LT1115
Ultralow Noise,
Low Distortion, Audio Op Amp
FEATURES
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DESCRIPTIO
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Voltage Noise: 1.2nV/√Hz Max at 1kHz
0.9nV/√Hz Typ at 1kHz
Voltage and Current Noise 100% Tested
Gain-Bandwidth Product: 40MHz Min
Slew Rate: 10V/µs Min
Voltage Gain: 2 Million Min
Low THD at 10kHz, A
V
= –10, R
L
= 600Ω: 0.002%
V
O
= 7V
RMS
Low IMD, CCIF Method, A
V
= +10: 0.002%
R
L
= 600Ω
V
O
= 7V
RMS
The LT
®
1115 is the lowest noise audio operational ampli-
fier available. This ultralow noise performance (0.9nV/√Hz
at 1kHz) is combined with high slew rates (>15V/µs) and
very low distortion specifications.
The RIAA circuit shown below using the LT1115 has very
low distortion and little deviation from ideal RIAA
response (see graph).
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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High Quality Audio Preamplifiers
Low Noise Microphone Preamplifiers
Very Low Noise Instrumentation Amplifiers
Low Noise Frequency Synthesizers
Infrared Detector Amplifiers
Hydrophone Amplifiers
Low Distortion Oscillators
TYPICAL APPLICATIO
18V
RIAA Phonograph Preamplifier (40/60db Gain)
18V
+
INPUT
R
IN
47.5k (MM)
100Ω (MC)
COM
C
IN
(SELECT
PER
PHOTO
CART-
RIDGE)
3
+
–
7
6
1µF
35V
+
1µF
35V
100Ω
2N4304*
~250Ω
SELECT
FOR 2mA
1
2
A2
LT1010CT
3
R
BOOST
49.9Ω
4
5
562Ω
OUTPUT
3900pF
2
A1
LT1115
4
2mA
1µF
35V
R
L
25k
V
+
499Ω
18V
17.8k
330pF
+
COM
470µF
35V
22.6Ω
+
V
–
470µF
35V
–18V
210Ω
SINGLE
POINT
BOARD
GROUND
OPEN—MM
CLOSED—MC
82.5k
4.7µF
FILM
3900pF
+
2200µF
16V
NOTE: BYPASS SUPPLIES WITH LOW ESR CAPS
OTHER CAPS: HIGH QUALITY FILM
+
+
–18V
1µF
35V
DEVIATION (dB)
–18V
210k
15nF
RESISTORS 1%
*OR USE 2mA CURRENT SOURCE
MM = MOVING MAGNET
MC = MOVING COIL
LT1115 • TA01
U
Measured Deviation from RIAA
Response. lnput at 1kHz = 1mV
RMS
Pre-Emphasized
1.0000
0.80000
0.60000
0.40000
0.20000
0.0
–0.2000
–0.4000
–0.6000
–0.8000
–1.000
20
100
1k
FREQUENCY (Hz)
10k
50k
LT1115 • TA02
U
U
V
S
=
±
18V
R
S
= 25Ω
T
A
= 25
°
C
MEASURED
COMPUTER
SIMULATED
1115fa
1
ETC [ ETC ]
