Limit cycle behavior in the double-loop bandpass Sigma-Delta A/D converter

Hein and Zakhor analyzed the limit-cycle behavior of the low-pass double-lo op converter. This brief demonstrates that the limit cycles in a bandpass S igma-Delta double-loop converter are identical to the low-pass case. It is shown that the double-loop converter can have two independent limit cycles occurring simultaneously. Simulations confirm that the bandpass converter s tate variables can be designed to stay within designed bounds, as in the lo w-pass (baseband) case. Hence, stability is improved as the likelihood of s tages saturating and clipping is significantly reduced.