“Why does my voltage reference drop 50 mV when the digital is turned on?”
“Why does the room temperature value differ after a temperature cycle?”
“That @*#& bandgap reference!”
If you have heard any or all of these statements you know that Bandgap references cause more re-spins per transistor than any other circuit. While simple on the surface, significant errors can be introduced by minor oversights. AC noise can cause DC shifts. The reference voltage can vary over time, or be at a different value after a temperature cycle. Mismatches and opamp imperfections can cause far larger errors than expected.
These issues are magnified with sub-1 volt references.
