High-Q gyrator-based monolithic active tunable bandstop filter

A monolithic bandstop active tunable filter has been designed and realised. The filter is based on a gyrator-type active resonator, implemented using only three active devices. The centre frequency of the realised notch filter is around 2.0 GHz, with a tuning range greater than 400 MHz. The chip dimensions are 1.2×1.2 mm² including coplanar RF test pads. Measured performances of the realised chip include a typical in-band rejection greater than 35 dB over all the operating bandwidth, a stopband span less than 50 MHz, together with an input/output match greater than 14 dB. Positive supply only has been employed