Title :
Digital quadrature mixing of lowpass sigma-delta modulators for switch-mode power amplifiers
Author :
Finnerty, Keith ; Dooley, John ; Farrell, Ronan
Author_Institution :
CTVR - The Telecommun. Res. Centre, Nat. Univ. of Ireland Maynooth, Maynooth, Ireland
Abstract :
In this paper a phase compensation technique for the digital up conversion of a quadrature signal for amplification with switch mode power amplifiers is proposed. When a digital signal generator is used to generate the complex envelope signal care must be taken to compensate for the phase skew between the two paths. If phase compensation is not implemented an image caused by up converting the complex envelope of the modulation signal is created. By compensating for phase skew between the I and Q signal paths it is possible to remove this image signal and enable the transmission of multi carrier signals. As a direct result of this technique there is a reduction in the filtering effort at the output of the power amplifier to meet spectral mask requirements.
Keywords :
amplification; power amplifiers; sigma-delta modulation; switched mode power supplies; amplification; digital quadrature mixing; image signal; lowpass sigma-delta modulators; multicarrier signals; phase compensation technique; switch-mode power amplifiers; Delay; Finite impulse response filter; Frequency modulation; Noise; Power amplifiers; Sigma delta modulation; class S; delta-sigma converters; power amplifiers;
Conference_Titel :
Circuit Theory and Design (ECCTD), 2011 20th European Conference on
Conference_Location :
Linkoping
Print_ISBN :
978-1-4577-0617-2
Electronic_ISBN :
978-1-4577-0616-5
DOI :
10.1109/ECCTD.2011.6043341
