A fast method for adaptation of quadrature modulators and demodulators in amplifier linearization circuits

Imperfections in analog quadrature modulators and demodulators-gain and phase imbalance and DC offset-have a devastating effect on amplifier linearization circuits. Correction circuits have a simple structure, but their parameters must be adjusted adaptively. This paper introduces an adaptation method based on a training sequence consisting solely of a tone at one or more amplitudes. It is faster and more robust than previously published methods