Mixed-Signal Front-End (MxFE™) Baseband
Transceiver for Broadband Applications
AD9861
FEATURES
FUNCTIONAL BLOCK DIAGRAM
Receive path includes dual 10-bit analog-to-digital
converters with internal or external reference, 50 MSPS
and 80 MSPS versions
Transmit path includes dual 10-bit, 200 MSPS digital-to-
analog converters with 1×, 2×, or 4× interpolation and
programmable gain control
Internal clock distribution block includes a programmable
phase-locked loop and timing generation circuitry,
allowing single-reference clock operation
20-pin flexible I/O data interface allows various interleaved
or noninterleaved data transfers in half-duplex mode and
interleaved data transfers in full-duplex mode
VIN+A
ADC
ADC
DATA
MUX
AND
Rx DATA
VIN–A
VIN+B
LATCH
VIN–B
I/O
INTERFACE
CONTROL
I/O
INTERFACE
CONFIGURATION
BLOCK
FLEXIBLE
I/O BUS
[0:19]
LOW-PASS
INTERPOLATION
FILTER
IOUT+A
DATA
LATCH
AND
DAC
DAC
IOUT–A
IOUT+B
Tx DATA
DEMUX
IOUT–B
AUX
ADC
Configurable through register programmability or
optionally limited programmability through mode pins
AUX
DAC
Independent Rx and Tx power-down control pins
64-lead LFCSP package (9 mm × 9 mm footprint)
3 configurable auxiliary converter pins
ADC CLOCK
CLKIN
AUX
DAC
DAC CLOCK
PLL
APPLICATIONS
AUX
ADC
Broadband access
AD9861
Broadband LAN
Communications (modems)
AUX
DAC
03606-0-001
Figure 1.
GENERAL DESCRIPTION
of custom digital back ends or open market DSPs.
The AD9861 is a member of the MxFE family—a group of
integrated converters for the communications market. The
AD9861 integrates dual 10-bit analog-to-digital converters
(ADC) and dual 10-bit digital-to-analog converters (TxDAC®).
Two speed grades are available, -50 and -80. The -50 is opti-
mized for ADC sampling of 50 MSPS and less, while the -80 is
optimized for ADC sample rates between 50 MSPS and 80 MSPS.
The dual TxDACs operate at speeds up to 200 MHz and
include a bypassable 2× or 4× interpolation filter. Three
auxiliary converters are also available to provide required
system level control voltages or to monitor system signals. The
AD9861 is optimized for high performance, low power, small
form factor, and to provide a cost-effective solution for the
broadband communication market.
In half-duplex systems, the interface supports 20-bit parallel
transfers or 10-bit interleaved transfers. In full-duplex systems,
the interface supports an interleaved 10-bit ADC bus and an
interleaved 10-bit TxDAC bus. The flexible I/O bus reduces pin
count and, therefore, reduces the required package size on the
AD9861 and the device to which it connects.
The AD9861 can use either mode pins or a serial program-
mable interface (SPI) to configure the interface bus, operate the
ADC in a low power mode, configure the TxDAC interpolation
rate, and control ADC and TxDAC power-down. The SPI
provides more programmable options for both the TxDAC path
(for example, coarse and fine gain control and offset control for
channel matching) and the ADC path (for example, the internal
duty cycle stabilizer, and twos complement data format).
The AD9861 uses a single input clock pin (CLKIN) to generate
all system clocks. The ADC and TxDAC clocks are generated
within a timing generation block that provides user programma-
ble options such as divide circuits, PLL multipliers, and switches.
The AD9861 is packaged in a 64-lead LFCSP (low profile, fine
pitched, chip scale package). The 64-lead LFCSP footprint is
only 9 mm × 9 mm, and is less than 0.9 mm high, fitting into
tightly spaced applications such as PCMCIA cards
A flexible, bidirectional 20-bit I/O bus accommodates a variety
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
www.analog.com
© 2003 Analog Devices, Inc. All rights reserved.
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