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A band-stop filter is used to remove a narrow band of frequencies from the signal path of a receiver or a transmitter. For a conventional notch filter, the maximum attenuation (notch depth) occurs at a single frequency midway between the specified edges (3dB) of the lower and upper pass-bands, and the selectivity can be described as the ratio of the notch depth to the bandwidth between the edges of the pass-bands. The unloaded quality factor Q (Qu) of the filter's resonators limits both notch depth and selectivity. This proposal suggests an optimized version of varactor-tuned microwave band-stop filter designed using a novel inductive spiral signal line incorporated with shunt varactors featuring an expected Qu of ~110 and notch depth of ~30dB at center frequencies from 2GHz to 8GHz.

Publication Date


Project Designation

Independent Research

Primary Advisor

Guru Subramanyam

Primary Advisor's Department

Electrical and Computer Engineering


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A Novel High Quality Factor Tunable Band-stop Filter for Microwave Applications