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Input Quantization Noise Analysis

Module by: Douglas L. Jones

Summary: Analog-to-digital converters introduce quantization noise due to their finite wordlength. The signal-to-noise ratio (SNR) increases by 6 dB per bit.

All practical analog-to-digital converters (A/D) must quantize the input data. This can be modeled as an ideal sampler followed by a BB-bit quantizer.
fig1InputQuant.png
Figure 1
The signal-to-noise ratio (SNR) of an A/D is
SNR=10log10 P x P n =10log10 P x -10log10 Δ B 212=10log10 P x +4.77+6.02B SNR 10 10 P x P n 10 10 P x 10 10 Δ B 2 12 10 10 P x 4.77 6.02 B (1)
where P x P x is the power in the signal and P n P n is the power of the quantization noise, which equals its variance if it has a zero mean. The SNR increases by 6dB with each additional bit.

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