JP2018078175A - Implementation structure of common mode noise filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an implementation structure of a common mode noise filter that can be applied to both of a C-PHY standard and a D-PHY standard.SOLUTION: An implementation structure of a common mode noise filter according to the present invention comprises: a laminated body 14 including a first coil 11, a second coil 12, and a third coil 13 being independent each other; and a first-sixth external electrodes 11a, 11b, 12a, 12b, 13a, 13b connected respectively to both ends of the first-third coils 11-13, and each of distances between the first-third coils 11-13 is almost same, each length of the first-third coils 11-13 is almost same, and the first-fourth external electrodes 11a, 11b, 12a, 12b respectively connected to both ends of the first and the second coils 11, 12 are connected to two transmission lines 17, 18 connecting a camera module 16 to a main IC 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a small and thin common mode noise filter mounting structure used in various electronic devices such as digital devices, AV devices, and information communication terminals.

  Conventionally, the mobile industry processor interface (mpi) D-PHY standard has been adopted as a digital data transmission standard for connecting a main IC to a display or a camera in a mobile device, and the differential signal is transmitted using two transmission lines. The method is used. In recent years, the resolution of cameras has dramatically increased, and as a faster transmission method, three transmission lines are used to send different voltages from the transmission side to each transmission line, and the reception side takes the difference between each line. A differential output system is established as the mipiC-PHY standard and put into practical use.

  A conventional common mode noise filter of this type includes a laminated body 1 including three independent coils that are magnetically coupled to each other, and a plurality of external electrodes 2 that are respectively connected to both ends of each coil.

  Then, as shown in FIG. 20, a mounting structure in which each external electrode 2 is connected to three transmission lines 5 that connect the main IC 3 and a camera module 4 such as a display or a camera, and conforms to the C-PHY standard. An applicable common mode noise filter was provided.

  As a prior art document related to the invention of this application, for example, Patent Document 1 is known.

JP 2003-77727 A

  The camera module 4 such as a camera incorporates an image sensor that can output signals of both C-PHY standard and D-PHY standard. Depending on the customer's set design requirements, it is determined whether the signal is transmitted with a D-PHY standard signal as shown in FIG. 21 or the C-PHY standard signal, so that it may be applied to both transmission methods.

  However, the above-described conventional common mode noise filter mounting structure has a problem that both the C-PHY standard and D-PHY standard transmission methods cannot be shared by one component.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a common mode noise filter mounting structure applicable to both the C-PHY standard and the D-PHY standard.

In order to solve the above-mentioned object, the present invention is connected to the laminated body including the first coil, the second coil, and the third coil independent from each other, and both ends of the first to third coils. First to sixth external electrodes, the distances between the first to third coils being substantially the same,
The first to third coils have substantially the same length, and the first to fourth external electrodes respectively connected to both ends of the first and second coils are connected to the main IC and the camera module. And at least one of the fifth and sixth external electrodes connected to both ends of the third coil is not directly connected to the ground, and both or one of the fifth and sixth external electrodes is connected. The mounting structure is connected to the ground via an element such as a capacitor.

  The mounting structure of the common mode noise filter of the present invention can correspond to the transmission system of the C-PHY standard in a camera camera module or the like, and when a D-PHY standard signal is output, The second coil can transmit a D-PHY standard signal through two transmission lines, and can eliminate common mode noise generated in the two transmission lines.

  Further, when used for the D-PHY standard, in the mounting structure of the present invention, when common mode noise enters, the third coil that is not connected to the transmission line is the first coil and the second coil. Since the strengthening magnetic coupling is not hindered, the attenuation amount of the common mode noise at a specific frequency is increased, thereby improving the common mode noise removal characteristics.

  Further, at least one of the fifth and sixth external electrodes connected to the third coil 13 is not directly connected to the ground, and both or one of the fifth and sixth external electrodes is connected to an element such as a capacitor. By connecting to the ground, the attenuation characteristic of the common mode noise can be adjusted without deteriorating the loss characteristic of the differential signal.

The figure which shows the mounting structure of the common mode noise filter in Embodiment 1 of this invention Schematic diagram of the common mode noise filter The figure which shows the typical example of the attenuation characteristic of the common mode noise and the differential signal at the time of using with the C-PHY standard of the common mode noise filter The figure which shows the attenuation characteristic of the common mode noise and the differential signal when the signal of D-PHY standard is output with the mounting structure of the common mode noise filter Schematic diagram of a common mode noise filter in which the fifth and sixth external electrodes connected to the third coil are directly connected to the ground. The figure which shows the attenuation characteristic of the common mode noise when the signal of D-PHY standard is output in FIG. 5, and a differential signal The figure which shows the mounting structure of the other example of the common mode noise filter in Embodiment 1 of this invention The figure which shows the attenuation characteristic of the common mode noise and the differential signal when the signal of D-PHY standard is output in FIG. The figure which shows the mounting structure of the other example of the common mode noise filter in Embodiment 1 of this invention The figure which shows the mounting structure of the other example of the common mode noise filter The figure which shows the attenuation characteristic of the common mode noise and the differential signal when the signal of D-PHY standard is output in FIG. The figure which shows the mounting structure of the other example of the common mode noise filter in Embodiment 1 of this invention The figure which shows the mounting structure of the other example of the common mode noise filter The figure which shows the mounting structure of the other example of the common mode noise filter The figure which shows the mounting structure of the common mode noise filter in Embodiment 2 of this invention The figure which shows the attenuation characteristic of the common mode noise and the differential signal when the signal of D-PHY standard is output with the mounting structure of the common mode noise filter The figure which shows the mounting structure of the other example of the common mode noise filter in Embodiment 2 of this invention The figure which shows the mounting structure of the other example of the common mode noise filter The figure which shows the mounting structure of the other example of the common mode noise filter Diagram showing mounting structure of conventional common mode noise filter Diagram showing the mounting structure of the common mode noise filter

(Embodiment 1)
FIG. 1 is a diagram showing a mounting structure of a common mode noise filter according to Embodiment 1 of the present invention, and FIG. 2 is a schematic diagram of the common mode noise filter.

  As shown in FIG. 2, the common mode noise filter according to the first exemplary embodiment of the present invention includes a laminated body 14 including a first coil 11, a second coil 12, and a third coil 13 that are magnetically coupled to each other and are independent. And first to sixth external electrodes 11a, 11b, 12a, 12b, 13a, 13b connected to both ends of the first to third coils 11-13, respectively.

  Further, as shown in FIG. 1, the mounting structure is connected to first and second external electrodes 11 a and 11 b connected to both ends of the first coil 11 and to both ends of the second coil 12. The third and fourth external electrodes 12a and 12b are respectively connected to two transmission lines 17 and 18 that connect the main IC 15 and a camera module 16 such as a display or a camera. The fifth and sixth external electrodes 13a and 13b connected to both ends of the third coil 13 are not connected to an external transmission line. The main IC 15 and the camera module 16 are connected via two transmission lines 17 and 18 connected in series and the first and second coils 11 and 12.

  FIG. 1 shows a case where the transmission line is used as a D-PHY standard using two transmission lines 17 and 18. In the present invention, there are two transmission lines 17 to 19, respectively, and common mode noise is present. The two filters are shown. The two transmission lines 17 to 19 and the two common mode noise filters have the same positional relationship and wiring. When used as the C-PHY standard, another transmission line (transmission line of the camera module 16) 19 and the fifth and sixth external electrodes 13a and 13b are connected as shown in FIG.

  The first coil 11, the second coil 12, and the third coil 13 are formed in a spiral shape or a spiral shape, and the distance between the coils is substantially equal, and the lengths of the respective coils are also substantially equal. Therefore, the magnetic coupling of the first, second, and third coils 11, 12, and 13 is well balanced, and the first, second, and third coils 11, 12, and 13 are generated between each other. Therefore, it is possible to prevent the deterioration of the C-PHY differential signal.

  As described above, in the common mode noise filter mounting structure according to the first embodiment of the present invention, when common mode noise enters the C-PHY standard transmission system mounting structure (structure as shown in FIG. 20). 3 strengthens the magnetic fields generated in the three transmission lines 17 to 19 by the first to third coils 11, 12 and 13, generates a high impedance, and reduces the common mode noise attenuation as shown in FIG. 3. Can be obtained.

Further, when a D-PHY standard signal is output from the camera module 16 or the like, common mode noise generated in the two transmission lines 17 and 18 by the first coil 11 and the second coil 12 can be removed. Furthermore, since the third coil 13 adjacent to the first coil 11 and the second coil 12 does not inhibit the strengthening magnetic coupling between the first coil 11 and the second coil 12, it is due to stronger magnetic coupling. Since a high impedance can be obtained, the attenuation amount of the common mode noise is increased, thereby obtaining an effect of improving the common mode noise removal characteristics.

  FIG. 4 shows the attenuation characteristics of the common mode noise and the differential signal when the D-PHY standard signal is output in the common mode noise filter mounting structure according to the first embodiment of the present invention shown in FIG. It can be seen that the attenuation of common mode noise increases, but the differential signal does not deteriorate.

  On the other hand, as shown in FIG. 5, when the fifth and sixth external electrodes 13a and 13b connected to the third coil 13 are directly connected to the ground, the first coil 11 is detected when common mode noise enters. The third coil 13, which is a ground wire wired in parallel to the first coil 11 and the second coil 12, forms a closed circuit of the ground and magnetically shields the magnetic coupling between the first coil 11 and the second coil 12. As a result, the magnetic coupling between the first coil 11 and the second coil 12 cannot be strengthened, whereby a high impedance cannot be obtained, and the ability to remove common mode noise is impaired.

  FIG. 6 shows the attenuation characteristics of common mode noise and differential signals when a D-PHY standard signal is output in the mounting structure shown in FIG. It can be seen that the attenuation of the common mode noise is significantly reduced.

  Furthermore, in the differential data transmission of the D-PHY standard, the fifth and sixth external electrodes 13a and 13b that are connected to the third coil 13 that is not used for the differential data transmission (not connected to the external transmission line). By connecting to both or one of them with an element or ground as described below, the attenuation characteristic of the common mode noise can be adjusted without deteriorating the loss characteristic of the differential signal.

  As shown in FIG. 7, the fifth external electrode 13a connected to one end of the third coil 13 is connected to the transmission line 19 of the other camera module 16, and this transmission line 19 is connected to the ground. You may let them. In such a configuration, when common mode noise enters, the high frequency common mode noise is grounded by the capacitive component generated between the first coil 11 or the second coil 12 and the third coil 13. Therefore, as shown in FIG. 8, it is possible to improve the attenuation characteristics of common mode noise in a higher frequency region, and it is also possible to attenuate common mode noise in a wide frequency band. .

  Furthermore, as shown in FIG. 9, if the fifth external electrode 13a is directly connected to the ground, in addition to the above effects, common mode noise can be released to the ground side of the mounting substrate on the main IC 15 side. In addition, if the ground on the camera module 16 side and the ground on the main IC 15 side are connected with an impedance element including a magnetic material such as ferrite to separate the ground in the high frequency region, the flexible connected to the camera module 16 side is possible. There is an effect that noise emission from the flexible cable can be further reduced without noise flowing back to the cable ground line.

  As shown in FIG. 10, a capacitor C1 may be connected between the ground and the fifth external electrode 13a. By adjusting the capacitance of the capacitor C1, the ground connection of the third coil 13 can be made frequency dependent, so that the frequency of the attenuation pole can be adjusted.

  FIG. 11 shows the attenuation characteristics of common mode noise and differential signals when a D-PHY standard signal is output when the capacitance of the capacitor C1 is set to a predetermined value in the mounting structure shown in FIG. By adjusting the attenuation pole of the common mode noise that appeared in the vicinity of 2 GHz in FIG. 8 to the vicinity of 3 GHz, a wideband common mode noise characteristic can be obtained. When the capacitance of the capacitor C1 is changed, the frequency which becomes another attenuation pole different from the attenuation pole in the vicinity of 1 GHz can be changed and adjusted.

  Further, as shown in FIG. 12, an inductor L1 may be further connected between the ground and the fifth external electrode 13a. Since the frequency characteristic and the resonance frequency of the capacitor C1 vary, an attenuation pole can be formed in a lower frequency region, whereby common mode noise can be attenuated in a wide frequency band even in a low frequency region.

  Further, as shown in FIG. 13, when the fifth external electrode 13a is connected to the ground via the capacitor C1, the sixth external electrode 13b connected to the other end of the third coil 13 is You may connect directly to ground.

  In the configuration of FIG. 13, a resistor R1 may be connected between the sixth external electrode 13b and the ground, as shown in FIG. Since the anti-resonance point generated between the first attenuation pole and the second attenuation pole of the common mode noise attenuation characteristic can be suppressed, common mode noise can be attenuated in a wide frequency band.

(Embodiment 2)
FIG. 15 is a diagram showing a mounting structure of the common mode noise filter according to the second embodiment of the present invention. In the second embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The second embodiment of the present invention is different from the first embodiment of the present invention described above in that a stub (open stub) 20 is connected to the fifth external electrode 13a as shown in FIG.

  In the mounting structure shown in FIG. 15, a plurality of attenuation poles can be obtained in the high frequency band due to the frequency dependence of the impedance of the stub 20, that is, the periodicity viewed from the frequency axis.

  FIG. 16 shows the attenuation characteristics of the common mode noise and the differential signal when the D-PHY standard signal is output in the common mode noise filter mounting structure according to the second embodiment of the present invention shown in FIG. It can be seen that a plurality of attenuation poles appear due to the common mode noise in the high frequency band.

  In addition, as shown in FIG. 17, a short stub 20 a in which a ground is connected to the tip of the stub 20 may be formed. In addition to the effects of FIG. 15, an attenuation pole can be obtained even in a low frequency band.

  In the configuration of FIG. 15, as shown in FIG. 18, a ground may be further connected to the sixth external electrode 13b. A plurality of attenuation poles can be obtained in the high frequency band, and attenuation poles can also be obtained in the low frequency band.

  Furthermore, as shown in FIG. 19, a resistor R2 may be connected between the sixth external electrode 13b and the ground. Since the anti-resonance point generated between the poles where the attenuation is large can be suppressed, the common mode noise can be attenuated in a wide frequency band.

The connection of the stubs 20 and 20a shown in FIGS. 15 to 19 eliminates the need for external components.

  Moreover, the frequency used as an attenuation pole can be adjusted by adjusting the length of the stubs 20 and 20a.

  The stubs 20 and 20a can be adjusted to a length effective for noise by using the wiring pattern of the transmission path as it is.

  As shown in FIGS. 3, 4, 8, 11, and 16, the mounting structure of the common mode noise filter in the first and second embodiments of the present invention is the fifth and sixth external electrodes 13a. Even if the connection to 13b is changed, there is little influence on the magnetic coupling of the first coil 11 and the second coil 12, and the loss characteristics in the differential mode hardly change, and the D-PHY standard differential The common mode noise attenuation characteristic can be adjusted according to the common mode noise situation of the electronic device without degrading the signal.

  In FIGS. 13, 14, 18, and 19, the ground connected to the sixth external electrode 13b and the ground connected to the camera module 16 may be shared as shown in FIG. In the case of the embodiment in which the sixth external electrode 13b is opened as typified by FIG. 9, the same applies even when the fifth external electrode 13a is open and the sixth external electrode 13b is connected to the element or the ground. An effect is obtained.

  Further, the 6-terminal filter adapted to the C-PHY standard 3-wire set has been described. However, an array type that is a 12-terminal filter adapted to the C-PHY standard 3-wire 2-pair may be used.

  Further, in the first and second embodiments, examples of the camera module 16 and the main IC 15 are shown. However, the main IC 15 and a device conforming to the MIPI C-PHY standard and D-PHY standard as represented by the display. This also applies to transmission between.

  And each structure of the 1st coil 11, the 2nd coil 12, and the 3rd coil 13 is what connected two or more coil conductors in series, or what connected two or more coil conductors in parallel It may be composed of

  The mounting structure of the common mode noise filter according to the present invention has an effect that it can be applied to both the C-PHY standard and the D-PHY standard, and is used particularly for digital devices, AV devices, information communication terminals, and the like. This is useful in a small and thin common mode noise filter or the like.

11 1st coil 11a 1st external electrode 11b 2nd external electrode 12 2nd coil 12a 3rd external electrode 12b 4th external electrode 13 3rd coil 13a 5th external electrode 13b 6th external Electrode 14 Laminate 15 Main IC
16 Camera module 17, 18 Transmission line 19 Camera module transmission line 20, 20a Stub

Claims (12)

A laminated body including a first coil, a second coil, and a third coil independent from each other, and first to sixth external electrodes respectively connected to both end portions of the first to third coils. The first to third coils have substantially the same distance from each other, the first to third coils have substantially the same length, and both ends of the first and second coils are respectively A mounting structure of a common mode noise filter in which the connected first to fourth external electrodes are connected to a transmission line connecting a main IC and a camera module. The mounting structure for a common mode noise filter according to claim 1, wherein the fifth and sixth external electrodes connected to both ends of the third coil are not connected to the transmission line. The fifth external electrode connected to one end of the third coil is connected to a transmission line connected to the camera module, and a ground is connected between the fifth external electrode and the transmission line. The mounting structure of the common mode noise filter according to claim 1. The mounting structure for a common mode noise filter according to claim 1, wherein the fifth external electrode connected to one end of the third coil is directly connected to the ground. 5. The common mode noise filter mounting structure according to claim 4, wherein a capacitor is connected between the fifth external electrode and the ground. 6. The common mode noise filter mounting structure according to claim 5, wherein an inductor is connected between the fifth external electrode and the ground. The mounting structure for a common mode noise filter according to claim 5, wherein the sixth external electrode connected to the other end of the third coil is directly connected to the ground. The mounting structure of the common mode noise filter according to claim 7, wherein a resistor is connected between the sixth external electrode and the ground. The mounting structure for a common mode noise filter according to claim 1, wherein the fifth external electrode connected to one end of the third coil is connected to an open stub. The mounting structure for a common mode noise filter according to claim 9, wherein the sixth external electrode connected to the other end of the third coil is directly connected to the ground. The mounting structure of the common mode noise filter according to claim 10, wherein a resistor is connected between the sixth external electrode and the ground. The mounting structure for a common mode noise filter according to claim 9, wherein a ground is connected to a tip of the open stub.