Which factor does ENOB reflect that is not captured by the nominal bit depth?

• A. Power consumption
• B. Clock frequency
• C. Distortion and Noise present in the conversion
• D. Input impedance

Answer: (C)

ENOB measures how many bits of an ideal converter would give the same performance as the real one, by folding all real-world imperfections into a single number. The key idea is that the nominal bit depth assumes perfect linearity and only quantization noise. It doesn’t account for distortions or extra noise that creep into the signal during conversion. Those distortion components (like nonlinearities and harmonics) and various noise sources lower the actual signal quality, so the effective resolution drops. ENOB is basically a reflection of the combined effect of distortion and noise on the conversion, which is why it can be significantly different from the stated bit depth. Power usage, clock speed, and input impedance describe other design aspects and don’t directly determine ENOB, even though they can influence noise and distortion indirectl by affecting how the converter operates.