A double bandpass N-path filter for LTE carrier aggregation receivers in 28nm CMOS

A tunable double bandpass integrated filter is introduced. The filter is designed based on the impedance transfer identity of the N-path filtering. The filter´s dual bandpass nature, makes it suitable to be employed as a high Q filter at the input of LTE receivers. It can be used to suppress out-of-band blockers in the non-contiguous carrier aggregation mode. Each of the two passbands can be tuned to be centered at each of the two LTE carriers. The design is simulated for LTE band 2 and the simulation results showed blocker suppression of 10 dB for blockers at the duplex distance and 12 dB of suppression for blockers at double the duplex distance.