IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 10, Issue 5 Ver. II (Sep – Oct. 2015), PP 126-130 www.iosrjournals.org DOI: 10.9790/1676-1052126130 www.iosrjournals.org 126 | Page Low Noise Amplifier Design for Wide-band Wireless Receivers in Frequency Range S-Band Iman Farjamtalab 1 , Seyed Mohsen Mirhosseini 1 1 (Department of Electrical Engineering/ Central Tehran Branch, Islamic Azad University, Tehran, Iran) Abstract: In this work, we have presented a design technique for the low-noise amplifier of wide-bandwireless receivers in frequency range 2 to 4 GHz (S-Band). We have utilized ADS software in order to analyze the design method. In the first part, we have described the design of low noise amplifier for wide-band based on lumped element by utilizing ATF-10136 amplifier technology in ADS software. In the second part, we have designed low noise amplifier for the frequency range 2 to 4GHz wide-band based on microstrip matching network. The simulation results indicate the excellence of microstrip matching network in comparison to lumped element matching network in this work. Keywords: Low Noise Amplifier; Noise Figure; Stability; matching Network; ADS. I. Introduction A low noise amplifier is one of the most important blocks of the front-end of any sensitive RF receiver setup [1]. The S band is the part of the microwave band of the electromagnetic spectrum that has been defined for radio waves with frequencies range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. The S band is utilized by surface ship radar, weather radar, and some communications satellites. II. Circuit Design A low noise amplifier (LNA) is a part in the receiver path of a wireless system. The main objective of the LNA is to achieve large gain and low noise figure. This objective should be achieved at the input of the LNA a general impedance of 50 ohm is considered [2]. Our wide-band low noise amplifier (WLNA) amplifies signals in frequency range for 2 to 4GHz. The weak radio signals from cosmic sources like the sun are received using a feed horn of a 4.5m parabolic dish The L-band pyramidal horn has a single polarization. The required specifications of the WLNA following the feed are gain (S21) > 10 dB, Noise Figure (NF) < 1dB. An LNA design presents a challenge because of a simultaneous requirement of high gain, low noise figure and perfect input and output matching. The S- parameters of the device, the matching networks, and the terminations are all utilized to evaluate stability [3]. Figure1.block diagram of a microwave amplifier.   =  11 +  12  21  ܮ 1 − 22  ܮ (1)  ݋ ݐݑ =  22 +  12  21  ݏ 1 − 11  ݏ (2) According to the figure1, Γ S must be the conjugate match reflection coefficient (S11) < -10 dBand stability factor (K) >1. The characteristic impedance of the circuit is 50 ohm [1]. Furthermore, gain must be (S21) >10 dB and Noise Figure (NF) < 1dB. Similarly, Γ L should be the conjugate match of the output impedance of the transistor [4].