Low frequency, current mode programmable KHN filters using large-valued active resistors

The present work proposes a new current-mode, programmable Kerwin Huelsman Newcomb (KHN) filter suitable for very low frequency processing. The proposed implementation, developed with only six current mirrors and two large-valued, programmable active resistors, solves some of the more challenging problems of low frequency filtering. HSPICE simulation results using BSIM3.3 models for a 0.5-μm CMOS technology, are shown. Center frequencies in the range of 12.4Hz-33Hz, total harmonic distortion less than 1%, and static power consumption of 1.05mW, were observed.