LT1028_01 Datasheet, PDF (15/20 Pages) Linear Technology – Ultralow Noise Precision High Speed Op Amps

TYPICAL APPLICATIO S
Paralleling Amplifiers to Reduce Voltage Noise
+
A1
1.5k
LT1028
–
7.5Ω
470Ω
+
A2
1.5k
LT1028
–
7.5Ω
470Ω
+
An
1.5k
LT1028
–
7.5Ω
470Ω
4.7k
–
LT1028
+
OUTPUT
1. ASSUME VOLTAGE NOISE OF LT1028 AND 7.5Ω SOURCE RESISTOR = 0.9nV/√Hz.
2. GAIN WITH n LT1028s IN PARALLEL = n × 200.
3. OUTPUT NOISE = √n × 200 × 0.9nV/√Hz.
4.
INPUT
REFERRED
NOISE
=
OUTPUT NOISE
n × 200
=
0.9
√n
nV/√Hz.
5. NOISE CURRENT AT INPUT INCREASES √n TIMES.
6. IF n = 5, GAIN = 1000, BANDWIDTH = 1MHz, RMS NOISE, DC TO 1MHz = ^2µV = 0.9µV.
√5
1028/1128 TA03
LT1028/LT1128
Phono Preamplifier
10Ω
787Ω
15V
0.1µF
10k
2_– 7
100pF
6
LT1028
3₊
4
0.33µF
OUTPUT
47k
–15V
MAG PHONO
INPUT
ALL RESISTORS METAL FILM
1028/1128 TA06
Tape Head Amplifier
0.1µF
499Ω
31.6k
10Ω
2_–
6
LT1028
TAPE HEAD
INPUT
3₊
OUTPUT
ALL RESISTORS METAL FILM
1028/1128 TA07
Low Noise, Wide Bandwidth Instrumentation Amplifier
–INPUT
+
LT1028
300Ω
10k
–
820Ω
68pF
50Ω
10Ω
+INPUT
–
820Ω
LT1028
+
68pF
300Ω
GAIN = 1000, BANDWIDTH = 1MHz
INPUT REFERRED NOISE = 1.5nV/√Hz AT 1kHz
WIDEBAND NOISE –DC to 1MHz = 3µV_RMS
IF BW LIMITED TO DC TO 100kHz = 0.55µV_RMS
–
LT1028
+
10k
SINE
DRIVE
OUTPUT
1028/1128 TA08
Gyro Pick-Off Amplifier
GYRO TYPICAL–
NORTHROP CORP.
GR-F5AH7-5B
+
•
LT1028
OUTPUT TO SYNC
DEMODULATOR
–
1k
100Ω
1028/1128 TA09
15