Design Procedure for Loss Compensation of Planar Microwave Filters Using Negative Resistances For Tuneable Bandstop and Bandpass Applications

In this paper, we present a method to synthesise microwave active bandpass and bandstop filters using negative resistance circuits and/or active inductance circuits realised in MMIC technology. We show measurements of a negative resistance circuit which is after associated with passive lumped elements to realise an active bandstop filter, tuneable in frequency. We also present the synthesis of an adjustable active inductance close to an ideal element over the 3.8-4.2 GHz band. This element is introduced in a passive bandpass filter to compensate its losses and realise a high-Q selective structure.