Semiconductor package having an isolation wall to reduce electromagnetic coupling
A system and method for packaging a semiconductor device that includes a wall to reduce electromagnetic coupling is presented. A semiconductor device has a substrate on which a first circuit and a second circuit are formed proximate to each other. An isolation wall of electrically conductive material is located between the first circuit and the second circuit, the isolation wall being configured to reduce inductive coupling between the first and second circuits during an operation of the semiconductor device. Several types of isolation walls are presented.
1. A method of fabricating a semiconductor device, the method comprising:
forming a first circuit on a substrate;
forming a second circuit on a substrate adjacent to the first circuit;
forming a lead frame from an electrically conductive sheet, wherein the lead frame includes first and second leads within a plane of the electrically conductive sheet and a wall section that is transverse to the plane of the electrically conductive sheet;
electrically coupling the first circuit to the first lead with a first wire bond array;
electrically coupling the second circuit to the second lead with a second wire bond array; and
locating the wall section between the first circuit and the second circuit, the wall section extending above a height of the first and second wire bond arrays, and the wall section being configured to reduce electromagnetic coupling between the first circuit and the second circuit during an operation of the semiconductor device.
2. The method as recited in claim 1 , wherein the wall section initially is within the plane of the electrically conductive sheet, and the method further comprises bending the wall section transverse to the plane of the electrically conductive sheet.
3. The method as recited in claim 1 , wherein the wall section is connected by a link to a remainder of the lead frame and the link is bent so that the wall section is transverse to the remainder of the lead frame.
4. The method as recited in claim 1 , wherein the wall section is formed of electrically conductive material.
5. The method as recited in claim 1 , further comprising electrically connecting the wall section to a ground potential node.
6. The method as recited in claim 5 , wherein electrically connecting the wall section to the ground potential node is performed by one of soldering, brazing, and adhering the wall section to the ground potential node.
7. The method as recited in claim 5 , wherein electrically connecting the wall section to the ground potential node includes receiving the wall section within an aperture in the ground potential node.
8. The method as recited in claim 1 , wherein the first circuit is a carrier amplifier of a Doherty amplifier; and the second circuit is a peaking amplifier of the Doherty amplifier.
9. A method of fabricating a Doherty amplifier, the method comprising:
forming a carrier amplifier on a substrate, the carrier amplifier including a first transistor and a first wire bond array electrically coupled between the first transistor and a first lead;
forming a peaking amplifier on the substrate adjacent to the carrier amplifier, the peaking amplifier including a second transistor and a second wire bond array electrically coupled between the second transistor and a second lead; and
locating an isolation wall formed of electrically conductive material between the carrier amplifier and the peaking amplifier above a surface of the substrate, the isolation wall formed of a body of material that is oriented perpendicular to the surface of the substrate and extending above a height of the first and second wire bond arrays, the isolation wall being configured to reduce an electromagnetic coupling between the carrier amplifier and the peaking amplifier during an operation of the Doherty amplifier, wherein the isolation wall is formed by a section of a lead frame that also includes the first lead and the second lead.
10. The method as recited in claim 9 , wherein the lead frame is formed by an electrically conductive sheet, and the isolation wall is formed by a section of the lead frame that is transverse to a plane of the electrically conductive sheet.
11. The method as recited in claim 10 , wherein the section is connected by a link to a remainder of the lead frame and the method further comprises bending the link so that the section is transverse to the remainder of the lead frame.
12. The method as recited in claim 9 , further comprising electrically connecting the isolation wall to a ground potential node.
13. The method as recited in claim 12 , wherein the isolation wall is electrically connected to the ground potential node by one of solder, brazing material, and adhesive.
14. The method as recited in claim 12 , wherein electrically connecting the isolation wall to a ground potential node comprises receiving the isolation wall within an aperture in the ground potential node.