TR2018-021

Truly Aliasing-Free Digital RF-PWM Power Coding Scheme for Switched-Mode Power Amplifiers


    •  Tanovic, O., Ma, R., "Truly Aliasing-Free Digital RF-PWM Power Coding Scheme for Switched-Mode Power Amplifiers", IEEE Radio and Wireless Symposium (RWS), DOI: 10.1109/RWS.2018.8304948, March 2018.
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      • @inproceedings{Ma2018mar,
      • author = {Tanovic, Omer and Ma, Rui},
      • title = {Truly Aliasing-Free Digital RF-PWM Power Coding Scheme for Switched-Mode Power Amplifiers},
      • booktitle = {IEEE Radio and Wireless Symposium (RWS)},
      • year = 2018,
      • month = mar,
      • doi = {10.1109/RWS.2018.8304948},
      • url = {https://www.merl.com/publications/TR2018-021}
      • }
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  • Research Area:

    Electric Systems


This paper presents a novel method for multilevel power coding and upconversion to RF frequency, by the means of a digital radio-frequency pulse width modulation (RF-PWM). Delta-sigma modulation and memoryless predistortion are used to cancel spectral aliasing effects, inherent to digital RFPWM operation, and achieve high linearity of the transmitter. In this method, time-domain characterization of a multilevel digital RF-PWM was fully exploited in order to provide optimal parameter selection for the Delta-sigma modulation, which in turn enables aliasingfree digital RF-PWM that runs at reasonable clock speeds. Experiments with an arbitrary waveform generator are used to demonstrate effectiveness of the proposed novel power encoding scheme. The novel algorithm offers in-band SNR of -45dB, while maintaining coding efficiency of about 55%, for a 20MHzbandwidth 64QAM signal, while mere RF-PWM, running at the same clock speed, can achieve SNR of only -10dB.