Abstract
For a receiver sub-block, Low Noise Amplifier is the first stage after the receiving antenna and as a key device, its amplification and noise figure (NF) affects the whole performance of the receiving part. In this paper we present a full graphical visualization in terms of gain, standing wave ratio (SWR) and noise for a GaAs HJ-FET transistor in two operating cases; (1) NFmin, (2) Unity SWRout. The set of curves and contours presented will provide the designer with enough visual information about the transistor operating boundaries and will also visually assist on choosing the appropriate matching points for a wideband operation according to the desired (transducer gain G(T); SWR) for case (1) and (G(T); SWRin; NF) for case (2). Numerical examples are given for each operating case and verified via a microwave circuit design software package to demonstrate the adequacy of the proposed graphical techniques. The results from simulations compare favourably with the visually estimated values.