To alleviate the folded noise due to coefficient mismatches between the two channels in two-channel time-interleaved(TI)ΣΔ modulators
a novel architecture of high-order two-channel time-interleaved ΣΔ modulator is proposed. By adding a zero to the Nyquist frequency in the conventional noise transfer function(NTF)
a new type of NTF is obtained. The amount of the folded noise can be reduced because the amplitude of the new NTF at high frequencies is reduced by the added zero. A single-channel single-loop fourth-order 3-bit distributed feedforward ΣΔ modulator is proposed to implement the new NTF. The architecture of the two-channel TI ΣΔ modulator is derived from the single-channel modulator based on the theory of multirate system and block digital filter. The degradation of the signal-to-noise-plus-distortion ratio of the proposed modulator is only 3.1 dB with 1% coefficient mismatches
which shows that the proposed architecture is insensitive to coefficient mismatches.
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