Radio frequency data communications device

• US 6,278,698 B1
• Filed: 09/14/1998
• Issued: 08/21/2001
• Est. Priority Date: 05/13/1996
• Status: Expired due to Term

• 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:
  US09/152,663
• Time in Patent Office: 1,072 Days
• Field of Search: 370/311, 340/825.54, 340/10.1, 340/10.33, 342/42, 342/44, 342/51, 342/142, 327/333, 455/343
• US Class Current: 370/311
• 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 identification device comprising:

an integrated circuit including a microprocessor, a receiver configured to receive radio frequency commands from an interrogation device and having an output coupled to the microprocessor, a transmitter configured to transmit a signal identifying the device to the interrogator in response to a command from the microprocessor, and a wake-up timer circuit coupled to the receiver and configured to determine if a signal received by the receiver is a radio frequency command from the interrogation device, the integrated circuit at times switching between a sleep mode and a receiver on mode, more power being consumed in the receiver on mode than in the sleep mode, the integrated circuit switching from the receiver on mode to a microprocessor on mode when logic in a wake-up timer circuit determines that a signal received by the receiver is a radio frequency command from the interrogation device, the receiver further including an amplifier powered by a selectively engageable voltage source engaged in the receiver on mode but not in the sleep mode, the amplifier including first and second inputs for receiving an input signal to be amplified, the inputs respectively including coupling capacitors, a differential amplifier having inputs respectively connected to the first and second inputs through the coupling capacitors, and having an output, selectively engageable resistances between the voltage source and respective inputs of the differential amplifier, second selectively engageable resistances between the voltage source and respective inputs of the differential amplifier, the second resistances respectively having smaller values than the first mentioned resistances, the second resistances being engaged then disengaged in response to the integrated circuit switching from the sleep mode to the receiver on mode.

2. A radio frequency identification device in accordance with claim 1 and further comprising a voltage divider, and wherein the first mentioned and second resistances are connected to the voltage source via the voltage divider.

3. A radio frequency identification device in accordance with claim 1 wherein the first mentioned resistances comprise respective transistors.

4. A radio frequency identification device in accordance with claim 1 wherein the first mentioned resistances comprise respective p-type transistors.

5. A radio frequency identification device in accordance with claim 1 wherein the second resistances comprise respective transistors.

6. A radio frequency identification device in accordance with claim 1 wherein the second resistances comprise respective p-type transistors.

7. A method of operating a radio frequency identification device comprising an integrated circuit including a microprocessor, a receiver configured to receive radio frequency commands from an interrogation device, the receiver including an amplifier, the receiver having an output coupled to the microprocessor, the integrated circuit including a transmitter configured to transmit a signal identifying the device to the interrogator in response to commands from the microprocessor and a wake-up timer circuit coupled to the receiver and configured to determine when a signal received by the receiver is a radio frequency command from the interrogation device, the method comprising:

switching the integrated circuit between a sleep mode and a receiver on mode, more power being consumed in the receiver on mode than in the sleep mode;

powering the amplifier by a selectively engageable voltage source engaged in the receiver on mode but not in the sleep mode, the amplifier including first and second inputs for receiving an input signal to be amplified, the inputs respectively including coupling capacitors, the amplifier including a differential amplifier having inputs respectively connected to the first and second inputs through the coupling capacitors, and having an output;

engaging first selectively engageable resistances between the voltage source and respective inputs of the differential amplifier; and

engaging second selectively engageable resistances between the voltage source and respective inputs of the differential amplifier, the second resistances respectively having smaller values than the first mentioned resistances, the second resistances being engaged then disengaged in response to the integrated circuit switching from the sleep mode to the receiver on mode.

8. The method of claim 7, further comprising;

turning on transistors forming the first selectively engageable resistances in response to the receiver on mode;

waiting for a predetermined interval; and

turning off the transistors forming the first selectively engageable resistances while maintaining the receiver on mode.

9. The method of claim 7, further comprising:

turning on transistors forming the first and second selectively engageable resistances in response to the receiver on mode;

waiting for a predetermined interval; and

turning off the transistors forming the first selectively engageable resistances but not the transistors forming the second selectively engageable resistances while maintaining the receiver on mode.

10. The method of claim 7, further comprising;

turning on p-type transistors forming the first selectively engageable resistances in response to the receiver on mode;

waiting for a predetermined interval; and

turning off the p-type transistors forming the first selectively engageable resistances while maintaining the receiver on mode.

11. The method of claim 7, further comprising:

turning on p-type transistors forming the first and second selectively engageable resistances in response to the receiver on mode;

waiting for a predetermined interval; and

turning off the p-type transistors forming the first selectively engageable resistances but not the p-type transistors forming the second selectively engageable resistances while maintaining the receiver on mode.

12. The method of claim 7, further comprising:

determining, via logic in the wake-up timer circuit, when a signal received by the receiver is a radio frequency command from the interrogator; and

switching from the receiver on mode to a microprocessor on mode when logic in the wake-up timer circuit determines that a signal received by the receiver is a radio frequency command from the interrogation device.