A comparison of digital tan and sine filters with the generating analog filter

✍ Scribed by S.N. Hazra; S.C. Dutta Roy

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 300 KB
• Volume: 292
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/0016-0032(71)90054-8

✦ Synopsis

One method of designing digital filters is to start with the magnitude squared analog function and replace (w/w,)2 (w, = cut-off frequency) by either [tan (&'/2)/tan (w, T/2)12 or [sin (&!'/2)/sin (w, T/2)12, where T is the sampling period. In the first case we get the so-called digital tan filter, whereas the second case gives the digital sine filter (1, 2). The purpose of this paper is to make a critical comparison of these two types of filters with the generating analog filter with regard to performance in the transition-as well as the stop-bands. The parameters used for comparison are: (1) slope at cut-off frequency, (2) asymptotic decibel attenuation and (3) transition ratio. Specific examples of analog filters considered are the Butterworth, Chebyshev and Papoulis optimum types (3).