Design of a Dual-Band Bandpass Filter Using Active Inductor Principle

A new topology of a dual-band active bandpass filter is presented in this paper. This structure consists of two transconductances constituting the active inductor, which represents the core of the filter and which is responsible for delivering the resonance frequency of the filter, connected at its input to a varactor used to tune the centre frequency. The two peaks of the dual-band filter can be tuned in frequency while maintaining the same power of gain and the same bandwidth. Good out-of-band rejection is observed of -13 dB and -11 dB on both bands with a very high quality factor that exceeds 1500.The filter is designed for 5G applications around 28GHz and 38 GHz and for satellite uplinks.