HFA11XXEVAL Intersil, HFA11XXEVAL Datasheet - Page 4

• Manufacturer Part Number: HFA11XXEVAL
• Description: EVALUATION PLATFORM HFA11XX
• Manufacturer: Intersil

Specifications of HFA11XXEVAL

• Channels Per Ic: 1 - Single
• Amplifier Type: General Purpose
• Board Type: Partially Populated
• Utilized Ic / Part: 8-DIP Package
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Operating Temperature: -
• Output Type: -
• Current - Output / Channel: -
• Voltage - Supply, Single/dual (±): -
• -3db Bandwidth: -
• Slew Rate: -
• Current - Supply (main Ic): -

Application Information
Relevant Application Notes
The following Application Notes pertain to the HFA1150:
These publications may be obtained from Intersil’s web site
(http://www.intersil.com).
Performance Differences Between Packages
The HFA1150 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 the SOIC and SOT-23 packages
yield performance differences (notably bandwidth and
bandwidth related parameters) between the two devices -
see Electrical Specification tables for details.
Because of these performance differences, designers
should evaluate and breadboard with the same package
style to be used in production.
Note that some “Typical Performance Curves” have
separate graphs for each package type. Graphs not labeled
with a specific package type are applicable to both
packages.
Optimum Feedback Resistor
The enclosed frequency response graphs detail the
performance of the HFA1150 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
All current feedback amplifiers require a feedback resistor,
even for unity gain applications, and the R
with the internal compensation capacitor, sets the dominant
pole of the frequency response. Thus, the amplifier’s
bandwidth is inversely proportional to R
optimized for a R
of +2. Decreasing R
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
trade-off of stability for bandwidth. The table below lists
recommended R
expected bandwidth.
• AN9787 - An Intuitive Approach to Understanding
• AN9420 - Current Feedback Amplifier Theory and
• AN9663-Converting from Voltage Feedback to Current
• AN9891-Operating the HFA1150 from 5V Single
Current Feedback Amplifiers
Applications
Feedback Amplifiers
Supply
F
F
values for various gains, and the
= 576Ω/499Ω (SOIC/SOT-23), at a gain
F
decreases stability, resulting in
CL
4
isn’t as severe as that of a
F
can be decreased in a
F
. The HFA1150 is
F
, in conjunction
F
.
HFA1150
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 25) makes this op amp an
even better choice for low power 5V systems. Refer to
Application Note AN9891 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 700MHz/540MHz (SOIC/SOT-23, A
decreasing R
the maximum bandwidth is obtained without sacrificing
stability. In spite of this, bandwidth still decreases as the load
capacitance increases. For example, at A
C
bandwidth drops to 110MHz at A
C
S
L
L
= 22pF, the SOIC bandwidth is 410MHz, but the
= 390pF.
and C
A
+10
+1
+2
+5
-1
CL
L
form a low pass network at the output, thus
S
OPTIMUM FEEDBACK RESISTOR
as C
L
383, (+R
549, (+R
increases (as illustrated by the curves),
SOIC/SOT-23
422/464
576/499
348/422
178/348
R
F
S
(Ω)
S
= 226)/
= 100)
S
V
) in series with the output
= +2, R
V
= +2). By
BANDWIDTH (MHz)
V
S
SOIC/SOT-23
= +2, R
= 5Ω,
650/540
600/500
700/540
480/400
380/300
S
and C
S
= 20Ω,
L