Passive.

intravenous immunoglobulin therapy edited by M.D.kazatchkine 1992 Microwave planar passive circuts and filters Helszajn, J 1994 Power system harmonics and passive filter designs Das, J. C. 2015 Synthesis of passive networks Guillemin, Ernst A. 1977 The circuits and filters handbook edited by Wai-Kai Chen 2009