HFA3-0002-5 INTERSIL [Intersil Corporation], HFA3-0002-5 Datasheet - Page 10

• Manufacturer Part Number: HFA3-0002-5
• Description: Low Noise Wideband Operational Amplifier
• Manufacturer: INTERSIL [Intersil Corporation]

Applications Information
Offset Voltage Adjustment
The HFA-0002, due to its low offset voltage, will typically not
require any external offset adjustment. If certain applications
do require lower offset, the following diagram shows one
possible configuration.
The power supply lines must be well decoupled to filter any
power supply noise. A 20K trim pot will allow an offset
adjustment of about 3mV, referred to input.
PC Board Layout Guidelines
When designing with the HFA-0002, good high frequency
(RF) techniques should be used when doing pc board
layouts. A massive ground plane should be used to maintain
a low impedance ground. PC board traces should be kept as
short as possible and kept wide to minimize trace inductance
and impedance. Stray capacitance at the op amps output
and at the high impedance inputs should be kept to a
minimum, to prevent any unwanted phase shift and band-
width limiting.
When breadboarding remember to keep feedback resistor
values low (≤5kΩ) for optimum performance. The use of
metal film resistors for values over 200Ω and carbon film
resistors under 200Ω typically gives the best performance.
Remember to keep all lead lengths as short as possible to
minimize lead inductance.
Sockets will add parasitic capacitance and inductance and
therefore can limit AC performance as well as reduce
stability. If sockets must be used, a low profile socket with
minimum pin to pin capacitance will minimize any perfor-
mance degradation.
Power supply decoupling is essential for high frequency op
amps. A 0.01µF high quality ceramic capacitor at each
supply pin in parallel with a 1µF tantalum capacitor will pro-
vide excellent decoupling. Chip capacitors produce the best
results due to the ease of placement next to the op amp and
they have negligible lead inductance. If leaded capacitors
are used, again the lead lengths should be kept to a
minimum.
Saturation Recovery
When an op amp is over driven output devices can saturate
2
3
7
+5V
FIGURE 29.
-
5V
+
4
1
20K
5
6
HFA-0002
2-617
and sometime take a long time to recover. By clamping the
input to safe levels, output saturation can be avoided. If
output saturation cannot be avoided, the recovery time for
an input sine wave at 25% overdrive is 100ns.