Broadband Tunable CMOS RF Bandpass filter using a Modified Active Inductor Topology

In this paper, a modified active inductor based bandpass RF filter is proposed that achieves a broad tuning frequency range. A bandpass filter based on the proposed active inductor is shown be operated from 2 to 6.1 GHz. The filter's passband frequency and quality factor is tuned by changing the biasing voltage of PMOS current mirror. The second and higher order harmonic suppression is better than at least 19dB. The proposed active filter is designed using UMC 180 nm RF/MM process parameters and works with a 1.8V DC power supply. The filter also exhibits input port return losses up to 14dB over the range 2–6 GHz, making it fairly well matched over its functional bandwidth.