Loop Filter Design Considerations for Noise-Shaping in SAR ADCs

Noise-shaping (NS) techniques in SAR ADCs are becoming increasingly popular because they allow a higher resolution in the oversampled bandwidth while maintaining power efficiency. This is achieved by high-pass shaping the comparator noise. The noise transfer function plays a critical role in determining the overall noise-shaping benefit. With various NS implementations available in the literature, this paper aims to categorize and provide a comparative study of the passive and active ways of loop filter implementations in NS SAR ADCs. The paper also discusses the advantages and challenges of these techniques. The effectiveness of the hybrid ADC architecture is demonstrated through behavioral simulation results.