LT6604-2.5
Dual Very Low Noise,
Differential Amplifier and
2.5MHz Lowpass Filter
FEATURES
DESCRIPTION
TheLT®6604-2.5consistsoftwomatched,fullydifferential
amplifiers,eachwitha4thorder,2.5MHzlowpassfilter.The
fixed frequency lowpass filter approximates a Chebyshev
response. By integrating a filter and a differential ampli-
fier, distortion and noise are made exceptionally low. At
unity gain, the measured in-band signal-to-noise ratio is
an impressive 86dB. At higher gains, the input referred
noise decreases, allowing the part to process smaller
input differential signals without significantly degrading
the signal-to-noise ratio.
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Dual Differential Amplifier with 2.5MHz Lowpass Filters
4th Order Filters
Approximates Chebyshev Response
Guaranteed Phase and Gain Matching
Resistor-Programmable Differential Gain
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>86dB Signal-to-Noise (3V Supply, 1V
Output)
RMS
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Low Distortion (1MHz, 1V
HD2: 92dBc
Output, 800Ω Load)
RMS
HD3: 88dBc
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Specified for Operation with 3V, 5V and 5V Supplies
Fully Differential Inputs and Outputs
Gain and phase are well matched between the two chan-
nels. Gain for each channel is independently programmed
usingtwoexternalresistors. TheLT6604-2.5enableslevel
shifting by providing an adjustable output common mode
voltage, making it ideal for directly interfacing to ADCs.
The LT6604-2.5 is fully specified for 3V operation. The
differential design enables outstanding performance up
Adjustable Output Common Mode Voltage
Small 4mm × 7mm × 0.75mm QFN Package
APPLICATIONS
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Dual Differential ADC Driver and Filter
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Single-Ended to Differential Converter
to a 4V signal level for a single 3V supply.
P-P
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Matched, Dual, Differential Gain or Filter Stage
See the back page of this datasheet for a complete list of
relatedsingleanddualdifferentialamplifierswithintegrated
2.5MHz to 20MHz lowpass filters.
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Common Mode Translation of Differential Signals
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High Speed ADC Antialiasing and DAC Smoothing in
Wireless Infrastructure or Networking Applications
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.v
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High Speed Test and Measurement Equipment
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Medical Imaging
TYPICAL APPLICATION
Channel to Channel Gain Matching
3V
18
50 TYPICAL UNITS
LT6604-2.5
LTC22xx
DUAL ADC
+
T
= 25°C
16
14
12
10
8
A
V A
3V
50Ω
1580Ω
GAIN = 1
f = 2.5MHz
IN
+INA
+
+
–OUTA
+OUTA
V
+
AIN
–
–
+
MIDA
18pF
18pF
V
DOUT
OCMA
50Ω
0.01μF
–INA
–
+
–
+
1580Ω
1580Ω
+
V B
3V
+INB
V
6
50Ω
–OUTB
+OUTB
+
AIN
–
–
MIDB
4
V
DOUT
OCMB
50Ω
2
0.01μF
+
–INB
–
–
0
–
1580Ω
V
–0.25 –0.15 –0.05 0 0.05
GAIN MATCH (dB)
0.15
0.25
660425 TA01
660425 TA01b
660425f
1