the transition of the attenuation frequency to the low band compatible, either increase the size so as to have an area capable of reducing a large signal generated in a band of several 100 MHz, or incorporate a heating resistor in the circuit to reduce the signal by heat generation. Is being treated. When the resistance heats up, the battery life is shortened due to the voltage drop and energy consumption, and a high voltage is also required.

The thin film LC filter according to the present invention described with reference to FIG. 1 can cover these problems and contribute to downsizing of the entire system.

Further, the miniaturization of the system caused by the shift of the operating frequency to high frequency causes high frequency noise. High frequency noise propagating between adjacent strip lines for downsizing can be significantly reduced by the high attenuation of the thin film LC filter described above.

In the above description, when the capacitors are arranged alternately with the inductors, the intervals between them are 10 μm to 10 μm.
Although it is set to 0 μm, if the interval can be further reduced by improving the manufacturing technique, it is possible not only to supplement a larger capacitance than in the past with a stray capacitance, but also to promote further miniaturization.

Further, in the above description, the capacitors are alternately arranged in parallel with the inductors, but the invention is not limited to the parallel arrangement, and only a part of the capacitors may be arranged to obtain a predetermined capacitance value. They may be arranged close to each other.

[0035]

【Example】

[Embodiment 1] Next, a first embodiment of the invention will be described with reference to FIGS.

FIG. 6 is a thin film triple LC showing the first embodiment.
It is an equivalent circuit diagram of a filter. The circuit shown in FIG.
It was produced by the element arrangement of FIG. 7, and the characteristics of FIG. 8 have been confirmed.

The thin film LC filter shown in the figure has a six-turn thin film inductor 21 having an inductance value L4 = L5 = L6 = 160 nH and a capacitance value C4 = 3.
The thin film capacitor 22 having 2 pF, C5 = 13 pF, and C6 = 1 pF and the thin film capacitor 22 are alternately arranged in parallel in close proximity to a predetermined value, and are manufactured by a thin film process. The result is a typical stray capacitance as shown in FIG. The value and the inductance value are shown.

Capacitance value C14 = 10 pF, C15 =
3pF and C16 = 1pF are inductors L4 and L4, respectively.
5, stray capacitance generated in parallel in each coil, and capacitance value C10 = 0.015 pF is stray capacitance of the system, and inductance value L14 = 1 nH, L15 =
0.5nH and L16 = 2nH are capacitors C4,
Inductance values generated in series with C5 and C6, respectively, and related resistance values are omitted in the drawing.

As shown in FIG. 8, the simulation result indicated by the broken line and the low-pass filter characteristic obtained by actual measurement were in good agreement, and a good actual measurement result was obtained.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10.

FIG. 9 is a schematic plan view of a thin film triple LC filter showing the second embodiment, and the characteristics are confirmed by FIG.

The illustrated thin film LC filter is a two-turn thin film inductor 23 having an inductance value L7 = L8 = L9 = 60 nH and a capacitance value C7 = 3.
The thin film capacitor 22 having 2 pF, C8 = 13 pF, and C9 = 1 pF and the thin film capacitor 22 are alternately arranged in parallel in close proximity to a predetermined value, and are manufactured by a thin film process.

As shown in FIG. 10, the low-pass filter characteristic obtained by actually measuring the thin film LC filter has a small amount of attenuation due to a small inductance value, but is sufficiently close to the simulation result shown by the broken line. The actual measurement results have been obtained.

[0044]

As described above, according to the present invention, a plurality of inductors that are connected in series to form a signal line, a plurality of inductors, and a conductor that connects the inductors and the inductors to each other and a ground line are self-contained. A thin film LC filter having a capacitor arranged so as to replenish a predetermined stray capacitance by bringing the conductor connected to the above into close proximity is obtained. With this configuration, a miniaturized thin film LC filter can be obtained, and a desired capacitance value can be obtained even when a small thin film capacitor having a small capacitance value is provided.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing an example of filter characteristics in the case of the close arrangement in FIG.

FIG. 3 is a perspective view showing an example of a typical thin film inductor.

FIG. 4 is a perspective view showing an example of a typical thin film capacitor.

5 is a characteristic diagram showing an example of filter characteristics in the case of the wide area arrangement of FIG. 1. FIG.

FIG. 6 is an equivalent circuit diagram showing a first embodiment of the present invention.

FIG. 7 is a schematic plan view showing a first embodiment of the present invention.

8 is a characteristic diagram showing an example of the filter characteristic according to FIG. 7. FIG.

FIG. 9 is a schematic plan view showing the first embodiment of the present invention.

10 is a characteristic diagram showing an embodiment of the filter characteristic shown in FIG.

FIG. 11 is an equivalent circuit diagram showing a conventional example.

FIG. 12 is a schematic plan view showing a conventional example.

[Explanation of symbols]

 5 magnetic substance 6 conductor coil 8 upper electrode 9 dielectric layer 10 lower electrode 12, 21, 23 inductor 13, 22, 24 capacitor 14 signal line 15 ground line

Claims (5)

[Claims] 1. In a thin film LC filter composed of a thin film inductor and a thin film capacitor, the thin film inductors and the thin film capacitors are alternately arranged adjacent to each other with a predetermined narrow interval, and the thin film capacitor further comprises:
A thin film LC filter, which is arranged so as to have a predetermined stray capacitance between a ground line connected to the thin film capacitor and a signal line formed by connecting the thin film inductors in series. 2. The thin film inductor and the thin film capacitor according to claim 1, wherein the thin film inductor and the thin film capacitor are closely spaced so as to have a predetermined stray capacitance between a signal line formed by connecting the thin film inductors in series and the thin film capacitor. A thin film LC filter, which is alternately and adjacently arranged in parallel. 3. The thin film inductor and the thin film capacitor according to claim 1, wherein the distance between the signal line and the ground line is formed between 10 μm and 100 μm, and the thin film inductor and the thin film capacitor are alternately and adjacently arranged in parallel. Thin film LC
filter. 4. The thin film inductor and the thin film capacitor according to claim 1, wherein an electrode (connecting either a signal line or a ground line) above and below a dielectric layer of the thin film capacitor and an adjacent inductor (forming a signal line). ), And a thin film LC filter, which are alternately arranged in parallel so as to have a predetermined stray capacitance. 5. The thin film inductor and the thin film capacitor according to claim 1, wherein the thin film inductor and the thin film capacitor are closely spaced so as to have a predetermined stray capacitance between a signal line formed by connecting the thin film inductors in series and the thin film capacitor. Alternately parallel to have a predetermined stray capacitance between the electrodes (connecting either the signal line or the ground line) above and below the dielectric layer of the thin film capacitor and the adjacent inductor (forming the signal line). A thin film LC filter, which is arranged adjacent to the.