A reconfigurable Digital Down Converter architecture for multistandard GNSS receiver

This paper presents the design of a reconfigurable Digital Down Converter (DDC) for a quad standard GNSS receiver. By considering GPS, GALILEO, GLONASS and BEIDOU standard specifications, a bandpass RF sampling-based GNSS receiver is designed. After direct digitization of input signals by choosing properly the sampling frequency, an eight-path reconfigurable DDC is proposed before Digital Signal Processing (DSP) stage in order to down-convert GNSS signals to baseband, reduce sampling rates and therefore relax the processing complexity. The trends related to the implementation of a reconfigurable Direct Digital Synthesizer (DDS) as the critical component in the DDC are also addressed. The DDS implementation results show both low complexity and high performance.