Mapping duality as a means to allow finite beta(F) compensation in bipolarlog filters

Log-domain filters are a promising design paradigm for analog signal proces sing. They achieve tunability and operation up to high frequencies, with vo ltage and power requirements typically better than those of conventional fi ltering architectures. Implementation can be based only on capacitors, curr ent sources and an exponential, differential V/I converter referred to as t he E-cell. Non-idealities in the E-cell, like the presence of non-negligibl e input currents due to finite beta(F), can reduce system performance. The aim of this paper is to investigate E-cell-based design strategies and to i ntroduce a duality principle whose exploitation can allow finite beta(F) co mpensation. As a validation, HSPICE simulation results are illustrated for a second-order bandpass filter. Copyright (C) 2000 John Wiley & Sons, Ltd.