GROUP DELAY BASED BACK CHANNEL POST CURSOR ADAPTATION

摘要

Described embodiments provide for de-coupling between adaptation of decision feedback equalizer (DFE) filter taps and transmitter (TX) post cursor filtering in group delay (GD)-based adaptation. Consequently, an excessive build-up of transmitter post cursor effects and its excessive equalization cancellation by the DFE may be substantially reduced or eliminated. By breaking this coupling, a transmitter does not over equalize a signal, the DFE does not attempt to “undo” the over equalization, and a variable gain amplifier (VGA) in the receiver front end data path generally does not apply gain to amplify the signal back again due to the reduced DC level. GD-based TX post cursor adaptation may reduce over equalization effect and hence save power and increase performance by not over equalizing the signal.

主权项

1. A method of group delay-based post cursor adaptation in a communication system, the method comprising the steps of:
receiving, at a local receiver, a serial signal from a communication channel from a remote transmitter, wherein at least a portion of interference introduced into the serial signal passing through the communication channel is compensated for by applying a transmit (TX) filter in the remote transmitter to the serial signal, wherein the TX filter includes at least one pre- and post-cursor tap with corresponding pre- and post-cursor tap coefficients, respectively; enhancing and applying equalization to the received serial signal; determining either a hold, an increment request, or a decrement request for the post cursor tap coefficient of the TX filter to compensate for channel distortions; forwarding each increment request and each decrement request to a remote receiver by a local transmitter through a back communication channel; detecting either over equalization or under equalization at the local receiver; and
if over equalization is detected, generating a request for a reduction of absolute value for the post cursor tap coefficient of the TX filter, andotherwise, if under equalization is detected, generating a request for an increase of absolute value for the post cursor tap coefficient of the TX filter.