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Unfiltered
Filtered
Results
Setup | Measured Frequency (MHz) | Unfiltered Vpk-pk | Filtered Vpk-pk | Suppression factor ([Unfiltered Vpk-pk]/[Filtered Vpk-pk]) |
|---|---|---|---|---|
| Unity Amplifier (2.2M Resistors) | 27 | 7.44 | 2.16 | 3.44 |
| Unity Amplifier (100k Resistors) | 7.44 | 1.20 | 6.2 | |
| Unity Amplifier (100k Resistors + 0.1uf decoupling capacitors) | 7.5 | 2.56 | 2.93 | |
| Bypass Capacitors only (0.1uF Capacitors) | 5.92 | 3.04 | 1.95 |
The conclusion so far
So far it seems that the Unity amplifier set up is the best at suppressing EMI noise in a common mode-rejection setup. Interestingly, by reducing the resistor values the amplifier was better at suppressing the EMI noise. But adding decoupling capacitors add little to no affect (if not worsen) to the EMI suppression. My current speculation is that the lower variation on resistance allowed for the better rejection of EMI. Next time I would like to try lower tolerance resistors and another common-mode rejection setup that uses a ferrite choke coil instead.
Button Debouncing
Abstract
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