EL2044 データシートの表示（PDF） - Elantec -> Intersil
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EL2044 Datasheet PDF : 13 Pages
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EL2044C
Low Power/Low Voltage 120MHz Unity-Gain Stable Operational Amplifier
The output drive capability of the EL2044C allows it to
drive up to 2 back-terminated loads with good video per-
formance. For more demanding applications such as
greater output drive or better video distortion, a number
of alternatives such as the EL2120C, EL400C, or
EL2073C should be considered.
Output Drive Capability
The EL2044C has been designed to drive low imped-
ance loads. It can easily drive 6VPP into a 150Ω load.
This high output drive capability makes the EL2044C an
ideal choice for RF, IF and video applications. Further-
more, the current drive of the EL2044C remains a
minimum of 35mA at low temperatures. The EL2044C
is current-limited at the output, allowing it to withstand
shorts to ground. However, power dissipation with the
output shorted can be in excess of the power-dissipation
capabilities of the package.
Capacitive Loads
For ease of use, the EL2044C has been designed to drive
any capacitive load. However, the EL2044C remains
stable by automatically reducing its gain-bandwidth
product as capacitive load increases. Therefore, for max-
imum bandwidth, capacitive loads should be reduced as
much as possible or isolated via a series output resistor
(RS). Similarly, coax lines can be driven, but best AC
performance is obtained when they are terminated with
their characteristic impedance so that the capacitance of
the coaxial cable will not add to the capacitive load seen
by the amplifier. Although stable with all capacitive
loads, some peaking still occurs as load capacitance
increases. A series resistor at the output of the EL2044C
can be used to reduce this peaking and further improve
stability.
Printed-Circuit Layout
The EL2044C is well behaved, and easy to apply in most
applications. However, a few simple techniques will
help assure rapid, high quality results. As with any high-
frequency device, good PCB layout is necessary for
optimum performance. Ground-plane construction is
highly recommended, as is good power supply bypass-
ing. A 0.1µF ceramic capacitor is recommended for
bypassing both supplies. Lead lengths should be as short
as possible, and bypass capacitors should be as close to
the device pins as possible. For good AC performance,
parasitic capacitances should be kept to a minimum at
both inputs and at the output. Resistor values should be
kept under 5kΩ because of the RC time constants associ-
ated with the parasitic capacitance. Metal-film and
carbon resistors are both acceptable, use of wire-wound
resistors is not recommended because of their parasitic
inductance. Similarly, capacitors should be low-induc-
tance for best performance.
The EL2044C Macromodel
This macromodel has been developed to assist the user
in simulating the EL2044C with surrounding circuitry. It
has been developed for the PSPICE simulator (copywrit-
ten by the Microsim Corporation), and may need to be
rearranged for other simulators. It approximates DC,
AC, and transient response for resistive loads, but does
not accurately model capacitive loading. This model is
slightly more complicated than the models used for low-
frequency op-amps, but it is much more accurate for AC
analysis.
The model does not simulate these characteristics
accurately:
noise
settling-time
CMRR
PSRR
non-linearities
temperature effects
manufacturing variations
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