Final Electrical Specifications
LT6600-2.5
Very Low Noise, Differential
Amplifier and 2.5MHz Lowpass Filter
June 2003
FEATURES
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DESCRIPTIO
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Programmable Differential Gain via Two External
Resistors
Adjustable Output Common Mode Voltage
Operates and Specified with 3V, 5V,
±5V
Supplies
0.5dB Ripple 4th Order Lowpass Filter with 2.5MHz
Cutoff
86dB S/N with 3V Supply and 1V
RMS
Output
Low Distortion, 1V
RMS
, 800Ω Load
1MHz: 95dBc 2nd, 88dBc 3rd
Fully Differential Inputs and Outputs
Compatible with Popular Differential Amplifier
Pinouts
SO-8 Package
The LT
®
6600-2.5 combines a fully differential amplifier
with a 4th order 2.5MHz lowpass filter approximating a
Chebyshev frequency response. Most differential amplifi-
ers require many precision external components to tailor
gain and bandwidth. In contrast, with the LT6600-2.5, two
external resistors program differential gain, and the filter’s
2.5MHz cutoff frequency and passband ripple are inter-
nally set. The LT6600-2.5 also provides the necessary level
shifting to set its output common mode voltage to accom-
modate the reference voltage requirements of A/Ds.
Using a proprietary internal architecture, the LT6600-2.5
integrates an antialiasing filter and a differential amplifier/
driver without compromising distortion or low noise
performance. At unity gain the measured in band
signal-to-noise ratio is an impressive 86dB. At higher
gains the input referred noise decreases so the part can
process smaller input differential signals without signifi-
cantly degrading the output signal-to-noise ratio.
The LT6600-2.5 also features low voltage operation. The
differential design provides outstanding performance for
a 4V
P-P
signal level while the part operates with a single 3V
supply. The LT6600-2.5 is available in an SO-8 package.
For similar devices with higher cutoff frequency, refer to
the LT6600-10 and LT6600-20 data sheets.
APPLICATIO S
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High Speed ADC Antialiasing and DAC Smoothing in
Networking or Cellular Base Station Applications
High Speed Test and Measurement Equipment
Medical Imaging
Drop-in Replacement for Differential Amplifiers
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
5V
12
0
0.1µF
1580Ω
–12
–24
7
0.01µF
V
IN+
1580Ω
8
–
GAIN (dB)
V
IN–
1
3
4
V
OUT+
V
OUT–
–36
–48
–60
–72
2 LT6600-2.5
+
6
5
660025 TA01a
–84
–96
100k
1M
10M
FREQUENCY (Hz)
50M
660025 TA01b
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-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
Amplitude Response
V
S
=
±2.5V
U
U
660025i
1
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