clc450 National Semiconductor Corporation, clc450 Datasheet - Page 7

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

The CLC450 is a current feedback amplifier built in an
advanced complementary bipolar process. The CLC450
operates from a single 5V supply or dual ±5V supplies.
Operating from a single supply, the CLC450 has the
following features:
The CLC450 performance is further enhanced in ±5V
supply applications as indicated in the ±5V Electrical
Characteristics table and ±5V Typical Performance plots.
Current Feedback Amplifiers
Some of the key features of current feedback technology
are:
Current feedback operation can be described using a simple
equation. The voltage gain for a non-inverting or inverting
current feedback amplifier is approximated by Equation 1.
Single Supply Operation (V
The specifications given in the +5V Electrical Character-
istics table for single supply operation are measured with
a common mode voltage (V
age around which the inputs are applied and the
output voltages are specified.
Operating from a single +5V supply, the Common Mode
Input Range (CMIR) of the CLC450 is typically +0.8V to
+4.2V. The typical output range with R
to +4.0V.
V
Note: R
to V
consumption and maximum
output swing.
in
Provides 100mA of output current while
consuming 7.5mW of power
Offers low -79/-75dB 2nd and 3rd harmonic
distortion
Provides BW > 60MHz and 1MHz distortion
< -65dBc at V
Independence of AC bandwidth and voltage gain
Inherently stable at unity gain
Adjustable frequency response with feedback resistor
High slew rate
Fast settling
cm
Figure 1: Non-Inverting Configuration
for minimum power
t
, R
V
L
and R
cm
R
t
g
are tied
V
cm
R
o
3
2
g
= 2.5V
CLC450
-
+
V
CC
7
4
cm
pp
CC
6.8 F
0.1 F
V
V
) of 2.5V. V
+
R
in
o
f
= +5V, V
6
CLC450 DESIGN INFORMATION
A
v
V
1
cm
L
R
=100
EE
R
R
L
V
CLC450 OPERATION
g
f
cm
o
= GND)
is the volt-
is +1.0V
7
where:
The denominator of Equation 1 is approximately equal to
1 at low frequencies. Near the -3dB corner frequency, the
interaction between R
performance. The value of the feedback resistor has a
large affect on the circuits performance. Increasing R
has the following affects:
Refer to the Feedback Resistor Selection section for
more details on selecting a feedback resistor value.
For single supply DC coupled operation, keep input
signal levels above 0.8V DC. For input signals that drop
below 0.8V DC, AC coupling and level shifting the signal
are recommended. The non-inverting and inverting
configurations for both input conditions are illustrated in
the following 2 sections.
DC Coupled Single Supply Operation
Figures 1 and 2 show the recommended non-inverting
and inverting configurations for input signals that remain
above 0.8V DC.
V
V
in
o
V
in
Note: R
for non-inverting input.
R
to V
consumption and maximum
output swing.
A
R
Z(j ) is the CLC450’s open loop transimpedance
Decreases loop gain
Decreases bandwidth
Reduces gain peaking
Lowers pulse response overshoot
Affects frequency response phase linearity
Z j
b
gain
, R
v
f
R
cm
1
V
L
V
is the feedback resistor
is the closed loop DC voltage gain
f
and R
for minimum power
Figure 2: Inverting Configuration
cm
cm
b
A
, provides DC bias
Z(j )
R
R
v
t
t
is the loop gain
R
are tied
f
R
b
V
V
in
o
g
A
v
3
2
f
and Z(j ) dominates the circuit
Equation 1
CLC450
-
-
+
+
V
R
R
CC
g
7
4
f
6.8 F
0.1 F
Select R
desired R
+
R
f
6
t
V
to yield
in
cm
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= R
R
L
V
t
|| R
o
g
f