Method and apparatus for minimizing intermodulation with an asymmetric resonator

Abstract

A method and apparatus to control intermodulation in a circuit for filtering over the air signals by creating an asymmetric resonator is disclosed. By creating the asymmetric resonator, the intermodulation from out of band signals is reduced while keeping the filter size relatively unchanged. In general, the intermodulation is reduced by lowering the current density in the resonator (e.g., so as to maintain the linearity of the electrical characteristics of the resonator), and more specifically by utilizing the principle that the inductive elements in a resonator experience the largest current changes. Therefore, the size of the inductor is changed in order to accommodate the larger power. An additional feature of the present invention is that not every inductive element of the filter needs to be enlarged. Generally only the first (or alternatively the first and second) resonators need to be increased in size. Another feature of the present invention is the physical order in which the filters are laid out. Laying out the components with the bandpass filter first can prevent (or significantly reduce) intermodulation generated by those components due to out-of-band interference signals.

Dependencies are inferred from the claim text.