Differential Receiver; Jitter; Total Jitter (Dj + Rj); Deterministic Jitter (Dj) - Xilinx RocketIO User Manual

Differential Receiver

Differential Receiver
The differential receiver accepts the V
calculation V
All input data must be differential and nominally biased to a common mode voltage of
0.5 V – 2.5 V, or AC coupled. Internal terminations provide for simple 50Ω or 75Ω
transmission line connection.
The differential receiver parameters are shown in

Table 4-3: Differential Receiver Parameters

Jitter

Jitter is defined as the short-term variations of significant instants of a signal from their
ideal positions in time (ITU). Jitter is typically expressed in a decimal fraction of Unit
Interval (UI), e.g. 0.3 UI.

Total Jitter (DJ + RJ)

Deterministic Jitter (DJ)

DJ is data pattern dependant jitter, attributed to a unique source (e.g., Inter Symbol
Interference (ISI) due to loss effects of the media). DJ is linearly additive.

Random Jitter (RJ)

RJ is due to stochastic sources, such as substrate, power supply, etc. RJ is additive as the
sum of squares, and follows a bell curve.

Clock and Data Recovery

The serial transceiver input is locked to the input data stream through Clock and Data
Recovery (CDR), a built-in feature of the RocketIO transceiver. CDR keys off the rising and
falling edges of incoming data and derives a clock that is representative of the incoming
data rate.
The derived clock, RXRECCLK, is presented to the FPGA fabric at 1/20th the incoming
data rate. This clock is generated and locked to as long as it remains within the specified
component range. This range is shown in
UG024 (v1.5) October 16, 2002
RocketIO™ Transceiver User Guide
- V electronically.
P N
Parameter
V Serial input differential peak
IN
to peak (RXP/RXN)
V Common mode input voltage
ICM
range
T Differential input skew
ISKEW
T Receive data total jitter
JTOL
tolerance (peak to peak)
T Receive data deterministic
DJTOL
jitter tolerance (peak to peak)
Notes:
1. UI = Unit Interval
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and V signals, carrying out the difference
P N
Table
Min
175
500
Table 4-4.
1-800-255-7778
4-3.
Typ Max Units Conditions
1,000 mV
2500 mV
75 ps
(1)
0.65 UI
0.41 UI
R
87