•Small differences in the size of the input stage transistors.
• Differences in the doping of the input stagetransistors.
• Differences in the thickness of the base diffusion of the input stage transistors.
• Current mirror inaccuracies.
• Resistor mismatch.
• Packaging/mounting stress.
• Dynamic considerations: Thermal and light and radiation.
• Circuits aren’t perfect (despite those IC designer’s egos).
How to reduce offset?
• Tweak and adjust the input stage
• Tweak and adjust later stages
•Tweak and adjust the output