DWA Algorithms for Multibit Complex Bandpass ∆ΣAD Modulators of Arbitrary Signal Band

This paper describes Data-Weighted-Averaging (DWA) algorithms for multibit complex bandpass ∆ΣAD modulators with arbitrary signal bands. In most of bandpass ∆ΣAD modulators, their sampling frequency is chosen as four times of the center frequency of their signal band in order to simplify the following digital filter design. But with this relationship, their performance would be limited by the third harmonics of the input signal because it is aliased into the signal band; hence recently some bandpass ∆ΣAD modulators whose the sampling frequency is not at four times of their signal center frequency are proposed to avoid this problem. Our proposed DWA algorithms are applicable to such multibit complex bandpass ∆ΣAD modulators whose sampling frequency is not necessarily at four times of the signal center frequency; these algorithms are realized by applying our previously developed multi-bandpass (N-path) DWA algorithms to 2-channel DACs in complex modulators. We have verified their operation by Matlab simulation.