Datasheet

LF442
www.ti.com SNOSC03E –APRIL 1999–REVISED OCTOBER 2013
Unconventional Log Amplifier
Q1, Q2, Q3 are included on LM389 amplifier chip which is temperature-stabilized by the LM389 and Q2-Q3, which act
as a heater-sensor pair.
Q1, the logging transistor, is thus immune to ambient temperature variation and requires no temperature
compensation at all.
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