Radio frequency data communications device

• US 6,825,773 B1
• Filed: 09/11/1998
• Issued: 11/30/2004
• Est. Priority Date: 05/13/1996
• Status: Expired due to Fees

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Ovard, David K., Tuttle, John R., Rotzoll, Robert R., Tuttle, Mark E., Lowrey, Tyler, Higgins, Brian P., Yu, Shu-Sun, Devereaux, Kevin M., Pax, George E., OʼToole, James E.
• Primary Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US09/152,024
• Time in Patent Office: 2,272 Days
• Field of Search: 340/825.72, 340/10.1, 340/572, 307/498, 370/310, 370/313, 370/311, 370/314, 375/359, 343/702, 455/193.1, 455/126, 342/42, 342/44, 342/51, 333/81.A, 438/570, 422/68.1
• US Class Current: 340/13.25
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G06K 19/0716 at least one of the integrated circuit chips comprising a sensor or an interface to a sensor
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07758 arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10059 transponder driven
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H03L 7/0995 the oscillator comprising a ring oscillator
• CPC Class Codes: H03L 7/148 said digital means comprising a counter or a divider

Abstract

A radio frequency identification device comprises an integrated circuit including a receiver, a transmitter, and a microprocessor. The receiver and transmitter together define an active transponder. The integrated circuit is preferably a monolithic single die integrated circuit including the receiver, the transmitter, and the microprocessor. Because the device includes an active transponder, instead of a transponder which relies on magnetic coupling for power, the device has a much greater range.

Claims

1. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode having first and second terminals, the first terminal being coupled to the antenna; and

a current source directly connected to the second terminal of the Schottky diode to drive current through the antenna and the Schottky diode.

2. A system comprising:

an antenna;

a transponder including an inductorless receiver having a Schottky diode detector including a Schottky diode having a first terminal coupled to the antenna and having a second terminal; and

means for driving current through both the antenna and the Schottky diode in a direction from the first terminal to the second terminal, the driving means being directly connected to the second terminal.

3. A system comprising:

an antenna;

a transponder including an inductorless receiver having a Schottky diode detector including a Schottky diode having a first terminal coupled to the antenna and having a second terminal; and

means for driving current through both the antenna and the Schottky diode in a direction from the second terminal to the first terminal, the driving means being directly connected to the second terminal.

4. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode having a cathode coupled to the antenna and having an anode, the Schottky diode detector further including a capacitor connected between the anode and ground, and including a capacitor having a first contact connected to the anode and having a second contact defining an output of the Schottky diode detector; and

a current source connected to the anode to drive current through the antenna and the Schottky diode in a direction from the anode to the cathode, wherein the current source is directly connected to the anode.

5. A system comprising:

an antenna;

a transponder including an inductorless receiver having a Schottky diode detector including a Schottky diode having a cathode coupled to the antenna and having an anode; and

means for driving current through both the antenna and the Schottky diode in a direction from the anode to the cathode, the driving means being directly connected to the anode.

6. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode having a cathode coupled to the antenna and having an anode, the Schottky diode detector further including a capacitor connected between the anode and ground, and including a capacitor having a first contact connected to the anode and having a second contact defining an output of the Schottky diode detector, the integrated circuit further including a clock recovery circuit recovering a clock from falling edges only of a signal at the output of the Schottky diode detector; and

a current source coupled to drive current through the antenna and the Schottky diode in a direction from the anode to the cathode, the current source being directly connected to the anode.

7. A method of recovering a clock in a radio frequency communications system, the method comprising:

providing an antenna;

providing an inductorless receiver having a Schottky diode detector including a Schottky diode having a cathode coupled to the antenna and having an anode, the Schottky diode detector further including a capacitor connected between the anode and ground, and including a capacitor having a first contact connected to the anode and having a second contact defining an output of the Schottky diode detector;

driving current, using a current source, through the antenna and the Schottky diode in a direction from the anode to the cathode, the current source being directly connected to the anode; and

recovering a clock from falling edges only of a signal at the output of the Schottky diode detector.

8. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode having first and second terminals, the first terminal coupled to the antenna; and

a current source directly connected to the second terminal of the Schottky diode to drive current through the antenna and the Schottky diode to adjust bias current across the Schottky diode to realize a desired resistance across the Schottky diode, thereby enabling tuning and detuning of the receiver.

9. The system of claim 8, wherein the current source is configured to forward bias the Schottky diode to realize a desired resistance across the Schottky diode.

10. The system of claim 8, further comprising:

a capacitor provided between the cathode and ground, wherein the capacitor provides a radio frequency short to ground to enable substantially all of RF voltage to appear across the Schottky diode, thereby minimizing a baseband signal produced by the Schottky diode.

11. The system of claim 10, further comprising:

a second capacitor connected to parallel to the capacitor, wherein the second capacitor is configured to permit different bias levels in the detector.

12. The system of claim 8, wherein the antenna comprises first and second ends, and the first end is connected to a bias voltage and the second end is connected to the first terminal of the Schottky diode.

13. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode having first and second terminals, the first terminal coupled to the antenna;

a current source directly connected to the second terminal of the Schottky diode to drive current through the antenna and the Schottky diode to adjust bias current across the Schottky diode, thereby enabling tuning and detuning of the receiver, and wherein the current source is configured to forward bias the Schottky diode to realize a desired resistance across the Schottky diode; and

a capacitor circuit to provide a radio frequency short to ground to enable substantially all of RF voltage to appear across the Schottky diode to minimize a baseband signal produced by the Schottky diode and to further permit different bias levels in the detector.

14. The system of claim 13, wherein the capacitor circuit comprises first and second capacitors connected in parallel.

15. A radio frequency communications system comprising:

an antenna;

an integrated circuit including an inductorless receiver having a Schottky diode detector including a Schottky diode; and

a current source directly connected to the Schottky diode to drive current through the antenna and the Schottky diode, wherein one end of the antenna is coupled to a bias voltage source to provide a current sink, wherein the Schottky diode comprises first and second terminals, the first terminal being coupled to the antenna and the second terminal being coupled to the current source.

16. A radio frequency communications system comprising:

an antenna having first and second ends;

an inductorless receiver having a Schottky diode detector including a Schottky diode, the Schottky diode having first and second terminals; and

a current source directly connected to the Schottky diode to drive current through the antenna and the Schottky diode, the first terminal being coupled to the first end of the antenna and the second terminal being coupled to the current source, the second end of the antenna being coupled to a bias voltage source to provide a current sink.