Define the term 'effective number of bits' (ENOB) in ADC performance, and how it relates to SNR.

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Multiple Choice

Define the term 'effective number of bits' (ENOB) in ADC performance, and how it relates to SNR.

Explanation:
ENOB tells you how many bits a perfect ADC would need to achieve the same signal-to-noise ratio as the real converter. For an ideal N-bit ADC with a full‑scale sine input, the SNR is approximately 6.02·N + 1.76 dB. If you know the measured SNR, you can convert to ENOB with ENOB = (SNR − 1.76) / 6.02, and you can also express the forward relation as SNR = 6.02·ENOB + 1.76. This is why the chosen formula is correct: it faithfully maps the real-world SNR to an equivalent number of bits. For example, an SNR of 90 dB corresponds to ENOB ≈ (90 − 1.76)/6.02 ≈ 14.7 bits. The other forms either omit the 1.76 dB offset or use incorrect algebra, so they don’t match the standard relationship between ENOB and SNR.

ENOB tells you how many bits a perfect ADC would need to achieve the same signal-to-noise ratio as the real converter. For an ideal N-bit ADC with a full‑scale sine input, the SNR is approximately 6.02·N + 1.76 dB. If you know the measured SNR, you can convert to ENOB with ENOB = (SNR − 1.76) / 6.02, and you can also express the forward relation as SNR = 6.02·ENOB + 1.76. This is why the chosen formula is correct: it faithfully maps the real-world SNR to an equivalent number of bits. For example, an SNR of 90 dB corresponds to ENOB ≈ (90 − 1.76)/6.02 ≈ 14.7 bits. The other forms either omit the 1.76 dB offset or use incorrect algebra, so they don’t match the standard relationship between ENOB and SNR.

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