Constraints Analysis for Oversampling AtoD Converter Structures on VLSl Implementation

Requirements, applied to analog components and characteristics for oversampling A-to-D converter structures with second order loop transfer function, were analyzed through numerical and mathematical analyses. The results suggest that a first order predictive encoder, with first order noise shaping, is best suited to high resolution future VLSl implementation. It is most difficult to achieve a theoretical second order ¿-¿ modulation signal-to-noise ratio, because of the amplifier performance requirements. The operational amplifier gain should only be greater than kR/n, as long as the amplifier response is linear, where R is the oversampling ratio, ¿ is the angular stop band frequency and k is a. parameter depending on structures and integrator circuit configuration, if a switched capacitor integrator is employed in a noise shaping technology. A second order delta modulation coder does not seem to be applicable to a precision converter, but to a high speed converter instead.