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Improved design of a multifeedback bandpass filter
Author(s) -
Biey Mario,
Premoli Amedeo
Publication year - 1975
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.4490030210
Subject(s) - band pass filter , allowance (engineering) , filter (signal processing) , usable , ideal (ethics) , computer science , amplifier , filter design , control theory (sociology) , basis (linear algebra) , open loop gain , operational amplifier , electronic engineering , mathematics , engineering , telecommunications , bandwidth (computing) , mechanical engineering , philosophy , geometry , control (management) , epistemology , artificial intelligence , world wide web , computer vision
The multifeedback second‐order RC active filter is of considerable interest and has been studied extensively. Nevertheless, its behaviour has been in general analysed without making allowance for the non‐ideal characteristics of the embedded operational amplifier (OA). This paper presents some formulas that can be used for improving the design of such a filter. They were derived on the basis of an OA model that takes into account both input and output resistances, unity‐gain frequency, and dc‐gain. They make use of algorithms characterized by a relative simplicity and quite a good approximation. Their application makes the filter easy to tune and usable for high frequencies, while at the same time the dependence of the Q ‐value on temperature variations in the operational amplifier is minimized. Two universal graphs are given in the text. They simplify the use of the new formulas in obtaining the analysis and the synthesis of the multifeedback second order filter. Experimental results that check the validity of the proposed formulas are presented.