EL5367IU-T13 데이터 시트보기 (PDF) - Renesas Electronics
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EL5367IU-T13 Datasheet PDF : 11 Pages
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EL5367
Pin Descriptions
16-PIN QSOP PIN NAME
3
INPA
6
INPB
8
INPC
1
INMA
14
INMB
11
INMC
2
VSMA
4
VSMB
7
VSMC
16
VSPA
13
VSPB
10
VSPC
15
OUTA
12
OUTB
9
OUTC
FUNCTION
Non-inverting input
Non-inverting input
Non-inverting input
Inverting
Inverting
Inverting
Negative supply
Negative supply
Negative supply
Positive supply
Positive supply
Positive supply
Output
Output
Output
Applications Information
Product Description
The EL5367 is a current-feedback operational amplifier that
offers a wide -3dB bandwidth of 1GHz and a low supply
current of 8.5mA per amplifier. The EL5367 works with
supply voltages ranging from a single 5V to 10V and it is also
capable of swinging to within 1V of either supply on the
output. Because of their current-feedback topology, the
EL5367 does not have the normal gain-bandwidth product
associated with voltage-feedback operational amplifiers.
Instead, its -3dB bandwidth remains relatively constant as
closed-loop gain is increased. This combination of high
bandwidth and low power, together with aggressive pricing
make the EL5367 an ideal choice for many low-power/high-
bandwidth applications such as portable, handheld, or
battery-powered equipment.
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high frequency device, good printed circuit
board layout is necessary for optimum performance. Low
impedance ground plane construction is essential. Surface
mount components are recommended, but if leaded
components are used, 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 0.01µF 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) Even when
ground plane construction is used, 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 additional series
inductance. Use of sockets, particularly for the SO package,
should be avoided if possible. Sockets add parasitic
inductance and capacitance which will result in 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
value feedback and gain resistors exacerbates the problem
by further lowering the pole frequency (increasing the
possibility of oscillation).
The EL5367 frequency response is optimized with the
resistor values in Figure 3. With the high bandwidth of this
amplifier, these resistor values might cause stability
problems when combined with parasitic capacitance, thus
ground plane is not recommended around the inverting input
pin of the amplifier.
Feedback Resistor Values
The EL5367 has been designed and specified at a gain of +2
with RF approximately 392. This value of feedback resistor
gives 800MHz of -3dB bandwidth at AV = 2 with about 0.5dB
of peaking. Since the EL5367 is current-feedback amplifier, it
is also possible to change the value of RF to get more
bandwidth. As seen in the curve of Frequency Response for
Various RF and RG, bandwidth and peaking can be easily
modified by varying the value of the feedback resistor.
Because the EL5367 is a current-feedback amplifier, its
gain-bandwidth product is not a constant for different closed-
loop gains. This feature actually allows the EL5367 to
maintain reasonable constant -3dB bandwidth for different
gains. As 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 RF below the specified 250 and still retain
stability, resulting in only a slight loss of bandwidth with
increased closed-loop gain.
FN7457 Rev 1.00
November 9, 2004
Page 8 of 11
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