Abstract—An original design methodology for the selection of output matching network for a concurrent dual-band Low Noise Amplifier (LNA) that is targeted for the use in the GSM 1.8 GHz and WLAN 2.4 GHz range has been proposed in this paper. A particle swarm optimization (PSO) based technique is used to get the optimized values of the output load network components. An RF switch has been incorporated before the LNA module to increase the isolation between the different communication bands. The concurrent dual-band LNA is simulated with these entire component values in CADENCE with CMOS 0.18μm technology. Index Terms—Dual-band concurrent Low Noise Amplifier, Output Matching Network, Particle Swarm Optimization based technique, RF switch. I. INTRODUCTION HE increasing number of communication protocols and their widely varying frequency spectrums have made multistandard wireless communication systems greatly relevant in today’s wireless applications. The need for standardized communication equipment across different geographical regions as well as to satisfy consumer demands of easy translation across different communication protocols makes the combination of two or more radio-frequency (RF) bands in one wireless receiver desirable. In these dual-band wireless receivers, dual-band low-noise amplifiers (LNAs) are one of the critical blocks determining the overall system performance. Designed to have low-noise figures while providing moderate to high gain, the LNAs also increase the sensitivity of the dual-band wireless receivers and also have high linearity to prevent interference from undesired signals. There are several implementations covering GSM or WLAN b/g/a frequencies. But they use parallel LNAs which is not a cost efficient solution. A concurrent LNA is therefore a better choice because it enables saving die area and power consumption when compared to the parallel LNA approach. A few CMOS concurrent implementations have already been proposed [1], [2]. However, there is no information about the selection of dual-band input/output network elements. In this article we explore the concurrent LNA topology using 0.18 μm CMOS9 process. The use of additional components like RF switch has gained Manuscript received on May 25, 2010. K. Datta, R. Datta, A. Dutta and T. K. Bhattacharyya are all with the Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology Khragpur, India. email:(kunal.cal, rohit.sunny, asudeb.dutta, tarun.k.bhattacharyya)@gmail.com popularity in recent times. Modern communication standards now demand not only high gain in the band of interest but also extremely low interference in the adjacent bands. Since the GSM and WLAN frequency bands are quite near each other in the spectrum, an RF switch has also been incorporated in the design, to increase isolation between the signals of the different frequency bands. This article is organized as follows. In section II, we describe the overall concurrent dual-band LNA module and discuss the operation of the RF switch. Section III deals with the general concurrent LNA design theory. There we discuss about the input matching theory and also discuss about the switching topology which matches the dual-band LNA to either selection procedure for the output network elements. In section IV, we discuss the design of the concurrent output matching network considering both ideal, non-ideal components as well as particle swarm optimization. In section V, we apply this methodology to design a concurrent dual-band LNA with RF switch dedicated to work in GSM 1.8 GHz and WLAN 2.4 GHz range. II. DUAL BAND LNA MODULE & RF SWITCH A. Description of LNA Module Fig. 1 shows the total dual band LNA module comprising of the RF switch and the cascode dual band LNA . The operation of the overall system is controlled by the ‘MODE’ signal. RF SWITCH DUAL BAND LNA VREF(1,2) Vdd Vdd MODE Input Signal 1.8 GHz Input Signal 2.4 GHz RF OUT Fig. 1. Block Schematic of the dual-band LNA with RF Switch When MODE=0 (low), the GSM band signal (1.8 GHz) is transmitted and when MODE=1 (high), the WLAN (2.4 GHz) Kunal Datta, Rohit Datta, Ashudeb Dutta, and T. K. Bhattacharyya T PSO Optimized Concurrent Dual-Band LNA with RF Switch for Better Inter-Band Isolation 5th European Conference on Circuits and Systems for Communications (ECCSC'10), November 23–25, 2010, Belgrade, Serbia 59