A Tunable Bandwidth and Center Frequency 6-Path BPF with Improved 3 kth Harmonics Rejection

In this work, the design of a multipath 3kth(k∈N) harmonic rejection bandpass filter with tunable bandwidth and center frequency is proposed. The proposed filter architecture employs a nested filter structure with tunable non-identical loads in each filter to achieve the overall 3kth harmonic rejection. This architecture also alleviates the need of an additional harmonic weighting stage to achieve an improved harmonic rejection. Six phase non-overlapping scheme is utlized to control the center frequency of a six path differential nested filter structure. The proposed harmonic rejection filter implemented in 28-nm is functional from the frequency range of 500 MHz to 2.9 GHz with channel bandwith tunable from 20 – 200 MHz. The overall harmonic rejection achieved at 1 G Hz is 58.6 dB. The achieved in-band IIP3 is −14 dBm and noise figure is 6–8 dB in the entire frequency band.