LT1225CS8 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LT1225CS8 Datasheet PDF : 8 Pages
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LT1225
APPLICATI S I FOR ATIO
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.
AV = – 5, CL = 1000pF
AV = 5, CL = 10,000pF
LT1225 AI04
The LT1225 can drive coaxial cable directly, but for best
pulse fidelity the cable should be doubly terminated with
a resistor in series with the output.
Compensation
The LT1225 has a typical gain-bandwidth product of
150MHz which allows it to have wide bandwidth in high
gain configurations (i.e., in a gain of 10 it will have a
bandwidth of about 15MHz). The amplifier is stable in a
noise gain of 5 so the ratio of the output signal to the
inverting input must be 1/5 or less. Straightforward gain
configurations of 5 or –4 are stable, but there are a few
configurations that allow the amplifier to be stable for
lower signal gains (the noise gain, however, remains 5 or
more). One example is the summing amplifier shown in
the typical applications section below. Each input signal
has a gain of –RF/RIN to the output, but it is easily seen that
this configuration is equivalent to a gain of – 4 as far as the
amplifier is concerned. Lag compensation can also be
used to give a low frequency gain less than 5 with a high
frequency gain of 5 or greater. The example below has a
DC gain of one, but an AC gain of 5. The break frequency
of the RC combination across the amplifier inputs should
be approximately a factor of 10 less than the gain band-
width of the amplifier divided by the high frequency gain
(in this case 1/10 of 150MHz/5 or 3MHz).
TYPICAL APPLICATI S
Lag Compensation
VIN
500Ω
100pF
+
LT1225
–
2k
VOUT
AV = 1, f < 3MHz
LT1225 TA03
Wein Bridge Oscillator
#327
LAMP
430Ω
1.5k
100pF
–
LT1225
+
100pF
1.5k
VOUT
>10VP-P
1MHz
LT1225 TA05
Cable Driving
VIN
+
LT1225
–
R1
1k
R2
250Ω
R3
75 Ω
75Ω CABLE
VOUT
R4
75Ω
LT1225 TA04
Summing Amplifier
RF
RIN
VIN1
RIN
VIN2
RIN
VINn
RIN
=
nRF
4
–
LT1225
+
VOUT
LT1225 TA06
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.
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