LT6600-15
1
660015fb
TYPICAL APPLICATION
DESCRIPTION
Very Low Noise, Differential
Amplifi er and 15MHz Lowpass Filter
The LT
®
6600-15 combines a fully differential amplifi er with a
4th order 15MHz lowpass fi lter approximating a Chebyshev
frequency response. Most differential amplifi ers require
many precision external components to tailor gain and
bandwidth. In contrast, with the LT6600-15, two external
resistors program differential gain, and the fi lter’s 15MHz
cutoff frequency and passband ripple are internally set.
The LT6600-15 also provides the necessary level shifting
to set its output common mode voltage to accommodate
the reference voltage requirements of A/Ds.
Using a proprietary internal architecture, the LT6600-15
integrates an antialiasing fi lter and a differential amplifi er/
driver without compromising distortion or low noise perfor-
mance. At unity gain the measured in band signal-to-noise
ratio is an impressive 76dB. 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 LT6600-15 also features low voltage operation. The
differential design provides outstanding performance for
a 2V
P-P
signal level while the part operates with a single
3V supply.
The LT6600-15 is packaged in an SO-8 and is pin compat-
ible with standalone differential amplifi ers.
An 8192 Point FFT Spectrum
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
FEATURES
APPLICATIONS
n
Programmable Differential Gain via Two External
Resistors
n
Adjustable Output Common Mode Voltage
n
Operates and Specifi ed with 3V, 5V, ±5V Supplies
n
0.5dB Ripple 4th Order Lowpass Filter with 15MHz
Cutoff
n
76dB S/N with 3V Supply and 2V
P-P
Output
n
Low Distortion, 2V
P-P
, 800 Load, V
S
= 3V
1MHz: 86dBc 2nd, 90dBc 3rd
10MHz: 63dBc 2nd, 69dBc 3rd
n
Fully Differential Inputs and Outputs
n
Compatible with Popular Differential Amplifi er
Pinouts
n
SO-8 Package
n
High Speed ADC Antialiasing and DAC Smoothing in
Networking or Cellular Base Station Applications
n
High Speed Test and Measurement Equipment
n
Medical Imaging
n
Drop-In Replacement for Differential Amplifi ers
–
+
–
+
R
IN
536Ω
R
IN
536Ω
0.01µF
0.1µF
25Ω
25Ω
5.6pF
3V
3V
–
+
V
MID
V
OCM
V
IN
V
CM
A
IN
V
+
V
–
D
OUT
LT6600-15
LTC2249
3
4
1
7
2
8
5
6
660015 TA01a
GAIN = 536Ω/R
IN
2.2µF
5.6pF
5.6pF
FREQUENCY (MHz)
0
AMPLITUDE (dB)
–60
–30
–20
40
660015 TA01b
–70
–80
–120
10
20
30
–100
0
–10
–40
–50
–90
–110
INPUT 10.7MHz
2V
P-P
f
SAMPLE
= 80MHz