GB2273818A

GB2273818A - Composite electronic component

Info

Publication number: GB2273818A
Application number: GB9326361A
Authority: GB
Inventors: Harufumi Mandai; Noboru Kato; Koji Shiroki
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 1992-12-26
Filing date: 1993-12-23
Publication date: 1994-06-29
Anticipated expiration: 2013-12-23
Also published as: GB9326361D0; GB2273818B; DE4342818C2; JP2822825B2; DE4342818A1; JPH06204397A

Description

2273818 Composite Electronic Component The Dresent invention relates to a

composite electronic component, particularly, the invention relates to a composite electronic component having an electronic part such as an inductor or an IC on a body in which capacitance is also present.

DescriDtion of Prior Art

Fia. 13 is a exDloded DersDective view showina an example of conventional LC f ilter 1 which is by way of background to the invention. The LC filter 1 is composed of plural layers 2 consisting of dielectric material. An earth electrode 3, capacitor electrodes 4 and 5, a capacitor electrode 6 and a capacitor electrode 7 are formed on the layers 2 respectively. The earth electrode 3 has a space at a centre portion, and the earth electrode 3 is led out to both ends of the layer 2. The caDacitor electrodes 4 and 5 are formed so as to be opposed to the earth electrode 3 and the capacitor electrodes 4,5.

The capacitor electrode 6 is formed so as to be opposed to the capacitor electrode 4, and is led out to the opposite - 1 portion to the lead-out portion of the capacitor electrode 5. Therefore, capacitance is made between the capacitor electrode 4 and the capacitor electrode 6. The capacitor electrode 7 is formed so as to be opposed to the capacitor electrode 6, and is led out to the opposite portion to the lead-out portion of the capacitor electrode 4. Therefore, capacitance is made between the capacitor electrode 6 and the capacitor electrode 7.

Two connecting electrodes 8a and 8b are formed on the upper layer 2. The connecting electrodes 8a and 8b are led out respectively to the corresponding portions to the leadout portions of the capacitor electrodes 4 and 5. An inductor 9 and the like is connected to the connecting electrodes 8a. and 8b. The capacitor electrodes 4, 7 and the connecting electrode 8a are connected by an external electrode, and the capacitor electrodes 5, 6 and the connecting electrode 8b are connected by an external electrode.

As shown in Fig. 14, the LC filter 1 has a parallel circuit of capacitances. The parellel circuit can be expressed as one capacitance equivalently as shown in Fig. 15. A resonance circuit is formed by connecting the capacitance and the inductance in parallel. The resonance circuit is earthed via two capacitances.

However, in the conventional LC filter, the lead-out 2 portion of the capacitor electrode 6 is long. An unnecessary inductance is generated at the lead-out portion, and the inductance is connected to the capacitance in series as shown in Fig. 14 and Fig. 15.

Desired characteristics cannot be obtained reliablv in the case of the unnecessary inductance. It has been proposed that a through-hole is formed in the layers, and the electrodes are connected via the through-hole for suppressing the effect of unnecessary inductance.

However, manufacturing of the composite electronic comDonent becomes complex, because the through-hole must be produced at the time of manufacture.

In the conventional LC filter, it is difficult to obtain a required capacitance because capacitance is made by the electrodes in the body. In general the LC resonance circuit requires capacitance dispersion below 2%, whereas the LC resonance circuit of Fig. 13 has the capacitance dispersion of about 5%.

It is an object of the present invention to provide a composite electronic component which scarcely generates unnecessary inductance, and has a capacitance whose dispersion is small.

According to the invention there is provided a composite electronic component comprising:

a body composed of dielectric material, plural capacitor electrodes formed in said body 3 and led out reSDectively to an end Dortion of said body, a common electrode or)Dosed to said caDacitor electrodes in said bodv to form a number of series circuits of caDacitance and a further electronic Dart or device connected to said caDacitances circuits wherein said series circuits of caDacitances are connected in parallel in said body.

Plural series circults-of canacitances are formed bv o-oDosina the common electrode and Dlural caDacitor electrodes in common, and the series circuits are connected in Darallel. Combined caDacitance becomes small bv connecting the caDacitances in series, and the capacitance dispersion can be small. Combined capacitance become larae bv connectina the series circuits of caDacitances, and required capacitance can be obtained.

The minimum aeneration of the unnecessarv inductance can be obtained at the lead-out portion of the capacitor electrode by making the lead-out portion in the shortest distance.

According to the present invention, the capacitance dispersion can be small by connecting caDacitances in series. Therefore, required capacitance value having small dispersion can be obtained by connecting plural capacitances 4 whose dispersion are small in parallel. A designed characteristics can be obtained because unnecessary inductance can be in minimum value.

These and other objects, features, aspects and advantages of the present invention will become more apparent from -the detailed description of the following embodiments described in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a perspective view showing an LC filter as an example of the present invention.

Fig. 2 is an exploded perspective view showing the layers of a body based on the LC filter of Fig. 1 Fig. 3 is an equivalent circuit diagram of the LC filter shown in Fig. 1 and Fig. 2.

Fig. 4 is an equivalent circuit diagram combined in part of the circuit shown in Fig. 3 Fig. 5 is an equivalent circuit diagram of a delay equalizer as an another example of the present invention.

Fig. 6 is an equivalent circuit diagram combined in part of the circuit shown in Fig. 5 Fig. 7 is an exploded perspective view showing a highpass filter as a still another example of the present invention.

Fig. 8 is an equivalent circuit diagram of the highpass filter shown in Fig. 7.

Fig. 9 is an equivalent circuit diagram combined in part of the circuit shown in Fig. 8.

Fig. 10 is an exploded perspective view showing an active filter a.s. the other example of the present invention.

Fig. 11 i s an equivalent circuit diagram of the active filter shown irr Fig. 10.

Fig. 12 is an equivalent circuit diagram combined in part of the circuit shown in Fig. 11.

Fig. 13 is an exploded perspective view showing a conventional LC filter which is background of the present invention.

Fig. 14 is an equivalent circuit diagram of the LC filter shown in Fig. 13.

Fig. 15 is an equivalent circuit diagram combined in part of the circuit shown in Fig. 14.

Fig. 1 is a perspective view showing an example of the present invention. In this embodiment, an LC filter is explained as an example of composite electronic c inent. The X filter 10 includes a body 12 consisted of dielectric material. As shown in Fig. 2, the body 12 is composed of plural layers. An earth electrode 16 is formed on a first 6 layer 14. The earth electrode 16 is formed on almost the whole surface of the first layer 14, and has a space 18 at a central portion. The earth electr ode 16 is led out to the opposite ends of the first layer 14.

A second layer 20 is laminated on the earth electrode 16. A first capacitor electrode 22 and a second capacitor electrode 24 are formed on the second layer 20. The first capacitor electrode 22 and the-second capacitor electrode 24 are formed respectively so as to be opposed to the portions of the earth electrode 16 where are both sides of the space 18. The first capacitor electrode 22 and the second capacitor electrode 24 are led out to one end of the second layer 20.

A third layer 26 is laminated on the first capacitor electrode 22 and the second capacitor electrode 24. A common electrode 28 is formed on the third layer 26 at a center portion. The common electrode 28 is formed so as to be opposed in common to the first capacitor electrode 22 and the second capacitor electrode 24.

A fourth layer 30 is laminated on the common electrode 28. A third capacitor electrode 32 and a fourth capacitor electrode 34 are formed on the fourth layer 30. The third capacitor electrode 32 and the fourth capacitor electrode 34 are formed respectively at opposite portions to the first capacitor electrode 22 and the second capacitor electrode 7 24. Therefore, the common electrode 28 is opposed in common to the third capacitor electrode 32 and the fourth capacitor electrode 34. The third capacitor electrode 32 and the' fourth capacitor electrode 34 are led out to one end of the fourth layer 30.

A fifth layer 36 is laminated on the third capacitor electrode 32 and the fourth capacitor electrode 34. Two connecting electrodes 38 and.40 are formed on the fifth layer 36. The connecting electrodes 38 and 40 are led out to one end of the fifth layer 36. An inductor 42 is connected to the connecting electrodes 38 and 40.

The layers 14, 20, 26, 30 and 36 are incorporated together, and external electrodes 44a, 44b, 44c and 44d are formed on its side faces. The external electrode 44a is connected to the first capacitor electrode 22, the third capacitor electrode 32 and the connecting electrode 38. The external electrode 44c is connected to the second capacitor electrode 24, the fourth capacitor electrode 34 and the connecting electrode 40. The external electrodes 44b and 44d are connected to the earth electrode 16.

As shown in Fig. 3, in the LC filter 10, capacitance is made between the first capacitor electrode 22 and the common electrode 28, and capacitance is made between the second capacitor electrode 24 and the common electrode 28. Therefore, series circuit of capacitances is connected to 8 inductance made at the inductor 42 in parallel. Capacitance is made between the third capacitor electrode 32 and the common electrode 28, and capacitance is made between the fourth capacitor electrode 34 and the common electrode 28. Therefore, another series circuit of capacitances is connected to ind.uctance made at the inductor 42 in parallel. In the LC filter 10, two series circuits of capacitors and inductance are'connected in parallel. Capacitance is made between the first capacitor electrode 22 and the earth electrode 16, and capacitance is made between the second capacitor electrode 24 and the earth electrode 16. Therefore, the circuit composed of inductance and capacitances is earthed via two capacitances.

The circuit shown in Fig. 3 can be expressed equivalently as a circuit shown in Fig. 4. Four capacitances shown in Fig. 3 are expressed as one capacitance in Fig. 4, the capacitance in Fig. 4 is combined capacitance of four capacitances of Fig. 3. In the LC filter 10, a resonance circuit is formed with a parallel circuit of inductance and capacitances. When plural capacitances are connected in series, combined capacitance becomes small. Therefore, error of capacitance can be reduced by connecting plural capacitances in series even if dispersion exists in capacitance formed between the capacitor electrodes and the common electrode. Combined capacitance becomes large by 9 connecting the series circuits of capacitances in parallel. The dispersion of the whole combined capacitance is small because plural capacitances having small dispersion are combined.

In the LC filter 10, the lead-out portions of the capacitor electrodes 22, 24, 32, 34 and the earth electrode 16 are led out to the end of respective layers in a shortest distance. Therefore, inductance generating at the lead-out portions can be suppressed to minimum value. Since the capacitance dispersion is small and generation of unnecessary inductance is little, almost designed characteristics can be obtained. A process of trimming and the like for adjustment is unnecessary because capacitance dispersion is small.

A secondary delay equalizer can be obtained by earthing the earth electrode 16 via inductance as sown in Fig. 5 and Fig. 6. In the circuit shown in Fig. 6, three capacitances are connected in a delta shape.

Fig. 7 is an exploded perspective view showing a highpass filter. In the high-pass filter 50, a first capacitor electrode 54, a second capacitor electrode 56 and a third cap acitor electrode 58 are formed on a first layer 52. Two common electrodes 62 and 64 are formed on a second layer 60. The common electrode 62 is f ormed so as to be opposed in common to the capacitor electrodes 54 and 56, and the common electrode 64 is formed so as to be opposed in common to the capacitor electrodes 56 and 58.

A fourth capacitor electro de 68, a fifth capacitor electrode 70 and a sixth capacitor electrode 72 are formed on a third layer 66. The capacitor electrodes 68, 70 and 72 are formed respectively at opposite portions to the capacitor electrodes 54, 56 and 58. Connecting electrodes 76 and 78 are formed on a fourth layer 74, and an inductor 80 is connected to the connecting electrodes 76 and 78. The first capacitor electrode 54 and the fourth capacitor elctrode 68 are connected by an external electrode, and the second capacitor electrode 56, the fifth capacitor electrode 70 and the connecting electrode 76 are connected by an external electrode, and the third capacitor electrode 58 and the sixth capacitor electrode 72 are connected by an external elctrode. The connecting electrode 78 is earthed.

The high-pass filter 50 has T equivalent circuit as shown in Fig. 8 and Fig. 9, since capacitances are made between the capacitor electrodes and opposed common electrodes. The high-pass f ilter 50 has required capacitance! small capacitance dispersion and little unnecessary inductance similarly to the LC filter shown in Fig. 1 and Fig. 2. Therefore, almost designed characteristics can be obtained without the process of trimming and the like.

Fig. 10 is an exploded perspective view showing an example of active filter. In the active filter 90, a fifth layer 92 is laminated on the first layer of the body shown in Fig. 7. A seventh capacitor electrode 94 is formed on the fifth layer 92 at an opposite portion to the second capacitor electr-ode 56. An operational amplifier 96 and two resistors 98 and 100 are fixed on the fourth layer 74. The active filter 9,0 has an equivalent circuit shown in Fig. 11 and Fig. 12. The active filter 90 has required capacitance, small capacitance dispersion and little unnecessary inductance. Therefore, almost designed characteristics can be obtained without the process of trimming and the like.

While the invention has been particularly described and shown, it is to be understood that such description is for illustrative purpose and examples only and not of limitation, the scope of the invention is determined solely by the terms of the appended claimes.

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Claims

A composite electronic component comprising:

a bodv comnosed of dielectric material, Dlural caDacitor electrodes f ormed in said bodv and led out resDectivelv to an end nortion of said body.

a common electrode 01DDosed to said car)acitor electrodes in said bodv to form a number of series circuits of caDacitance and a further electronic Dart or device connected to said caDaci-11--ances circuits wherein said series circuits of caDacitances are connected in Parallel in said bodv.
2. A comDosite electronic comDonent according to claim 1, wherein said body is composed of plural layers which are laminated together.
3. A comDosite electronic comDonent accordina to claim 2, wherein said capacitor electrodes and said common electrode are formed re5Dectively on said layers, and said capacitor electrodes are led out respectively to the end of said layers in the shortest distance.
4. A composite electronic component according to claim 1, 2 or 3 wherein connecting electrodes are formed on said bodv for connecting said electronic part.
5. A comDosite electronic comnonent substantially as 13 described with reference to and as illustrated in any one or more of Fiaures 1 to 12 of the accompanying 1 drawinas.

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