DS100DF410 Datasheet, PDF (9/43 Pages) Texas Instruments – Low Power 10GbE Quad Channel Retimer

DS100DF410
www.ti.com
SNLS399A – JANUARY 2012 – REVISED FEBRUARY 2013
FUNCTIONAL DESCRIPTION
The DS100DF410 is a low-power 10GbE 4-channel retimer. Each of the four channels operates independently.
Each channel includes a Continuous-Time Linear Equalizer (CTLE) which compensates for the presence of a
dispersive transmission channel between the source and the DS100DF410's input.
Each channel of the DS100DF410 also includes a five-tap Decision Feedback Equalizer (DFE). This is a
nonlinear, symbol-spaced adaptive equalizer which compensates for signal impairments that are not properly
compensated by the CTLE. The DFE provides improved compensation for crosstalk and inter-symbol
interference (ISI).
Each channel includes an independent Voltage-Controlled Oscillator (VCO) and Phase-Locked Loop (PLL) which
produce a clean clock. The clean clock produced by the VCO and the PLL is phase-locked to the incoming data
clock, but the high-frequency jitter on the incoming data is attenuated by the PLL, producing a clean clock with
substantially reduced jitter. This clean clock is used to retime the incoming data, removing high-frequency jitter
from the data stream and producing a data output signal with reduced jitter.
Each channel of the DS100DF410 features an output driver with settable differential output voltage and settable
output de-emphasis. The output de-emphasis compensates for dispersion in the transmission channel at the
output of the DS100DF410.
These three functions together make up the data path for the DS100DF410.
IN_n+
IN_n-
EQ
100
SMBus
Signal
Detect
Retimer
OUTBUF
CDR
100
SMBus
OUT_n+
OUT_n-
SDC
SDA
Figure 1. DS100DF410 Data Path Block Diagram — One of Four Channels
Device Data Path Operation
The data path operation of the DS100DF410 comprises three functional sections as shown in the data path block
diagram of Figure 1. The three functional sections are as follows.
• Channel Equalization
• Clock and Data Recovery
• Output Driver
Channel Equalization
Physical transmission media such as traces on printed circuit boards (PCBs) or copper cables exhibit a low-pass
frequency response characteristic. The magnitude of the high-frequency loss varies with the length of the
transmission media and with the loss of the materials which comprise it. This differential high-frequency loss and
the frequency-dependent group delay of the transmission media introduce inter-symbol interference in the high-
speed broadband signals propagating through the transmission media.
The DS100DF410 applies a frequency-response equalization function to the incoming data stream. The
equalization function reduces the effect of the frequency-dependent loss in the transmission media between the
transmitter output and the input of the DS100DF410. The DS100DF410 includes a Continuous Time Linear
Equalizer or CTLE. The CTLE is designed to provide a controlled-amount of high-frequency boost to the signal in
the frequency domain to compensate for the frequency-dependent loss in the transmission media.
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