A CMOS Integrated N-Path Filter

N-path configuration filters are an interesting realization of bandpass filters. Their center frequency depends only on the clock and not on the value of integrated elements. Clock noise is the main limiting factor. A careful layout of the circuits described above minimizes this effect. A 4-path filter, integrated in silicon-gate technology, illustrates the performance of such circuits. It was designed for a commutation frequency of 10 KHz and a Q-factor of 50. At a supply voltage of 1,5 V, the total power consumption is lower than lμA. The maximum input voltage is limited to 150 mV and clock noise can be reduced below 1 mV. Circuit area is about 1,2 mm2 .