  A switched-capacitor N-path circuit can be employed for filtering an RF
signal, as well as a passive downconverter. A known limitation of an N-path
filter is that in addition to downconverting signals around the desired center
frequency, the circuit also downconverts signals located around harmonics of
the center frequency. An N-path filter that uses a PWM representation of a
sinusoidal LO to mitigate harmonic downconversion is proposed in this work.
Single-edge natural sampling pulse-width modulated (PWM) clocks are used to
drive the switches in the N-path filter. The potential for employing PWM for
providing gain control is also described.
