10-Bit, 125 MSPS High Performance
TxDAC® D/A Converter
a
AD9750*
FUNCTIONAL BLOCK DIAGRAM
FEATURES
High Performance Member of Pin-Compatible
TxDAC Product Family
125 MSPS Update Rate
+5V
REFLO
+1.20V REF
REFIO
AVDD
ACOM
AD9750
ICOMP
150pF
10-Bit Resolution
0.1F
0.1F
CURRENT
SOURCE
ARRAY
Excellent Spurious Free Dynamic Range Performance
SFDR to Nyquist @ 5 MHz Output: 76 dBc
Differential Current Outputs: 2 mA to 20 mA
Power Dissipation: 190 mW @ 5 V
Power-Down Mode: 20 mW @ 5 V
On-Chip 1.20 V Reference
FS ADJ
R
SET
DVDD
+5V
IOUTA
IOUTB
SEGMENTED
SWITCHES
LSB
SWITCH
DCOM
CLOCK
SLEEP
CLOCK
LATCHES
CMOS-Compatible +2.7 V to +5.5 V Digital Interface
Packages: 28-Lead SOIC and TSSOP
Edge-Triggered Latches
DIGITAL DATA INPUTS (DB9–DB0)
The AD9750 is a current-output DAC with a nominal full-scale
output current of 20 mA and > 100 kΩ output impedance.
APPLICATIONS
Wideband Communication Transmit Channel:
Direct IF
Basestations
Wireless Local Loop
Digital Radio Link
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.
Direct Digital Synthesis (DDS)
Instrumentation
The on-chip reference and control amplifier are configured for
maximum accuracy and flexibility. The AD9750 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 AD9750 full-scale current
to be adjusted over a 2 mA to 20 mA range while maintaining
excellent dynamic performance. Thus, the AD9750 may oper-
ate at reduced power levels or be adjusted over a 20 dB range to
provide additional gain ranging capabilities.
PRODUCT DESCRIPTION
The AD9750 is a 10-bit resolution, wideband, second generation
member of the TxDAC series of high performance, low power
CMOS digital-to-analog-converters (DACs). The TxDACfamily,
which consists of pin compatible 8-, 10-, 12-, and 14-bit DACs,
is specifically optimized for the transmit signal path of commu-
nication systems. All of the devices share the same interface
options, small outline package and pinout, thus providing an up-
ward or downward component selection path based on perfor-
mance, resolution and cost. The AD9750 offers exceptional ac and
dc performance while supporting update rates up to 125 MSPS.
The AD9750 is available in 28-lead SOIC and TSSOP packages.
It is specified for operation over the industrial temperature range.
The AD9750’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
reduced to a mere 65 mW, without a significant degradation in
performance, by lowering the full-scale current output. Also, a
power-down mode reduces the standby power dissipation to
apprixmatley 20 mW.
PRODUCT HIGHLIGHTS
1. The AD9750 is a member of the wideband TxDAChigh 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 AD9750 uses a
proprietary switching technique that enhances dynamic
performance beyond that previously attainable by higher
power/cost bipolar or BiCMOS devices.
The AD9750 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.
3. On-chip, edge-triggered input CMOS latches interface to
+2.7 V to +5 V CMOS logic families. The AD9750 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 AD9750 to operate at reduced power levels.
TxDAC is a registered trademark of Analog Devices, Inc.
*Protected by U.S. Patents Numbers 5450084, 5568145, 5689257, 5612697 and
5703519. Other patents pending.
5. The current output(s) of the AD9750 can be easily config-
ured for various single-ended or differential circuit topologies.
REV. 0
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otherwise under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 1999