High power shunt switch with high isolation and ease of assembly
View Patent ↗A high power shunt switch comprises a leadframe including a paddle for supporting a shunt element, and a plurality of bond pads located around a periphery of the paddle, wherein at least a first subset of the bond pads are aligned in a substantially straight-line configuration. A shunt element is fixedly attached to the paddle and wire bonded to a top surface of one the bond pads. An encapsulant is disposed on the paddle, the shunt element, the plurality of bond pads, and the wire bond, thereby forming an encapsulated package structure. The package structure is positioned and attached to a transmission line such that the bottom surfaces of each of the at least first subset of bond pads are in simultaneous contact with the transmission line. The package structure and the transmission line are fixedly attached to a suitable substrate.
1. A high power shunt switch comprising:
a leadframe including paddle for supporting a shunt element, and a plurality of bond pads located around a periphery of the paddle, wherein at least a first subset of the bond pads are aligned in a substantially straight-line configuration;
a shunt element fixedly attached to the paddle;
a wire bond for connecting the shunt element to a top surface of one the at least first subset of bond pads;
an encapsulant disposed on the paddle, the shunt element, the plurality of bond pads, and the wire bond, thereby forming a package structure; and
a transmission line attached to bottom surfaces of each of the at least first subset of bond pads, thereby forming an electrical connection between the shunt element and the transmission line, wherein the transmission line and package structure are fixedly attached to a suitable substrate.
2. The shunt switch of claim 1 , wherein the package structure is one of a plastic quad flat no lead (PQFN) package, a land grid array (LGA) package and a ball grid array (BGA) package.
3. The shunt switch of claim 1 , wherein the shunt element is a PIN diode.
4. The shunt switch of claim 1 , wherein the shunt element is a NIP diode.
5. The shunt switch of claim 1 , wherein the shunt element is a field effect transistor (FET).
6. The shunt switch of claim 1 , wherein the shunt element is a metal-semiconductor FET (MESFET).
7. The shunt switch of claim 1 , wherein the transmission line is a grounded coplanar waveguide transmission line.
8. The shunt switch of claim 1 , wherein the transmission line is a microstrip line.
9. The shunt switch of claim 1 , wherein the shunt element is a multi-diode element comprising multiple diodes, the shunt switch element further comprising:
a plurality of wire bonds, one each for connecting each diode element to a corresponding one of the at least first subset of bond pads.
10. The shunt switch of claim 1 , wherein the paddle extends from one end of the package structure to another end of the package structure, and wherein the at least first subset of bond pads is located on one side of the paddle.
11. The shunt switch of claim 1 , wherein the plurality of bond pads includes eight (8) bond pads, four (4) of which comprise the at least first subset of bond pads.
12. The shunt switch of claim 1 , wherein a bottom surface of the package structure defines a dielectric gap, said dielectric gap being located between the bottom surfaces of the bond pads connected to the transmission line and a bottom surface of the paddle.
13. The shunt switch of claim 12 , wherein the package structure is attached to the substrate by reflow soldering the package structure to a ground plain defined on said substrate.
14. The shunt switch of claim 13 , further comprising a plurality of package structures, wherein each of the plurality of package structures is positioned and attached to the transmission line at an electrical length from another of the plurality of package structures.
15. The shunt switch of claim 14 , wherein at least one of the package structures comprises a multi-diode element, said at least one package structure further comprising:
a plurality of wire bonds, one each for connecting each of the multi-diode elements to a corresponding one of the at least first subset of bond pads.
16. The shunt switch of claim 15 , wherein at least one of the package structures comprises eight (8) paddles, four of which comprise the at least first subset of bond pads corresponding to said at least one package structure.
17. The shunt switch of claim 16 , wherein the plurality of package structures are attached to the substrate by reflow soldering the package structures to a ground plain defined on said substrate.