Altera Cyclone V Device Handbook page 299

1-12
Transmitter Buffer
Table 1-4: Description of the Transmitter Buffer Features
Features provided by the Pseudo Current Mode Logic (PCML) output buffer to the integrated circuitry.
Category
Improve Signal Integrity
Save Board Space and
Cost
Reduce Power
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Features
Programmable Controls the current mode drivers for signal amplitude to
Differential handle different trace lengths, various backplanes, and receiver
Output Voltage requirements. The actual V
(V ) setting and the transmitter termination value.
OD
Programmable Boosts the high-frequency components of the transmitted
Pre-Emphasis signal, which may be attenuated when propagating through
the transmission medium. The physical transmission medium
can be represented as a low-pass filter in the frequency
domain. Variation in the signal frequency response that is
caused by attenuation significantly increases the data-
dependent jitter and other intersymbol interference (ISI)
effects at the receiver end. Use the pre-emphasis feature to
maximize the data opening at the far-end receiver.
Programmable Controls the rate of change for the signal transition.
Slew Rate
On-Chip Biasing Establishes the required transmitter common-mode voltage
(TX V
available only if you enable OCT. When you disable OCT,
you must implement off-chip biasing circuitry to establish
the required TX V
Differential OCT The termination resistance is adjusted by the calibration
circuitry, which compensates for PVT.
You can disable OCT and use external termination. However,
you must implement off-chip biasing circuitry to establish
the required TX V
use external termination.
Programmable Controls the impedance of V
V Current reduces current consumption from the on-chip biasing
CM
Strength circuitry.
Description
level is a function of the current
OD
) level at the transmitter output. The circuitry is
CM
level.
CM
level. TX V
CM
CM
Transceiver Architecture in Cyclone V Devices
is tri-stated when you
CM
. A higher impedance setting
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CV-53001
2013.05.06