An adaptive filter includes, in part, a linear filter, and a non-linear resonator coupled to the linear filter and adapted to resonate at a frequency that is an integer multiple of the frequency of a received RF signal. The adaptive filter filters out the received RF signal. The resonant frequency may be twice the frequency of the received RF signal. The adaptive filter optionally includes a second non-linear resonator coupled to the linear filter and adapted to resonate at a frequency defined by a sum of the integer multiple of the frequency of the received signal and an offset frequency.