Patent ID: 6434204
Filing Date: 2002-08-13
Classification: H04L

Abstract:
A method for adjusting the DC offset controls for the correction circuit voltage values Icor and Qcor of a quadrature modulated RF signal produced by a radio transmitter having I and Q channels and having I and Q correction circuits, to cancel the residual DC offsets Iâ€²DC and Qâ€²DC said method comprising the steps of:(a) setting the I and Q correction circuit voltage values Icor and Qcor to a known offset voltage value D; (b) injecting said known offset voltage value D into said I and Q correction circuits in different combinations of positive and negative values of +D and âˆ’D; (c) measuring the RF carrier power output of said radio transmitter for each of said combinations of +D and âˆ’D; (d) determining new values for said correction circuit voltage values Icor and Qcor and, (e) setting said DC offset controls for said correction circuit voltage values Icor and Qcor on said radio transmitter for said I and Q channels at said new values determined in step (c), wherein said DC offsets Iâ€²DC and Qâ€²DC for said I and Q signals are within a predetermined range.