LTC6957-1/LTC6957-2/
LTC6957-3/LTC6957-4
Low Phase Noise, Dual
Output Buffer/Driver/
Logic Converter
FEATURES
DESCRIPTION
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Low Phase Noise Buffer/Driver
The LTC®6957-1/LTC6957-2/LTC6957-3/LTC6957-4 is a
family of very low phase noise, dual output AC signal
buffer/driver/logic level translators. The input signal can
be a sine wave or any logic level (≤2V ). There are four
members of the family that differ inPt-hPeir output logic
signal type as follows:
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Optimized Conversion of Sine Wave Signals to
Logic Levels
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Three Logic Output Types Available
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LVPECL
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LVDS
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CMOS
LTC6957-1: LVPECL Logic Outputs
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Additive Jitter 45fs
(LTC6957-1)
RMS
LTC6957-2: LVDS Logic Outputs
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Frequency Range Up to 300MHz
3.15V to 3.45V Supply Operation
Low Skew 3ps Typical
Fully Specified from –40°C to 125°C
12-Lead MSOP and 3mm × 3mm DFN Packages
LTC6957-3: CMOS Logic, In-Phase Outputs
LTC6957-4: CMOS Logic, Complementary Outputs
The LTC6957 will buffer and distribute any logic signal
with minimal additive noise, however, the part really
excels at translating sine wave signals to logic levels. The
early amplifier stages have selectable lowpass filtering
to minimize the noise while still amplifying the signal to
increase its slew rate. This input stage filtering/noise limit-
ing is especially helpful in delivering the lowest possible
phase noise signal with slow slewing input signals such
as a typical 10MHz sine wave system reference.
APPLICATIONS
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System Reference Frequency Distribution
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High Speed ADC, DAC, DDS Clock Driver
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Military and Secure Radio
Low Noise Timing Trigger
Broadband Wireless Transceiver
High Speed Data Acquisition
Medical Imaging
Test and Measurement
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All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents 7969189 and 8319551.
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TYPICAL APPLICATION
3.3V
Additive Phase Noise at 100MHz
0.1µF
ꢑꢏꢙꢐ
ꢂꢔꢈꢢꢞꢃꢟꢃꢈꢡꢃꢡ ꢂꢔꢈꢃ ꢣꢓꢠꢃ ꢔꢈꢒꢇꢄ
ꢓꢄ ꢤ7ꢕꢖꢥ ꢋ5ꢐꢐꢥꢠ
ꢎ
ꢅꢝꢂ
ꢁꢔꢞꢄꢓ ꢦ ꢁꢔꢞꢄꢖ ꢦ ꢢꢈꢡ
+
V
SD1
ꢑꢏꢙ5
ꢑꢏ5ꢐ
ꢑꢏ55
ꢑꢏ6ꢐ
ꢑꢏ65
FILTA
FILTB
TO PLL CHIPS
OR SYSTEM
SAMPLING CLOCKS
ꢞꢄꢉ6957ꢟꢛ ꢋꢞꢠꢡꢂꢎ
ꢞꢄꢉ6957ꢟꢙ ꢋꢉꢝꢀꢂꢎ
OUT1
100MHz
+7dBm
SINE WAVE
10nF
+
IN
OCXO
–
IN
50Ω
10nF
OUT2
ꢞꢄꢉ6957ꢟꢜ
ꢋꢉꢝꢀꢂꢎ
ꢞꢄꢉ6957ꢟꢏ ꢋꢞꢠꢒꢃꢉꢞꢎ
ꢏꢚ ꢏꢐꢚ
ꢀꢁꢁꢂꢃꢄ ꢁꢅꢃꢆꢇꢃꢈꢉꢊ ꢋꢌꢍꢎ
GND
SD2
6957 TA01a
ꢏꢐꢐ
ꢏꢐꢐꢚ
ꢏꢝ
6957ꢏꢛꢜꢙ ꢄꢓꢐꢏb
6957fb
1
For more information www.linear.com/LTC6957-1