Not linear models
1) Circuit equivalent of a diode valve:
Parallel is constituted from an ability that is that one between the cathode and the anode, in parallel to it has the series of an inductance, a resistance and the parallel between a not linear conductance and an ability also not linear it, this last one holds account of the fact that to second of the polarization of the diode valve the emptying region more or less is emptied and therefore the varied ability being tied to the distance between the bearers.
2) Members intrinseci and estrinseci:
The members intrinseci are those whose value depends on the polarization is therefore not linear and comes generally described by means of a function to the contrary of how much is had for the members estrinseci that they can be described with a number and correspond to you adorned you of the circuit.
3) Necessity to carry out fast measures:
to) the curve that describes the behavior of a diode valve it is not isoterma, the values are function of the temperature in fact salting or coming down along the curve that that it changes it is that in a case the diode valve is cold and for via of its thermal inertia us will put a Pò to scaldarsi while in the other case is already warm.
b) In the semiconductors there are of the impurità that act as from traps and carry out the recombination process which it embezzles of the bearers, the time of detrappolamento is of some ms therefore much elevating regarding the ns that they characterize the period correspondent to the advanced frequencies to the GHz. The consequence of this effect is that the characteristics of a FET introduce a feature with rds negative.
4) characterization of a not linear device:
to) a circuit is associated to the device equivalent to parameters concentrates to you, in truth one to distributed parameters would be more relating but its long and complex elaboration therefore for the plan prefers this less reliable but faster solution
b) the interpolante function between a group of approximately already 20 is chosen realized
5) First method for the extraction of the equivalent circuit from the measures:
We consider the model of diode valve previously described, the value of the members pu² to be determined to leave from the following measures with logical steps:
to) they are carried out of the measures that give to the real part and the imaginary part to us of the stiffness introduced from the diode valve
b) one writes an objective
function g(Cpar , L par , Rpar ,the 0 , h , G, to, g) that it contains
all the parameters that characterize the equivalent circuit and comes
defined one distance 
c) from initially a value whichever to h andthe 0 after which varying them it is attempted to diminish the distance
6) According to method for the extraction of the equivalent circuit from the misure:
The value of the members is gained subsequently before estrinseci and that one of the members intrinseci by means of the following procedure:
to) Applying one current much elevating the members intrinseci of the diode valve therefore from the value of the real part of the Z measured for f=0 pu² deducing the parasite drag can themselves be neglected while the inductance and the ability parasite can be characterized to leave from the location of the resonance frequency. These measures come calls âmisure freddeâ? and concur the location of the value of adorned to you
b) We pass from the Z to the Y and embezzle the already famous ability parallel after which it is returned to the Z and the inductance is embezzled series also it notices from the previous step, is still passed to the y to this point from the intersection with the axis of the formers of the real part of the admittance determines the intrinsic conductance while from the slope of the imaginary part the intrinsic ability is determined.
c) the procedure must be repeated for every point of considered polarization of interpola interest after which