How do professional designs compensate for offset voltage in opamps?
Depending upon your application there may be low cost opamps that have negligible offset voltages.
A common approach in modern CMOS opamps is to use an arrangement called chopper-stabilization. This can give microvolt level offsets with no adjustment needed.
This technique uses an auxiliary amplifier with CMOS switches that alternately swap the polarity of the input voltage. The output of that amplifier is then averaged to negate the effects of any offset voltage. This output is not used directly but instead is used as an offset adjustment voltage for the main conventional amplifier so high-frequency performance is not affected. The static offset and any temperature-related drift can both be cancelled. Even low-frequency noise (often known as 1/f noise) can be cancelled.
This is an especially good match to CMOS technology with its ability to fabricate good extremely low offset switches but with relatively large offsets in linear stages. CMOS linear circuitry is normally at a disadvantage with respect to 1/f noise as well that can be reduced.
This is not without its drawbacks, in particular, it can result in noise at the switching frequency and have a long recovery time after saturation, so it is not usually suitable for circuits where this occurs.
Chopper Stabilized Op Amps - Analog Devices