lm6164 National Semiconductor Corporation, lm6164 Datasheet - Page 8

• Manufacturer Part Number: lm6164
• Description: High Speed Operational Amplifier
• Manufacturer: National Semiconductor Corporation

www.national.com
Simplified Schematic
Applications Tips
The LM6364 has been compensated for gains of 5 or greater
(over specified ranges of temperature, power supply voltage,
and load). Since this compensation involved adding
emitter-degeneration resistors in the op amp’s input stage,
the open-loop gain was reduced as the stability increased.
Gain error due to reduced A
gains; thus, the uncompensated LM6365 is appropriate for
gains of 25 or more. If unity-gain operation is desired, the
LM6361 should be used. The LM6361, LM6364, and
LM6365 have the same high slew rate (typically 300 V/µs),
regardless of their compensation.
The LM6364 is unusually tolerant of capacitive loads. Most
op amps tend to oscillate when their load capacitance is
greater than about 200 pF (in low-gain circuits). However,
load capacitance on the LM6364 effectively increases its
compensation capacitance, thus slowing the op amp’s re-
sponse and reducing its bandwidth. The compensation is not
ideal, though, and ringing or oscillation may occur in
low-gain circuits with large capacitive loads. To overcompen-
sate the LM6364 for operation at gains less than 5, a series
resistor-capacitor network should be added between the in-
put pins (as shown in the Typical Applications, Noise Gain
Compensation) so that the high-frequency noise gain rises
to at least 5.
VOL
is most apparent at high
8
Power supply bypassing will improve the stability and tran-
sient response of the LM6364, and is recommended for ev-
ery design. 0.01 µF to 0.1 µF ceramic capacitors should be
used (from each supply “rail” to ground); if the device is far
away from its power supply source, an additional 2.2 µF to
10 µF (tantalum) may be required for extra noise reduction.
Keep all leads short to reduce stray capacitance and lead in-
ductance, and make sure ground paths are low-impedance,
especially where heavier currents will be flowing. Stray ca-
pacitance in the circuit layout can cause signal coupling be-
tween adjacent nodes, so that circuit gain unintentionally
varies with frequency.
Breadboarded circuits will work best if they are built using
generic PC boards with a good ground plane. If the op amps
are used with sockets, as opposed to being soldered into the
circuit, the additional input capacitance may degrade circuit
performance.
DS009153-3