Approaches to ultra-narrow-band analogue IC filter design using switched-capacitors

The standard single path switched capacitor technique, when applied to Ultra Narrow-Band (UNB) applications has several disadvantages. The use of frequency translation and multi-path techniques has resolved several problems encountered and they are reviewed. Particular attention is paid to the N*M-path architecture which uses pseudo-N-path (PNP) filters as sub-filters. The revived use of PNP path filters has led to the development of several novel Finite Gain Insensitive (FGI) PNP integrators to enhance the performance of PNP filters. Though theoretical results presented on the N*M architecture and FGI-PNP integrators are very encouraging, measured results are not yet available. Therefore this paper presents a research program to explore practical aspects of N*M-path architecture and FGI-PNP circuits