ICS1893 Datasheet, PDF (49/152 Pages) Integrated Circuit Systems – 3.3-V 10Base-T/100Base-TX Integrated PHYceiver™

ICS1893 - Release
Chapter 7 Functional Blocks
7.4.4 100Base-TX Operation: Adaptive Equalizer
The ICS1893 has a TP-PMD sublayer that uses adaptive equalization circuitry to compensate for signal
amplitude and phase distortion incurred from the transmission medium. At a data rate of 100 Mbps, the
transmission medium (that is, the cable) introduces significant signal distortion because of high-frequency
attenuation and phase shift. The high-frequency loss occurs primarily because of the cable skin effect that
causes the conductor resistance to rise as the square of the frequency rises.
The ICS1893 has an adaptive equalizer that accurately compensates for these losses in shielded
twisted-pair (STP) and unshielded twisted-pair (UTP) cables. The DSP-based adaptive equalizer uses a
technique that compensates for a wide range of cable lengths. The optimizing parameter for the
equalization process is the overall bit error rate of the ICS1893. This technique closes the loop on the entire
data reception process and provides a very high overall reliability.
7.4.5 100Base-TX Operation: Twisted-Pair Transmitter
The ICS1893 uses the same Twisted-Pair Transmit pins (TP_TXP and TP_TXN) for both 10Base-T and
100Base-TX operations. Each twisted-pair transmitter module is a current-driven, differential driver that
can supply either of the following:
• A two-level 10Base-T (that is, Manchester-encoded) signal
• A three-level 100Base-TX (that is, MLT-3 encoded) signal
The ICS1893 interfaces with the medium through an isolation transformer (sometimes referred to as a
magnetic module). The ICS1893’s transmitter uses wave-shaping techniques to control the output signal
rise and fall times (thereby eliminating the need for external filters) and interfaces directly to the isolation
transformer.
Note:
1. In reference to the ICS1893, the term ‘Twisted-Pair Transmitter’refers to the set of Twisted-Pair
Transmit output pins (TP_TXP and TP_TXN).
2. For information on the 10Base-T Twisted-Pair Transmitter, see Section 7.5.11, “10Base-T Operation:
Twisted-Pair Transmitter”.
7.4.6 100Base-TX Operation: Twisted-Pair Receiver
The ICS1893 uses the same Twisted-Pair Receive pins (TP_RXP and TP_RXN) for both 10Base-T and
100Base-TX operations. The internal twisted-pair receiver modules interface with the medium through an
isolation transformer. The 100Base-TX receiver module accepts and processes a differential three-level
100Base-TX (that is, MLT-3 encoded) signal from the isolation transformer. (In contrast, the 10Base-T
receiver module accepts and processes a differential two-level, Manchester- encoded, 10Base-T signal
from the isolation transformer).
Note:
1. In reference to the ICS1893, the term ‘Twisted-Pair Receiver’refers to the set of Twisted-Pair Receive
output pins (TP_RXP and TP_RXN).
2. For information on the 10Base-T Twisted-Pair Receiver, see Section 7.5.12, “10Base-T Operation:
Twisted-Pair Receiver”.
ICS1893 Rev C 6/6/00
Copyright © 2000, Integrated Circuit Systems, Inc.
All rights reserved.
49
June, 2000