2.2.2 Second Order Effects  

The current-voltage equations in the previous section however are ideal in nature. These have been derived keeping various secondary effects out of consideration.

Threshold voltage and body effect : as has been discussed at length in Sec. 2.1.6, the threshold voltage V_th does vary with the voltage difference V_sb between the source and the body (substrate). Thus including this difference, the generalized expression for the threshold voltage is reiterated as

..................................... (2.10)

in which the parameter , known as the substrate-bias (or body-effect ) coefficient is given by

.Typical values of range from 0.4 to 1.2. It may also be written as