RF and microwave filter design by means of single transistor active inductor: A review

RF and Microwave active filters design by the use of grounded active inductor (AI) is here presented. The proposed single transistor AI emulates an inductor behaviour by implementing a passive variable phase and amplitude compensating network and amplifiers, forming a similar gyrator-C architecture allowing its use in LC filters architectures at high frequencies with high quality factor and reduced occupied chip area. The design method can be applied with success, in particular, for the design of bandpass filters with very high performances in terms integration and application from RF to Microwave frequency range achieving active filters with relatively high dynamic range, constant Q and also easy frequency tuning capability.