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Modelling, estimation and compensation of imbalances in quadrature transceivers
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : University of Stellenbosch
2011
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| _version_ | 1867613926913474561 |
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| access_status_str | Open Access |
| author | De Witt, Josias Jacobus |
| author2 | Van Rooyen, G-J. |
| author_browse | De Witt, Josias Jacobus Van Rooyen, G-J. |
| author_facet | Van Rooyen, G-J. De Witt, Josias Jacobus |
| author_sort | De Witt, Josias Jacobus |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/6808 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:54.909Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2011 |
| publishDateRange | 2011 |
| publishDateSort | 2011 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/6808 Modelling, estimation and compensation of imbalances in quadrature transceivers De Witt, Josias Jacobus Van Rooyen, G-J. University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Frequency translation Quadrature mixing I/Q imbalance compensation Software-defined radio Dissertations -- Electronic engineering Theses -- Electronic engineering Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. ENGLISH ABSTRACT: The use of the quadrature mixing topology has been severely limited in the past due to its sensitivity towards mismatches between its signal paths. In recent years, researchers have suggested that digital techniques can be used to compensate for the impairments in the analogue quadrature mixing front-end. Most authors, however, focus on the modelling and compensation of frequency-independent imbalances, reasoning that this approach is sufficient for narrow band signal operation. This common assumption is, however, becoming increasing less applicable as the use of wider bandwidth signals and multi-channel systems becomes more prevalent. In this dissertation, baseband equivalent distortion models are derived, which model frequency-independent, as well as frequency-dependent contributions towards the imbalances of the front-end. Both lowpass and bandpass imbalances are modelled, which extends current modelling approaches found in literature. The resulting baseband models are shown to be capable of explaining the imbalance characteristics observed in practical quadrature mixing front ends, where existing models fail to do so. The developed imbalance models is then used to develop novel frequency-dependent imbalance extraction and compensation techniques, which directly extract the exact quadrature imbalances of the front end, using simple test tones. The imbalance extraction and compensation procedures are implemented in the digital baseband domain of the transceiver and do not require high computational complexity. The performance of these techniques are subsequently verified through simulations and a practical hardware implementation, yielding significant improvement in the image rejection capabilities of the quadrature mixing transceiver. Finally, a novel, blind imbalance compensation technique is developed. This technique is aimed at extracting frequency-independent I/Q imbalances in systems employing digital modulation schemes. No test tones are employed and the imbalances of the modulator and demodulator are extracted from the second order statistics of the received signal. Simulations are presented to investigate the performance of these techniques under various operating conditions. AFRIKAANSE OPSOMMING: Die gebruik van die haaksfasige mengtopologie word geweldig beperk deur die sensitiwiteit vir wanbalanse wat mag bestaan tussen die twee analoog seinpaaie. In die afgelope paar jaar het navorsers digitale metodes begin voorstel om te kompenseer vir hierdie wanbalanse in die analooggebied. Meeste navorsers fokus egter op frekwensie-onafhanklike wanbalanse. Hulle staaf hierdie aanslag deur te redineer dat dit ’n aanvaarbare aaname is vir ’n nouband stelsel. Hierdie algemene aanvaarding is egter besig om minder akkuraat te raak, namate wyeband- en multikanaalstelses aan die orde van die dag raak. In hierdie tesis word basisband-ekwiwalente wanbelansmodelle afgelei wat poog om die effek van frekwensie-afhanklike en -onafhanklike wanbalanse akkuraat voor te stel. Beide laagdeurlaat- en banddeurlaatwanbalanse word gemodelleer, wat ‘n uitbreiding is op die huididge modellerings benaderings wat in literatuur gevind word. Dit word aangetoon dat die modelle van hierdie tesis daarin slaag om die karakteristieke van ’n werklike haaksfasige mengstelsel akkuraat te vervat – iets waarin huidige modelle in die literatuur nie slaag nie. Die basisband-ekwiwalente modelle word dan gebruik om nuwe digitale kompensasie metodes te ontwikkel, wat daarin slaag om die frekwensie-afhanklike wanbalanse van die haaksfasige mengstelsel af te skat, en daarvoor te kompenseer in die digitale deel van die stelsel. Hierdie kompensasiemetodes gebruik eenvoudige toetsseine om die wanbalanse af te skat. Die werksverrigting van hiedie kompensasiemetodes word dan ondersoek deur middel van simulasies en ’n praktiese hardeware-implementasie. Die resultate wys daarop dat hierdie metodes daarin slaag om ’n aansienlike verbetering in die beeldonderdrukkingsvermo¨ens van die haaksfasige mengers te weeg te bring. Laastens word daar ook ’n blinde kompensasiemetode ontwikkel, wat gemik is op frekwensie- onafhanklike wanbalanse in digital-modulasie-skama stelsels. Vir hierdie metodes is geen toetsseine nodig om die wanbalanse af te skat nie, en word dit gedoen vanuit die tweede-orde statistiek van die ontvangde sein. Die werksverrigting van hierdie tegnieke word verder bevestig deur middel van simulasies. Doctoral 2011-02-28T10:36:21Z 2011-03-14T08:43:23Z 2011-02-28T10:36:21Z 2011-03-14T08:43:23Z 2011-03 Thesis http://hdl.handle.net/10019.1/6808 en_ZA University of Stellenbosch 216 p. : ill. application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Frequency translation Quadrature mixing I/Q imbalance compensation Software-defined radio Dissertations -- Electronic engineering Theses -- Electronic engineering De Witt, Josias Jacobus Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title | Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title_full | Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title_fullStr | Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title_full_unstemmed | Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title_short | Modelling, estimation and compensation of imbalances in quadrature transceivers |
| title_sort | modelling estimation and compensation of imbalances in quadrature transceivers |
| topic | Frequency translation Quadrature mixing I/Q imbalance compensation Software-defined radio Dissertations -- Electronic engineering Theses -- Electronic engineering |
| url | http://hdl.handle.net/10019.1/6808 |
| work_keys_str_mv | AT dewittjosiasjacobus modellingestimationandcompensationofimbalancesinquadraturetransceivers |