LT1115_15 Datasheet, PDF (7/16 Pages) Linear Technology – Ultralow Noise, Low Distortion, Audio Op Amp

LT1115
TYPICAL PERFOR A CE CHARACTERISTICS
Small-Signal Transient Response
Maximum Output vs Frequency
(Power Bandwidth*)
30
V_S = ± 18V
T_A = 25°C
25
R_L = 2kΩ
Closed-Loop Output Impedance
100
I_O = 1mA
V_S = ±18V
10 ^{TA = 25°C}
FPO
A_V = –1,
R_S = R_f = 2kΩ
C_f = 30pF
C_L = 80pF
0.2µs/DIVISION
20
15
10
*POWER BANDWIDTH
fP
=
SLEW RATE
πE_OP
5 _{fP = POWER BANDWIDTH}
E_P-P = PEAK-TO-PEAK AMPLIFIER
0
OUTPUT VOLTAGE
10k
100k
1M
FREQUENCY (Hz)
10M
LT1115 • TPC29
1
A_V = 1000
0.1
A_V = 5
0.01
0.001
10
100
1k
10k 100k 1M
FREQUENCY (Hz)
LT1115 • TPC30
CCIF Testing
Note: The CCIF twin-tone intermodulation test inputs two closely
FPO ^{spaced equal amplitude tones to the device under test (DUT). The}
analyzer then measures the intermodulation distortion (IMD)
produced in the DUT by measuring the difference tone equal to the
spacing between the tones.
The amplitude of the lMD test input is in sinewave peak equivalent
terms. As an example, selecting an amplitude of 1.000V will result in
the complex IMD signal having the same 2.828V peak-to-peak
amplitude that a 1.000V sinewave has. Clipping in a DUT will thus
occur at the same input amplitude for THD + N and IMD modes.
APPLICATIO S I FOR ATIO
The LT1115 is a very high performance op amp, but
not necessarily one which is optimized for universal
application. Because of very low voltage noise and the
resulting high gain-bandwidth product, the device is most
applicable to relatively high gain applications. Thus, while
the LT1115 will provide notably superior performance to
the 5534 in most applications, the device may require
circuit modifications to be used at very low noise gains.
The part is not generally applicable for unity gain followers
or inverters. In general, it should always be used with good
low impedance bypass capacitors on the supplies, low
impedance feedback values, and minimal capacitive load-
ing. Ground plane construction is recommended, as is a
compact layout.
Voltage Noise vs Current Noise
The LT1115’s less than 1nV/√Hz voltage noise matches
that of the LT1028 and is three times better than the lowest
voltage noise heretofore available (on the LT1007/1037).
A necessary condition for such low voltage noise is
operating the input transistors at nearly 1mA of
collector currents, because voltage noise is inversely
proportional to the square root of the collector current.
Current noise, however, is directly proportional to the
square root of the collector current. Consequently, the
LT1115’s current noise is significantly higher than on
most monolithic op amps.
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7