L-band MMIC active filter techniques for future satellite payloads

The authors describe the realisation of MMIC bandpass active filters for space applications, with target filter design specifications in the L-band. In the microwave frequency region, active filters can offer many significant advantages such as compensation for losses accompanied with passive elements and the possibility of having positive gain rather than loss. In addition, if these filters are realised as MMIC it would be advantageous not only because of their compact size but also because of their consistency with other well established circuits such as amplifiers, mixers, and phase shifters. The authors describe two different active filter approaches: the cascaded cells approach, where passive resonators are coupled together by active devices to prevent them interacting; and the use of FET-based active inductors to replace passive inductors in integrated circuit filters