User guide

Supported modes for VGA:
• Manual Mode:
• In this mode, manual VGA values can be set in Assignment Editor/.qsf or using Avalon MM
interface.
• Triggered Adaptation Mode:
• In this adaptation mode, VGA gain values are controlled by the Adaptive Parametric Tuning
Engine. This mode uses the converged VGA values given by the Adaptive Parametric Tuning
Engine.
VGA adaptation mode is synched-up with CTLE adaptation mode. CTLE in Triggered Adaptation or
Manual mode makes VGA also in Triggered Adaptation or Manual, respectively.
Note: To know more about how to configure VGA in different modes, refer to How to Enable CTLE and
DFE
Related Information
• How to Enable CTLE and DFE on page 5-12
Decision Feedback Equalization (DFE)
DFE amplifies the high frequency components of a signal without amplifying the noise content. It
compensates for inter-symbol interference (ISI). DFE minimizes post-cursor ISI by adding or subtracting
weighted versions of the previously received bits from the current bit. DFE works in synchronization with
the TX pre-emphasis and downstream RX CTLE. This enables the RX CDR to receive the correct data that
was transmitted through a lossy and noisy backplane.
DFE advantage over CTLE is improved Signal to Noise Ratio (SNR): DFE amplifies the power of the high
frequency components without amplifying the noise power.
UG-01143
2015.05.11
Decision Feedback Equalization (DFE)
5-9
Arria 10 Transceiver PHY Architecture
Altera Corporation
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