Interference cancellation in receivers with interference frequency estimation

An interference cancellation technique is described for improving the dynamic range of receivers. Feed-forward cancellation is employed to attenuate interferers by extracting interferers in a parallel auxiliary receiver path, and subtracting these at the output of the LNA, so that the linearity requirement of the down-conversion mixer within the main path of the receiver can be relaxed. The auxiliary path in this implementation needs an estimate of the center frequency of the interferer, which may be modulated in general. A PLL-based technique is employed for this purpose. Measurement results of a prototype implementation are used to validate the approach.