clc450 National Semiconductor Corporation, clc450 Datasheet - Page 8

• Manufacturer Part Number: clc450
• Description: Single Supply, Low-power, High Output, Current Feedback Amplifier
• Manufacturer: National Semiconductor Corporation

AC Coupled Single Supply Operation
Figures 3 and 4 show possible non-inverting and invert-
ing configurations for input signals that go below 0.8V
DC. The input is AC coupled to prevent the need for
level shifting the input signal at the source. The resistive
voltage divider biases the non-inverting input to V
= 2.5V (For V
Dual Supply Operation
The CLC450 operates on dual supplies as well as single
supplies. The non-inverting and inverting configurations
are shown in Figures 5 and 6.
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Figure 3: AC Coupled Non-Inverting Configuration
Figure 5: Dual Supply Non-Inverting Configuration
low frequency cutoff
low frequency cutoff
V
V
o
o
Figure 4: AC Coupled Inverting Configuration
V
V
V
in
in
V
in
in
V
1
in
C
R
R
R
c
R
R
g
t
f
g
CC
f
V
2.5
V
R
= +5V).
C
2
2.5
CC
R
2
CC
3
2
c
g
g
2 R C
2 R C
CLC450
-
+
V
V
1
CC
EE
in c
7
4
1
g c
R
R
R
R
6.8 F
0.1 F
0.1 F
6.8 F
, where: R
+
R
f
6
+
R
C
3
3
2
2
g
CLC450
CLC450
-
+
-
+
V
V
in
CC
CC
7
4
7
4
R
2
6.8 F
0.1 F
V
6.8 F
0.1 F
+
+
R
o
R
f
f
6
6
R
R
CC
source
V
V
÷ 2
o
o
8
Feedback Resistor Selection
The feedback resistor, R
frequency response of a current feedback amplifier.
Optimum performance of the CLC450, at a gain of +2V/V,
is achieved with R
plots
illustrate the recommended R
recommended values of R
width with minimal peaking. Within limits, R
adjusted to optimize the frequency response.
As a rule of thumb, if the recommended R
then the bandwidth will be cut in half.
Unity Gain Operation
The recommended R
is 1.5k . R
inverting node may require a slight increase in R
maintain a flat frequency response.
Bandwidth vs. Output Amplitude
The bandwidth of the CLC450 is at a maximum for
output voltages near 1V
for smaller and larger output amplitudes. Refer to the
Frequency Response vs. V
Load Termination
The CLC450 can source and sink near equal amounts of
current. For optimum performance, the load should be
tied to V
Driving Cables and Capacitive Loads
When driving cables, double termination is used to
prevent reflections. For capacitive load applications, a
small series resistor at the output of the CLC450 will
improve stability and settling performance. The
Frequency Response vs. C
vs. C
recommended series resistance value for optimum
flatness at various capacitive loads.
Figure 6: Dual Supply Inverting Configuration
L
V
Decrease R
extend bandwidth
Increase R
compress bandwidth
plots, in the typical performance section, give the
in
in
cm
.
g
R
the
b
is left open. Parasitic capacitance at the
f
f
3
2
equal to 1k . The frequency response
f
Typical
to roll off frequency response and
to peak frequency response and
-
+
CLC450
f
V
V
CC
EE
for unity gain (+1V/V) operation
7
4
pp
f
f
, affects the loop gain and
. The bandwidth decreases
6.8 F
0.1 F
0.1 F
6.8 F
provide the maximum band-
+
o
R
f
L
f
6
plots.
+
Performance
for several gains. These
and Recommended R
Note: R
for the non-inverting input.
Select R
R
in
= R
V
t
b
|| R
t
o
provides DC bias
to yield desired
f
g
.
is doubled,
f
sections
can be
f
to
s