Adaptive CMOS analog circuits for 4G mobile terminals—Review and state-of-the-art survey Jose ´ M. de la Rosa à , Rafael Castro-Lo ´pez, Alonso Morgado, Edwin C. Becerra-Alvarez, Rocio del Rı ´o, Francisco V. Ferna ´ ndez, Bele ´n Pe ´ rez-Verdu ´ Institute of Microelectronics of Seville (IMSE-CNM, CSIC) and Universidad de Sevilla, Ed. CICA-CNM, Avda. Reina Mercedes S/N, 41012-Sevilla, Spain article info Article history: Received 31 March 2008 Accepted 1 July 2008 Available online 9 August 2008 Keywords: Reconfigurable mixed-signal and RF circuits Adaptive analog circuits Beyond-3G wireless communications abstract The fourth-generation (4G) of cellular terminals will integrate the services provided by previous generations second-generation/third-generation (2G/3G) with other applications like global positioning system (GPS), digital video broadcasting (DVB) and wireless networks, covering metropolitan (IEEE 802.16), local (IEEE 802.11) and personal (IEEE 802.15) areas. This newgeneration of hand-held wireless devices, also named always-best-connected systems, will require low-power and low-cost multi- standard chips, capable of operating over different co-existing communication protocols, signal conditions, battery status, etc. Moreover, the efficient implementation of these chipsets will demand for reconfigurable radio frequency (RF) and mixed-signal circuits that can adapt to the large number of specifications with minimum power dissipation at the lowest cost. Nanometer CMOS processes are expected to be the base technologies to develop 4G systems, assuring mass production at low cost through increased integration levels and extensive use of digital signal processing. However, the integration in standard CMOS of increasingly complex analog/RF parts imposes a number of challenges and trade-offs that make their design critical. These challenges are addressed in this paper through a comprehensive revision of the state-of-the- art on transceiver architectures, building blocks and design trade-offs of reconfigurable and adaptive CMOS RF and mixed-signal circuits for emerging 4G systems. & 2008 Elsevier Ltd. All rights reserved. 1. Introduction Very few social and technological revolutions in the history of humankind have become as vertiginous as the one experienced during the transition from the 20th to the 21st century. In fact, it would be very difficult to explain our present society without resorting to the so-called Information Technologies and, particu- larly, to some technological achievements such as the Internet or cellular phones. As an illustration of the market penetration of these advances, recent studies reveal that the mobile phone is the electronic device most used by European citizens and that the number of mobile subscribers worldwide has grown over 100-fold in the last 10 years [1]. Such is the pervasiveness of mobile communications that it has become a significant contributor to national gross domestic product in the majority of western countries [2], and indeed it is expected to experience the highest growth in the information and communication sector, making ubiquitous communications a reality [3]. Although cellular communication is yet a young technology when compared to other scientific and engineering achievements, its evolution has not precedents. Only a few years ago, mobile phones were electronic systems with a single functionality: voice transmission. These systems, based on analog modulation schemes such as AMPS, were called first-generation (1G) cellular or mobile phones. The second generation (2G), based on digital modulation and mainly using the GSM standard, increased their functionality with respect to 1G, making the transmission of short message services (SMS), with data rates of up to 10 kilobits/ second (kb/s), possible. In the last few years, with the develop- ment of the third generation (3G) of cellular telecommunications, mobile phones have become multimedia electronic devices, combining different functionalities, among others: digital video camera, multimedia players, short-range connectivity (of up to 1 Mb/s using Bluetooth) to other electronic devices and broadband connectivity to the Internet with data rates of up to 2 Mb/s using the UMTS/WCDMA standard. This trend is foreseen to continue and it is expected that in the next few years, the fourth-generation (4G) systems, also named always-best-connected or Beyond 3G (B3G) systems, will foster the convergence of services provided by previous generations (2G/3G) with other applications like global positioning system (GPS), digital video broadcasting (DVB) and wireless networks covering metropolitan areas (WMAN or WiMAX, based on the IEEE 802.16 standard), local areas (WLAN, IEEE 802.11) and personal areas (WPAN, IEEE 802.15), as well as ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/mejo Microelectronics Journal 0026-2692/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.mejo.2008.07.001 à Corresponding author. Tel.: +34955056666. E-mail address: jrosa@imse.cnm.es (J.M. de la Rosa). Microelectronics Journal 40 (2009) 156–176