Abstract

This paper presents a new methodology based on actively coupled resonators, for achieving microwave active filters. In this method, which lends itself to narrowband and wideband filtering applications, we associate core cells with different resonance frequencies, adjusted separately, to synthesise a Butterworth, Chebyshev or other all-pole approximation. Two 1-pole bandpass filters centred at 9GHz, with 3dB bandwidth of 500 MHz, high gain of 17 dB and 21 dB, including a very low-noise active filter which exhibits a noise figure of 1.7 dB are realised in a first part. A 3-pole bandpass filter centred at 12GHz is also presented to validate this method, it has a gain of 15.5 dB ± 0.2 over a 1.5 GHz bandwidth and rejections better than 60 dB at 7 GHz and 18 GHz.