1. Introduction

The wireless industry is experiencing explosive growth with applications like GSM cellular telephony, Bluetooth, and wireless LAN becoming commodities of everyday life. One major factor contributing to this growth is the emerging presence of CMOS technology in commercial analog and radio frequency integrated circuits (RFIC). Traditionally, technologies such as Gallium Arsenide (GaAs) and Silicon Germanium (SiGe) are chosen over CMOS for fabricating RF circuits because of stringent noise, linearity, gain, and power efficiency requirements in addition to the high speed, low power, and high yield requirements characteristic of digital integrated circuits. The drawbacks of these technologies, however, are their high cost and slow scaling needed to achieve high integration. This was evident in the past where improvements in RF circuit performance have been slower than those of the digital microprocessor industry that is guided by Moore's law. Recently, with the drive towards system-on-chip (SOC) integration, there has been a tremendous interest in implementing RF circuits such as low noise amplifiers (LNA), mixers, power amplifiers (PA) and voltage-controlled oscillators (VCO) in digital CMOS technology. The reasons are quite obvious: if CMOS RF circuits are able to provide similar performance as their GaAs and SiGe counterparts, they may experience thenir own version of Moore's law with regard to integration ease and low fabrication cost. Here, we present some recent advances and design trends in CMOS RF ICs at both the architectural and circuit levels. The paper is divided into six sections. Section II addresses key issues in receiver architectures. Section...