Fast frequency synthesizer concept based on digital tuning and I/Q signal processing

Abstract

In this thesis, the problems of I/Q imbalances and carrier leakage are considered. Since traditional filtering techniques are not adequate for practical requirements, digital predistortion in the low-frequency part of the synthesizer is presented as a possible solution to compensate them. Adaptive algorithms are employed in the estimation of the distortion parameters due to their flexibility and ease of control. The use of the envelope as a reference signal eliminates the need of calibration signals. The results indicate that the performance of the proposed frequency synthesizer is feasible because the I/Q imbalances and the carrier leakage can be efficiently compensated during the normal operation of the synthesizer, considering also rapidly changing imbalances and finite word length effects. /Kir10