Phase Noise Analysis of PLL Based Frequency Synthesizers for Multi-Radio Mobile Terminals

This paper deals with phase noise analysis and design aspects of PLL based frequency synthesizers for cognitive multi-radio mobile terminals. Principal features of PLL based frequency synthesizers are presented and simulated. This document describes various issues of the loop filter design and the overall impact on the frequency synthesizer performance in terms of the phase noise, settling time and the spurious suppression capability. Phase noise requirements for main communication standards in the frequency band 800 MHz to 6 GHz are investigated as well.

I. Introduction

During the recent past, there has been a significant progress in wireless communications in terms of the integration of various communication standards into a single mobile terminal. Instead of using multiple transceivers for different standards, the goal is to employ a single reconfigurable radio transceiver that is able to achieve all requirements of different communication standards. The goal of this evolution is to reduce the number of external components and to increase the integration in the low-cost CMOS technology. Another stage which pursues the evolution towards the cognitive radio and implies flexibility of each stage of the communication chain is the cognitive multi-radio. Cognitive multi-radio has the capability of the multi-standard concept and moreover it is capable to perform an efficient environment spectrum scanning in order to switch accordingly to an appropriate communication standard.