Accurate expression for the noise temperature of common emitter microwave transistors

The standard equivalent II network noise treatment of microwave transistors with constant parameters suffers from two defects: 1) There is a considerable input conductance at high frequencies that varies as ω²and has full thermal noise associated with it; it increases the noise figure. 2) There is a considerable correlation between input noise and output noise at high frequencies, it reduces the noise figure, and its effect predominates. Both effects are taken into account in our treatment, and a final expression for is derived that is easily evaluated. Due to the fact that the two errors partly compensate each other, the older equivalent II network with constant elements is accurate within 20 percent up to the cutoff frequency fT.