HFA1130 Intersil Corporation, HFA1130 Datasheet - Page 4

• Manufacturer Part Number: HFA1130
• Description: 850MHz/ Output Limiting/ Low Distortion Current Feedback Operational Amplifier
• Manufacturer: Intersil Corporation

Electrical Specifications
NOTES:
Application Information
Optimum Feedback Resistor (R
The enclosed plots of inverting and non-inverting frequency
response detail the performance of the HFA1100/1120 in
various gains. Although the bandwidth dependency on A
isn’t as severe as that of 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
feedback resistor, even for unity gain applications, and the R
in conjunction with the internal compensation capacitor, sets
the dominant pole of the frequency response. Thus, the
amplifier’s bandwidth is inversely proportional to R
HFA1100, 1120 designs are optimized for a 510 R
gain of +1. Decreasing R
decreases 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
The table below lists recommended R
gains, and the expected bandwidth.
Clamp Operation
General
The HFA1130 features user programmable output clamps to
limit output voltage excursions. Clamping action is obtained
by applying voltages to the V
5) of the amplifier. V
sets the lower clamp level. If the amplifier tries to drive the
output above V
Negative Clamp Range
Positive Clamp Range
Clamp Input Bias Current
Clamp Input Bandwidth
2. Test Level: A. Production Tested; B. Typical or Guaranteed Limit Based on Characterization; C. Design Typical for Information Only.
3. See Typical Performance Curves for more information.
F
can be decreased in a trade-off of stability for bandwidth.
PARAMETER
A
+10
+19
H
+1
+2
+5
-1
CL
F
, or below V
. All current feedback amplifiers require a
H
sets the upper output limit, while V
F
R
in a unity gain application
510
430
360
150
180
270
F
L
( )
H
, the clamp circuitry limits the
4
and V
V
SUPPLY
L
F
F
BW (MHz)
)
terminals (pins 8 and
V
values for various
H
= 5V, A
850
580
670
520
240
125
or V
CONDITIONS
L
TEST
= 100mV
V
F
= +1, R
. The
F
, at a
P-P
CL
F
L
= 510 , R
F
HFA1130
,
(NOTE 2)
LEVEL
TEST
B
B
A
B
L
= 100 , Unless Otherwise Specified (Continued)
output voltage at V
respectively. The low input bias currents of the clamp pins
allow them to be driven by simple resistive divider circuits, or
active elements such as amplifiers or DACs.
Clamp Circuitry
Figure 1 shows a simplified schematic of the HFA1130 input
stage, and the high clamp (V
feedback amplifiers, there is a unity gain buffer (Q
between the positive and negative inputs. This buffer forces -IN to
track +IN, and sets up a slewing current of (V
This current is mirrored onto the high impedance node (Z) by
Q
via another unity gain buffer. If no clamping is utilized, the high
impedance node may swing within the limits defined by Q
Q
current flowing through -IN is reduced to only that small current
(-I
Tracing the path from V
clamp voltage on the high impedance node. V
by 2V
Q
+IN
TEMP.
X3
N4
P5
BIAS
(
FIGURE 1. HFA1130 SIMPLIFIED V
o
25
25
25
25
-Q
. Note that when the output reaches it’s quiescent value, the
C)
begins to conduct whenever the high impedance node
BE
) required to keep the output at the final voltage.
X4
, where it is converted to a voltage and fed to the output
(Q
Q
Q
N6
V-
V+
N1
P1
MIN
Q
Q
and Q
-
-
-
-
P3
N3
V-
H
Q
I
Q
CLAMP
N2
P2
or V
P6
V+
-IN
-5.0 to +2.0
-2.0 to +5.0
H
) to set up the base voltage on Q
L
to Z illustrates the effect of the
TYP
500
( the clamp accuracy),
H
50
) circuitry. As with all current
Q
Q
N4
P4
Z
Q
Q
N5
P5
(EXTERNAL)
H
CLAMP CIRCUITRY
MAX
+1
200
R
-
-
-
F
Q
Q
-IN
N6
P6
- V
FOR V
H
X1
OUT
decreases
200
(30K
- Q
50K
L
UNITS
)/R
)
MHz
X2
P4
V
V
A
V
)
F
R
H
.
V
P5
and
1
OUT
.