Hi Srikanth,
The first and foremore objective of a CTLE is to flatten the
interconnect transfer function up to a given frequency, e.g. the
fundamental frequency of operation (Nyquist in case of NRZ/PAM2). In
addition to amplification of frequencies near Nyquist, this may include
evenly attenuating the lower frequencies. Both aspects support a
peaking response of the filter.
Note that the CTLE is typically combined with some sort of gain
adjustment (cf. "automatic gain control"), so that the overall signal
is not necessarily attenuated.
The choice of equalization and its location (near Tx vs near Rx) is a
trade-off between signal distortion and the available peak-to-peak
voltage swing.
For an exploration of how the CTLE design can be linked with the
transfer function of the interconnect, you may find this paper helpful:
https://ieeexplore.ieee.org/document/7943999
Regards,
Torsten
On Wed, 2022-03-09 at 11:00 +0000, Srikanth.Pillalamarri wrote:
Hi,
I am trying to understand CTLE behavior and functionality as I'm
going to use it. Fundamentally a CTLE equalizer inverts the frequency
response of the channel (Low-pass filter) by boosting the high
frequency content.
Peak AC gain should be selected at the Nyquist frequency to counter
the loss induced by the channel.
I am clear about the AC gain of CTLE. However, some cases CTLE
response show negative DC gain, which I'm unable to understand.
Typically, a channel loss starts at 0dB(at DC) and increase linearly
with frequency. Compensating high frequency loss should be ok, but
what is the need to suppress low frequency content using CTLE filter?
[cid:image001.png@01D833D3.0CDC4D70]
Thanks,
Srikanth
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
