Core formulas
| Step size Δ (LSB) | = V_FS / 2^N (full-scale / 2^N) |
|---|---|
| Quantization noise | σ_q = Δ / √12 |
| SQNR (ideal) | ≈ 6.02 · N + 1.76 dB |
| ENOB (from SINAD) | = (SINAD − 1.76) / 6.02 |
Resolution / dynamic range
| Bits | Levels | SQNR (dB) | Use |
|---|---|---|---|
| 8 | 256 | 49.9 | Basic MCU ADC |
| 10 | 1 024 | 61.96 | Arduino (10-bit) |
| 12 | 4 096 | 74.0 | General MCU ADCs, audio for noise floors |
| 14 | 16 384 | 86.0 | Precision instrument |
| 16 | 65 536 | 98.08 | CD audio |
| 20 | 1 048 576 | 122.2 | Precision sigma-delta |
| 24 | 16.7 M | 146.2 | Audio DAW / weigh-scale |
| 32 | 4.3 G | 194.2 | Rare — limited by noise floor |
Practical notes
- ENOB is always less than advertised resolution due to noise and non-linearity.
- Oversampling + averaging: 4× oversampling gives 1 extra bit of effective resolution (up to the noise floor).
- Dithering: add small noise before quantization to decorrelate quantization error from signal.
- Input referred noise sets practical floor — beyond ~22 effective bits, thermal noise dominates.
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