AN1636 Datasheet, PDF (26/42 Pages) STMicroelectronics – UNDERSTANDING AND MINIMISING ADC CONVERSION ERRORS

UNDERSTANDING AND MINIMISING ADC CONVERSION ERRORS
Figure 22. Cross-talk between I/Os
Analog-in
Analog-in
Analog-in
Digital
I/O
Digital
I/O
Digital
I/O
Digital and analog
signal passing close
to each other
Digital and analog
signal tracks crossing
each other on different
side of the PCB
Recommended
Grounding between
signals
Shielding the analog signal by placing ground tracks across it helps reduce noise
produced by cross talk etc.
4.8 EMI-INDUCED NOISE
Electromagnetic emissions from neighboring circuits may introduce high frequency noise into
an analog signal because the PCB tracks may act like an antenna.
You can reduce the emission noise by proper shielding and layout techniques. The possible
sources of emissions must be physically separated from the receptors. You can separate
them electrically by proper grounding and shielding.
You can minimize the reception noise by using filtering techniques so that high frequency
noise is filtered.
Figure 23. EMI sources
Analog
Source
Electro-
magnetic
Noise
I/O
coupled
Noise
ADC
Induced
noise from
PCB tracks
Internal
Noise
Microcontroller
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