Periodic bandwidth widening for inductive coupled communications

• US 9,385,790 B1
• Filed: 12/31/2014
• Issued: 07/05/2016
• Est. Priority Date: 12/31/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bhat, Anoop, Shrivastava, Kumar Anurag, Mukherjee, Subhashish
• Primary Examiner(s): Perez, James M
• Application Number:
  US14/587,817
• Publication Number:
  US 20160191123A1
• Time in Patent Office: 552 Days
• Field of Search: 375219-228, 375256-258, 375/259, 375268-270, 375/286, 375/287, 375/289, 375/295, 375300-301, 375309-315, 375/316, 375320-321, 375/340
• US Class Current: 1/1
• CPC Class Codes: H04B 5/263 Multiple coils at either side
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04L 27/04 Modulator circuits; Transmitter circuits

Abstract

A method of inductive coupled communications includes providing a first resonant tank (first tank) and a second resonant tank (second tank) tuned to essentially the same resonant frequency, each having antenna coils and switches positioned for changing a Q and a bandwidth of their tank. The antenna coils are separated by a distance that provides near-field communications. The first tank is driven to for generating induced oscillations to transmit a predetermined number of carrier frequency cycles providing data. After the predetermined number of cycles, a switch is activated for widening the bandwidth of the first tank. Responsive to the oscillations in the first tank, the second tank begins induced oscillations. Upon detecting a bit associated with the induced oscillations, a switch is activated for widening the bandwidth of the second tank and a receiver circuit receiving an output of the second tank is reset.

Claims

1. A method of resonant inductive coupled communications, the method comprising:

driving a first resonant tank (first tank) for generating induced oscillations with a modulated carrier signal, said first tank tuned to a first resonant frequency and including first antenna coils, so that said first antenna coils transmit a predetermined number of carrier frequency cycles (predetermined number of cycles) for providing data that is first transition coded;

said first tank further including;

a first capacitor coupled in parallel to said first antenna coils;

a first resistor coupled in series between said first antenna coils; and

a first switch coupled in series between said first antenna coils;

after said predetermined number of cycles, activating said first switch for widening a bandwidth and changing a Q factor of said first tank;

responsive to said oscillations in said first tank, beginning induced oscillations in a second resonant tank (second tank), said second tank tuned to a second resonant frequency that is essentially equal said first resonant frequency and including;

a second antenna coil that is separated from said first antenna coils by a distance that provides near-field communications;

a second capacitor coupled in parallel to said second antenna coil; and

a second switch coupled in parallel to said second antenna coil; and

responsive to detecting a bit associated with said induced oscillations of said second tank, activating said second switch for widening a bandwidth and changing a Q factor of said second tank, and resetting a receiver sense circuit coupled to receive an output of said second tank.

2. The method of claim 1, further comprising:

opening said first switch to bring said first resistor into said first tank; and

opening said second switch to remove a second resistor from said second tank.

3. The method of claim 1, wherein said modulated carrier signal is an amplitude-shift keyed (ASK) signal.

4. The method of claim 1, wherein said receiver sense circuit includes an amplifier;

coupled to receive an output of said second tank at inputs of said amplifier; and

coupled in series to a rectifier and peak detector and a delay block.

5. The method of claim 1, wherein a product of a maximum Q factor for said first tank and a maximum Q factor for said second tank is ≧

50.

6. The method of claim 1, wherein said modulated carrier signal is at a carrier frequency from 500 MHz to 4 GHz.

7. The method of claim 1, wherein said first tank is formed on a first chip and said second tank is formed on a second chip, and said first antenna coils and said second antenna coil comprise metal loops.

8. The method of claim 7, wherein said first chip and said second chip are positioned lateral to one another on a split leadframe within a multi-chip package (MCP), and said first chip and said second chip both include mold compound thereover and therebetween.

9. The method of claim 7, wherein said first chip and said second chip are in a stacked configuration on a substrate within a multi-chip package (MCP).

10. The method of claim 1, wherein said driving said first tank to oscillate comprises applying a periodic wave tuned to said first resonant frequency modulated by said data.

11. A resonant inductive coupled communications system, comprising:

a first resonant tank (first tank) tuned to a first resonant frequency and including;

first antenna coils;

a first capacitor coupled in parallel to said first antenna coils;

a first resistor coupled in series between said first antenna coils; and

a first switch coupled in series between said first antenna coils;

a second resonant tank (second tank) tuned to a second resonant frequency that is essentially equal said first resonant frequency and including;

second antenna coil that is separated from said first antenna coils by a distance that provides near-field communications;

a second capacitor coupled in parallel to said second antenna coil; and

a second switch coupled in parallel to said second antenna coil;

receiver sense circuitry coupled to an output of said second tank;

said first tank arranged to generate induced oscillations when driven by a modulated carrier signal, so that said first antenna coils transmit a predetermined number of carrier frequency cycles (predetermined number of cycles) for providing data that is first transition coded;

a transmit controller for activating said first switch for widening a bandwidth and changing a Q factor of said first tank after said predetermined number of cycles;

said second tank arranged to begin induced oscillations responsive to said oscillations in said first tank; and

said receiver sense circuitry arranged to activate said second switch for widening a bandwidth and changing a Q factor of said second tank and to reset itself, responsive to detecting a bit associated with said induced oscillations of said second tank.

12. The system of claim 11, wherein:

opening said first switch is for bringing said first resistor into said first tank; and

opening said second switch is for removing a second resistor from said second tank.

13. The system of claim 11, wherein said first tank is formed on a first chip, and said second tank is formed on a second chip, and said first antenna coils and said second antenna coil comprise metal loops.

14. The system of claim 13, wherein said first chip and said second chip are positioned lateral to one another on a split leadframe within a multi-chip package (MCP), and said first chip and said second chip both include mold compound thereover and therebetween.

15. The system of claim 11, wherein said modulated carrier signal is an amplitude-shift keyed (ASK) signal.

16. The system of claim 11, wherein said receiver sense circuitry includes an amplifier;

coupled to receive an output of said second tank at inputs of said amplifier; and

coupled in series to a rectifier and peak detector and a delay block.

17. The system of claim 11, wherein a product of a maximum Q factor for said first tank and a maximum Q factor for said second tank is ≧

50.

18. The system of claim 11, wherein said modulated carrier signal is at a carrier frequency from 500 MHz to 4 GHz.

19. The system of claim 13, wherein said first chip and said second chip are in a stacked configuration on a substrate within a multi-chip package (MCP).

20. The system of claim 11, wherein said driving said first tank to oscillate comprises applying a periodic wave tuned to said first resonant frequency modulated by said data.