WIRELESS POWER TRANSFER IN-BAND COMMUNICATION SYSTEM

• US 20140314170A1
• Filed: 10/25/2013
• Published: 10/23/2014
• Est. Priority Date: 10/26/2012
• Status: Active Grant

• Current Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Original Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Inventors: Plumb, William, Wang, Zhen, Zvonar, Zoran, Riehl, Patrick Stanley, Satyamoorthy, Anand, Tustin, Philip Frank
• Granted Patent: US 9,363,041 B2
• Time in Patent Office: Days
• US Class Current: 375/282
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 25/4904 using self-synchronising codes, e.g. split-phase codes
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level

Abstract

A wireless charging in-band communication system includes a transmitter module that formats a message using CRC calculation and attaches the results of the CRC calculation to the message for message error detection. The transmitter includes channel encoding for message error correction. A modulation module performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source. A synchronization module prepending the message with a synchronization sequence having Golay complementary codes. Moreover, the in-band communication includes a receiver module that receives the message from the transmitter module. The receiver module includes an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module. The receiver module includes a front end filter used for pulse shaping and noise rejection. A preamble detection block includes a Golay complementary code correlator used for message detection, synchronization, and equalization coefficient estimation and selection. A decoding module performs biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding Also, the decoding module performs equalization, error correction channel decoding,and error detection (CRC).

Claims

1. A wireless charging in-band communication system comprising:

a transmitter module that formats a message using CRC calculation and attaches the results of the CRC calculation to the message for message error detection, the transmitter includes channel encoding for message error correction, and a modulation module that performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source, and a synchronization module that prepends the message with a synchronization sequence having Golay complementary codes; and

a receiver module that receives the message from the transmitter module, the receiver module includes an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module, the receiver module includes a front end filter used for pulse shaping and noise rejection, a preamble detection block having a Golay complementary code correlator used for message detection, synchronization, and equalization coefficient estimation and selection, and a decoding module that performs biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding, the decoding module performs equalization, error correction channel decoding, and error detection (CRC).

2. The wireless charging in-band communication system of claim 1, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

3. The wireless charging in-band communication system of claim 1, wherein the input signal from the impedance sensing circuit is oversampled and the downsampling and pulse shaping filters increase the number of effective bits.

4. The wireless charging in-band communication system of claim 1, wherein the pulse shaping filters utilizes DC removal block to remove DC components of a message.

5. The wireless charging in-band communication system of claim 1, wherein the transmitter and receiver modules utilize BCH or Hamming code for developing a codeword.

6. The wireless charging in-band communication system of claim 5, wherein the codeword comprises information bits and redundant bits.

7. The wireless charging in-band communication system of claim 5, wherein the codeword comprises 15 bits.

8. The wireless charging in-band communication system of claim 1, wherein transmitter module utilizes biphase modulation.

9. The wireless charging in-band communication system of claim 1, wherein the receiver module comprises a sliding window time correlator or a circular correlator.

10. The wireless charging in-band communication system of claim 1, wherein the preamble detector comprises an Optimized Golay Correlator (OGC) with the noise estimation and DC offset estimation and removal.

11. The wireless charging in-band communication system of claim 1, wherein the synchronization module provides a gap between the preamble and message maybe used to allow timing adjustments done by the preamble detector in the receiver to take effect at the output of the digital front end filter in time for the message to be received.

12. The wireless charging in-band communication system of claim 1, wherein the biphase demodulation module uses an inverted version of the correlation sequence to reduce the number of consecutive “

1”

s.

13. The wireless charging in-band communication system of claim 1, wherein the biphase demodulation module comprises coarse DC offset removal as part of the analog front end filter and fine DC offset done digitally.

14. The wireless charging in-band communication system of claim 5, wherein the codeword comprises 13 bits.

15. A method of performing the operations of a wireless charging in-band communication system comprising:

formatting a message using CRC calculation and attaching the results of the CRC calculation to the message for message error detection;

performing biphase modulation for DC balanced signals using a modulation module, including impedance switching to change reflected impedance seen by the source;

prepending the message with a synchronization sequence having Golay complementary codes using a synchronization module;

receiving the message from the transmitter module using a receiver module;

providing an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module;

providing a front end filter used for pulse shaping and noise rejection;

using a Golay complementary code correlator for message detection, synchronization, and equalization coefficient estimation and selection;

performing biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding using a biphase demodulator module; and

performing equalization, error correction channel decoding, and error detection (CRC).

16. The method system of claim 15, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

17. The method system of claim 15, wherein the input signal from the impedance sensing circuit is oversampled and the downsampling and pulse shaping filters increase the number of effective bits.

18. The method system of claim 15, wherein the pulse shaping filters utilizes DC removal block to remove DC components of a message.

19. The method system of claim 15, wherein the transmitter and receiver modules utilize BCH or Hamming code for developing a codeword.

20. The method system of claim 19, wherein the codeword comprises information bits and redundant bits.

21. The method system of claim 19, wherein the codeword comprises 15 bits.

22. The method system of claim 15, wherein transmitter module utilizes biphase modulation.

23. The method system of claim 15, wherein the receiver module comprises a sliding window time correlator or a circular correlator.

24. The method of claim 15, wherein the preamble detector comprises an Optimized Golay Correlator (OGC) with the noise estimation and DC offset estimation and removal.

25. The method of claim 15, wherein the synchronization module provides a gap between the preamble and message maybe used to allow timing adjustments done by the preamble detector in the receiver to take effect at the output of the digital front end filter in time for the message to be received.

26. The method of claim 15, wherein the biphase demodulation module uses an inverted version of the correlation sequence to reduce the number of consecutive “

1”

s.

27. The method of claim 15, wherein the biphase demodulation module comprises coarse DC offset removal as part of the front end filter and fine DC offset.

28. The method of claim 19, wherein the codeword comprises 13 bits.