Digital Cauer-Type Ladders for Stable Filters

摘要

The stability of digital ladder filters related to LC Cauer ladder low-pass filters by Bruton's LDI transformation is studied. Necessary and sufficient conditions for the digital LDI Cauer filter to be lossless and for a corresponding doubly terminated filter to be stable are derived. A concurrence relation between the stability and sampling rate requirements is shown for implementations by switched capacitors, by which appropriate sampling rate generally guarantee also the sufficiency condition for stability. Keywords include: Digital ladder filters, LC Cauer ladder, Low-pass filters, LDI transformation. (Reprints)