JP6012539B2 - Noise filter - Google Patents

Description

  The present invention relates to a noise filter that removes noise superimposed on a signal line, and more particularly to a noise filter configured using a conductive pattern formed on a laminate such as a printed circuit board.

  In general, when an electric circuit is configured, a bypass capacitor is inserted between the signal line or the like and the ground line in order to remove noise superimposed on the signal line or the power supply line, or in series with the signal line or the like. An inductor (coil) is inserted into the. In these configurations, the noise superimposed on the signal line or the like is released to the ground line via a bypass capacitor having a low high-frequency impedance, or the propagation of noise in the signal line or the like is prevented by a coil having a high-frequency impedance. The noise is removed.

  On the other hand, since a coil as a single electric component is generally formed by winding a conductive wire in a spiral shape, there is a limit to downsizing the size. For this reason, when an electrical component coil is mounted on the printed circuit board constituting the control device, the component mounting space on the printed circuit board is expanded in the height direction, and the housing constituting the control device is reduced in size. It becomes difficult.

  Therefore, when a noise filter is used in an electric circuit, if a necessary inductor can be formed in advance as a wiring pattern on a printed circuit board, a coil as a single electric component becomes unnecessary, which is convenient for downsizing the apparatus. It is.

  Conventionally, as a printed wiring board in which an inductor is configured with a wiring pattern, a power distribution layer provided on the inner layer of a multilayer printed circuit board is sandwiched between magnetic substance mixed insulators to increase distributed inductance, and current distribution with a small DC impedance is applied to the power supply layer. And a branch wiring for distributing current from the trunk wiring to each circuit block, and the branch wiring is formed in a zigzag or cross shape to further increase the inductance of the branch wiring portion. A multilayer printed circuit board that is enhanced and functions as an inductor is also known (Patent Document 1).

  In this printed circuit board, the distributed inductance of the power supply layer is increased and the inductance of the branch wiring is increased, so that the AC impedance of the power supply pattern seen from each circuit block is increased, and the power supply current fluctuation of one circuit block is the power supply of the other circuit block. This prevents the line from being affected.

  However, in the above conventional multilayer printed circuit board, the energy of the power source current fluctuation blocked by the inductance of the branch wiring portion is consumed solely by the eddy current generated in the branch wiring portion and generates heat. For this reason, depending on the arrangement of the branch wiring part, it is difficult to effectively dissipate the heat generated in the part, and the substrate temperature rises and affects the operation of the semiconductor elements and the like on the substrate. .

  In addition, since the inductance of the portion of the branch wiring is increased by forming a folded pattern or the like, the length of the current path is significantly longer than that of a coil having the same inductance, and is affected by external noise. It becomes easy. Therefore, it is not desirable to use such a planar wiring pattern having a long path length as an inductor for a noise filter from the viewpoint of improving the resistance to external noise.

JP-A-9-139573

  From the above background, in a noise filter composed of a conductive pattern formed on a laminate such as a printed circuit board, noise superimposed on the signal line can be efficiently removed without increasing the path length of the signal line. It is desired to be removed.

The present invention relates to a noise filter formed on a laminate such as a printed circuit board, and the noise filter has a layer in which a conductive pattern made of a conductive material is formed and a layer made of an insulating material. A laminated body, a first conductive pattern, a second conductive pattern configured in a spiral manner around the first conductive pattern, and the second conductive pattern connected to both ends of the second conductive pattern. And a resistor constituting a closed circuit together with the conductive pattern.
According to one aspect of the present invention, the laminate is a multilayer printed circuit board.
According to another aspect of the invention, the stack is an integrated circuit.
According to another aspect of the present invention, a portion of the insulating material that is interposed between the first conductive pattern and the second conductive pattern is made of a magnetic insulating material.
According to another aspect of the present invention, the cutoff frequency of the electrical signal propagating through the first conductive pattern is adjusted by the electrical resistance value of the resistor.
The present invention is also a control device including the noise filter.
According to one aspect of the present invention, the control device controls the operation of the vehicle.

  According to the present invention, in a noise filter constituted by a conductive pattern formed on a laminate such as a printed circuit board, noise superimposed on the signal line can be efficiently reduced without increasing the path length of the signal line. Can be removed.

It is a figure which shows the structure of the multilayer wiring board which comprises the noise filter which concerns on one Embodiment of this invention. It is a figure which shows the structure of the noise filter which concerns on one Embodiment of this invention. It is the figure which showed typically the structure of the noise filter which concerns on one Embodiment of this invention using a circuit symbol. It is a figure which shows the equivalent circuit of the noise filter which concerns on one Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
The noise filter according to the present embodiment is configured using a multilayer printed wiring board (hereinafter referred to as a multilayer wiring board). The “multilayer wiring board” used in the present embodiment is an example of a laminated body having a layer formed with a conductive pattern made of a conductive material and a layer made of an insulating material. For example, the multilayer wiring board may be formed on a semiconductor substrate constituting a three-dimensional integrated circuit. In the case of a semiconductor substrate constituting such a three-dimensional integrated circuit, the “layer on which the conductive pattern is formed” refers to a layer formed by film formation (for example, metal deposition) on the substrate. In addition, a layer having a predetermined depth from the substrate surface including a conductive portion formed by diffusing metal into the substrate is also meant.

  This noise filter is used in, for example, a control circuit, and removes or reduces noise superimposed on a sensor signal or the like input to the control circuit. The control circuit may be an electronic control unit (ECU, Electronic Control Unit) that controls the operation of the vehicle, for example.

A configuration of a noise filter according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a diagram showing a configuration of a multilayer wiring board constituting the noise filter. The multilayer wiring board 100 is a multilayer printed board having, for example, five conductor layers 102, 104, 106, 108, and 110. Each conductor layer is made of a metal (for example, copper) which is a conductive material.

The multilayer wiring board 100 includes insulator layers 122 to 128 made of an insulating material (for example, glass epoxy) between the conductor layers 102 to 110.
The conductor layer 102 is, for example, a front surface on which an electrical component is mounted. The conductor layer 110 and the conductor layer 108 which are the back surfaces are connected to, for example, a power source, and are respectively connected to a ground layer and a power source layer. Used as

FIG. 2 is a diagram illustrating the configuration of the noise filter.
The noise filter 10 includes a first conductive pattern through which an electric signal on which noise is superimposed propagates. The first conductive pattern includes conductive patterns 200 and 202 formed on the conductive layer 102, a conductive pattern 204 formed on the conductive layer 104, and the conductive patterns 200 and 202 electrically connected to the conductive pattern 204, respectively. The vias 206 and 208 are connected to each other.

  The via is generally made of a conductive material having a cylindrical shape, but in FIG. 2, the via is shown by a dotted line in order to simplify the drawing and facilitate understanding. Further, when the present noise filter is configured as a part of the three-dimensional integrated circuit, for example, a silicon through electrode can be used instead of the via.

  Further, the noise filter 10 has a second conductive pattern formed in a spiral shape that turns around the first conductive pattern. Here, “spiral-like” includes not only a shape that turns while drawing a circle but also a shape that turns while drawing another shape such as a rectangle.

  The second conductive pattern includes conductive patterns 210 and 212 formed on the conductive layer 102, conductive patterns 214 and 216 formed on the conductive layer 106, conductive patterns 210 and 212, and conductive patterns 214 and 216. Vias 218, 220, 222, 224, 226, 228, 230, and 232. As shown in the drawing, the conductive patterns 210 to 216 and the vias 218 to 232 form a spiral-like conductive path that turns around the conductive pattern 204 that forms a part of the first conductive pattern.

  Furthermore, the noise filter 10 includes a chip resistor 240 that is a resistor that forms a closed circuit together with the second conductive pattern. In FIG. 2, the chip resistor 240 is drawn independently in the upper part of the drawing in order to facilitate understanding of the arrangement of each conductive pattern, but actually the chip resistor 240 has two terminals ( The hatched portion in the figure is electrically connected to a rectangular land 234 that forms part of the conductive pattern 210 and a rectangular land 238 that is connected to the via 232 via the conductive pattern 236, respectively. A closed circuit is formed together with the pattern.

FIG. 3 schematically shows a three-dimensional configuration of the noise filter 10 shown in FIG. 2 using circuit symbols. The line 300 is a first conductive pattern composed of the conductive patterns 200, 204, 202, and the like, and a current I _sig such as an electric signal on which noise is superimposed flows.

  The coil L302 is a spiral coil that turns around the line 300, and represents a second conductive pattern composed of conductive patterns 210, 214, 212, 216, and the like. A resistor R304 represents a chip resistor 240 that is connected to the second conductive pattern by lands 234 and 238 to form a closed circuit.

  The electrical signal flowing through the line 300 that is the first conductive pattern generates a magnetic field (hereinafter, an ambient magnetic field) around the line 300. This ambient magnetic field fluctuates due to an alternating current component such as noise superimposed on the electric signal flowing through the line 300, and the electromotive force is generated in the coil L302, which is the second conductive pattern, due to the magnetic field fluctuation. An alternating current flows through a closed circuit constituted by the resistor R304.

  The alternating current flowing in the closed circuit generates a new magnetic field in the coil L302, and an electromotive force is generated in the line 300 in a direction that prevents the current change due to the noise or the like due to the fluctuation of the new magnetic field. Thereby, the impedance with respect to alternating current components, such as noise, in line 300 becomes high, and the propagation of the noise concerned is stopped.

  Since the noise filter 10 having the above-described configuration is configured by a conductive pattern formed on the multilayer wiring board 100, a winding coil as an electrical component for noise removal is conventionally used as a signal transmission pattern (in the line 300). It is not necessary to connect them in series. For this reason, it is possible to reduce the size of the apparatus by limiting the height of electrical components mounted on the surface of the multilayer wiring board 100 (for example, the conductor layer 102).

  In the conventional configuration, since the winding coil is connected in series to the signal transmission pattern, the mounting position is limited by the arrangement of the signal transmission pattern. For this reason, the heat generated when the coil consumes noise power increases the temperature in the vicinity of the signal transmission pattern, and affects the operation of the semiconductor components and the like existing around the temperature.

  On the other hand, in the noise filter 10, noise power is consumed as heat by the resistor R304, that is, the chip resistor 240, and the chip resistor 240 is separated from the second conductive pattern through another conductive pattern. Since the chip resistor 240 is moved to a place with good heat dissipation efficiency (for example, on the conductor layer 110 which is the back surface ground layer or in the vicinity of the heat sink (not shown)). In addition, the temperature increase of the multilayer wiring board 100 as a whole can be suppressed.

FIG. 4 is a diagram illustrating an equivalent circuit of the noise filter 10.
The first conductor pattern also has an inductance when it is composed of a linear conductor pattern, and the first conductor pattern and the second conductor pattern are composed of two magnetically coupled coils. It can be understood as equivalent to a transformer.

  A transformer T400 illustrated in FIG. 4 represents a state in which the first conductive pattern and the second conductive pattern are magnetically coupled. Here, the coil L402 is a coil having an inductance corresponding to the first conductive pattern, and the coil L404 is a coil having the same inductance as that of the second conductive pattern.

  The resistor R406 represents a minute electric resistance of the first conductive pattern, and the resistor R408 represents a combined resistance of the electric resistance of the second conductive pattern and the electric resistance of the chip resistor 240.

Here, the self-inductances of the coils L402 and L404 are L _sig and L _fil , the mutual inductance of the coils L402 and L404 is M, and the resistance values of the resistors R406 and R408 are R _sig and R _fil , respectively. Is I _sig , the current flowing through the coil L404 is I _fil , and the voltage applied to the resistor R406 and the coil L402 is V _sig , the following equation is established.

Therefore, from the above equations (1) and (2), the impedance Z _sig of the first conductor pattern portion is given by the following equation.

である。 here,

It is.

となる周波数ωでは、Z_sigが十分大きな値となり、従ってノイズの伝搬が阻止され除去されることとなる。 From equation (4)

At the frequency ω, Z _sig becomes a sufficiently large value, and therefore noise propagation is prevented and eliminated.

The right side of equation (5) represents the frequency at which noise propagation is blocked (blocking frequency, hereinafter referred to as ω ₀ ). As is clear from equation (5), the blocking frequency ω ₀ is the _value of R _fil Adjustment can be made by changing the value, and thus changing the resistance value of the chip resistor 240, which is a resistor connected to the second conductive pattern.

  In the present embodiment, the insulator layers 122 to 128 are made of a glass epoxy material or the like. However, the present invention is not limited to this. For example, the insulator layers 122 to 128 are interposed between the first conductor pattern and the second conductor pattern. The first conductive pattern and the second conductive pattern are made of a material having magnetism (for example, an insulating material mixed with a magnetic material) as an insulating layer to be formed, that is, the material of the insulating layers 122 and 124 in this embodiment. The magnetic coupling of can be strengthened.

In this case, the mutual inductance M is increased and the blocking frequency ω ₀ can be shifted to the low frequency side, so that the adjustment range of ω ₀ according to the resistance value of the chip resistor 240 can be expanded. When the magnetic insulator layer is interposed between the first and second conductive patterns as described above, magnetic interference occurs between adjacent noise filters 10 when the plurality of noise filters 10 are formed. It is desirable to arrange the adjacent noise filters 10 so that their magnetic field generation directions are orthogonal to each other.

  DESCRIPTION OF SYMBOLS 10 ... Noise filter, 100 ... Multilayer wiring board, 102-110 ... Conductor layer, 122-128 ... Insulator layer, 200-204, 210-216, 236 ... Conductive pattern, 206, 208, 218 to 232 ... via, 234, 238 ... land, 240 ... chip resistor, 300 ... line, L302, L402, L404 ... coil, R304, R406, R408 ..Resistance, T400 ... Transformer.

Claims (7)

A laminate having a layer formed with a conductive pattern made of a conductive material and a layer made of an insulating material;
A first conductive pattern;
A second conductive pattern configured in a spiral shape swirling around the first conductive pattern;
A resistor connected to both ends of the second conductive pattern and constituting a closed circuit with the second conductive pattern;
Noise filter with   The noise filter according to claim 1, wherein the laminate is a multilayer printed board.   The noise filter according to claim 1, wherein the stacked body is an integrated circuit.   4. The insulating material according to claim 1, wherein a portion of the insulating material interposed between the first conductive pattern and the second conductive pattern is made of a magnetic insulating material. The noise filter according to one item. The noise filter according to any one of claims 1 to 4, wherein a cutoff frequency of an electric signal propagating through the first conductive pattern is adjusted by an electric resistance value of the resistor.   A control device comprising the noise filter according to any one of claims 1 to 5.   The control device according to claim 6, wherein the control device controls an operation of the vehicle.

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