Title :
Compensation of frequency-selective I/Q imbalances in wideband receivers: models and algorithms
Author :
Valkama, Mikko ; Renfors, Markku ; Koivunen, Visa
Author_Institution :
Telecommun. Lab., Tampere Univ. of Technol., Finland
Abstract :
To achieve satisfactory performance in analog I/Q (inphase/quadrature) processing-based wireless receivers, the matching of amplitudes and phases of the I and Q branches becomes vital. In practice, there is always some imbalance and the image attenuation produced by the analog processing remains finite. Especially in wideband receivers, where the existence of strong image band signals makes the attenuation requirements extremely stringent, analog processing is incapable of providing adequate image rejection. We derive a general frequency-dependent signal model for an imbalanced analog front-end and present two alternative methods utilizing digital processing to enhance the analog front-end image rejection. Based on the obtained results, the proposed methods provide adequate image signal rejection with very few assumptions, even in the difficult cases of frequency-selective and/or time-varying imbalances
Keywords :
amplitude estimation; compensation; interference suppression; phase estimation; radio receivers; signal processing; time-varying channels; amplitude phase matching; analog I/Q processing; analog front-end; compensation; digital processing; frequency-dependent signal model; frequency-selective imbalances; image attenuation; image signal rejection; inphase/quadrature processing; performance; time-varying imbalances; wideband receivers; wireless receivers; Attenuation; Demodulation; Digital signal processing; Filters; Frequency; Interference cancellation; Laboratories; Signal processing; Signal processing algorithms; Wideband;
Conference_Titel :
Wireless Communications, 2001. (SPAWC '01). 2001 IEEE Third Workshop on Signal Processing Advances in
Conference_Location :
Taiwan
Print_ISBN :
0-7803-6720-0
DOI :
10.1109/SPAWC.2001.923837