AccessRunner
Controller-less ADSL Modem Device Set for PCI Applications
Digital Interface (DI)
Analog Front End (AFE) Interface
The DI Transmit Block performs the following
functions: transmit data multiplexing and buffering,
fast and interleave data stream framing, transmit
data synchronization control, eoc/aoc insertion, CRC
encoding, scrambling, FEC encoding, and data
interleaving.
The AFE Interface performs the following functions:
transmit signal filtering, time domain equalization,
and time domain signal power averaging, and echo
cancellation (EC).
Microcontroller Interface
The DI Receive Block performs the following
functions: data de-interleaving, FEC decoding,
descrambling, CRC check, receive data
synchronization and receive clock generation,
demultiplexing and buffering of receive data and
receive eoc/aoc.
The microcontroller interface enables the host
computer via the PCI controller to set parameters to
control DSP sequencing and to read/write
coefficients or data.
20441 Line Driver
QAM Encoder/Decoder
The 20441 line driver is designed for use in full-rate
and G.lite (G.992.2) ADSL modems. It is optimized
for ideal ADSL performance providing low noise,
high bandwidth, and superior linearity. The 20441
line driver transmits a DMT modulated signal in the
25 – 132 kHz band. It operates from a single 5V
±TBD% supply, refer to
The QAM Encoder/Decoder performs the following
functions: constellation encoding, clock recovery,
receive gain compensation, frequency domain
equalization (FEQ), slicing, and constellation
decoding. The block also performs other functions
like frequency domain signal processing, signal
power, error power averaging and computations
related to frequency domain training.
Figure 3.
The driver is optimized for ADSL performance: it has
a very low noise figure, high bandwidth and good
linearity.
FFT
The FFT performs IFFT for modulation of the
transmit symbol, and FFT for demodulation of the
receive symbol.
248.4
OUTP_DRV
INP_DRV
+
+
+
400
INM_DRV
248.4
OUTM_DRV
Current Control
Line Driver
(20441)
RBIAS
Block
(
)
DSL015_003
Figure 3. AccessRunner 20441 Line Driver
4
Conexant
Proprietary Information
Doc. No. 100394B
October 19, 1999
CONEXANT [ CONEXANT SYSTEMS, INC ]
