Acm. Dequeiroz et Lp. Caloba, ON THE ELIMINATION OF REACTIVE ELEMENT LOOPS AND THE USE OF SPECIAL APPROXIMATIONS IN THE DESIGN OF OTA-C FILTERS, Analog integrated circuits and signal processing, 13(3), 1997, pp. 311-319
Loops of reactive elements in passive filters cause a series of proble
ms in OTA-C simulations of these structures. These loops call be elimi
nated in a systematic way by the procedures described in the paper. Th
e use of special approximations in the design of the passive prototype
filters allows the elimination of multiple loops of reactive elements
that appear in usual LC ladder filters with finite transmission zeros
. This leads to more efficient active simulations, where problems with
floating capacitors, DC or high-frequency instability, or limited ope
rating frequency are avoided.