A completely integrated 1.8 volt 5 GHz tunable image reject notch filter

This paper presents a topology for an integrated image reject notch filter. The filter circuitry is combined with a standard LNA topology thus minimizing the additional current required to perform this function on-chip. In applications where NF is not the dominant consideration, the filter could do double duty as an LNA stage. A prototype circuit exhibited the following performance: 70 dB of image rejection, a NF of 4.2 dB, 14 dB of gain in the pass band, and an IIP3 of -6 dBm.