Altera Stratix GX Transceiver - Manual (Page 155)

Altera Corporation 6–1
January 2005
6. GigE Mode
Introduction The Gigabit Ethernet (GigE) mode in Stratix ® GX devices supports a
subset of the IEEE GigE standard. Stratix GX devices have Physical
Coding Sub-layer (PCS) functions and Physical Medium Attachment
(PMA) functions as Hard Intellectual Property (IP).
Stratix GX devices provide the following GigE features:
■ Serial data rate of 1.25 Gigabits per second
■ Input clock reference range of 62.5 to 625 MHz (these values are the
minimum and maximum for an input reference clock with a data rate
of 1.25 Gbps and an 8-bit data width)
■ Parallel interface width of 8 bits
■ 8B/10B encoding decoder
■ Word aligner supports 10-bit code groups
■ Rate compensation or elastic buffer
■ Gigabit Media Independent Interface (GMII) to PCS code conversion
on transmit
The GMII is an intermediate or parallel interface that connects the PCS
sub-layer with the media access control (MAC) in a system that supports
GigE mode. The GigE physical layer is divided into three sub-layers: the
PCS, the PMA, and the physical medium dependent (PMD) layers. If you
implement a GMII-compliant interface, that interface offers data rates up
to 1,000 Mbps at either half- or full-duplex modes.
The PCS provides synchronization, encoding, decoding, and rate
matching services to the MAC. The PCS also provides autonegotiation to
the network to negotiate speeds, carrier-detect signals, and
collision-detect signals.
The PMA sublayer provides the PCS with a media-independent interface
that a variety of serial physical media can connect to. This sublayer
handles the serialization and deserialization of the data.
The PMD sublayer defines the physical attachments, such as connectors
for different media types.
Figure 6–1 shows the positioning of these layers.