Measuring demodulator imbalance in radio frequency receivers by tone test
2009 (English)In: 19th IMEKO World Congress 2009, 2009, 462-465 p.Conference paper (Refereed)
The measurement of in-phase/quadrature (IQ) imbalance parameters of radio frequency direct downconversion receivers by tone test is considered. The receiver is excited by a radio frequency sinewave, and the digital baseband output is used as the sole basis for the determination of the IQ imbalance parameters, which are the gain imbalance, quadrature skew and local oscillator leakage. A set of parameters is estimated from the baseband output of the direct downconversion receiver and the required parameters are then calculated by a transformation. The universal software radio peripheral (USRP) is a widespread hardware for research, education, and development regarding future wireless communication receivers. A set of USRPs are tested. It is shown that for the receivers studied, gain imbalance and quadrature skew may be predicted accurately (that is, < 0.1 dB and < 1 deg, respectively) by employing baseband data covering a handful of full periods of the excitation stimuli. The work also shows that local oscillator leakage may suffer from systematic bias error of the order of 15 dB. To obtain leakage estimates with an uncertainty in the order of one dB, the measurement time has to be increased by two orders of magnitude.
Place, publisher, year, edition, pages
2009. 462-465 p.
Radio receiver IQ imbalance, Tone test, Universal software radio peripheral (USRP)
IdentifiersURN: urn:nbn:se:kth:diva-85875ScopusID: 2-s2.0-84871542735ISBN: 978-161567593-7OAI: oai:DiVA.org:kth-85875DiVA: diva2:500228
19th IMEKO World Congress 2009; Lisbon; Portugal; 6 September 2009 through 11 September 2009
QC 201202172012-02-132012-02-132014-09-23Bibliographically approved