REV. PrA
Preliminary Technical Data
PRELIMINARY TECHNICAL DATA
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a
AD9748*
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
8-Bit, 165 MSPS
TxDAC® D/A Converter
FUNCTIONAL BLOCK DIAGRAMFEATURES
High-Performance Member of Pin-Compatible
TxDAC Product Family
Excellent Spurious-Free Dynamic Range and Noise
Performance
Two’s Complement or Straight Binary Data Format
Differential Current Outputs: 2 mA to 20 mA
Power Dissipation: 135 mW @ 3.3 V
Power-Down Mode: 15 mW @ 3.3 V
On-Chip 1.20 V Reference
CMOS-Compatible Digital Interface
Package: 32-Lead Leadframe Chip Scale Package
(LFCSP)
Edge-Triggered Latches
APPLICATIONS
Wideband Communication Transmit Channel:
Direct IF
Base Stations
Wireless Local Loop
Digital Radio Link
Direct Digital Synthesis (DDS)
Instrumentation
150pF
+1.20V REF
AVDD
ACOM
CURRENT
SOURCE
ARRAY
3.3V
SEGMENTED
SWITCHES
LSB
SWITCHES
REFIO
FS ADJ
DVDD
DCOM
3.3V
R
SET
0.1H9262F
CLK+
IOUTA
IOUTB
LATCHES
AD9748
SLEEP
DIGITAL DATA INPUTS (DB7-DB0)
MODE1
MODE2CLK-
CLKVDD
CLKCOM
3.3V
PRODUCT DESCRIPTION
The AD9748 is a 8-bit resolution, wideband, third generation
member of the TxDAC series of high-performance, low power
CMOS digital-to-analog converters (DACs). The TxDAC family,
consisting of pin-compatible 8-, 10-, 12-, and 14-bit DACs, is
specifically optimized for the transmit signal path of communica-
tion systems. All of the devices share the same interface options,
small outline package, and pinout, providing an upward or down-
ward component selection path based on performance, resolution,
and cost. The AD9748 offers exceptional ac and dc performance
while supporting update rates up to 165 MSPS.
The AD9748’s low power dissipation makes it well suited for
portable and low power applications. Its power dissipation can be
further reduced to a mere 60 mW with a slight degradation in
performance by lowering the full-scale current output. Also, a
power-down mode reduces the standby power dissipation to
approximately 15 mW. A segmented current source architecture
is combined with a proprietary switching technique to reduce
spurious components and enhance dynamic performance. Edge-
triggered input latches and a 1.2 V temperature compensated
band gap reference have been integrated to provide a complete
monolithic DAC solution. The digital inputs support 3 V
CMOS logic families.
PRODUCT HIGHLIGHTS
1. New 32-lead LFCSP package.
2. The AD9748 is the 8-bit member of the pin-compatible
TxDAC family that offers excellent INL and DNL
performance.
3. Differential or single-ended clock input (LVPECL or
CMOS).
4. Data input supports two’s complement or straight binary
data coding.
5. High-speed, single-ended CMOS clock input supports
165 MSPS conversion rate.
6. Low power: Complete CMOS DAC function operates on
135 mW from a 3.0 V to 3.6 V single supply. The DAC
full-scale current can be reduced for lower power operation,
and a sleep mode is provided for low power idle periods.
7. On-chip voltage reference: The AD9748 includes a 1.2 V
temperature-compensated band gap voltage reference.
TxDAC is a registered trademark of Analog Devices, Inc.
*Protected by U.S. Patent Numbers 5568145, 5689257, and 5703519.