E.03ADC Performance Calculator
Calculate the theoretical performance limits of an ADC from its resolution and sample rate.
Results
- Ideal SNR
- —
- LSB
- —
- Codes
- —
- Nyquist
- —
- Processing gain
- —
- SNR in band
- —
- ENOB
- —
Formulas
- Ideal SNR (full-scale sine)
- SNR = 6.02 · N + 1.76 dB
- LSB
- LSB = V_FS / 2^N
- Processing gain
- PG = 10 · log₁₀(fs / 2·BW)
- Effective number of bits
- ENOB = (SINAD − 1.76) / 6.02
Interpreting the results
Ideal SNR includes only quantisation noise; in a real ADC, thermal noise, clock jitter and non-linearities reduce SNR. ENOB calculated from datasheet SINAD is therefore always lower than the nominal resolution.
If the signal band of interest is narrower than the Nyquist band (oversampling or digital filtering), noise is spread over a wider band, so in-band SNR improves by the processing gain.
References
- Analog Devices, MT-001: Taking the Mystery out of the Infamous Formula “SNR = 6.02N + 1.76dB”
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