TR2017-143

Optimal Delta-Sigma Modulation Based Noise Shaping for Truly Aliasing-Free digital PWM


    •  Ma, R., Tanovic, O., Teo, K.H., "Optimal Delta-Sigma Modulation Based Noise Shaping for Truly Aliasing-Free digital PWM", European Microwave Conference, DOI: 10.23919/EuMC.2017.8230951, October 2017.
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      • @inproceedings{Ma2017oct2,
      • author = {Ma, Rui and Tanovic, Omer and Teo, Koon Hoo},
      • title = {Optimal Delta-Sigma Modulation Based Noise Shaping for Truly Aliasing-Free digital PWM},
      • booktitle = {European Microwave Conference},
      • year = 2017,
      • month = oct,
      • doi = {10.23919/EuMC.2017.8230951},
      • url = {https://www.merl.com/publications/TR2017-143}
      • }
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  • Research Area:

    Electric Systems


In recent years, carrier based pulse-width modulation (PWM) has been extensively used for reducing input signal resolution in all-digital transmitters, and is known to provide better coding efficiency than other power encoding methods, e.g. delta-sigma modulation (DSM). Unfortunately, high levels of in-band distortion introduced by fully digitally implemented PWM, limit its usage in transceivers realized for software defined radio. In this paper, we exploit time-domain characterization of digital PWM in-band distortion, and propose a multilevel power encoding scheme based on DSM-PWM hybrid architecture with carefully selected design parameters, which enable optimal in-band distortion cancellation with low hardware complexity. Experiments with an arbitrary waveform generator are used to demonstrate effectiveness of the proposed novel power encoding scheme, and are compared with a standard multilevel PWM. The novel power encoding scheme offers -20dB improvement in SNR, while maintaining similar coding efficiency of roughly 73%.