High-Qfactor shunt-switched N-path filters

At its fundamental resonant frequency, a shunt-switched N-path filter is similar to an LCR resonant circuit, except that the selectivity or Q factor achievable, which is a direct function of the passive components employed, may be very much better than normally available in tuned circuits. The limit on the maximum attainable Q factor is shown to depend on the impedance of the shunt arm switches and filter load, as well as the speed of the switches.