High-order single-loop double-sampling sigma-delta modulator topologies for broadband applications

This paper presents novel low-voltage high order single loop sigma-delta modulator structures for wideband applications. The proposed architectures employ the technique of double-sampling to double the effective oversampling ratio (OSR) without increasing the sampling frequency. To alleviate the quantization noise folding into the inband frequency region which is a result of the mismatch between the sampling capacitors of the feedback’s digital-to-analog converter (DAC) paths, a zero is placed at the half of the sampling frequency of the modulator’s noise transfer function (NTF). The problem of this additional zero in the NTF is solved through the proposed modulator architectures with a very simple design procedure.

• Type: Conference
• Year: 2005
• Where: ISCAS
• Authors: Mohammad Yavari, Omid Shoaei
• Keywords: ISCAS 2005, Loop Sigma-delta Modulator, Modulator’s Noise Transfer, Sampling Frequency