Sigma-delta domain bandpass and band-elimination wave filters

Abstract

This paper presents sigma-delta (SD) domain bandpass and band-elimination wave filters modeled after analog distributed parameter filters (ADPF) built up of coupled transmission lines. The bandpass and band-elimination filters have the following advantages: (i) Design techniques of ADPFs can be applied directly and (ii) shift registers and sorting networks both of which are spatially uniform in structure and local in internal connections are the main parts of the SD domain filters. We designed an SD domain bandpass filter and confirmed by computer simulation that it possessed the same frequency response characteristics with the theoretical characteristics of the reference ADPF. We also designed a band-elimination filter from which coefficient multipliers were removed and for which shift registers of different lengths were employed to simplify further the filter structure. Finally, we investigate the fault-tolerant capability of a bandpass block for transient errors of internal circuit cells. With the help of computer simulation, we found that the bandpass block did not fail in operation and did not output high surge noise in the presence of the errors although its output quality decreased.