LT6600CS8-5-PBF LINER [Linear Technology], LT6600CS8-5-PBF Datasheet - Page 7

• Manufacturer Part Number: LT6600CS8-5-PBF
• Description: Very Low Noise, Differential Amplifi er and 5MHz Lowpass Filter
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Interfacing to the LT6600-5
The LT6600-5 requires 2 equal external resistors, R
set the differential gain to 806Ω/R
fi lter are the voltages V
external components, Figure 1. The difference between
V
age of V
Similarly, the voltages V
and 5 of the LT6600-5 are the fi lter outputs. The differ-
ence between V
voltage. The average of V
mode output voltage.
Figure 1 illustrates the LT6600-5 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
output voltage is 1.65V and the differential output voltage
IN
+
and V
IN
+
IN
and V
–
is the differential input voltage. The aver-
OUT
IN
–1
–
+
2
1
0
3
2
1
0
3
2
1
0
is the common mode input voltage.
and V
V
V
V
500mV
OUT
IN
V
V
IN
IN
OUT
+
+
–
+
OUT
P-P
and V
and V
+
(DIFF)
V
and V
–
V
V
IN
IN
IN
+
is the differential output
+
–
P-P
OUT
IN
–
IN
. The common mode
OUT
–
presented to these
. The inputs to the
t
appearing at Pins 4
t
t
–
V
V
IN
IN
is the common
V
V
–
+
V
IN
IN
IN
–
+
+
806Ω
806Ω
0.1μF
0.1μF
62pF
200Ω
200Ω
62pF
0.01μF
0.01μF
806Ω
806Ω
IN
, to
+
–
0.01μF
Figure 1
Figure 2
Figure 3
1
7
2
8
2V
+
–
LT6600-5
3
3.3V
6
1
7
2
8
0.01μF
is 2V
output voltage is determined by the voltage at Pin 2. Since
Pin 2 is shorted to Pin 7, 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 Pin 7
(refer to the Distortion vs Input Common Mode Level
graphs in the Typical Performance Characteristics).
Figure 2 shows how to AC couple signals into the LT6600-5.
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 806Ω gain setting resistor
form a high pass fi lter, attenuating signals below 2kHz.
Larger values of coupling capacitors will proportionally
reduce this highpass 3dB frequency.
In Figure 3 the LT6600-5 is providing 12dB of gain. The
gain resistor has an optional 62pF in parallel to improve
+
1
7
2
8
–
0.1μF
–
+
LT6600-5
4
5
–
+
3
3.3V
LT6600-5
6
3
6
5V
+
–
P-P
0.1μF
+
–
0.1μF
4
5
4
5
for frequencies below 5MHz. The common mode
V
V
OUT
OUT
V
V
OUT
OUT
+
–
V
V
+
–
OUT
OUT
+
–
3
2
1
0
3
2
1
0
V
V
3
2
1
0
V
V
V
V
V
OUT
OUT
OUT
OUT
+
–
V
V
+
–
66005 F01
OUT
OUT
66005 F03
+
–
66005 F02
t
t
LT6600-5
66005fa
7