Lecture 5: Oversampling and Noise ShapingXILIANG LUO

2014/10

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

WSS

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

White Noise:

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

Oversamplingimprove A/D accuracy

Noise Shaping in A/D

To make a significant reduction of number of quantization bits,the required oversampling ratio is too much, which is too costly

Oversampling + noise spectrum shaping much higher gain

Noise Shaping in A/D

Direct quantization uniform noise PSDNoise shaping non-uniform noise PSD, preferably, most noise is outside the signal band!

Noise Shaping in A/DNoise-shaping quantizer, aka sampled-data Delta-Sigma modulator

1-bit

Noise Shaping in A/D

Noise Shaping in A/D

Noise Shaping in A/D

Noise Shaping in A/D

Noise Shaping in A/D

PSD after downsampling

Noise Shaping in A/D

Direct Quantization:

Noise Shaping:

Noise Shaping in D/A

quantization error

Noise Shaping in D/A

1st order noise-shaping for oversampled D/A quantization

Noise Shaping in D/A

Noise Shaping in D/A

Summary 1. Nyquist-Sampling

2. Process continuous time signal with discrete system

3. Downsampling/Upsampling

4. Polyphase decomposition

5. D/A, A/D, Noise Shaping