Final Electrical Specifications
LTC1668
16-Bit, 50Msps DAC
February 2000
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FEATURES
DESCRIPTIO
The LTC®1668 is a 16-bit, 50Msps differential current
output DAC implemented on a high performance BiCMOS
process with laser trimmed, thin-film resistors. The com-
bination of a novel current-steering architecture and a
high performance process produces a DAC with excep-
tional AC and DC performance. This 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.
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50Msps Update Rate
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16-Bit Resolution
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High Spectral Purity: 87dB SFDR at 1MHz fOUT
Differential Current Outputs
30ns Settling Time
5pV-s Glitch Impulse
Low Power: 180mW from ±5V Supplies
TTL/CMOS (3.3V or 5V) Inputs
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Small Package: 28-Pin SSOP
Operating from ±5V supplies, the LTC1668 can be con-
figured to provide full-scale output currents up to 10mA.
The differential current outputs of the DAC allow single-
endedortruedifferentialoperation. The–1Vto1Voutput
compliance of the LTC1668 allows the outputs to be con-
nected directly to external resistors to produce a differ-
ential output voltage without degrading the converter’s
linearity.Alternatively,theoutputscanbeconnectedtothe
summing junction of a high speed operational amplifier,
or to a transformer.
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APPLICATIO S
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Cellular Base Stations
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Multicarrier Base Stations
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Wireless Communication
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Direct Digital Synthesis (DDS)
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xDSL Modems
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Arbitrary Waveform Generation
Automated Test Equipment
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Instrumentation
The LTC1668 is available in a 28-pin SSOP and is fully
specified over the industrial temperature range.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
16-Bit, 50Msps DAC
5V
0.1µF
Single Tone SFDR
–5
V
LTC1668
DD
f
f
= 25Msps
REFOUT
2.5V
CLOCK
= 1.007MHz
–15
–25
–35
–45
–55
–65
–75
–85
–95
–105
OUT
REFERENCE
R
SET
2k
AMPLITUDE = 0dBFS
0.1µF
I
REFIN
= –8.5dBm
SFDR = 86dBc
52.3Ω
52.3Ω
I
I
OUT A
+
+
–
16-BIT
HIGH SPEED
DAC
1V
P-P
DIFFERENTIAL
V
OUT
OUT B
–
COMP1
COMP2
LADCOM
C1
0.1µF
V
SS
AGND DGND CLK
DB15
DB0
C2
0.1µF
1668 TA01
0.05
6.3
12.55
FREQUENCY (1.25MHz/DIV)
CLOCK 16-BIT DATA
INPUT INPUT
0.1µF
1668 G01
–5V
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
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