Enter ADC design values
This section uses a 3-column layout on large screens, 2-column on smaller screens, and 1-column on mobile.
Typical LSB size by resolution
| Resolution | Total Levels | LSB at 0–3.3 V | LSB at 0–5.0 V |
|---|---|---|---|
| 8-bit | 256 | 12.890625 mV | 19.531250 mV |
| 10-bit | 1,024 | 3.222656 mV | 4.882813 mV |
| 12-bit | 4,096 | 0.805664 mV | 1.220703 mV |
| 16-bit | 65,536 | 0.050354 mV | 0.076294 mV |
Use this table as a quick benchmark when comparing common engineering ADC designs.
How the calculator works
1) Total codes: Levels = 2N
Here, N is the ADC resolution in bits.
2) Effective external input span:
External Min = Vref Low / Gain
External Max = Vref High / Gain
Span = External Max − External Min
3) ADC resolution step size:
LSB = Span / 2N
4) Output code:
Code = floor((Vin − External Min) / LSB)
5) Reconstructed voltage:
Vreconstructed = External Min + (Code + 0.5) × LSB
6) Quantization error and ideal SNR:
Error = Vin − Vreconstructed
Max Error = ±0.5 × LSB
Ideal SNR = 6.02N + 1.76 dB
7) Oversampling gain in theoretical bits:
Bits after oversampling = N + 0.5 × log2(OSR)
Usage steps
- Select unipolar or bipolar operation.
- Enter the ADC resolution bits.
- Enter reference low and reference high in volts.
- Add any front-end gain that scales the allowed external input range.
- Enter the test input voltage.
- Optionally enter noise RMS and oversampling ratio for ENOB insight.
- Press Calculate ADC Resolution.
- Review the summary cards, graph, and download the result as CSV or PDF.
ADC Resolution Calculator FAQs
1) What does ADC resolution mean?
ADC resolution is the number of discrete codes an analog-to-digital converter can produce. Higher bit depth creates more levels and a smaller LSB step size.
2) How do I calculate the LSB size?
Divide the effective input span by 2 raised to the number of bits. A smaller LSB means finer measurement granularity and lower quantization step size.
3) Why does the calculator use 2N levels?
Each extra bit doubles the number of possible output codes. That is why an N-bit converter provides 2N total digital levels.
4) Does bipolar mode change the core math?
The main logic stays similar. The converter still divides the full active span into equal bins, but the allowed input range includes negative values.
5) What does front-end gain change?
Gain scales the external input range that fits inside the ADC reference window. More gain reduces the external span and also shrinks the external LSB size.
6) What is quantization error?
Quantization error is the difference between the true analog input and the nearest representable ADC level. Its ideal limit is ±0.5 LSB.
7) How does oversampling help resolution?
Oversampling can improve effective resolution when noise and filtering conditions are suitable. Theoretical improvement follows 0.5 × log2(OSR) added bits.
8) What is ENOB?
ENOB means effective number of bits. It estimates real converter performance after noise and non-ideal behavior reduce the usable resolution below the nominal bit count.