q explain shocklys equation and its significance

Question

Q. Explain shockly's equation and its significance in plotting the transfer characteristics ?

The linear relationship does not exists in the output of the JFET, the relationship is given by the shockley's equation.

    I_D = I_DSS(1-V_GS/V_P)²

where  I_D ----> drain current at the given value of  VGS.

I_DSS ----> drain source saturation current.

V_GS ----> gate source voltage.

V_P----> pinch off voltage.

Significance:-

The squared term of the equation will result in the no linear relationship between I_D and V_GS, producing the graph shown below.

For the dc analysis to be performed , a graphical manner rather than mathematical approach will in general be more direct. The solution is defined by the point of intersection of VDS =0 V and ID axis. The transfer characteristics employed by shockley's equation are unaffected by the network in which the device is employed. The transfer characteristics are a plot of the output current versus an input-controlling quantity. There is therefore a direct transfer from input to the output variables when employing the curve.