G.SHDSL ANALOG FRONT-END
FEATURES
a71 E1, T1, AND SUBRATE OPERATION
a71 COMPLIES WITH G.SHDSL AND HDSL2
a71 16-BIT, DELTA-SIGMA CONVERTERS
a71 ON-CHIP DRIVER AND PGA
a71 PROGRAMMABLE tx AND rx FILTERS
a71 SERIAL DIGITAL INTERFACE
a71 750mW POWER DISSIPATION AT E1
a71 +5V POWER (5V OR 3.3V DIGITAL)
a71 SSOP-28 PACKAGE
a71 –40°C TO +85°C TEMPERATURE RANGE
DESCRIPTION
Texas Instrument’s analog front-end chip, the AFE1230, is
designed to greatly reduce the size and cost of G.SHDSL
and HDSL2 application designs. It provides a transceiver as
the line interface between the Digital Signal Processor
(DSP) and the local loop. The AFE1230 is designed to
handle upstream and downstream data transmission over a
wide range of data rates from 64kbps to 2.5Mbps. Function-
ally, this unit consists of a transmitter and receiver section.
The transmitter section consists of a digital interpolation
filter, a 16-bit, delta-sigma Digital-to-Analog (D/A) con-
verter, a digitally programmable fifth-order or seventh-order
SC (Switched Capacitor) low-pass filter, and a differential
output line driver. The receiver section includes an input
Programmable Gain Amplifier (PGA), a 16-bit, delta-sigma
Analog-to-Digital (A/D) converter, and a programmable
decimation filter.
The AFE1230 receives a 16-bit data word plus an 8-bit control
byte via the serial interface to facilitate the D/A conversion
and control functions. The subsequent analog signal is sent to
the on-chip line driver that provides 14.5dBm power into a
135Ω line for G.SHDSL operation. In addition, the on-chip
line driver can be used as an output buffer with an external line
driver, such as the OPA2677, to generate over 17dBm power
into a 135Ω line for HDSL2 operation. With an appropriate
DSP, the transmitted Power Spectral Density (PSD) complies
with either the G.SHDSL standard or with the HDSL2 stan-
dard (via an OPA2677 used as an external driver).
In the receive path, the input amplifier sums the signals from
the line and hybrid path to perform first-order analog echo
cancellation. The resultant signal is then digitized by the rest
of the receive section into a 16-bit digital word that is sent to
the external DSP.
This IC operates on a single 5V supply, while the digital supply
can be from 3.3V to 5V. It is housed in a SSOP-28 package.
The typical power consumption is 750mW at E1 rates with
G.SHDSL (560mW for HDSL2 operation) and an operation
temperature range of –40°C to +85°C.
A
F
E
1
2
3
0
∆Σ 16-Bit
A/D Converter
PGA
Input
Amplifier
Patents PendingAFE1230
Driver/
Buffer
txLINE
txLINE
hybINPUT
hybINPUT
rxINPUT
rxINPUT
tx and rx
Digital
Interface
Registers
Programmable
Digital
LPF
Digital
Interpolation
LPF
Programmable
SC
LPF
∆Σ 16-Bit
D/A Converter
MCLK
txBaud
txData
rxBaud
rxData
AFE1230
SBWS015A – AUGUST 2001
www.ti.com
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright © 2001, Texas Instruments Incorporated
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.