MEMS millimeter wave switches

Abstract

An RF switch useable up to millimeter wave frequencies and higher frequencies of 30 GHz and above. Four embodiments of the invention are configured as ground switches. Two of the ground switch embodiments are configured with a planar air bridge. Both of these embodiments are configured so that the bridge length is shortened between the transmission line and ground by introducing grounded stops. The other two ground switch embodiments include an elevated metal seesaw. In these embodiments, a shortened path to ground is provided with relatively low inductance by proper sizing and positioning of the seesaw structure. Lastly, broadband power switch embodiment is configured to utilize only a small portion of the air bridge to carry the signal. The relatively short path length results in a relatively low inductance and resistance lowers the RF power loss of the switch, thereby increasing the RF power handling capability of the switch.

What is claimed and desired to be covered by a Letters Patent is as follows: 
     
       1. A ground switch for use in millimeter wave applications, the grounding switch comprising:
 a transmission line defining an RF input and an RF output at opposing ends;   an RF contact formed on said transmission line;   one or more ground contacts adapted to be connected to ground, spaced apart from said transmission line and an air bridge, for grounding said transmission line;   an air bridge beam formed adjacent said transmission line, said air bridge beam rigidly connected to a substrate at each end, said beam spaced away from said RF contact and said one or more ground contacts in an at rest position and configured to contact said RF contact and said one or more ground contacts in an actuated position; and   one or more control pads disposed adjacent said transmission line, said one or more control pads adapted to receive biasing voltage to cause said beam to deflect to said actuated position.   
     
     
       2. The ground switch as recited in  claim 1 , wherein said air bridge is generally transverse to said transmission line. 
     
     
       3. The ground switch as recited in  claim 2 , wherein said RF ground contact is formed on said transmission line. 
     
     
       4. The ground switch as recited in  claim 3 , wherein said air bridge beam is formed above said transmission line. 
     
     
       5. The ground switch as recited in  claim 4  A ground switch for use in millimeter wave applications, the ground switch comprising:
 a continuous transmission line defining an RF input and an RF output at opposing ends; 
 an RF contact formed on said transmission line between the RF input and RF output; 
 one or more ground contacts adapted to be connected to ground, spaced apart from said transmission line and an air bridge, for grounding said transmission line; 
 an air bridge beam having a metal portion and formed adjacent said transmission line, said air bridge beam rigidly connected to a substrate at each end, said beam spaced away from said RF contact and said one or more ground contacts in an at rest position and configured so that the metal portion of the air bridge beam makes contact with said RF contact and said one or more ground contacts in an actuated position to form an RF conductive path to ground for the RF contact; and 
 one or more control pads disposed adjacent said transmission line, said one or more control pads adapted to receive biasing voltage to cause said beam to deflect to said actuated position, 
 wherein said one or more ground contacts are formed on the same side of said air bridge beam as said RF contact. 
 
     
     
       6. The ground switch as recited in claim  1  5, wherein said air bridge beam is generally parallel to said transmission line. 
     
     
       7. The ground switch as recited in  claim 6 , A ground switch for use in millimeter wave applications, the ground switch comprising:
 a continuous transmission line defining an RF input and an RF output at opposing ends; 
 an RF contact formed on said transmission line between the RF input and RF output; 
 one or more ground contacts adapted to be connected to ground, spaced apart from said transmission line and an air bridge, for grounding said transmission line; 
 an air bridge beam having a metal portion and formed adjacent said transmission line, said air bridge beam rigidly connected to a substrate at each end, said beam spaced away from said RF contact and said one or more ground contacts in an at rest position and configured so that the metal portion of the air bridge beam makes contact with said RF contact and said one or more ground contacts in an actuated position to form an RF conductive path to ground for the RF contact; and 
 one or more control pads disposed adjacent said transmission line, said one or more control pads adapted to receive biasing voltage to cause said beam to deflect to said actuated position, 
 wherein said RF contact and said one or more ground contacts are formed on opposing sides of said air bridge beam. 
 
     
     
       8. The ground switch as recited in  claim 1 , wherein at least two or more control pads are provided. 
     
     
       9. The ground switch as recited in  claim 8 , A ground switch for use in millimeter wave applications, the ground switch comprising:
 a continuous transmission line defining an RF input and an RF output at opposing ends; 
 an RF contact formed on said transmission line between the RF input and RF output; 
 one or more ground contacts adapted to be connected to ground, spaced apart from said transmission line and an air bridge, for grounding said transmission line; 
 an air bridge beam having a metal portion and formed adjacent said transmission line, said air bridge beam rigidly connected to a substrate at each end, said beam spaced away from said RF contact and said one or more ground contacts in an at rest position and configured so that the metal portion of the air bridge beam makes contact with said RF contact and said one or more ground contacts in an actuated position to form an RF conductive path to ground for the RF contact; and 
 one or more control pads disposed adjacent said transmission line, said one or more control pads adapted to receive biasing voltage to cause said beam to deflect to said actuated position, 
 wherein said control pads are formed on at least one side of said air bridged bridge beam. 
 
     
     
       10. The ground switch as recited in  claim 8 , wherein said control pads are formed on both sides of said air bridged beam. 
     
     
       11. The ground switch of claim 5 wherein the air bridge beam comprises a layer of movable metal and the RF contact extends outwardly from said transmission line. 
     
     
       12. The ground switch of claim 7 wherein the air bridge beam comprises a layer of movable metal and the RF contact extends outwardly from said transmission line. 
     
     
       13. The ground switch of claim 9 wherein the air bridge beam comprises a layer of movable metal and the RF contact extends outwardly from said transmission line. 
     
     
       14. The ground switch of claim 5 wherein the air bridge beam deforms in the actuated position so that an intermediate portion of the air bridge beam bends towards the transmission line. 
     
     
       15. The ground switch of claim 7 wherein the air bridge beam deforms in the actuated position so that an intermediate portion of the air bridge beam bends towards the transmission line. 
     
     
       16. The ground switch of claim 9 wherein the air bridge beam deforms in the actuated position so that an intermediate portion of the air bridge beam bends towards the transmission line. 
     
     
       17. The ground switch of claim 5 wherein the air bridge beam is disposed to move as a seesaw from the at rest position to the actuated position. 
     
     
       18. The ground switch of claim 7 wherein the air bridge beam is disposed to move as a seesaw from the at rest position to the actuated position. 
     
     
       19. The ground switch of claim 9 wherein the air bridge beam is disposed to move as a seesaw from the at rest position to the actuated position. 
     
     
       20. The ground switch recited in claim 5, wherein said air bridge beam is generally transverse to said transmission line. 
     
     
       21. The ground switch recited in claim 7, wherein said air bridge beam is generally transverse to said transmission line. 
     
     
       22. The ground switch recited in claim 9, wherein said air bridge beam is generally transverse to said transmission line.