A Dual-Band RF Front-End Architecture for Accurate and Reliable GPS Receivers

This paper presents a dual-band RF front-end architecture designed for simultaneously receiving the L1 and L5 signals of the Global Positioning System (GPS). The use of the new L5 signal can improve the accuracy and reliability of the typical mass-market receivers that rely only on the L1 signal. The proposed architecture is based on a compact microstrip diplexer that separates the two bands of interest providing the necessary filtering. Each band is down-converted independently and then both are combined at intermediate frequency (IF) in order to obtain one analog output. This front-end architecture is suitable for implementing a programmable high accuracy GPS receiver using a generic digital signal processing platform. The current work focuses on the diplexer design as well as the selection of the sampling rate and frequency plan required to avoid band overlapping before and after the analog to digital conversion. Satisfactory measurement results of the diplexer are presented.