Improvement of ultra-wideband LNA parameters; multi-objective algorithm for flatness over bandwidth less 3dB

Abstract

In this paper, we proposed a low noise amplifier (LNA) for ultra wideband (UWB) applications using TSMC 0.18µm CMOS technology. Our design consists of two simple stages with a connected resistive feedback. The first stage utilizes self degeneration techniques and cascade structure to obtain a wide band input matching and low noise figure. A common source amplifier with resistive feedback technique as the two stage achieves high flat gain. Having a gain-flatness over the entire frequency range is one challenge in UWB Circuits. On The other hand, having a high gain, low noise figure, input and output matching for all frequency bands are significant for the designer. For having the best trade-offs between these two cases, both genetic and Multi-Objective PSO optimization techniques are used. Proposed optimization application of Multi-Objective Algorithm has been successfully applied to LNA, optimization variable and compare with other reasearch. Symmetric nature is obtained both in terms of S- parameter as well as flatness over a wide bandwidth for of the gain and noise figure. These results are compared with other optimization techniques such as Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). This algorithm provides: gain more than 15dB, low noise figure (lower than 3.5dB) over a wide bandwidth (less than 3 dB), more reverse isolation than <−45 dB and better input/output matching within a supply voltage of 1.8V.