ha5013 Intersil Corporation, ha5013 Datasheet - Page 7

• Manufacturer Part Number: ha5013
• Description: Triple, 125mhz Video Amplifier
• Manufacturer: Intersil Corporation

Application Information
Optimum Feedback Resistor
The plots of inverting and non-inverting frequency response,
see Figure 8 and Figure 9 in the typical performance section,
illustrate the performance of the HA5013 in various closed loop
gain configurations. Although the bandwidth dependency on
closed loop gain isn’t as severe as that of a voltage feedback
amplifier, there can be an appreciable decrease in bandwidth at
higher gains. This decrease may 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 R
compensation capacitor, sets the dominant pole of the
frequency response. Thus, the amplifier’s bandwidth is
inversely proportional to R
for a 1000 R
application decreases stability, resulting in excessive peaking
and overshoot. At higher gains the amplifier is more stable, so
R
The table below lists recommended R
gains, and the expected bandwidth.
PC Board Layout
The frequency response of this amplifier depends greatly on
the amount of care taken in designing the PC board. The
use of low inductance components such as chip resistors
and chip capacitors is strongly recommended. If leaded
components are used the leads must be kept short
especially for the power supply decoupling components and
those components connected to the inverting input.
Attention must be given to decoupling the power supplies. A
large value (10 F) tantalum or electrolytic capacitor in
parallel with a small value (0.1 F) chip capacitor works well
in most cases.
A ground plane is strongly recommended to control noise.
Care must also be taken to minimize the capacitance to
ground seen by the amplifier’s inverting input (-IN). The
larger this capacitance, the worse the gain peaking, resulting
in pulse overshoot and possible instability. It is
recommended that the ground plane be removed under
traces connected to -IN, and that connections to -IN be kept
F
can be decreased in a trade-off of stability for bandwidth.
GAIN
(A
+10
-10
+1
+2
+5
-1
CL
)
F
at a gain of +1. Decreasing R
F
, in conjunction with the internal
R
1000
1000
68f1
750
383
750
F
( )
F
. The HA5013 design is optimized
7
F
. All current feedback
F
values for various
BANDWIDTH
F
in a unity gain
(MHz)
100
125
95
52
65
22
HA5013
as short as possible to minimize the capacitance from this
node to ground.
Driving Capacitive Loads
Capacitive loads 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 an isolation resistor (R) in series with the output as
shown in Figure 6.
The selection criteria for the isolation resistor is highly
dependent on the load, but 27 has been determined to be
a good starting value.
Power Dissipation Considerations
Due to the high supply current inherent in triple amplifiers,
care must be taken to insure that the maximum junction
temperature (T
exceeded. Figure 7 shows the maximum ambient
temperature versus supply voltage for the available package
styles (PDIP, SOIC). At V
package styles may be operated over the full industrial range
of -40
calculations, which take into account output power, be
performed by the designer.
FIGURE 7. MAXIMUM OPERATING AMBIENT TEMPERATURE
FIGURE 6. PLACEMENT OF THE OUTPUT ISOLATION
130
120
110
100
o
90
80
70
60
50
40
30
20
10
V
C to 85
IN
5
RESISTOR, R
vs SUPPLY VOLTAGE
o
J
C. It is recommended that thermal
, see Absolute Maximum Ratings) is not
R
100
T
R
I
7
SUPPLY VOLTAGE ( V)
+
-
S
= 5V quiescent operation both
PDIP
9
SOIC
R
R
F
11
C
L
13
V
OUT
15