REV. B
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a
AD9760
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., 2000
10-Bit, 125 MSPS
TxDAC
®
D/A Converter
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Member of Pin-Compatible TxDAC
Product Family
125 MSPS Update Rate
10-Bit Resolution
Excellent Spurious Free Dynamic Range Performance
SFDR to Nyquist @ 40 MHz Output: 52 dBc
Differential Current Outputs: 2 mA to 20 mA
Power Dissipation: 175 mW @ 5 V to 45 mW @ 3 V
Power-Down Mode: 25 mW @ 5 V
On-Chip 1.20 V Reference
Single +5 V or +3 V Supply Operation
Packages: 28-Lead SOIC and TSSOP
Edge-Triggered Latches
APPLICATIONS
Communication Transmit Channel:
Basestations
Set Top Boxes
Digital Radio Link
Direct Digital Synthesis (DDS)
Instrumentation
PRODUCT DESCRIPTION
The AD9760 and AD9760-50 are the 10-bit resolution members
of the TxDAC series of high performance, low power CMOS
digital-to-analog converters (DACs). The AD9760-50 is a lower
performance option that is guaranteed and specified for 50 MSPS
operation. The TxDAC
family that consists of pin compatible 8-,
10-, 12- and 14-bit DACs is specifically optimized for the trans-
mit signal path of communication systems. All of the devices
share the same interface options, small outline package and
pinout, thus providing an upward or downward component
selection path based on performance, resolution and cost. Both
the AD9760 and AD9760-50 offer exceptional ac and dc
performance while supporting update rates up to 125 MSPS
and 60 MSPS respectively.
The AD9760’s flexible single-supply operating range of 2.7 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 45 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
approximately 25 mW.
The AD9760 is manufactured on an advanced CMOS process. A
segmented current source architecture is combined with a propri-
etary 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 inte-
grated to provide a complete monolithic DAC solution. Flexible
supply options support +3 V and +5 V CMOS logic families.
TxDAC is a registered trademark of Analog Devices, Inc.
The AD9760 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 AD9760 can be driven
by the on-chip reference or by a variety of external reference
voltages. The internal control amplifier that provides a wide
(>10:1) adjustment span allows the AD9760 full-scale current
to be adjusted over a 2 mA to 20 mA range while maintaining
excellent dynamic performance. Thus, the AD9760 may oper-
ate at reduced power levels or be adjusted over a 20 dB range to
provide additional gain ranging capabilities.
The AD9760 is available in a 28-lead SOIC and TSSOP packages.
It is specified for operation over the industrial temperature range.
PRODUCT HIGHLIGHTS
1. The AD9760 is a member of the TxDAC
product family that
provides an upward or downward component selection path
based on resolution (8 to 14 bits), performance and cost.
2. Manufactured on a CMOS process, the AD9760 uses a pro-
prietary switching technique that enhances dynamic perfor-
mance beyond what was previously attainable by higher
power/cost bipolar or BiCMOS devices.
3. On-chip, edge-triggered input CMOS latches interface readily
to +3 V and +5 V CMOS logic families. The AD9760 can
support update rates up to 125 MSPS.
4. A flexible single-supply operating range of 2.7 V to 5.5 V and
a wide full-scale current adjustment span of 2 mA to 20 mA
allow the AD9760 to operate at reduced power levels.
5. The current output(s) of the AD9760 can be easily config-
ured for various single-ended or differential circuit topologies.
50pF
COMP1
+1.20V REF
AVDD ACOM
REFLO
COMP2
CURRENT
SOURCE
ARRAY
0.1F
+5V
SEGMENTED
SWITCHES
LSB
SWITCHES
REFIO
FS ADJ
DVDD
DCOM
CLOCK
+5V
R
SET
0.1F
CLOCK
I
OUTA
I
OUTB
0.1F
LATCHES
AD9760
SLEEP
DIGITAL DATA INPUTS (DB9–DB0)
