Datasheet

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LT1028/LT1128

FEATURES

DESCRIPTIO

APPLICATIO S

■

Voltage Noise

1.1nV/√Hz Max at 1kHz

0.85nV/√Hz Typ at 1kHz

1.0nV/√Hz Typ at 10Hz

35nV

P-P

Typ, 0.1Hz to 10Hz

■

Voltage and Current Noise 100% Tested

■

Gain-Bandwidth Product

LT1028: 50MHz Min

LT1128: 13MHz Min

■

Slew Rate

LT1028: 11V/µs Min

LT1128: 5V/µs Min

■

Offset Voltage: 40µV Max

■

Drift with Temperature: 0.8µV/°C Max

■

Voltage Gain: 7 Million Min

■

Available in 8-Pin SO Package

The LT

1028(gain of –1 stable)/LT1128(gain of +1 stable)

achieve a new standard of excellence in noise performance

with 0.85nV/√Hz 1kHz noise, 1.0nV/√Hz 10Hz noise. This

ultralow noise is combined with excellent high speed

specifications (gain-bandwidth product is 75MHz for

LT1028, 20MHz for LT1128), distortion-free output, and

true precision parameters (0.1µV/°C drift, 10µV offset

voltage, 30 million voltage gain). Although the LT1028/

LT1128 input stage operates at nearly 1mA of collector

current to achieve low voltage noise, input bias current is

only 25nA.

The LT1028/LT1128’s voltage noise is less than the noise

of a 50Ω resistor. Therefore, even in very low source

impedance transducer or audio amplifier applications, the

LT1028/LT1128’s contribution to total system noise will

be negligible.

Ultralow Noise Precision

High Speed Op Amps

Flux Gate Amplifier

Voltage Noise vs Frequency

–

DEMODULATOR

SYNC

OUTPUT TO

DEMODULATOR

LT1028

50Ω

SQUARE

WAVE

DRIVE

1kHz

FLUX GATE

TYPICAL

SCHONSTEDT

#203132

1028/1128 TA01

FREQUENCY (Hz)

0.1

100

1028/1128 TA02

VOLTAGE NOISE DENSITY (nV/√Hz)

0.1

1/f CORNER = 3.5Hz

1/f CORNER = 14Hz

TYPICAL

MAXIMUM

= ±15V

= 25°C

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Low Noise Frequency Synthesizers

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High Quality Audio

■

Infrared Detectors

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Accelerometer and Gyro Amplifiers

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350Ω Bridge Signal Conditioning

■

Magnetic Search Coil Amplifiers

■

Hydrophone Amplfiers

TYPICAL APPLICATIO

, LTC and LT are registered trademarks of Linear Technology Corporation

Summary of content (20 pages)

PAGE 1
LT1028/LT1128 Ultralow Noise Precision High Speed Op Amps U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LT®1028(gain of –1 stable)/LT1128(gain of +1 stable) achieve a new standard of excellence in noise performance with 0.85nV/√Hz 1kHz noise, 1.0nV/√Hz 10Hz noise. This ultralow noise is combined with excellent high speed specifications (gain-bandwidth product is 75MHz for LT1028, 20MHz for LT1128), distortion-free output, and true precision parameters (0.
PAGE 2
LT1028/LT1128 W W W AXI U U ABSOLUTE RATI GS (Note 1) Supply Voltage –55°C to 105°C ................................................ ±22V 105°C to 125°C ................................................ ±16V Differential Input Current (Note 9) ...................... ±25mA Input Voltage ............................ Equal to Supply Voltage Output Short Circuit Duration .......................... Indefinite Operating Temperature Range LT1028/LT1128AM, M (OBSOLETE) .
PAGE 3
LT1028/LT1128 ELECTRICAL CHARACTERISTICS VS = ±15V, TA = 25°C, unless otherwise noted.
PAGE 4
LT1028/LT1128 ELECTRICAL CHARACTERISTICS 0°C ≤ TA ≤ 70°C. VS = ±15V, unless otherwise noted.
PAGE 5
LT1028/LT1128 U W TYPICAL PERFOR A CE CHARACTERISTICS 10Hz Voltage Noise Distribution Wideband Voltage Noise (0.1Hz to Frequency Indicated) Wideband Noise, DC to 20kHz 180 10 VS = ±15V TA = 25°C 500 UNITS MEASURED FROM 4 RUNS NUMBER OF UNITS 140 120 VS = ±15V TA = 25°C RMS VOLTAGE NOISE (µV) 158 148 160 100 80 70 57 60 40 28 20 8 74 3 2 2 2 12 0 0.6 0.1 VERTICAL SCALE = 0.5µV/DIV HORIZONTAL SCALE = 0.5ms/DIV 3 21 1 1 0.8 1.0 1.2 1.4 1.6 1.8 2.0 VOLTAGE NOISE DENSITY (nV/√Hz) 1 0.
PAGE 6
LT1028/LT1128 U W TYPICAL PERFOR A CE CHARACTERISTICS Distribution of Input Offset Voltage Offset Voltage Drift with Temperature of Representative Units VS = ±15V TA = 25°C 800 UNITS TESTED FROM FOUR RUNS 16 40 14 12 10 8 6 20 10 0 –10 –20 –30 4 2 –40 0 –50 –40 –30 –20 –10 0 10 20 30 40 50 OFFSET VOLTAGE (µV) –50 –50 –25 50 25 0 75 TEMPERATURE (°C) METAL CAN (H) PACKAGE 12 8 DUAL-IN-LINE PACKAGE PLASTIC (N) OR CERDIP (J) 5 1 2 3 4 TIME AFTER POWER ON (MINUTES) 50 BIAS CURRENT 20 10 OFFSET
PAGE 7
LT1028/LT1128 U W TYPICAL PERFOR A CE CHARACTERISTICS 160 70 VS = ±15V TA = 25°C RL = 2k 60 40 50 50 40 40 30 30 GAIN 20 20 20 10 0 0 10 VS = ±15V TA = 25°C CL = 10pF –10 10k 10 100 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) 100k 1M 10M FREQUENCY (Hz) TYPICAL PRECISION OP AMP 40 AV = –1, RS = 2k 30 AV = –10 RS = 200Ω AV = –100 RS = 20Ω 10 –10 100M LT1028 0.
PAGE 8
LT1028/LT1128 U W TYPICAL PERFOR A CE CHARACTERISTICS LT1028 Slew Rate, Gain-Bandwidth Product Over Temperature LT1028 Small-Signal Transient Response LT1028 Large-Signal Transient Response 50mV SLEW RATE (V/µs) 17 5V/DIV 20mV/DIV 10V 90 VS = ±15V –10V –50mV 1µs/DIV AV = –1, RS = RF = 2k, C F = 15pF 0.
PAGE 9
LT1028/LT1128 U W TYPICAL PERFOR A CE CHARACTERISTICS Common Mode Rejection Ratio vs Frequency V+ COMMON MODE REJECTION RATIO (dB) 140 –2 VS = ±5V –3 VS = ±15V –4 4 3 VS = ±5V TO ±15V 2 1 V 120 100 LT1128 50 25 0 75 TEMPERATURE (°C) 60 40 20 10 100k 10k 1k FREQUENCY (Hz) 100 LT1028/1128 • TPC37 TOTAL HARMONIC DISTORTION (%) AV = 1000 RL = 600Ω AV = –1000 RL = 2k AV = 1000 RL = 600Ω VO = 20VP-P VS = ±15V TA = 25°C 10 FREQUENCY (kHz) 0.01 INVERTING GAIN 0.
PAGE 10
LT1028/LT1128 U S I FOR ATIO – OISE U W U UO APPLICATI Voltage Noise vs Current Noise The LT1028/LT1128’s less than 1nV/√Hz voltage noise 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.
PAGE 11
LT1028/LT1128 U S I FOR ATIO – OISE U W U UO APPLICATI Noise Testing – Voltage Noise The LT1028/LT1128’s RMS voltage noise density can be accurately measured using the Quan Tech Noise Analyzer, Model 5173 or an equivalent noise tester. Care should be taken, however, to subtract the noise of the source resistor used. Prefabricated test cards for the Model 5173 set the device under test in a closed-loop gain of 31 with a 60Ω source resistor and a 1.8k feedback resistor.
PAGE 12
LT1028/LT1128 U S I FOR ATIO – OISE W U U UO APPLICATI Noise Testing – Current Noise Current noise density (In) is defined by the following formula, and can be measured in the circuit shown: 10Hz current noise is not tested on every lot but it can be inferred from 100% testing at 1kHz. A look at the current noise spectrum plot will substantiate this statement. The only way 10Hz current noise can exceed the guaranteed limits is if its 1/f corner is higher than 800Hz and/or its white noise is high.
PAGE 13
LT1028/LT1128 W U U UO APPLICATI S I FOR ATIO terminals, can exceed the inherent drift of the amplifier unless proper care is exercised. Air currents should be minimized, package leads should be short, the two input leads should be close together and maintained at the same temperature. The circuit shown to measure offset voltage is also used as the burn-in configuration for the LT1028/LT1128.
PAGE 14
LT1028/LT1128 W U U UO APPLICATI S I FOR ATIO If CF is only used to cut noise bandwidth, a similar effect can be achieved using the over-compensation terminal. The Gain, Phase plot also shows that phase margin is about 45° at gain of 10 (20dB). The following configura- tion has a high (≈70%) overshoot without the 10pF capacitor because of additional phase shift caused by the feedback resistor – input capacitance pole. The presence of the 10pF capacitor cancels this pole and reduces overshoot to 5%.
PAGE 15
LT1028/LT1128 U TYPICAL APPLICATIO S Paralleling Amplifiers to Reduce Voltage Noise Phono Preamplifier 10Ω + 1.5k A1 LT1028 787Ω – 7.5Ω 2 470Ω + 1.5k A2 LT1028 + OUTPUT 4 –15V OUTPUT ALL RESISTORS METAL FILM MAG PHONO INPUT + 470Ω + 47k LT1028 0.33µF 6 LT1028 3 – – 1028/1128 TA06 1.5k An LT1028 Tape Head Amplifier – 7.5Ω 10k 7 – 100pF 4.7k 7.5Ω 0.1µF 15V 0.1µF 470Ω 499Ω 31.6k 1. ASSUME VOLTAGE NOISE OF LT1028 AND 7.5Ω SOURCE RESISTOR = 0.9nV/√Hz. 2.
PAGE 16
LT1028/LT1128 U TYPICAL APPLICATIO S Super Low Distortion Variable Sine Wave Oscillator R1 C1 0.047 20Ω 20Ω C2 0.047 2k 1VRMS OUTPUT 1.5kHz TO 15kHz 1 f= 2πRC WHERE R1C1 = R2C2 4.7k 15V + 2k ( LT1028 R2 – 5.6k 2.4k ) LT1004-1.2V 10pF 22k 15µF + 10k – 2N4338 MOUNT 1N4148s IN CLOSE PROXIMITY 100k LT1055 560Ω TRIM FOR LOWEST DISTORTION + 20k 10k <0.0018% DISTORTION AND NOISE.
PAGE 17
LT1028/LT1128 W W SCHE ATIC DIAGRA NULL 8 R6 130Ω R5 130Ω NULL 1 V+ 7 Q4 R2 3k R1 3k 1.1mA 2.3mA 400µA C1 257pF 500µA Q17 R10 400Ω Q16 900µA R11 400Ω Q19 R10 C2 500Ω Q18 900µA Q26 Q6 Q5 3 3 1 1 Q11 NONINVERTING INPUT Q8 Q7 R11 100Ω Q9 C3 250pF 4.5µA 3 Q10 4.5µA Q22 Q24 4.5µA 4.5µA Q1 Q2 Q25 OUTPUT 6 1.5µA Q12 R12 240Ω Q13 C4 35pF Q14 Q27 1.5µA INVERTING INPUT 2 0 1.
PAGE 18
LT1028/LT1128 U PACKAGE DESCRIPTIO J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) OBSOLETE PACKAGE (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 0.045 – 0.068 (1.143 – 1.727) FULL LEAD OPTION 0.405 (10.287) MAX 0.005 (0.127) MIN 8 6 7 5 0.025 (0.635) RAD TYP 0.220 – 0.310 (5.588 – 7.874) 1 2 3 0.300 BSC (0.762 BSC) 4 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.008 – 0.018 (0.203 – 0.
PAGE 19
LT1028/LT1128 U PACKAGE DESCRIPTIO S Package 16-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) 0.386 – 0.394* (9.804 – 10.008) 16 15 14 13 12 11 10 9 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 2 3 4 5 6 7 8 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 0° – 8° TYP 0.050 (1.270) BSC 0.014 – 0.019 (0.355 – 0.483) TYP 0.016 – 0.050 (0.406 – 1.
PAGE 20
LT1028/LT1128 U TYPICAL APPLICATIO Low Noise Infrared Detector 5V 10Ω + 100µF 1k 33Ω SYNCHRONOUS DEMODULATOR + 100µF 10k* OPTICAL CHOPPER WHEEL 267Ω 5V 5V 1000µF 3 + IR RADIATION 10k* 39Ω PHOTOELECTRIC PICK-OFF 2 7 + 6 LT1028 2 1/4 LTC1043 4 12 10k –5V INFRA RED ASSOCIATES, INC.