11. High-Speed Differential
Interfaces in Cyclone II
Devices
CII51011-2.2
From high-speed backplane applications to high-end switch boxes,
low-voltage differential signaling (LVDS) is the technology of choice.
LVDS is a low-voltage differential signaling standard, allowing higher
noise immunity than single-ended I/O technologies. Its low-voltage
swing allows for high-speed data transfers, low power consumption, and
reduced electromagnetic interference (EMI). LVDS I/O signaling is a data
interface standard defined in the TIA/EIA-644 and IEEE Std. 1596.3
specifications.
Introduction
The reduced swing differential signaling (RSDS) and mini-LVDS
standards are derivatives of the LVDS standard. The RSDS and
mini-LVDS I/O standards are similar in electrical characteristics to
LVDS, but have a smaller voltage swing and therefore provide increased
power benefits and reduced EMI. National Semiconductor Corporation
and Texas Instruments introduced the RSDS and mini-LVDS
specifications, respectively. Currently, many designers use these
specifications for flat panel display links between the controller and the
drivers that drive display column drivers. Cyclone® II devices support
the RSDS and mini-LVDS I/O standards at speeds up to 311 megabits per
second (Mbps) at the transmitter.
Altera® Cyclone II devices can transmit and receive data through LVDS
signals at a data rate of up to 640 Mbps and 805 Mbps, respectively. For
the LVDS transmitter and receiver, the Cyclone II device’s input and
output pins support serialization and deserialization through internal
logic.
This chapter describes how to use Cyclone II I/O pins for differential
signaling and contains the following topics:
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Cyclone II high-speed I/O banks
Cyclone II high-speed I/O interface
LVDS, RSDS, mini-LVDS, LVPECL, differential HSTL, and
differential SSTL I/O standards support in Cyclone II devices
High-speed I/O timing in Cyclone II devices
Design guidelines
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Cyclone II device I/O banks are shown in Figures 11–1 and 11–2. The
EP2C5 and EP2C8 devices offer four I/O banks and EP2C15, EP2C20,
EP2C35, EP2C50, and EP2C70 devices offer eight I/O banks. A subset of
Cyclone II High-
Speed I/O Banks
Altera Corporation
February 2007
11–1
ALTERA [ ALTERA CORPORATION ]
