CertusPro-NX SerDes/PCS Usage Guide
Preliminary
Technical Note
FPGA-TN-02245-0.81
© 2020-2021 Lattice Semiconductor
47
All rights reserved. CONFIDENTIAL
SerDes/PCS Function Description
CertusPro-NX devices have one to three Quads of embedded SerDes/PCS logic. Each Quad, in turn, supports four
independent full-duplex data channels. A single channel can support a data link, and each Quad can support up to four
such channels.
The embedded SerDes CDR PLLs and Tx PLLs support data rates that cover a wide range of industry standard protocols.
SerDes (PMA)
shows a simplified functional block diagram of the SerDes (PMA) macro. Each of the SerDes macros includes
three main sub-functions, Transmitter (Tx), Receiver (Rx), and PLL Clock blocks. The Tx block receives 5, 8, 10, 16, or 20
bits of transition-encoded data synchronous with a Tx clock, serializes it into a single stream of differential transmitted
data and transmits to the lane. The transmitter supports multi-level output driver, multi-level transition emphasis, and
multi-level Common Mode levels.
Tx PLL
/M
/F
/N
CDR PLL
/M
/F
/N
Serializer
Deserializer
Transmitter
Receiver
AD
Amplitude Pre &
Post Cursor Settings
Tx Data
5, 8, 10, 16, 20 bits
Tx CLK
REF CLK
Rx CLK
Rx Data
5, 8, 10, 16, 20 bits
Equalization
Control
Near End Loopback
Control
Activity Detect
Schmitt Out
Impedance
Calibrator
TxDP
TxDN
REXT
RxDP
RxDN
Rx with Programmable
CTLE, DFE & Eye Monitor
Figure 6.1. Simplified Block Diagram of the SerDes (PMA)
Output amplitude control range nominally spans from V
diff_pp
= 0 to V
diff_pp
= VCCSDx nominal, with a 1/128 typical
resolution at full-scale. A 3-tap FIR based Tx equalizer is implemented to support de-emphasis and pre-shoot. The
de-emphasis control range nominally spans from 0dB to beyond 20dB. Pre-cursor and post-cursor coefficients are
negative, with each coefficient able to be quantized to typically 1/128 resolution with respect to normalized full-scale.
The Rx block receives the serialized data from the lane, de-serializes this into a 5, 8, 10, 16, or 20 bits digital data and
provides the de-serialized data and the recovered link clock. An Rx continuous time linear equalizer (CTLE) is provided
with programmable gain and a single tap decision feedback equalization circuit (DFE) is provided with programmable
tap weight.