The (complex) impedance presented to the input port of a device; the impedance a device is driven from. Generator impedance determines noise figure. It influences device gain and stability.
For maximum gain (minimum input reflection coefficient), G = s11'*
[The load impedance is equal to the conjugate of the input reflection coefficient, modified by any loading from the load impedance.]
For noise, G is set to present the correct correct impedance for minimum noise figure (opt).
Gain, Impedance, Impedance Matching, Load Impedance, Reflection Coefficient, S-Parameters