Historically, the biggest single problem with the application of
op amps has been the input offset voltage. This is indicated
by the fact that almost all important op amps from the μA741
and LM101 on have offered offset null adjustment pins, special
screening to low offset voltage values, and/or internal
VOS trimming (laser or Zener-zap). Also consider the extensive
series of specifications devoted to its variability with
temperature, time, common-mode voltage (CMRR), power
supply (PSRR), output voltage (AVOL), and sometimes even
down to variation of temperature drift with offset null correction.
Contrast this with the treatment afforded one other
important (error-causing) input parameter, input bias current,
which usually gets lust a specified value under one set of
conditions, a variation over temperature, and a term relating
to its matching between the two inputs. If variation with common-
mode voltage, power supply voltage, etc., is covered, it
is generally only in a “typical curve” buried in the middle of
the data sheet.