Self-calibrating highly integrated radio frequency front-end for parallel π/4 DQPSK decoding

This work describes a high-frequency front-end that is able to decode up to four π/4 DQPSK modulated 25 kHz carriers simultaneously in a 5 MHz downlink band located between 70 MHz and 6 GHz. The front-end is self-calibrating its time-variant phase- and timing-offsets by maximum likelihood estimators. The calibrating algorithm does not depend on a particular network protocol or training sequence and can easily be adapted to any other linear modulation schemes. Due to its small shape-factor caused by extensive conversion of analogue components into digital sections, the front-end is suitable for operation in hand-held measurement equipment.