An NIC‐based negative resistance circuit for microwave active filters

This article presents a method for synthesizing a negative resistance in MMIC technology. The circuit employed is a classical negative impedance converter (NIC) that has been terminated in an RLC one‐port specially designed to compensate for the parasitics of the active and passive elements. The procedure, which effectively translates a nonideal NIC design task into a well‐defined one‐port synthesis problem, is demonstrated in computer simulation for a four‐transistor MMIC network which achieves a purely real input resistance of −100 Ω over 1.5–2.5 GHz. An important application for NIC‐based circuits of this type is in the design of microwave active filters.