AN983 ETC [List of Unclassifed Manufacturers], AN983 Datasheet - Page 67

• Manufacturer Part Number: AN983
• Description: PCI/miniPCI-to-Ethernet LAN Controller
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Rev. 1.8
Regarding the 100BASE-TX receiving operation, the transceiver provides the receiving
functions of PMD, PMA, and PCS for receiving incoming data signals through category 5
UTP cable and an isolation transformer with turn’s ratio of 1: 1. It includes the adaptive
equalizer and baseline wander, data conversions of MLT3 to NRZI, NRZI to NRZ and serial
to parallel, the PLL for clock and data recovery, the de-scrambler, and the decoder of 5B/4B.
100BASE-TX Receiving Operation
Start-of-Stream Delimiter-SSD (/J/K/)
In a transmission stream, the first 16 nibbles are MAC preamble. In order to let
partner delineate the boundary of a data transmission sequence and to authenticate
carrier events, the transceiver will replace the first 2 nibbles of the MAC preamble
with /J/K/ code-groups.
End-of-Stream Delimiter-ESD (/T/R/)
In order to indicate the termination of the normal data transmissions, the transceiver
will insert 2 nibbles of /T/R/ code-group after the last nibble of FCS.
Scrambling
All the encoded data (including the idle, SSD, and ESD code-groups) is passed to data
scrambler to reduce the EMI and spread the power spectrum using a 10-bit scrambler
seed loaded at the beginning.
Data conversion of Parallel to Serial, NRZ to NRZI, NRZI to MLT3
After scrambled, the transmission data with 5B type in 25MHz will be converted to
serial bit stream in 125HMz by the parallel to serial function. After serialized, the
transmission serial bit stream will be further converted from NRZ to NRZI format.
After NRZI converted, the NRZI bit stream is passed through MLT3 encoder to generate
the TP-PMD specified MLT3 code. With this MLT3 code, it lowers the frequency and
reduces the energy of the transmission signal in the UTP cable and also makes the
system easily to meet the FCC specification of EMI.
Wave-Shaper and Media Signal Driver
In order to reduce the energy of the harmonic frequency of transmission signals, the
transceiver provides the wave-shaper prior the line driver to smooth but keep
symmetric the rising/falling edge of transmission signals. The wave-shaped signals
include the 100BASE-TX and 10BASE-T both are passed to the same media signal driver.
This design can simplify the external magnetic connection with single one.
Adaptive Equalizer and Baseline Wander
Since the high-speed signals over the unshielded (or shielded) twisted Pair cable will
induce the amplitude attenuation and phase shifting. Furthermore, these effects are
depends on the signal frequency, cable type, cable length and the connectors of the
AN983B
www.admtek.com.tw
ADMtek Inc.
PCI/miPCI Fast Ethernet Controller with integrated PHY
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