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