Controller-less ADSL Modem Device Set for PCI Applications
AccessRunner
11627 ADSL DMT Data Pump
Detailed Description
P46 PCI Bus Interface
The 11627 DMT data pump is a T1.413 Issue 2 and
G.992.1 compliant custom digital signal processing
(DSP) chip built specifically for DMT ADSL
transmission for use in ADSL modems. Brief
descriptions of each functional block within the data
pump are provided in the following sections; refer to
Figure 2.
The P46 PCI bus interface is the bridge device
between the 11627 ADSL DMT data pump and the
host computer. It provides the control, interface, and
data manipulation for the 11627 data pump, the
20431 AFE, the 20441 line driver, and hybrid
circuitry. It is compliant with the PCI Local Bus
Specification, Revision 2.2 and PCI Bus Power
Management Interface Specification, Version 1.0.
ATM Transmission Convergence (TC)
In the transmit direction, this block is in charge of
embedding ATM cells into the serial data streams
being fed into the digital interface.
20431 Analog Front End
The 20431 AFE is designed for use in full-rate and
G.lite (G.992.2) ADSL modems. The ADSL AFE
interfaces with the transmit line driver (20441) and
the hybrid receive circuitry on the analog side, and
with the ADSL DMT data pump (11627) on the digital
side. The receive section filters out the unwanted
echo and boosts the wanted signal before
performing an A/D conversion. The transmit section
converts digital data to analog signals and performs
a smoothing operation before presenting the signals
to the line driver.
In the receive direction, this block extracts the ATM
cell boundaries from the serial data streams coming
from the digital interface.
To reduce traffic on the PCI bus, the TC block
performs idle cell insertion in the transmit direction
and idle cell deletion and header error correction in
the receive direction.
The 20431 is designed to operate from a 3.3V supply
(nominal), assuming that it is regulated within ± 5%. The
maximum allowable supply voltage is 3.6V.
Digital
AM EncoderDecoder
Interface (DI)
FFT
AFE Interface
DI
Transmit
Block
Bit Parser
and QAM
Encoder
Transmit
Filter
DAC
Intf
IFFT
AFE
(20431)
EC
QAM
Decoder
and Bit
Parser
DI
Receive
Block
Time
Domain
Equalizer
PCI
Controller
(P46)
ADC
Intf
FFT
FEQ
Microcontroller
Interface
DMT Data Pump (11627)
DSL015002
Figure 2. AccessRunner 11627 DMT Data Pump Functional Block Diagram
Doc. No. 100394B
October 19, 1999
Conexant
Proprietary Information
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CONEXANT [ CONEXANT SYSTEMS, INC ]
