Radio frequency data communications device

• US 6,836,468 B1
• Filed: 08/14/2000
• Issued: 12/28/2004
• 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., Tuttle, Mark E., Lowrey, Tyler, Higgins, Brian P., Devereaux, Kevin M., Pax, George E., OʼToole, James E.
• Primary Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US09/639,034
• Time in Patent Office: 1,597 Days
• Field of Search: 370/310, 340/825.56, 340/10.5, 340/10.51, 340/10.52, 340/10.41, 340/10.34, 340/10.1, 340/572.3, 340/10.33, 342/50, 342/42, 342/44, 342/51, 455/106, 455/107, 455/41, 455/102
• US Class Current: 370/310
• 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 19/07758 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: 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 device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal using a modulation scheme to an interrogator in response to receiving an interrogation request from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), On-Off Keying (OOK), and Amplitude Modulation (AM), and being switchable to select between Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), On-Off Keying (OOK), and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active mode and the backscatter mode in response to a radio frequency (RF) command from the interrogator.

2. A radio frequency communications device in accordance with claim 1 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

3. A radio frequency communications device comprising:

a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

an integrated circuit coupled to the antenna and including a transmitter and a receiver, the transmitter selectively transmitting a signal using a modulation scheme, the transmitter being capable of transmitting using modulated backscatter modulation and also capable of transmitting using any of the following active modes;

Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), On-Off Keying (OOK), Amplitude Modulation (AM);

the transmitter being switchable between Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), On-Off Keying (OOK), and Amplitude Modulation (AM) when in an active mode, the transmitter further being switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

4. A radio frequency communications device in accordance with claim 3 and further comprising a battery coupled to the integrated circuit, wherein the integrated circuit is capable of transmitting greater distances than passive, magnetically coupled radio frequency communication devices.

5. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal using a modulation scheme to an interrogator in response to receiving an interrogation request, the transmitter being capable of transmitting using Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), and being switchable to select between Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active mode and the backscatter mode in response to a radio frequency (RF) command sent from the interrogator.

6. A radio frequency communications device in accordance with claim 5 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

7. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal using a modulation scheme to an interrogator in response to receiving an interrogation request from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), and being switchable to select between Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active mode and the backscatter mode in response to a signal from the interrogator.

8. A radio frequency communications device in accordance with claim 7 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

9. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), and being switchable to select between Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active transmission mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to selectively switch between the active and backscatter modes in response to a signal from the interrogator.

10. A radio frequency communications device in accordance with claim 9 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

11. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving a request from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, On-Off Keying (OOK), and being switchable to select between Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and On-Off Keying (OOK), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

12. A radio frequency communications device in accordance with claim 11 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

13. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving a request from the interrogator, the transmitter being capable of transmitting using Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), and being switchable to select between Direct Sequence Spread Spectrum, On-Off Keying (OOK), and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

14. A radio frequency communications device in accordance with claim 13 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

15. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving an interrogation request, the transmitter being capable of transmitting using Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), and being switchable to select between Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

16. A radio frequency communications device in accordance with claim 15 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

17. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving an interrogation request, the transmitter being capable of transmitting using Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and On-Off Keying (OOK), and being switchable to select between Binary Phase Shift Keying (BPSK), Direct Sequence Spread Spectrum, and On-Off Keying (OOK), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

18. A radio frequency communications device in accordance with claim 17 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

19. A radio frequency communications device comprising:

an integrated circuit having a power source, the integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal using a modulation scheme to an interrogator in response to receiving an interrogation request transmitted from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), and being switchable to select between Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, and the transmitter is configured to switch between the active mode and the backscatter mode in response to commands sent from the interrogator.

20. A radio frequency communications device in accordance with claim 19 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

21. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving an interrogation signal, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and On-Off Keying (OOK), and being switchable to select between Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and On-Off Keying (OOK), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active transmission mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

22. A radio frequency communications device in accordance with claim 21 and further comprising a dipole antenna having first and, second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

23. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving an interrogation request, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), and Direct Sequence Spread Spectrum, and being switchable to select between Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK), and Direct Sequence Spread Spectrum, wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

24. A radio frequency communications device in accordance with claim 23 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

25. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving an interrogation signal from the interrogator, the transmitter being capable of transmitting using Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), and being switchable to select between Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

26. A radio frequency communications device in accordance with claim 25 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

27. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving a request from the interrogator, the transmitter being capable of transmitting using Direct Sequence Spread Spectrum, and On-Off Keying (OOK), and being switchable to select between Direct Sequence Spread Spectrum, and On-Off Keying (OOK), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active transmission mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

28. A radio frequency communications device in accordance with claim 27 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

29. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving a command from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), and Direct Sequence Spread Spectrum, and being switchable to select between Frequency Shift Keying (FSK), and Direct Sequence Spread Spectrum, wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active transmission mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

30. A radio frequency communications device in accordance with claim 29 and further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

31. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme in response to receiving a request from the interrogator, the transmitter being capable of transmitting using Binary Phase Shift Keying (BPSK), and Direct Sequence Spread Spectrum, and being switchable to select between Binary Phase Shift Keying (BPSK), and Direct Sequence Spread Spectrum, wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to operate the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitter by the interrogator, wherein the transmitter is configured to switch between the active and backscatter modes in response to a command from the interrogator.

32. A radio frequency communications device in accordance with claim 31 further comprising a dipole antenna having first and second portions which define, in operation, first and second poles of the dipole antenna, respectively;

wherein the transmitter is switchable between backscatter and active modes in response to a radio frequency command received by the receiver, wherein in the backscatter mode the integrated circuit alternately reflects or does not reflect the carrier from the interrogator by shorting or isolating the first and second portions of the dipole antenna to transmit data to the interrogator.

33. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme upon receiving an interrogation signal from the interrogator, the transmitter being capable of transmitting using Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), and being switchable to select between Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum, and Amplitude Modulation (AM), wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator to enable operation of the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitted by the interrogator, wherein the modulation scheme is selectable by the interrogator, and the transmitter is configured to switch between the active mode and the backscatter mode in response to RF commands from the interrogator, and further wherein transmit frequency for the transmitter is recovered from a message received in the receiver via RF commands from the interrogator.

34. The system as in claim 33, further comprising a voltage controlled oscillator (VCO), wherein VCO control voltage is stored in digital form in a register of the receiver.

35. The system as in claim 33, wherein the transmit frequency recovered from the message is used by the integrated circuit to generate a DPSK subcarrier for modulated backscatter transmission.

36. A radio frequency communications device comprising:

an integrated circuit including a transmitter and a receiver, the transmitter selectively transmitting a signal to an interrogator using a modulation scheme upon receiving an interrogation signal from the interrogator, the transmitter being capable of selectively transmitting using a modulation scheme among a plurality of modulation schemes wherein, for the selected modulation scheme, a carrier for the transmitter is generated by the integrated circuit itself, instead of by the interrogator thereby rendering operation of the transmitter in an active mode, the integrated circuit further being switchable to transmit in a modulated backscatter mode in which the integrated circuit uses a carrier transmitted by the interrogator, wherein the modulation scheme is selectable by the interrogator, and the transmitter is configured to switch between the active mode and the backscatter mode in response to RF commands sent from the interrogator, and further wherein transmit frequency for the transmitter is recovered from a message received in the receiver via RF commands from the interrogator; and

a dipole antenna having first and second poles, wherein in the backscatter mode, the integrated circuit is configured to either reflect the carrier sent from the interrogator by shorting the first and second poles to transmit data to the interrogator, or not to reflect the carrier by isolating the first and second poles to prevent data transmission to the interrogator.

37. The system as in claim 36, further comprising a voltage controlled oscillator (VCO), wherein VCO control voltage is stored in digital form in a register of the receiver.

38. The system as in claim 36, wherein the transmit frequency recovered from the message is used by the integrated circuit to generate a DPSK subcarrier for modulated backscatter transmission.

39. The system as in claim 36, wherein the integrated circuit is held in a sleep mode until a radio frequency interrogation request is received by the receiver from the interrogator.

40. The system as in claim 39, further comprises a logic circuit to determine if the radio frequency interrogation request is valid, and if the request is determined to be valid, the transmitter is configured to transmit the signal to the interrogator, and if the request is determined to be invalid, the integrated circuitry is configured to revert back to the sleep mode.

41. The system as in claim 36, wherein the receiver operates independent of carrier frequency of an incoming signal from the interrogator.

42. The system as in claim 41, wherein clock for the integrated circuit is extracted from the incoming signal received from the interrogator.

43. The system as in claim 42, wherein if the transmitter is operating in the active mode, the clock that is extracted is multiplied up to a carrier frequency of the transmitter.

44. The system as in claim 42, wherein if the transmitter is operating in the backscatter mode, the clock that is extracted is made slower and then used.

45. The system as in claim 36, wherein if the backscatter mode is selected, the interrogator sends a continuous unmodulated RF signal during transmission of a message by the transmitter in response to a command from the interrogator.