Crosstalk cancellation for a common-mode channel

• US 8,442,099 B1
• Filed: 12/23/2010
• Issued: 05/14/2013
• Est. Priority Date: 09/25/2008
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Aquantia Corporation (Marvell Technology Group Limited)
• Inventors: Sederat, Hossein
• Primary Examiner(s): LEE, SIU M
• Application Number:
  US12/977,844
• Time in Patent Office: 873 Days
• Field of Search: 375/316, 375/219, 375/220, 375/222, 375/346, 375/349, 375/260, 375/285
• US Class Current: 375/219
• CPC Class Codes: H04B 3/30 Reducing interference caused by unbalanced currents in a normally balanced line
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating
• CPC Class Codes: H04L 1/0058 Block-coded modulation
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 25/0272 Arrangements for coupling to multiple lines, e.g. for differential transmission
• CPC Class Codes: H04L 25/0276 Arrangements for coupling common mode signals
• CPC Class Codes: H04L 25/0292 Arrangements specific to the receiver end

Abstract

A transceiver circuit is disclosed. The transceiver circuit comprises a receive path to receive a differential signal and a first crosstalk filter coupled to the receive path. A common-mode path is provided for carrying a common-mode signal. An RFI interference filter is coupled between the common-mode path and the receive path. Isolation circuitry decouples the RFI interference filter from the first crosstalk filter.

Claims

1. A transceiver circuit comprising:

a receive path to receive a differential signal;

a first crosstalk filter coupled to the receive path;

a common-mode path for carrying a common-mode signal;

a radio frequency interference filter coupled between the common-mode path and the receive path; and

isolation circuitry that comprises an adaptive filter to decouple the radio frequency interference filter from the first crosstalk filter.

2. The transceiver circuit according to claim 1 wherein:

the adaptive filter is a leakage adaptive filter.

3. The transceiver circuit according to claim 2 wherein the leakage adaptive filter generates a cancellation signal to compensate for differential-mode induced noise in the common-mode signal.

4. The transceiver circuit according to claim 3 wherein the leakage adaptive filter is disposed between the common-mode path and the receive path, and the cancellation signal compensates for far-end differential mode induce noise.

5. The transceiver circuit according to claim 2 and further comprising a transmit path.

6. The transceiver circuit according to claim 5 wherein the isolation circuitry further comprises a near-end leakage adaptive filter disposed between the transmit path and the common-mode path.

7. The transceiver circuit according to claim 1 wherein the first crosstalk filter comprises at least one of a near-end adaptive crosstalk filter and a far-end adaptive crosstalk filter.

8. The transceiver circuit according to claim 1 wherein the common-mode signal is based on the differential signal.

9. The transceiver circuit according to claim 8 wherein the common-mode signal comprises a detected common-mode component of the differential signal.

10. The transceiver circuit according to claim 1 and embodied in a 10GBASE-T transceiver integrated circuit chip.

11. A transceiver circuit comprising:

a plurality of receive paths for coupling to a plurality of physical channels, the plurality of receive paths comprising differential signal paths to receive respective differential signals;

crosstalk cancellation circuitry coupled to the differential signal paths to generate compensation signals to offset crosstalk in each of the differential signal paths;

at least one common-mode signal path for propagating a common-mode signal;

RFI cancellation circuitry disposed between the at least one common-mode channel and each of the plurality of differential signal paths; and

first leakage cancellation circuitry disposed between each of the differential signal paths and the at least one common-mode signal path.

12. The transceiver circuit according to claim 11 wherein the first leakage cancellation circuitry generates far-end leakage cancellation signals to compensate for far-end differential-mode noise on the common-mode path.

13. The transceiver circuit according to claim 11 and further comprising a plurality of transmit paths, and second leakage cancellation circuitry disposed between the at least one common-mode path and the plurality of transmit paths, and wherein the second leakage cancellation circuitry generates near-end leakage cancellation signals to compensate for near-end differential-mode noise on the common-mode path.

14. The transceiver circuit according to claim 11 embodied as an integrated circuit chip.

15. A method of signaling comprising:

receiving a differential signal;

cancelling crosstalk from the differential signal on a receive path;

cancelling RFI from the differential signal on a common mode path; and

decoupling the cancelling crosstalk from the cancelling RFI between the receive path and common mode path by leakage adaptive filters.

16. The method according to claim 15 wherein the cancelling crosstalk comprises adaptively filtering.

17. The method according to claim 16 wherein the cancelling RFI comprises detecting a common-mode component of the differential signal and adaptively filtering the common-mode component on a common-mode path to generate an RFI cancellation signal.

18. The method according to claim 17 wherein the decoupling the cancelling crosstalk from the cancelling RFI comprises adaptively filtering between the common-mode path and the receive path and generating a far-end leakage cancellation signal.

19. The method according to claim 15 and further including transmitting a differential signal along a transmit path, and wherein the decoupling comprises adaptively filtering between the common-mode path and the transmit path and generating a near-end leakage cancellation signal.