Apparatus for minimizing electromagnetic coupling between surface mount device inductors
A surface mount device inductor has a package casing sized to attenuate electromagnetic coupling between the inductor coils of the surface mount device inductors. The surface mount device inductor includes an inductor coil, an anode structure disposed over a first end of the inductor coil and a cathode structure disposed over a second end of the inductor coil opposite the first end, the cathode structure being spaced apart from the anode structure. One or both of the anode structure and the cathode structure comprise a shield portion disposed at least partially over the inductor coil to thereby reduce electromagnetic coupling between adjacent surface mount device inductors. The package casing makes the surface mount device inductors self-shielding. The surface mount device inductors can be incorporated into a radiofrequency module, and can be incorporated into a front end system of a wireless mobile device.
1. A surface mount device inductor mountable on a printed circuit board, comprising:
an inductor coil configured to generate a magnetic field along an axis when a current is applied to the inductor coil;
an anode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a first end of the inductor coil, the top wall disposed over at least a portion of the inductor coil; and
a cathode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a second end of the inductor coil opposite the first end, the top wall of the cathode structure disposed over at least another portion of the inductor coil, the cathode structure being spaced apart from the anode structure, the anode structure and the cathode structure including a shield portion disposed at least partially over the inductor coil to thereby reduce electromagnetic coupling, the shield portion of the anode structure and the cathode structure including the top wall thereof and a first portion of the left-side wall and of the right-side wall thereof that extends from the top wall to a location between the top wall and the bottom wall thereof, a second portion of the left-side wall and of the right-side wall thereof that is adjacent the end wall thereof extending from the top wall to the bottom wall thereof.
2. The surface mount device inductor of claim 1 wherein the shield portion is an ungrounded metal portion.
3. The surface mount device inductor of claim 1 wherein the shield portion of one of the anode structure and the cathode structure has a greater length than the shield portion of the other of the anode structure and the cathode structure.
4. The surface mount device inductor of claim 1 wherein the first portion of the left-side wall and of the right-side wall is spaced apart from the printed circuit board.
5. The surface mount device inductor of claim 1 wherein the axis extends transverse to a plane that defines the left-side wall of one or both of the anode structure and the cathode structure.
6. The surface mount device inductor of claim 1 wherein the axis extends transverse to a plane that defines the top wall of one or both of the anode structure and the cathode structure.
7. The surface mount device inductor of claim 1 wherein the anode structure is continuous and the cathode structure is continuous.
8. A radiofrequency module, comprising:
a printed circuit board including a substrate layer; and
one or more surface mount device inductors mounted on the substrate layer, each surface mount device inductor including: an inductor coil configured to generate a magnetic field along an axis when a current is applied to the inductor coil; an anode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a first end of the inductor coil, the top wall disposed over at least a portion of the inductor coil; and a cathode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a second end of the inductor coil opposite the first end, the top wall of the cathode structure disposed over at least another portion of the inductor coil, the cathode structure being spaced apart from the anode structure, the anode structure and the cathode structure including a shield portion disposed at least partially over the inductor coil to thereby reduce electromagnetic coupling, the shield portion of the anode structure and the cathode structure including the top wall thereof and a first portion of the left-side wall and of the right-side wall thereof that extends from the top wall to a location between the top wall and the bottom wall thereof, a second portion of the left-side wall and of the right-side wall thereof that is adjacent the end wall thereof extending from the top wall to the bottom wall thereof.
9. The radiofrequency module of claim 8 wherein the shield portion is an ungrounded metal portion.
10. The radiofrequency module of claim 8 wherein the shield portion of one of the anode structure and the cathode structure has a greater length than the shield portion of the other of the anode structure and the cathode structure.
11. The radiofrequency module of claim 8 wherein the first portion of the left-side wall and of the right-side wall is spaced apart from the substrate layer.
12. The radiofrequency module of claim 8 wherein the axis extends transverse to a plane that defines the left-side wall of one or both of the anode structure and the cathode structure.
13. The radiofrequency module of claim 8 wherein the axis extends transverse to a plane that defines the top wall of one or both of the anode structure and the cathode structure.
14. The radiofrequency module of claim 8 wherein the anode structure is continuous and the cathode structure is continuous.
15. A wireless mobile device comprising:
one or more antennas; and
a front end system that communicates with the one or more antennas, the front end system including one or more surface mount device inductors mounted on a substrate layer, each surface mount device inductor including: an inductor coil configured to generate a magnetic field along an axis when a current is applied to the inductor coil; an anode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a first end of the inductor coil; and a cathode structure having a box-like shape with a top wall, a bottom wall, a left-side wall, a right-side wall and an end wall that at least partially encloses a second end of the inductor coil opposite the first end, the top wall of the cathode structure disposed over at least another portion of the inductor coil, the cathode structure being spaced apart from the anode structure, the anode structure and the cathode structure including a shield portion disposed at least partially over the inductor coil to thereby reduce electromagnetic coupling, the shield portion of the anode structure and the cathode structure including the top wall thereof and a first portion of the left-side wall and of the right-side wall thereof that extends from the top wall to a location between the top wall and the bottom wall thereof, a second portion of the left-side wall and of the right-side wall thereof that is adjacent the end wall thereof extending from the top wall to the bottom wall thereof.
16. The wireless mobile device of claim 15 wherein the shield portion is an ungrounded metal portion.
17. The wireless mobile device of claim 15 wherein the shield portion of one of the anode structure and the cathode structure has a greater length than the shield portion of the other of the anode structure and the cathode structure.
18. The wireless mobile device of claim 15 wherein the first portion of the left-side wall and of the right-side wall is spaced apart from the substrate layer.
19. The wireless mobile device of claim 15 wherein the axis extends transverse to a plane that defines the left-side wall of one or both of the anode structure and the cathode structure.
20. The wireless mobile device of claim 15 wherein the axis extends transverse to a plane that defines the top wall of one or both of the anode structure and the cathode structure.
21. The wireless mobile device of claim 15 wherein the shield portion extends along a height relative to the substrate layer that is smaller than a height of the anode structure and a height of the cathode structure relative to the substrate layer.