EL2480CSZ-T13 Intersil, EL2480CSZ-T13 Datasheet - Page 9

• Manufacturer Part Number: EL2480CSZ-T13
• Description: IC OPAMP QUAD 250MHZ/3MA 14-SOIC
• Manufacturer: Intersil

Specifications of EL2480CSZ-T13

• Amplifier Type: Current Feedback
• Number Of Circuits: 4
• Slew Rate: 1200 V/µs
• -3db Bandwidth: 250MHz
• Current - Input Bias: 16µA
• Voltage - Input Offset: 2500µV
• Current - Supply: 3mA
• Current - Output / Channel: 55mA
• Voltage - Supply, Single/dual (±): 3 V ~ 12 V, ±1.5 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Gain Bandwidth Product: -

Applications Information
Product Description
The EL2480 is a current-feedback operational amplifier that
offers a wide -3dB bandwidth of 250MHz and a low supply
current of 3mA per amplifier. This product also features high
output current drive. The EL2480 can output 55mA per
amplifier. The EL2480 works with supply voltages ranging
from a single 3V to ±6V, and it is also capable of swinging to
within 1V of either supply on the input and the output.
Because of its current-feedback topology, the EL2480 does
not have the normal gain-bandwidth product associated with
voltage-feedback operational amplifiers. This allows its -3dB
bandwidth to remain relatively constant as closed-loop gain
is increased. This combination of high bandwidth and low
power, together with aggressive pricing make the EL2480
the ideal choice for many low-power/high-bandwidth
applications such as portable computing, HDSL, and video
processing.
The EL2480 is available in the industry standard SO
package. For triple application with disable, consider the
EL2386 (16-pin triple).
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high-frequency device, good printed circuit
board layout is necessary for optimum performance. Ground
plane construction is highly recommended. Lead lengths
should be as short as possible. The power supply pins must
be well bypassed to reduce the risk of oscillation. The
combination of a 4.7µF tantalum capacitor in parallel with a
0.1µF capacitor has been shown to work well when placed at
each supply pin.
For good AC performance, parasitic capacitance should be
kept to a minimum especially at the inverting input (see the
Capacitance at the Inverting Input section). Ground plane
construction should be used, but it should be removed from
the area near the inverting input to minimize any stray
capacitance at that node. Carbon or Metal-Film resistors are
acceptable with the Metal-Film resistors giving slightly less
peaking and bandwidth because of their additional series
inductance. Use of sockets, should be avoided if possible.
Sockets add parasitic inductance and capacitance which will
result in some additional peaking and overshoot.
Capacitance at the Inverting Input
Any manufacturer's high-speed voltage- or current-feedback
amplifier can be affected by stray capacitance at the
inverting input. For inverting gains this parasitic capacitance
has little effect because the inverting input is a virtual
ground, but for non-inverting gains this capacitance (in
conjunction with the feedback and gain resistors) creates a
pole in the feedback path of the amplifier. This pole, if low
enough in frequency, has the same destabilizing effect as a
zero in the forward open-loop response. The use of large
9
EL2480
value feedback and gain resistors further exacerbates the
problem by further lowering the pole frequency.
The experienced user with a large amount of PC board
layout experience may find in rare cases that the EL2480
has less bandwidth than expected.
The reduction of feedback resistor values (or the addition of
a very small amount of external capacitance at the inverting
input, e.g. 0.5pF) will increase bandwidth as desired. Please
see the curves for Frequency Response for Various R
R
Feedback Resistor Values
The EL2480 has been designed and specified at gains of +1
and +2 with R
give 250MHz of -3dB bandwidth at A
of peaking, and 180MHz of -3dB bandwidth at A
about 0.1dB of peaking. Since the EL2480 is current-
feedback amplifier, it is also possible to change the value of
R
Frequency Response For Various R
and peaking can be easily modified by varying the value of
the feedback resistor.
Because the EL2480 is current-feedback amplifier, its gain-
bandwidth product is not a constant for different closed-loop
gains. This feature actually allows the EL2480 to maintain
about the same -3dB bandwidth, regardless of closed-loop
gain. However, as closed-loop gain is increased, bandwidth
decreases slightly while stability increases. Since the loop
stability is improving with higher closed-loop gains, it
becomes possible to reduce the value of R
specified 560Ω and 750Ω and still retain stability, resulting in
only a slight loss of bandwidth with increased closed-loop
gain.
Supply Voltage Range and Single-Supply
Operation
The EL2480 has been designed to operate with supply
voltages having a span of greater than 3V, and less than
12V. In practical terms, this means that the EL2480 will
operate on dual supplies ranging from ±1.5V to ±6V. With a
single-supply, the EL2480 will operate from +3V to +12V.
As supply voltages continue to decrease, it becomes
necessary to provide input and output voltage ranges that
can get as close as possible to the supply voltages. The
EL2480 has an input voltage range that extends to within 1V
of either supply. So, for example, on a single +5V supply, the
EL2480 has an input range which spans from 1V to 4V. The
output range of the EL2480 is also quite large, extending to
within 1V of the supply rail. On a ±5V supply, the output is
therefore capable of swinging from -4V to +4V. Single-supply
output range is even larger because of the increased
negative swing due to the external pull-down resistor to
ground. On a single +5V supply, output voltage range is
about 0.3V to 4V.
G
F
, and Frequency Response for Various C
to get more bandwidth. As seen in the curve of
F
= 750Ω. These values of feedback resistors
F
V
and R
= +1 with about 2.5dB
F
G
IN
below the
, bandwidth
-.
V
= +2 with
F
and