Sometimes an amplifier is required to have an optimum or a specific noise figure. Gapher can calculate the input and output impedances require to give the amplifier that noise figure.

Designing an amplifier to a specified noise figure, use the Amplifier window enter the values for Rn, Fmin Noise, Gamma opt., the required Fnoise, the scattering parameters for 2.4 GHz and click the Calculate Noise button. Gapher will calculate all the variables. Drag the mouse over the Smith chart until the circles just touch, that is when the input and output impedance’s displayed are the same. That is the input impedance required. Select Calculate Conj. GammaL to calculate the output impedance the match as an ordinary amplifier.

Final circuit.