Identification system reader with multiplexed antennas

• US 6,118,189 A
• Filed: 11/06/1997
• Issued: 09/12/2000
• Est. Priority Date: 04/28/1995
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Flaxl, Thomas J.
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US08/965,081
• Time in Patent Office: 1,041 Days
• Field of Search: 307/112, 307/113, 307/116, 307/125, 307/126, 307/130, 307/139, 307/140, 307/141.8, 327/436, 327/482, 327/488, 327/416, 327/427, 327/108, 327/109-110, 323/349, 323/350
• US Class Current: 307/112
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching

Abstract

An electronic system 8 is disclosed herein. The system includes circuitry 10 for processing a signal and a plurality of antennas 12a-12b. A plurality of switches 22a-22b are also included. Each of the switches 22a-22b is coupled between the processing circuitry 10 and a corresponding one of the antennas 12a-12b. Each of the switches 22a-22b includes first and second power MOSFETs where the source of the first MOSFET is coupled to the source of the second MOSFET. The system further includes circuitry 28 for selecting of one of the plurality of switches 22a-22b to be on.

Claims

1. A switching circuit for coupling a first node to a second node, said switching circuit comprising:

a driver circuit which is floating;

a first transistor, having a source, a gate and a drain, with one control node coupled to the output of said driver circuit; and

a second transistor, having a source, a gate and a drain, with an other control node coupled to said output of said driver circuit and wherein said sources of said first and second transistors are coupled together and are floating and form said one of said control nodes coupled to said output of said driver circuit and said gates of said first and second transistors are coupled together and form the other of said control nodes coupled to said output of said driver circuit; and

wherein said first and second transistors are coupled in series so as to create a current path from a first node to a second node when said output of said driver circuit is at a first voltage level.

2. The circuit of claim 1 wherein said first and second transistors each comprise MOS transistors.

3. The circuit of claim 2 wherein said first and second transistors each comprise n-channel MOS transistors.

4. The circuit of claim 2 wherein said first transistor has a source coupled to a source of said second transistor.

5. The circuit of claim 1 wherein said first and second transistors comprise power transistors.

6. The circuit of claim 5 wherein said first transistor has a source coupled to a source of said second transistor.

7. The circuit of claim 1 wherein said first node is coupled to an antenna.