Selecting Integrated VCOs For GSM/EDGE Cellular Handsets

Introduction

The development of GSM/EDGE transceivers for cellular handsets presents a series of challenges, during a period when the need for reduced size, cost, and current consumption has led to functional integration in one or two increasingly feature-rich chips. Today, small-package IC transceivers are available that combine multiple low-noise amplifiers (LNAs), mixers, oscillators, phase-locked loops (PLLs), digital-to-analog converters (DACs), and amplifiers on a single device. The integration of voltage-controlled oscillators (VCOs), including inductors, is a complex task because of standards requirements and the need for these functions to coexist with other RF and digital circuits on the same chip. This article reviews the critical design requirements that handset designers need to consider when selecting VCOs integrated into GSM/EDGE transceiver ICs.

VCO Requirements

Due to the relatively narrow-band nature of the GSM/EDGE system and 3GPP TS45.005 standard, derived requirements for the VCOs tend to be very stringent. As such, the following five requirements must be met when selecting a VCO.

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•Feature Article: Selecting Integrated VCOs For GSM/EDGE Cellular Handsets