Gm-C simulation of floating frequency-dependent negative conductance and applications to active LC ladder filter

This paper presents a simulator for floating frequency-dependent negative conductance (FDNC) using the G_m-C technique with adjustable transconductance cells and grounded capacitors. The proposed configuration eliminates the need for passive resistors and component matching, resulting in a compact, resistorless design highly suitable for IC integration . The FDNC circuit offers precise electronic tunability of the equivalent M-element via external bias currents, which makes it particularly beneficial for processing analog signals. To validate its functionality, the proposed FDNC is applied to implement second-order low-pass and fourth-order band-pass active ladder filters. Simulations with TSMC 0.18-µm CMOS technology confirm the electronic tunability of M-element values between 1.95 nF/s and 18.22 nF/s, as well as filter cutoffs, demonstrating frequency operation from 20 kHz to 300 kHz. The design exhibits high accuracy, low component sensitivity, and excellent compatibility with integrated circuit realization, thereby representing a robust solution for modern analog filter synthesis.