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TL/H/7841
L
July 1987
LM381/LM381A Low Noise Dual Preamplifier
General Description
The LM381/LM381A is a dual preamplifier for the amplifica-
tion of low level signals in applications requiring optimum
noise performance. Each of the two amplifiers is completely
independent, with individual internal power supply decou-
pler-regulator, providing 120 dB supply rejection and 60 dB
channel separation. Other outstanding features include high
gain (112 dB), large output voltage swing (V
CC
b
2V) p-p,
and wide power bandwidth (75 kHz, 20 Vp-p). The LM381/
LM381A operates from a single supply across the wide
range of 9V to 40V.
Either differential input or single ended input configurations
may be selected. The amplifier is internally compensated
with the provision for additional external compensation for
narrow band applications. For additional information see
AN-64, AN-104.
Features
Y
Low noise D 0.5
m
V total input noise
Y
High gain D 112 dB open loop
Y
Single supply operation
Y
Wide supply range 9V–40V
Y
Power supply rejection D 120 dB
Y
Large output voltage swing (V
CC
b
2V)p-p
Y
Wide bandwidth 15 MHz unity gain
Y
Power bandwidth 75 kHz, 20 Vp-p
Y
Internally compensated
Y
Short circuit protected
Schematic Diagram
TL/H/7841–1
C
1995 National Semiconductor Corporation
RRD-B30M115/Printed in U. S. A.