Specifications

DP83848Q-Q1

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SNLS341C –MARCH 2011–REVISED MARCH 2015

5.5.1.2.1 Analog Front End

In addition to the Digital Equalization and Gain Control, the DP83848Q-Q1 includes Analog Equalization

and Gain Control in the Analog Front End. The Analog Equalization reduces the amount of Digital

Equalization required in the DSP.

5.5.1.2.2 Digital Signal Processor

The Digital Signal Processor includes Adaptive Equalization with Gain Control and Base Line Wander

Compensation.

Figure 5-6. 100BASE-TX Receive Block Diagram

5.5.1.2.2.1 Digital Adaptive Equalization and Gain Control

When transmitting data at high speeds over copper twisted-pair cable, frequency dependent attenuation

becomes a concern. In high-speed twisted-pair signalling, the frequency content of the transmitted signal

can vary greatly during normal operation based primarily on the randomness of the scrambled data

stream. This variation in signal attenuation caused by frequency variations must be compensated to

ensure the integrity of the transmission.

To ensure quality transmission when employing MLT-3 encoding, the compensation must be able to adapt

to various cable lengths and cable types depending on the installed environment. The selection of long

cable lengths for a given implementation, requires significant compensation which will over-compensate

for shorter, less attenuating lengths. Conversely, the selection of short or intermediate cable lengths

requiring less compensation will cause serious under-compensation for longer length cables. The

compensation or equalization must be adaptive to ensure proper conditioning of the received signal

independent of the cable length.

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