Double-sampling single-loop ΣΔ modulator topologies for broad-band applications

This paper presents novel double sampling high-order single loop sigma-delta modulator structures for wide-band applications. To alleviate the quantization noise folding into the inband frequency region, two previously reported techniques are used. The digital-to-analog converter´s sampling paths are implemented with the single-capacitor approach and an additional zero is placed at the half of the sampling frequency of the modulator´s noise transfer function (NTF). The detrimental effect of this additional zero on both the NTF and signal transfer function is also resolved through the proposed modulator architectures with a low additional circuit requirement.