clc420 National Semiconductor Corporation, clc420 Datasheet - Page 7

• Manufacturer Part Number: clc420
• Description: High-speed, Voltage Feedback Op Amp
• Manufacturer: National Semiconductor Corporation

Application Division
Description
The CLC420 is a high-speed, slew-boosted, voltage feed-
back amplifier with unity-gain stability. These features along
with matched inputs, low input bias and noise currents, and
excellent CMRR render the CLC420 very attractive for active
filters, differential amplifiers, log amplifiers, and transimped-
ance amplifiers.
DC accuracy
Unlike current-feedback amplifiers, voltage-feedback ampli-
fiers have matched inputs. This means that the non-inverting
and inverting input bias current are well matched and track
over temperature, etc. As a result, by matching the resis-
tance looking out of the two inputs, these errors can be re-
duced to a small offset current term.
Gain bandwidth product
Since
closed-loop bandwidth is approximately equal to the
gain-bandwidth product (typically 100MHz) divided by the
noise gain of the circuit (for noise gains greater than 5). At
lower noise gains, higher-order amplifier poles contribute to
higher closed-loop bandwidth. At low gains use the fre-
quency response performance plots given in the data sheet.
the
CLC420
is
a
voltage-feedback
FIGURE 1. Recommended Non-Inverting Gain Circuit
FIGURE 2. Recommended Inverting Gain Circuit
op-amp,
7
Another point to remember is that the closed-loop bandwidth
is determined by the noise gain, not the signal gain of the cir-
cuit. Noise gain is the reciprocal of the attenuation in the
feedback network enclosing the op amp. For example, a
CLC420 setup as a non-inverting amplifier with a
closed-loop gain of +1 (a noise gain of 1) has a 300MHz
bandwidth. When used as an inverting amplifier with a gain
of −1 (a noise gain of 2), the bandwidth is less, typically only
100MHz.
Full-power bandwidth, and slew-rate
The CLC420 combines exceptional full-power bandwidths
(40MHz, V
A
tive results are achieved by using slew-boosting circuitry to
keep the slew rates high while consuming very little power.
In non-slew boosted amplifiers, full-power bandwidth can be
easily determined from slew-rate measurements, but in
slew-boosting amplifiers, such as the CLC420, you can’t. For
this reason we provide data for both.
Slew rate is also different for inverting and non-inverting con-
figurations. This occurs because common-mode signal volt-
ages are present in non-inverting circuits but absent in in-
verting circuits. Once again data is provided for both.
v
= +1) with low (40mW) power consumption. These attrac-
0
= 5Vpp, A
DS012752-17
DS012752-16
v
= +1) and slew rates (1100V/µs,
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