Multi-Mode Mult-Band GNSS Receiver RF Front-End Chip System-Level Design

Global Navigation Satellite System (GNSS) has many powerful features, including positioning of all-weather navigation, timing and the frequency calculating of high-precision, high efficiency and automation of measurement precision, and has becoming a global, high-tech industry in various fields. In the representative of Global Positioning System (GPS) the single receiver of traditional mode cannot meet the growing demand for precision, how combing the other GNSS systems and GPS to achieve a high-precision and real-time navigating and positioning of more stable, reliable and secure has become a hot issue in today's research. As a result, researching for multi-mode multi-frequency GNSS receiver is of great significance.This article, as the example of GPS, GLONASS and Galileo systems, studies multi-mode multi-frequency GNSS receiver RF front-end system-level design. The RF front-end can be switched to receive three modes and receive signals of the two bands at the same time in any mode, including GPS L5/L1, GLONASS L2/L1 and Galileo E5a/E2-L1-E1. This paper chooses the structure of two-times frequency converting (with low frequency 27.5 MHz in GPS/Galileo mode, with 21 MHz in GLONASS mode), by the combinations and multi-phase filter to achieve separation and image suppression. In the frequency synthesizer, use one PLL, by the same integer-divider in which in GPS and Galileo mode, by the fractional-N in GLONASS mode. The second local frequency signal is provided by an integer-divider after PLL output. This article identifies the main system specifications of a multi-mode multi-frequency GNSS receiver RF front-end chip system, including gain, noise figure, dynamic range, phase noise, image rejection, and so on. The system was modeled and simulated with the ADS system simulation software, whose results showed that the system specifications had meted the design requirements.