Novel MCDM Scheme for Optimal Design of Low Noise Amplifier

Optimization is crucial in various design problems. In this direction, an optimization technique is used in designing a Low Noise Amplifier (LNA) for a 4 GHz frequency application. This paper deals with the development of a novel hybridized optimization technique, namely, Multi Choice Best Worst Grey Relation Analysis (MCBWGRA) to optimize the LNA circuit for increasing gain <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{S}_{21})$</tex>, stability factor (K), and lowering input reflection coefficient (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>), reverse voltage gain (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf>), output reflection coefficient (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</inf>), and Noise Figure (NF). Firstly, an LNA circuit was designed in Advanced Design System and the Design of Experiments (DOE) was decided using orthogonal arrays (OA), <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{L}_{25}$</tex>. The obtained experimental runs were used to find the optimized output parameters using the proposed technique. After applying the proposed method, the obtained optimized input values are <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{R}_{3}=660 \ \Omega, \mathrm{R}_{4}=12 \ \Omega, \mathrm{L}_{3}= 2 \ \text{nH}, \mathrm{C}_{4}=1.3 \ \text{pF}, \mathrm{C}_{5}=1.4 \ \text{pF}$</tex>. In this situation, outputs have magnitudes as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{S}_{11}=-11.395 \ \text{dB}$</tex>, S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</inf><tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$=-19.436 \ \text{dB}, \mathrm{S}_{12}=-17.896 \ \text{dB},\mathrm{S}_{21}=11.246 \ \text{dB}, \mathrm{K}=1.209, \text{NF}=0.877 \ \text{dB}$</tex> at 4 GHz. A circuit simulation of optimized LNA with microstrip lines and Electromagnetic (EM) Co-simulation was performed to check the output parameters of the optimized schematic simulation. The optimized circuit shows a considerably high increment of 8.51 % in gain and a 1.4 % decrease in noise figure over the unoptimized circuit.