LM6104M NSC [National Semiconductor], LM6104M Datasheet - Page 4

• Manufacturer Part Number: LM6104M
• Description: Quad Gray Scale Current Feedback Amplifier
• Manufacturer: NSC [National Semiconductor]

Applications Information
CURRENT FEEDBACK TOPOLOGY
The small-signal bandwidth of conventional voltage feed-
back amplifiers is inversely proportional to the closed-loop
gain based on the gain-bandwidth concept In contrast the
current feedback amplifier topology such as the LM6104
enables a signal bandwidth that is relatively independent of
the amplifier’s gain (see typical curve Frequency Response
vs Closed Loop Gain)
FEEDBACK RESISTOR SELECTION R
Current feedback amplifier bandwidth and slew rate are
controlled by R
tion capacitor set the dominant pole in the frequency re-
sponse The amplifier therefore always requires a feed-
back resistor even in unity gain
F
R
F
and the amplifier’s internal compensa-
F
4
Bandwidth and slew rate are inversely proportional to the
value of R
This makes the amplifier especially easy to compensate for
a desired pulse response (see typical curve Large Signal
Pulse Response) Increased capacitive load driving capabili-
ty is also achieved by increasing the value of R
The LM6104 has guaranteed performance with a feedback
resistor of 2 k
CAPACITIVE FEEDBACK
It is common to place a small lead capacitor in parallel with
feedback resistance to compensate voltage feedback am-
plifiers Do not place a capacitor across R
width of current feedback amplifiers The dynamic imped-
ance of capacitors in the feedback path of the LM6104 as
with any current feedback amplifier will cause instability
F
(see typical curve Frequency Response vs R
F
to limit the band-
F
F
)