PCB Design — question 3 of 10
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You've built a board with a microcontroller and a 12-bit ADC reading a sensor. The digital side works fine, but the ADC readings show several LSBs of noise that seem to track with when the MCU toggles a nearby GPIO or drives an SPI bus. Walk me through how you'd confirm this is a grounding/return-current issue and what you'd change on the next board.