Calibration for Echo Cancellation in a Full Duplex Communication System

Patent metadata

Field	Value
Publication number	US-2016248574-A1
Application number	US-201414440589-A
Country	US
Kind code	A1
Filing date	Sep 12, 2014
Priority date	Sep 12, 2014
Publication date	Aug 25, 2016
Grant date	—

Abstract

A method that calibrates a device for echo cancellation and a device with calibration for echo cancellation are provided. Devices may be calibrated such that the echo residual error is less than a threshold determined by the calibration accuracy. Non-ideal factors such as mismatch may be eliminated during calibration.

First claim

What is claimed is:

1 . A device for full duplex communication over a channel, the device comprising:
a driver and a replica driver, an input of the driver coupled to an input of the replica driver and an output of the driver coupled to an output of the replica driver and further coupled to a channel, the driver configured to produce an output data signal for transmission to the channel; an echo cancellation module coupled to the replica driver and the channel, the echo cancellation module configured to receive an input data signal from the channel, an echo of the output data signal, and a signal generated by the source replica driver configured to cancel the echo; and a calibration module coupled to receive an output of the echo cancellation module and to adjust the replica driver; wherein during a calibration mode, the calibration module is configured to:
couple a local clock signal to the driver and replica driver, the driver generating a reference signal from the local clock signal, the replica driver generating a calibration signal from the local clock signal, and the echo cancellation module generating a difference signal between the reference signal and the calibration signal;
for multiple iterations, adjust the replica driver so that the reference signal and the calibration signal cancel and record the corresponding values of the replica driver adjustment; and
calibrate the replica driver based on the recorded values of the replica driver adjustment.

2 . The device of claim 1 wherein the calibration module adjusts the replica driver based on whether the difference signal is above or below a reference voltage.

3 . The device of claim 2 wherein the reference voltage is zero volts.

4 . The device of claim 1 wherein the calibration module adjusts the replica driver based on whether the difference signal is within a threshold range of a reference voltage.

5 . The device of claim 1 wherein the calibration module adjusts the replica driver to sweep the calibration signal to be alternately greater than and less than the reference signal, and determines whether the reference signal and the calibration signal cancel based on when the calibration signal toggles between being greater than and less than the reference signal.

6 . The device of claim 1 wherein the replica driver is calibrated based on an average of the recorded values.

7 . The device of claim 1 wherein the calibration module further determines a calibration timing reference from the local clock signal, and determines whether the reference signal and the calibration signal cancel during time periods defined by the calibration timing reference.

8 . The device of claim 1 wherein the calibration module further determines a mask period from the local clock signal, and determines whether the reference signal and the calibration signal cancel during the mask period.

9 . The device of claim 8 wherein the local clock signal is constant during the mask period, and the calibration module determines whether the reference signal and the calibration signal cancel based on counting ones or zeroes during the mask period.

10 . The device of claim 1 wherein the calibration module adjusts the replica driver based on a phase of the difference signal.

11 . The device of claim 1 wherein the device is a source device, no input data signal is received during the calibration mode, and timing of the output data signal is based on a clock generated by the source device.

12 . The device of claim 1 wherein the device is a sink device, a remote clock signal is received as the input data signal during the calibration mode, and timing of the output data signal is based on the remote clock signal.

13 . The device of claim 12 wherein the calibration module further generates a DC offset configured to cancel an offset added by the remote clock signal.

14 . The device of claim 12 wherein the calibration module adjusts the replica driver based on a phase of the difference signal.

15 . The device of claim 12 wherein the local clock signal is phase shifted relative to the remote clock signal, and the calibration module adjusts the replica driver based on a phase difference between the difference signal and the reference signal.

16 . The device of claim 12 wherein the calibration module further determines a calibration timing reference from the remote clock signal, and determines whether the reference signal and calibration signal cancel during time periods defined by the calibration timing reference.

17 . A device for full duplex communication over a channel, comprising:
a driver configured to generate a reference signal; a replica driver configured to generate a calibration signal; and a calibration module coupled to the driver and the replica driver and configured to:
determine a first reference voltage,
adjust an amplitude the calibration signal linearly,
record a first amplitude and a second amplitude when a first difference of the amplitude of the calibration signal and an amplitude of the reference signal is equal to the first reference voltage, and
determine a calibration amplitude by averaging the first amplitude and the second amplitude.

18 . The device of claim 17 , wherein the calibration module is further configured to:
determine a second reference voltage, adjust a transition time of the calibration signal linearly, record a first transition time and a second transition time when a second difference of the amplitude of the calibration signal and the amplitude of the reference signal is equal to the second reference voltage, and determine a calibration transition time by averaging the first transition time and the second transition time.

19 . The device of claim 18 , wherein the calibration module comprises a digital-to-analog converter configured to generate the first reference voltage and the second reference voltage, and a comparator configured to compare the difference of the calibration signal and the reference signal to the first reference voltage or the second reference voltage.

Assignees

• Silicon Image Inc

Inventors

• Zhou Kai
• Tahk Shinje
• Lei Kai
• Wu Qiming
• Ahn Gijung
• Kim Min-Kyu
• Song Fei
• Luo Kexin

Classifications

• H04L5/1461 Primary

  Suppression of signals in the return path, i.e. bidirectional control circuits · CPC title

• H04B1/525

  with means for reducing leakage of transmitter signal into the receiver · CPC title

• H04M9/082

  using echo cancellers (echo cancellers per se H04B3/23) · CPC title

• H04L5/0091

  Signalling for the administration of the divided path, e.g. signalling of configuration information · CPC title

• H04B3/232 Primary

  using phase shift, phase roll or frequency offset correction · CPC title