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The Design of a Delta Sigma Modulator. Presented by: Sameh Assem Ibrahim. 24-July-2003. Introduction. Oversampling: f s > 2f m , OSR = f s /2f m > 1 Advantage 1: Relax anti-aliasing filter Advantage 2: Reduce in-band quantization noise and thus increase SNR
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The Design of a Delta Sigma Modulator Presented by: Sameh Assem Ibrahim 24-July-2003
Introduction • Oversampling: fs > 2fm , OSR = fs/2fm > 1 • Advantage 1: Relax anti-aliasing filter • Advantage 2: Reduce in-band quantization noise and thus increase SNR • Note that: A quantized signal ampled at (fs) will have all its noise power folded into the frequency band extending from 0 to (fs/2)
The need for delta sigma modulation • Nyquist converters: SNR = 1.76 + 6.02n • Overampled: SNR = 1.76+6.02n+10log(OSR) • Solution is Noise shaping through delta sigma modulators
+ + y(n) Integrator Integrator x(n) - - fs 1-Bit D/A Proposed Architecture and Specifications Analog input Digital FS Analog Output FN ΣΔ Modulator Decimator 1 bit Multiple bits
Simulink Model Comparator (1 bit Quantizer) Integrator1 Integrator2 To achieve stability DAC