LTC1666/LTC1667/LTC1668
12-Bit, 14-Bit, 16-Bit,
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50Msps DACs
FEATURES
DESCRIPTIO
The LTC®1666/LTC1667/LTC1668 are 12-/14-/16-bit,
50Msps differential current output DACs implemented on
a high performance BiCMOS process with laser trimmed,
thin-film resistors. The combination of a novel current-
steering architecture and a high performance process
produces DACs with exceptional AC and DC performance.
The LTC1668 is the first 16-bit DAC in the marketplace to
exhibit an SFDR (spurious free dynamic range) of 87dB
for an output signal frequency of 1MHz.
■
50Msps Update Rate
■
Pin Compatible 12-Bit, 14-Bit and 16-Bit Devices
■
High Spectral Purity: 87dB SFDR at 1MHz fOUT
■
5pV-s Glitch Impulse
■
Differential Current Outputs
■
20ns Settling Time
■
Low Power: 180mW from ±5V Supplies
■
TTL/CMOS (3.3V or 5V) Inputs
■
Small Package: 28-Pin SSOP
Operating from ±5V supplies, the LTC1666/LTC1667/
LTC1668 can be configured to provide full-scale output
currents up to 10mA. The differential current outputs of
theDACsallowsingle-endedortruedifferentialoperation.
The –1V to 1V output compliance of the LTC1666/
LTC1667/LTC1668 allows the outputs to be connected
directly to external resistors to produce a differential out-
putvoltagewithoutdegradingtheconverter’slinearity.Al-
ternatively,theoutputscanbeconnectedtothesumming
junction of a high speed operational amplifier, or to a
transformer.
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APPLICATIO S
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Cellular Base Stations
■
Multicarrier Base Stations
■
Wireless Communication
■
Direct Digital Synthesis (DDS)
■
xDSL Modems
■
Arbitrary Waveform Generation
Automated Test Equipment
■
■
Instrumentation
The LTC1666/LTC1667/LTC1668 are pin compatible and
are available in a 28-pin SSOP and are fully specified over
the industrial temperature range.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATION
LTC1668, 16-Bit, 50Msps DAC
5V
0.1µF
LTC1668 SFDR vs fOUT and fCLOCK
100
V
LTC1668
DD
REFOUT
2.5V
REFERENCE
5MSPS
R
SET
2k
0.1µF
90
I
REFIN
25MSPS
52.3Ω
I
I
OUT A
OUT B
80
70
60
50
50MSPS
+
+
–
16-BIT
HIGH SPEED
DAC
1V
P-P
DIFFERENTIAL
52.3Ω
V
OUT
–
COMP1
COMP2
LADCOM
C1
0.1µF
V
SS
AGND DGND CLK
DB15
DB0
DIGITAL AMPLITUDE = 0dBFS
C2
0.1µF
1666/7/8 TA01
0.1
1.0
10
100
f
(MHz)
OUT
CLOCK 16-BIT DATA
INPUT INPUT
0.1µF
1666/7/8 G05
–5V
1