The University of British Columbia

Integrated wireless receiver architectures such as direct-conversion receivers offer performance advantages over the conventional heterodyne-based receivers in terms of power consumption, size and implementation cost. The use of these monolithic receivers, however, has been limited mainly due to low-frequency disturbances, namely, DC-offset and 1/f noise (particularly in CMOS implementations). AC-coupling is a cost-effective method to minimize these low-frequency disturbances, but results in baseline wander effects, especially in spectrally efficient modulation schemes such as quadrature amplitude modulation (QAM) whose baseband signal spectrum contains a significant amount of energy near DC. In this work, the quantized feedback (QFB) technique is used to mitigate the baseline wander effect. The QFB block is extended to a complex (in mathematical sense) system that also compensates for carrier phase errors in the receiver local oscillator (LO). Simulation results demonstrate the effectiveness of this complex QFB technique.