High order oversampled sigma-delta modulator for IF signal

C. J. Kuo, C. T. Liu, C. J. Hou, Tai-Haur Kuo, C. C. Ho

研究成果: Article

摘要

The sigma-delta modulator (SDM) is an excellent choice for high resolution analog to digital converters. Currently a bandpass SDM is needed if an IF signal is to be converted into a digital bit stream directly. In this paper, we propose a new bandpass SDM architecture based on MASH topology, called bandpass MASH. Similar to conventional MASH, bandpass MASH is always stable because all its poles are zeros. Further, since the loop coefficients of the proposed architecture are ones, the circuit is simple to design and easy to implement via VLSI technology. In addition, it also performs better than several other bandpass SDM's. Behavior simulation shows that the proposed bandpass MASH achieves 17-bit resolution for an IF signal at 455 kHz. However, due to difficulty in analog circuit design and implementation, the HSPICE post-simulation only shows 9-bit resolution that is compatible with the chip measurement results shown in [1]. The proposed bandpass MASH is also implemented using the switched capacitor technique and functions correctly.

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All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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