Second-order sampling of wideband signals

Second-order sampling based digital demodulation technique is discussed and analyzed. Using a fractional delay filter, the modest image rejection of the basic second-order sampling scheme is improved to provide sufficient demodulation performance also for wideband receivers. Furthermore, a closed-form expression explicitly characterizing the obtainable image attenuation is derived. As illustrated by a design example, image attenuations in the order of 100 dB are theoretically achievable.

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