REV. A
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a
AD9754*
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
14-Bit, 125 MSPS High Performance
TxDAC
®
D/A Converter
FUNCTIONAL BLOCK DIAGRAM
150pF
+1.20V REF
AVDD
ACOM
REFLO
ICOMP
CURRENT
SOURCE
ARRAY
+5V
SEGMENTED
SWITCHES
LSB
SWITCHES
REFIO
FS ADJ
DVDD
DCOM
CLOCK
+5V
R
SET
0.1mF
CLOCK
IOUTA
IOUTB
0.1mF
LATCHES
AD9754
SLEEP
DIGITAL DATA INPUTS (DB13–DB0)
FEATURES
High Performance Member of Pin-Compatible
TxDAC Product Family
125 MSPS Update Rate
14-Bit Resolution
Excellent Spurious Free Dynamic Range Performance
SFDR to Nyquist @ 5 MHz Output: 83 dBc
Differential Current Outputs: 2 mA to 20 mA
Power Dissipation: 185 mW @ 5 V
Power-Down Mode: 20 mW @ 5 V
On-Chip 1.20 V Reference
CMOS-Compatible +2.7 V to +5.5 V Digital Interface
Package: 28-Lead SOIC, TSSOP Packages
Edge-Triggered Latches
APPLICATIONS
Wideband Communication Transmit Channel:
Direct IF
Basestations
Wireless Local Loop
Digital Radio Link
Direct Digital Synthesis (DDS)
Instrumentation
PRODUCT DESCRIPTION
The AD9754 is a 14-bit resolution, wideband, second genera-
tion member of the TxDAC series of high performance, low
power CMOS digital-to-analog-converters (DACs). The
TxDAC
family, which consists of pin compatible 8-, 10-, 12-
and 14-bit DACs, is specifically optimized for the transmit
signal path of communication systems. All of the devices share
the same interface options, small outline package and pinout,
providing an upward or downward component selection path
based on performance, resolution and cost. The AD9754 offers
exceptional ac and dc performance while supporting update
rates up to 125 MSPS.
The AD9754’s flexible single-supply operating range of +4.5 V to
+5.5 V and low power dissipation are well suited for portable and
low power applications. Its power dissipation can be further reduc-
ed to a mere 65 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 20 mW.
The AD9754 is manufactured on an advanced CMOS process.
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 bandgap reference have
been integrated to provide a complete monolithic DAC solution.
The digital inputs support +2.7 V and +5 V CMOS logic families.
The AD9754 is a current-output DAC with a nominal full-scale
output current of 20 mA and > 100 kΩ output impedance.
Differential current outputs are provided to support single-
ended or differential applications. Matching between the two
current outputs ensures enhanced dynamic performance in a
differential output configuration. The current outputs may be
tied directly to an output resistor to provide two complemen-
tary, single-ended voltage outputs or fed directly into a trans-
former. The output voltage compliance range is 1.25 V.
The on-chip reference and control amplifier are configured for
maximum accuracy and flexibility. The AD9754 can be driven
by the on-chip reference or by a variety of external reference
voltages. The internal control amplifier, which provides a wide
(>10:1) adjustment span, allows the AD9754 full-scale current
to be adjusted over a 2 mA to 20 mA range while maintaining
excellent dynamic performance. Thus, the AD9754 may operate
at reduced power levels or be adjusted over a 20 dB range to
provide additional gain ranging capabilities.
The AD9754 is available in 28-lead SOIC and TSSOP packages.
It is specified for operation over the industrial temperature range.
PRODUCT HIGHLIGHTS
1. The AD9754 is a member of the wideband TxDAC
high per-
formance product family that provides an upward or downward
component selection path based on resolution (8 to 14 bits),
performance and cost. The entire family of TxDACs is avail-
able in industry standard pinouts.
2. Manufactured on a CMOS process, the AD9754 uses a
proprietary switching technique that enhances dynamic per-
formance beyond that previously attainable by higher power/
cost bipolar or BiCMOS devices.
3. On-chip, edge-triggered input CMOS latches readily inter-
face to +2.7 V to +5 V CMOS logic families. The AD9754
can support update rates up to 125 MSPS.
4. A flexible single-supply operating range of +4.5 V to +5.5 V,
and a wide full-scale current adjustment span of 2 mA to
20 mA, allows the AD9754 to operate at reduced power levels.
5. The current output(s) of the AD9754 can be easily config-
ured for various single-ended or differential circuit topologies.
TxDAC is a registered trademark of Analog Devices, Inc.
*Protected by U.S. Patents Numbers 5450084, 5568145, 5689257, 5612697 and
5703519.
