AccessRunner ADSL-USB Modem Device Set Data Sheet
2.3.3
CX20431 AFE Description
The CX20431 Analog Front End (AFE) can support full-rate and G.lite (G.992.2) ADSL modems. The CX20431 AFE
interfaces with the CX20441 LD and the hybrid receive circuitry on the analog side, and with the CX11627 ADDP on the
digital side.
The receive section filters out the unwanted echo and boosts the wanted signal before performing an analog-to-digital (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.
Wakeup in G.lite mode is supported by tone detection circuitry integrated in the CX20431 AFE.
The CX20431 operates from a +3.3V supply.
A block diagram of the CX20431 AFE is shown in Figure 2-3.
CX20431 Analog Front End (AFE)
Digital Section
Analog Section
AGC
P5200
USB
Decimation
Low Pass
Filter
High Pass
Filter
Hybrid
OpAmp
ADC
Hybrid
Filter
Interface
Controller
(UIC)
Serial
Interface
Reference
Generators
CX11627
ADSL
Data Pump
(ADDP)
CX20441
Line Driver
(LD)
Interpolation
Filter
Low Pass
Filter
SC Filter
AGC
DAC
100427 F2-3_BD_P20431
Figure 2-3. CX20431 AFE Block Diagram
Conexant
100427B
2-5
CONEXANT [ CONEXANT SYSTEMS, INC ]
