LT6604-10 Linear Technology Corporation, LT6604-10 Datasheet - Page 9

• Manufacturer Part Number: LT6604-10
• Description: Dual Very Low Noise, Differential Ampli?er And 10mhz Lowpass Filter
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
Interfacing to the LT6604-10
Note: The LT6604-10 contains two identical fi lters. The
following applications information only refers to one fi lter.
The two fi lters are independent except that they share
the same negative supply voltage V
can be used simultaneously by replicating the example
circuits. The referenced pin numbers correspond to the
channel A fi lter.
The LT6604-10 channel requires two equal external resis-
tors, R
to the fi lter are the voltages V
external components, Figure 1. The difference between V
and V
V
larly, the voltages V
and 29 of the LT6604-10 are the fi lter outputs. The differ-
ence between V
voltage. The average of V
mode output voltage. Figure 1 illustrates the LT6604-10
IN
+
and V
IN
IN
–
, to set the differential gain to 402Ω/R
is the differential input voltage. The average of
IN
–
–1
2
is the common mode input voltage. Simi-
1
0
OUT
3
2
1
0
V
V
+
OUT
and V
+
and V
OUT
V
OUT
IN
IN
V
V
+
+
IN
+
IN
+
and V
–
and V
OUT
–
is the differential output
–
IN
appearing at Pins 27
OUT
t
t
–
–
presented to these
. The two fi lters
V
–
V
V
IN
IN
IN
is the common
+
–
+
IN
0.1μF
0.1μF
402Ω
402Ω
. The inputs
402Ω
402Ω
0.01μF
0.01μF
IN
34
+
4
6
2
Figure 1
Figure 2
1/2
–
LT6604-10
+
25
34
3.3V
7
4
6
2
operating with a single 3.3V supply and unity passband
gain; the input signal is DC coupled. The common mode
input voltage is 0.5V, and the differential input voltage is
2V
differential output voltage is 2V
10MHz. The common mode output voltage is determined
by the voltage at V
the output common mode is the mid-supply voltage. In
addition, the common mode input voltage can be equal
to the mid-supply voltage of V
Figure 2 shows how to AC couple signals into the LT6604-10.
In this instance, the input is a single-ended signal. AC
coupling allows the processing of single-ended or dif-
ferential signals with arbitrary common mode levels. The
0.1μF coupling capacitor and the 402Ω gain setting resistor
form a high pass fi lter, attenuating signals below 4kHz.
Larger values of coupling capacitors will proportionally
reduce this highpass 3dB frequency.
1/2
LT6604-10
+
–
+
–
25
0.1μF
3.3V
27
7
29
P-P
+
–
0.1μF
27
. The common mode output voltage is 1.65V, and the
29
V
V
OUT
OUT
+
–
V
V
OUT
OUT
+
–
OCM
3
2
1
0
V
3
2
1
0
. Since V
V
MID
V
V
P-P
OUT
OUT
OCM
V
V
.
OUT
OUT
+
–
660410 F01
for frequencies below
+
–
660410 F02
LT6604-10
is shorted to V
t
660410fb
MID
9
,