New method of analysis and design of frequency and bandwidth reconfigurable active filter

A new method of analysis and design of reconfigurable active bandpass filter is proposed. The proposed method involves matrix manipulation for equating passive inverter impedances with those of active inverter (both input and output impedances). Designing of active filter involves the designing of active inverter and active resonator. The filter performance is analysed in frequency range 500 MHz to 1.5 GHz. The narrow band filter is switched between two bands with varying fractional bandwidth and centre frequency. The physical implementation comprise elements employing ATF 21186 FET on RT Duroid 5880 substrate with dielectric constant 2.2 and thickness 0.127 mm. Active resonator comprises of an active capacitor and a passive inductor. The active inverter along with active resonator employed in active filter circuit provides reconfigurability in frequency (approximate to 200 MHz) as well as in bandwidth with the variation in gain of approximately 8-10 dB. The electrical performance of active band pass filter shows good agreement with the measured response. To best of my knowledge first time integration of active inverter and active capacitor is done. Intergration of such kind allows for frequency as well as bandwidth tuning. The electrical performance of active band pass filter shows slight deviation from with the measured response.