Improved building blocks for log-domain linear transformation filters

Improved log-domain blocks for obtaining the equivalents of passive elements according to the concept of linear transformation filtering are presented in this paper. The offered benefits, in comparison to the already introduced filter structures, are that the dc offset current presented at the output of the all pole filters and the dc instability, observed in the case of the filters where LC resonators are substituted, are now eliminated. The correct operation of the proposed blocks has been verified through simulation results