Double-Sampling Single-Loop Sigma-Delta Modulator Topologies for Broadband Applications

This paper presents novel double sampling high order single-loop sigma-delta modulator structures for wideband applications. To alleviate the quantization noise folding into the inband frequency region, two previously reported techniques are used. The DAC 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 (STF) is also resolved through the proposed modulator architectures with a low additional circuit requirement