7
LT1224
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Capacitive Loading
The LT1224 is stable with all capacitive loads. This is
accomplished by sensing the load induced output pole and
adding compensation at the amplifier gain node. As the
capacitive load increases, both the bandwidth and phase
margin decrease so there will be peaking in the frequency
domain and in the transient response. The photo of the
small-signal response with 1000pF load shows 50% peak-
ing. The large-signal response with a 10,000pF load shows
the output slew rate being limited by the short-circuit
current.
A
V
= –1, C
L
= 1000pF A
V
= 1, C
L
= 10,000pF
U
SA
O
PP
L
IC
AT
ITY
P
I
CA
L
LT1224 • TA08
+
–
V
OUT
LT1224
R1
619Ω
R3
825Ω
C1
500pF
C2
100pF
R2
619Ω
V
IN
–38dB AT 10MHz
SMALL SIGNAL OVERSHOOT = 10%
Two Op Amp Instrumentation Amplifier
1MHz, 2nd Order Butterworth Filter
Cable Driving
LT1224 • TA07
R2
1k
+
–
IN
V
OUT
V
R1
1k
R3
75
Ω
R4
75
Ω
75 CABLE
Ω
LT1224
DAC Current-to-Voltage Converter
The wide bandwidth, high slew rate and fast settling time
of the LT1224 make it well-suited for current-to-voltage
conversion after current output D/A converters. A typical
application is shown on the first page of this data sheet
with a DAC-08 type converter with a full-scale output of
2mA. A compensation capacitor is used across the feed-
back resistor to null the pole at the inverting input caused
by the DAC output capacitance. The combination of the
LT1224 and DAC settles to 40mV in 140ns for both a 0V
to 10V step and for a 10V to 0V step.
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of circuits as described herein will not infringe on existing patent rights.
The LT1224 can drive coaxial cable directly, but for best
pulse fidelity the cable should be doubly terminated with
a resistor in series with the output.
LT1224 • TA06
LT1224 • TA09
+
–
V
OUT
LT1224
R3
1k
R5
220Ω
V
IN
A
V
= 1 + + + = 102
TRIM R5 FOR GAIN
TRIM R1 FOR COMMON-MODE REJECTION
BW = 430kHz
+
–
LT1224
–
+
R2
1k
R1
10k
R4
10k
R4
R3
[
1
2
R2
R1
(
R3
R4
)
R2 + R3
R5
]
