A Tunable Bandwidth and Center Frequency 6-Path BPF with Improved 3 $k^{th}$ Harmonics Rejection

In this work, the design of a multipath
$3k^{th}(k\in N)$
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
$3k^{th}$
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
$IIP_{3}$
is −14 dBm and noise figure is 6–8 dB in the entire frequency band.