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Automatic Linearization and Feedforward Cancellation of Modulated Harmonics for Broadband Power Amplifiers

Ratnasamy, Varun
http://rave.ohiolink.edu/etdc/view?acc_num=osu1448974356

Abstract Details

2015, Master of Science, Ohio State University, Electrical and Computer Engineering.
The wireless devices industry has experienced exponential growth in the past decade, especially in the smartphone market. The emerging market opportunities in the areas of automotive applications, connected homes, and wearable technologies have contributed substantially to the ever-increasing number of wireless users. This dramatic growth in the number of spectrum users, along with insatiable demand for higher data rates for streaming services (such as Netflix, YouTube, Spotify, and gaming), has fueled the development of ultra-wideband and broadband communication schemes. Schemes such as Long Term Evolution (LTE), Orthogonal Frequency Division Multiplexing (OFDM), and Wideband Code Division Multiple Access (WCDMA) have been developed to utilize the frequency spectrum efficiently and meet the user capacity requirements. Since these high data rate schemes exhibit non-constant envelops with high PAPR, strict linearity requirements are imposed on PA to avoid spectral regrowth and intermodulation distortion. To ensure seamless compatibility, there is a strong trend towards implementing multi-band and ultra-wideband systems that accommodate different frequency bands (or technology such as 2G, 3G, and 4G) simultaneously while ensuring backward compatibility. However, this has raised further concerns about interference from harmonics (of lower bands) when the separation between two bands is sufficiently large. In practice, digital predistortion and switchable RF band-pass filters banks are used to tackle the problems of linearity and harmonic interference, respectively. However, due to their bulky and lossy nature the filter banks appear to be an unattractive and inflexible solution. Digitally controlled feed-forward harmonic cancellation is emerging as an alternative solution because of the frequency programming flexibility this filter-less solution brings to multi-band systems. This thesis focuses on joint distortion modelling of Broadband Power Amplifiers (PA) using a 2-D Least Square Cubic Spline, and presents a compensation algorithm for simultaneous automatic linearization and cancellation of modulated harmonics. The algorithm relies on a joint system identification of the nonlinearity, memory effects, and group delay of both the main and harmonic cancellation channels. The synchronized PA linearization depends solely on digital predistortion (using a frequency selective technique), whereas the filter-less cancellation of the modulated harmonics uses both predistortion and feed-forward cancellation.
Patrick Roblin (Advisor)
Steven Bibyk (Committee Member)
58 p.
Electrical Engineering
Linearization; Harmonic Cancellation; Power Amplifier; DPD

Recommended Citations

Citations

  • Ratnasamy, V. (2015). Automatic Linearization and Feedforward Cancellation of Modulated Harmonics for Broadband Power Amplifiers [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448974356

    APA Style (7th edition)

  • Ratnasamy, Varun. Automatic Linearization and Feedforward Cancellation of Modulated Harmonics for Broadband Power Amplifiers. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1448974356.

    MLA Style (8th edition)

  • Ratnasamy, Varun. "Automatic Linearization and Feedforward Cancellation of Modulated Harmonics for Broadband Power Amplifiers." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448974356

    Chicago Manual of Style (17th edition)

osu1448974356
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This open access ETD is published by The Ohio State University and OhioLINK.