88e3015 Marvell Semiconductor, Inc., 88e3015 Datasheet - Page 29

• Manufacturer Part Number: 88e3015
• Description: Integrated 10/100 Fast Ethernet Transceiver
• Manufacturer: Marvell Semiconductor, Inc.

2.3 Transmit and Receive Functions
The transmit and receive paths for the 88E3015/88E3018 device are described in the following sections.
2.3.1 Transmit Side Network Interface
2.3.1.1
The 88E3015/88E3018 device incorporates a multi-mode transmit DAC to generate filtered MLT-3, NRZI, or
Manchester coded symbols. The transmit DAC performs signal wave shaping to reduce EMI. The transmit DAC is
designed for very low parasitic loading capacitances to improve the return loss requirement, which allows the use
of low cost transformers.
2.3.1.2
In 100BASE-TX mode, slew rate control is used to minimize high frequency EMI. In 10BASE-T mode, the output
waveform is pre-equalized via a digital filter.
2.3.2 Encoder
2.3.2.1
In 100BASE-TX mode, the transmit data stream is 4B/5B encoded, serialized, and scrambled. Upon initialization,
the initial scrambling seed is determined by the PHY address. The datastream is then MLT-3 coded.
2.3.2.2
In 10BASE-T mode, the transmit data is serialized and converted to Manchester encoding.
2.3.2.3
In 100BASE-FX mode, the transmit data stream is 4B/5B encoded, serialized, and converted to NRZI.
2.3.3 Receive Side Network Interface
2.3.3.1
The 88E3015/88E3018 device incorporates an advanced high speed ADC on each receive channel with greater
resolution for better SNR, and therefore, lower error rates. Patented architectures and design techniques result in
high differential and integral linearity, high power supply noise rejection, and low metastability error rate.
2.3.3.2
The 88E3015/88E3018 device employs an advanced baseline wander cancellation circuit to automatically com-
pensate for this DC shift. It minimizes the effect of DC baseline shift on the overall error rate.
2.3.3.3
The digital adaptive equalizer removes inter-symbol interference at the receiver. The digital adaptive equalizer
takes unequalized signals from ADC output and uses a combination of feedforward equalizer (FFE) and decision
feedback equalizer (DFE) for the best-optimized signal-to-noise (SNR) ratio.
Copyright © 2006 Marvell
October 26, 2006, Advance
Analog to Digital Converter
Multi-mode TX Digital to Analog Converter
Slew Rate Control and Waveshaping
100BASE-TX
10BASE-T
100BASE-FX
Baseline Wander Canceller
Digital Adaptive Equalizer
Document Classification: Proprietary Information
CONFIDENTIAL
Transmit and Receive Functions
Doc. No. MV-S103657-00, Rev. C
Page 29