A reconfigurable high ultimate rejection inductorless band-pass filter by the use of N-path passive mixers

In this paper, a band-pass filter with a tunable bandwidth and the center frequency is introduced, which employs N-path and N x M-path passive mixer structures, for multiband multistandard wireless receivers. The center frequency of the proposed filter is tunable from 0.1 to 1 GHz, while its bandwidth is also adjustable from 6% to 34% of the center frequency at 100 MHz. The passband ripple is reduced by applying a Miller compensation technique, resulting in a worst-case ripple of only 1.6 dB over the entire tuning range. An additional eight-path filter is also utilized at the input of the circuit, which highly improves the out-of-band rejection of the filter as well as its out-of-band linearity. The noise figure and the input return loss are, respectively, better than 5 and 10 dB, and depending on the desired center frequency, the total power consumption of the proposed filter varies from 41 to 70 mW.