%0 Journal Article
%T Study of Linearity and Power Consumption Requirements of CMOS Low Noise Amplifiers in Context of LTE Systems and Beyond
%A Grzegorz Szczepkowski
%A Ronan Farrell
%J ISRN Electronics
%D 2014
%R 10.1155/2014/391240
%X This paper presents a study of linearity in wideband CMOS low noise amplifiers (LNA) and its relationship to power consumption in context of Long Term Evolution (LTE) systems and its future developments. Using proposed figure of merit (FoM) to compare 35 state-of-the-art LNA circuits published over the last decade, the paper explores a dependence between amplifier performance (i.e., combined linearity, noise figure, and gain) and power consumption. In order to satisfy stringent linearity specifications for LTE standard (and its likely successors), the paper predicts that LNA FoM increase in the range of +0.2£¿dB/mW is expected and will inevitably translate into a significant increase in power consumption¡ªa critical budget planning aspect for handheld devices, active antenna arrays, and base stations operating in small cells. 1. Introduction Long Term Evolution (LTE) is a next generation communication standard developed by 3rd Generation Partnership Project (3GPP) [1], allowing a high data rate transmission over radio interface. It represents a natural progression from voice transmission systems as GSM through UMTS (with increased spectral efficiency for data transmission) to data transmission scheme, where the majority of system throughput is used for high quality audiovisual streaming, internet access, file sharing, and gaming, with peak downlink bandwidths in excess of 100£¿Mbps [2]. Such a dramatic increase in data throughput corresponds to proportional increase in either a bandwidth (BW) or signal to noise ratio (SNR) or both at the same time. Both quantities cannot be made arbitrary high. SNR is a function of maximum transmitted power allowed for the system, distance to the receiver, and modulation scheme, and these parameters are usually optimised for the transmission. BW is controlled by the availability of a radio spectrum allocated for the system and, to certain extent, more bandwidth can be assigned to increase channel capacity if needed (providing that there is enough amount of unoccupied bandwidth left). Nowadays, the number of various wideband radio systems coexisting with LTE is significant and as a result, the radio spectrum has become relatively congested. For example, 3GPP specifies LTE frequency separation between frequency-division duplex (FDD) uplink and in the range of 45¨C400£¿MHz or even smaller distance (for time-division duplex (TDD) transmission bands) [1]. From a radio receiver perspective, in order to prevent unwanted signals from reaching processing stages, small frequency separation between bands imposes high selectivity (or
%U http://www.hindawi.com/journals/isrn.electronics/2014/391240/