LT1206C Linear Technology, LT1206C Datasheet - Page 10

• Manufacturer Part Number: LT1206C
• Description: 250mA/60MHz Current Feedback Amplifier
• Manufacturer: Linear Technology

LT1206
For applications where the full bandwidth of the amplifier
is not required, the quiescent current of the device may be
reduced by connecting a resistor from the shutdown pin to
ground. The quiescent current will be approximately 40
times the current in the shutdown pin. The voltage across
the resistor in this condition is V
60k resistor will set the quiescent supply current to 10mA
with V
The photos (Figures 4a and 4b) show the effect of reducing
the quiescent supply current on the large-signal response.
The quiescent current can be reduced to 5mA in the
inverting configuration without much change in response.
In noninverting mode, however, the slew rate is reduced
as the quiescent current is reduced.
10
A
PPLICATI
S
Figure 4a. Large-Signal Response vs I
R
R
R
R
Figure 4b. Large-Signal Response vs I
= 15V.
F
L
F
L
= 750
= 50
= 750
= 50
I
V
I
V
O
Q
Q
S
S
= 5mA, 10mA, 20mA
= 5mA, 10mA, 20mA
= 15V
= 15V
U
S
I FOR ATIO
U
+
– 3V
W
BE
Q
. For example, a
Q
, A
, A
LT1206 • F04a
LT1206 • F04b
V
V
= –1
= 2
U
Slew Rate
Unlike a traditional op amp, the slew rate of a current
feedback amplifier is not independent of the amplifier gain
configuration. There are slew rate limitations in both the
input stage and the output stage. In the inverting mode,
and for higher gains in the noninverting mode, the signal
amplitude on the input pins is small and the overall slew
rate is that of the output stage. The input stage slew rate
is related to the quiescent current and will be reduced as
the supply current is reduced. The output slew rate is set
by the value of the feedback resistors and the internal
capacitance. Larger feedback resistors will reduce the
slew rate as will lower supply voltages, similar to the way
the bandwidth is reduced. The photos (Figures 5a, 5b and
5c) show the large-signal response of the LT1206 for
various gain configurations. The slew rate varies from
860V/ s for a gain of 1, to 1400V/ s for a gain of – 1.
R
R
R
R
F
L
F
L
= 825
= 50
= RG = 750
= 50
Figure 5a. Large-Signal Response, A
Figure 5b. Large-Signal Response, A
V
S
= 15V
V
S
= 15V
V
V
LT1206 • F05a
LT1206 • F05b
= 1
= –1