AVOIDING THE NEED FOR A
HIGH-QUALITY ANALOG PREFILTER

• Sampling an analog signal, such as audio, at its nominal Nyquist rate requires a high-quality analog prefilter to bandlimit the input signal
  
  
• In an oversampling approach, a simple prefilter is used, and the signal is sampled at a rate f^'_s = Lf_s. A decimation filter (digital) is then used to reduce the bandwidth to f_s/2.
  
  
• This is summarized below:

• A second benefit of this approach is that fewer bits are required by the A/D converter by employing a technique known as "feedback quantization."