Frequency limitations of active-R filters using operational amplifiers

✍ Scribed by V. Kapustian; B.B. Bhattacharyya; M.N.S. Swamy

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 622 KB
• Volume: 308
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/0016-0032(79)90082-6

✦ Synopsis

Active

-R filters are designed using intemully compensated operational amplifiers (OA) and resistors only. A one-pole or 6 dB roll ofi model for the PA's is assumed in these designs. This model is adequate for active-RC filters. However, for active-R filters such an assumption leads to serious accuracy as well as stability problems, thereby limiting the highest operating frequency of these filters to well below their potential maximum. It is shown in this article that a two-pole or 12 dB roll ofi model more accurately reflects the behaviour of the OA's for the above active-R realizations. A quantitative measure of the limitation imposed by this model on such realizations is also presented. Extensive computer simulation and experimental tests have been carried out that verify closely the theoretical predictions.