Automatic calibration of a direct upconversion transmitter

This paper presents a novel method to measure and compensate the analog imperfections in a direct upconversion transmitter. The RF output spectrum is downconverted back to baseband frequencies by re-using the transmit mixer. Errors in the up- and downconversion process are now correlated, and the required measurements and mathematics are presented to extract estimates for the errors that cause imperfect image rejection and carrier feedthrough.