Radio frequency communication devices having backscatter and non-backscatter communication modes and hardware re-use

• US 10,461,783 B2
• Filed: 03/16/2018
• Issued: 10/29/2019
• Est. Priority Date: 03/16/2017
• Status: Active Grant

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Reynolds, Matthew S.
• Primary Examiner(s): Yun, Eugene
• Application Number:
  US15/923,238
• Publication Number:
  US 20180269909A1
• Time in Patent Office: 592 Days
• Field of Search: 455 91
• CPC Class Codes: H04B 1/04 Circuits
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Backscatter communication offers the potential for significant energy savings compared to conventional wireless links such as Bluetooth, Zigbee, WiFi, etc. However, backscatter communication requires the presence of a carrier source in the environment at an appropriate frequency. If such a carrier source is not available in the environment, backscatter communication may not be practical. Examples are presented for a radio frequency communication device having the option to use either backscatter communication, or non-backscatter communication, with the re-use of at least portions of the hardware components between the backscatter and non-backscatter communication modes.

Claims

1. A radio frequency communication device, comprising:

a backscatter transmitter circuit;

a non-backscatter transceiver circuit;

an antenna; and

a transistor in a transmit path of the non-backscatter transceiver circuit and electrically coupled to the antenna, the transistor configured to, in a backscatter modulator mode, vary an impedance presented to the antenna via the transmit path of the non-backscatter transceiver circuit;

wherein each of the backscatter transmitter circuit and the non-backscatter transmitter circuit are in electrical communication with the antenna.

2. The radio frequency communication device of claim 1, wherein a bias signal is applied to a control terminal of the transistor.

3. The radio frequency communication device of claim 2, wherein the transistor comprises a bipolar junction transistor and the control terminal comprises a base terminal.

4. The radio frequency communication device of claim 2, wherein the transistor comprises a field effect transistor and the control terminal comprises a gate terminal.

5. The radio frequency communication device of claim 2, wherein the bias signal comprises a baseband signal of a communication standard.

6. The radio frequency communication device of claim 5, wherein the communication standard comprises at least one of the Bluetooth, Wi-Fi, :

IEEE 802.11, Zigbee, Z-Wave, or LoRa communication standards.

7. The radio frequency communication device of claim 1, wherein during a first time interval, the transistor modulates the impedance presented to the antenna, and during a second time interval, the transistor amplifies a signal produced by the non-backscatter transmitter circuit.

8. The radio frequency communication device of claim 7, wherein a drain voltage or a collector voltage of the first transistor is substantially zero during the first time interval.

9. The radio frequency communication device of claim 1, wherein the transistor is further configured to vary the impedance presented to the antenna, when the backscatter transmitter circuit receives a wake signal.

10. The radio frequency communication device of claim 1, wherein a dc drain bias voltage of the transistor is zero during the backscatter modulator mode.

11. The radio frequency communication device of claim 1, further comprising:

a switch configured to switch between a transmit path of the non backscatter transceiver circuit and a receive path of the non-backscatter transceiver circuit.

12. The radio frequency communication device of claim 1, wherein the transistor is further configured to amplify, in a non-backscatter mode, a signal generated by the non-backscatter transceiver circuit.

13. The radio frequency communication device of claim 1, further comprising:

a radio frequency oscillator in electrical communication with a gate terminal of the transistor.

14. The radio frequency communication device of claim 13, wherein radio frequency communication device generates a backscatter signal during a first time interval, and a radio frequency transmission during a second time interval;

and wherein the radio frequency oscillator is disabled during the first time interval and enabled during the second time interval.

15. The radio frequency communication device of claim 14, wherein the de bias voltage is zero during the first time interval and is non-zero during the second time interval.

16. The radio frequency communication device of claim 13, wherein the radio frequency oscillator comprises a frequency synthesizer.

17. The radio frequency communication device of claim 1, wherein the transistor is further configured to, in the backscatter modulate mode, vary the impedance presented to the antenna by modulating a drain to source impedance of the transistor based on a sequence of symbols.

18. The radio frequency communication device of claim 17, wherein the sequence of symbols comprises a baseband signal having two or more voltage levels.

19. A method of transmitting a signal from a radio frequency communication device having an antenna, the method comprising:

determining a communication mode for the radio frequency communication device from among a plurality of modes including (a) a backscatter communication mode and (b) a non-backscatter communication mode; and

selecting a bias condition for a transistor based on the communication mode, wherein the transistor is in electrical communication with the first antenna, and wherein the transistor operates as an impedance modulator when the radio frequency communication device is in the backscatter communication mode and as an amplifier when the radio frequency communication device is in the non-backscatter communication mode, wherein selecting the bias condition for the transistor further based on a received signal sleep/wake line, wherein a sleep signal of the sleep/wake line indicates that the transistor operates as the impedance modulator, and wherein a wake signal of the sleep/wake line indicates that the transistor operates as the amplifier.