Patent ID: 9025645
Filing Date: 2015-05-05
Classification: H04B

Abstract:
1. A method of generating local oscillator (LO) in-phase/quadrature (IQ) imbalance correction data in a radio-frequency (RF) communication apparatus comprising a receiver and a transmitter, the method comprising: generating a baseband receiver signal in the receiver from an RF transmitter output signal transmitted from the transmitter, the transmitter output signal being generated by the transmitter from a known baseband test signal; generating difference signals indicating a characteristic difference between the receiver signal and the test signal in respective frequency bands of the receiver signal under influence of a phase shift applied to the transmitter output signal; acquiring a set of measurements of the difference signals as the transmitter output signal is phase-shifted through no greater than two (2) predetermined arbitrary phase shifts; computing joint LO IQ imbalance figures of merit (JFMs) from the acquired difference signal measurements that characterize respective signal processing artifacts in the receiver signal from joint signal processing in the transmitter and the receiver under influence of LO IQ imbalance in the transmitter and LO IQ imbalance in the receiver; determining the LO IQ imbalance correction data from the computed JFMs that characterize the transmitter LO IQ imbalance distinctly from the receiver LO IQ imbalance, wherein computing the JFMs comprises: determining an inverse of a matrix populated with complex weights indicative of the respective phase shifts under which each of the difference signals is measured, the matrix being populated in accordance with a set of equations defining the known relationship; and storing the inverse of the matrix as the transform matrix; wherein measuring the difference signal comprises: wherein determining the LO IQ imbalance correction data comprises: