HIGH POWER UHF SINGLE-POLE MULTI-THROW SWITCH

• US 20100289597A1
• Filed: 05/18/2009
• Published: 11/18/2010
• Est. Priority Date: 05/18/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Long, Robert S., Lopacki, John C., Wolfe, Allen R.
• Granted Patent: US 8,049,574 B2
• Time in Patent Office: Days
• US Class Current: 333/104
• CPC Class Codes: H01P 1/15 by semiconductor devices
• CPC Class Codes: H01P 5/12 Coupling devices having more than two ports H01P5/04 takes precedence

Abstract

A single pole multiple-throw switch for switching an RF signal to one of a plurality of outputs includes coupling the signal to a throw junction, said junction having connected thereto a plurality of switch legs, each leg includes a high voltage shunt diode spaced one quarter-wavelength from the throw junction; each diode mounted at its cathode end to a capacitor and adapted to receive a bias; wherein a controller applies a first DC bias to a selected one of the diodes to cause the selected diode to operate in reverse bias mode, such that the selected diode mounted on the corresponding capacitor provides a low insertion loss to pass the RF signal from the transmission line through the selected leg and to one of the outputs; and applies a second DC bias to the other diodes to cause the other diodes to operate in forward bias mode such that the other diodes mounted onto the corresponding capacitor provides a high insertion loss for blocking the RF signal to the remaining outputs.

Claims

1. A single pole multiple-throw microwave switch for selectively switching an RF signal to one of a plurality of output ports comprising:

a transmission line for coupling the signal to a throw junction, said throw junction having connected thereto a plurality of switch legs, each said leg including a high voltage shunt diode spaced about one quarter-wavelength from the throw junction;

each said diode mounted at its cathode end to a corresponding DC blocking capacitor and adapted to receive a bias voltage;

a controller that applies a first DC bias voltage to a selected one of the shunt diodes to cause the selected shunt diode to operate in a reverse bias mode and applies a second DC bias voltage to the other shunt diodes to cause the other shunt diodes to operate in a forward bias mode such that the selected shunt diode mounted on the corresponding capacitor provides a low insertion loss to pass the signal from the transmission line through a selected leg and to a selected output port; and

wherein the other shunt diodes provide a high insertion loss for blocking the signal from the transmission line to the remaining plurality of output ports.

2. The switch of claim 1, wherein shunt lines connect to the transmission line providing a DC path for current flowing through the other shunt diodes.

3. The switch of claim 2, wherein each shunt line includes a series inductor.

4. The switch of claim 1, wherein the shunt diode is a PIN diode.

5. The switch of claim 1, wherein the shunt diode connects to a node that joins an input inductor and an output inductor.

6. The switch of claim 5, wherein a transmission line joins the input inductor to the throw junction.

7. The switch of claim 5, wherein the input inductor and the output inductor are distributed inductors.

8. The switch of claim 6, wherein the the shunt lines are in parallel and feed the junction to extend bandwidth of said switch.

9. The switch of claim 1, wherein the controller includes a digital control and an associated switch driver to apply one of either a positive or negative DC bias to each leg of the single pole switch dependent upon the state of the controller.

10. A single-pole multi-throw microwave assembly for switching an RF signal from an input port to a selected one of a plurality of output ports comprising:

a conductive housing;

an RF circuit mounted in electrical isolation on one side of said housing;

a controller circuit in electrical isolation mounted on an opposite side of said housing;

said RF circuit including a throw junction attached to a plurality of switch legs, each of said switch legs attached to a corresponding single shunt silicon PIN diode having an anode connected to and spaced about ¼

-wavelength from the throw junction, wherein said PIN diode includes a cathode that connects to the controller circuit for applying a DC bias and further mounts in electrical contact to an upper plate of a capacitor; and

wherein said capacitor includes a lower plate in electrical contact to the housing; and

each of said switch legs further attaches to the output for providing a low impedance connection between the input port and the selected one of the plurality of output ports dependent upon the controller for applying a DC bias.

11. The assembly of claim 10, wherein the RF circuit further includes a transmission line from an RF source to the throw junction.

12. The assembly of claim 10, wherein the power capacity of the assembly is in the range of 10-25 kW.

13. The assembly of claim 10, wherein said PIN diode is contained in a diode package wherein said package mounts to said capacitor in a sub assembly that mounts in electrical contact with the housing.

14. The assembly of claim 13, wherein the capacitor includes an upper plate attached to an upper portion of the capacitor package.

15. The assembly of claim 14, wherein the capacitor includes a lower plate attached to a lower portion of the capacitor package.

16. The assembly of claim 14, wherein the PIN includes a cathode attached to an upper portion of the capacitor package.

17. The assembly of claim 16, wherein a mount attaches the PIN diode cathode to the upper portion of the capacitor package.

18. The assembly of claim 15, wherein the capacitor the lower portion of the capacitor package mounts to electrical ground.

19. The assembly of claim 18, wherein the attachment of the PIN diode cathode to the capacitor tunes out diode parasitics and resonates out the diode package inductance.

20. The assembly of claim 10, wherein the switch, the controller circuit includes a digital control and switch driver.