Passive symmetrical RLC filters suitable for active simulation

A filter synthesis procedure is presented which generates physically symmetrical or asymmetrical passive structures even for approximations having simple transmission zeros. The procedure is based on the unbalancing of a symmetrical lattice realization. The obtained networks are interesting as prototypes for fully integrated active simulation, due to the symmetrical layouts, and to the naturally gradient-insensitive structure made possible by the symmetry of sensitivities in the filter structure. Fifth- and fourth-order normalized elliptic lowpass filters are considered as examples.<>