HFA1155IH96 Intersil, HFA1155IH96 Datasheet - Page 4

• Manufacturer Part Number: HFA1155IH96
• Description: IC OPAMP CFA 380MHZ LP SOT23-5
• Manufacturer: Intersil

Specifications of HFA1155IH96

• Applications: Current Feedback
• Number Of Circuits: 1
• -3db Bandwidth: 365MHz
• Slew Rate: 1650 V/µs
• Current - Supply: 5.5mA
• Current - Output / Channel: 55mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 11 V, ±2.25 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: SC-74A, SOT-753
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Information
Relevant Application Notes
The following Application Notes pertain to the HFA1155:
These publications may be obtained from Intersil’s web site
(www.intersil.com).
Performance Differences Between Packages
The HFA1155 is a high frequency current feedback
amplifier. As such, it is sensitive to parasitic capacitances
which influence the amplifier’s operation. The different
parasitic capacitances of different packages yield
performance differences (notably bandwidth and bandwidth
related parameters).
Because of these performance differences, designers
should evaluate and breadboard with the same package
style to be used in production.
Optimum Feedback Resistor
The enclosed frequency response graphs detail the
performance of the HFA1155 in various gains. Although the
bandwidth dependency on A
voltage feedback amplifier, there is an appreciable decrease
in bandwidth at higher gains. This decrease can be minimized
by taking advantage of the current feedback amplifier’s unique
relationship between bandwidth and R
amplifiers require a feedback resistor, even for unity gain
applications, and the R
compensation capacitor, sets the dominant pole of the
frequency response. Thus, the amplifier’s bandwidth is
inversely proportional to R
R
stability, resulting in excessive peaking and overshoot (Note:
Capacitive feedback causes the same problems due to the
feedback impedance decrease at higher frequencies). At
higher gains the amplifier is more stable, so R
decreased in a trade-off of stability for bandwidth. The table
below lists recommended R
expected bandwidth.
F
• AN9787-An Intuitive Approach to Understanding
• AN9420-Current Feedback Amplifier Theory and
• AN9663-Converting from Voltage Feedback to Current
• AN9897-Operating the HFA1155 from 5V Single
= 604Ω, at a gain of +2. Decreasing R
Current Feedback Amplifiers
Applications
Feedback Amplifiers
Supply
F
, in conjunction with the internal
F
F
. The HFA1155 is optimized for
CL
values for various gains, and the
4
isn’t as severe as that of a
F
. All current feedback
F
decreases
F
can be
HFA1155
5V Single Supply Operation
This amplifier operates at single supply voltages down to
4.5V. The dramatic supply current reduction at this operating
condition (refer also to Figure 16) makes this op amp an
even better choice for low power 5V systems. Refer to
Application Note AN9897 for further information.
Driving Capacitive Loads
Capacitive loads, such as an A/D input, or an improperly
terminated transmission line will degrade the amplifier’s
phase margin resulting in frequency response peaking and
possible oscillations. In most cases, the oscillation can be
avoided by placing a resistor (R
prior to the capacitance.
Figure 1 details starting points for the selection of this
resistor. The points on the curve indicate the R
combinations for the optimum bandwidth, stability, and
settling time, but experimental fine tuning is recommended.
Picking a point above or to the right of the curve yields an
overdamped response, while points below or left of the curve
indicate areas of underdamped performance.
R
limiting system bandwidth well below the amplifier bandwidth
of 355MHz (A
illustrated by the curves), the maximum bandwidth is
obtained without sacrificing stability. In spite of this,
bandwidth still decreases as the load capacitance increases.
For example, at A
bandwidth is 290MHz, but the bandwidth drops to 90MHz at
A
V
S
and C
= +2, R
A
+10
+1
+2
+5
-1
CL
L
S
form a low pass network at the output, thus
= 6Ω, C
V
OPTIMUM FEEDBACK RESISTOR
= +2). By decreasing R
V
= +2, R
453, (+R
L
= 390pF.
SOT-23
R
576
604
475
182
F
S
(Ω)
S
= 30Ω, C
= 221)
S
) in series with the output
L
S
= 22pF, the
BANDWIDTH (MHz)
as C
L
SOT-23
increases (as
S
360
365
355
300
250
and C
L