A 0.1-1 GHz N-path Bandpass Filter with High In-band Linearity

A design methodology of high-order N-path active filter with high in-band linearity is introduced. Based on 130 nm CMOS SOI process, a tunable 6th-order differential N-path bandpass filter of 100-1000 MHz is designed, the feature is that it has a higher in-band input 1 dB compression point, which can be used in the application of higher power requirements. The main structure is based on the N-path filter and coupling of transconductance amplifier equivalent gyrators to achieve a flat passband shape and high linearity, and the passband shape is improved by using Miller compensation method. According to the results of the layout post-simulation, at the center frequency of 500 MHz, the filter’s amplitude of the passband S21 is -0.3 dB, the noise factor is 7.4 dB, the in-band input P1dB is 6.8 dBm, the bandwidth is 14.7 MHz, and the out-of-band suppression is 49 dB at 420 MHz.