Figure 2.7 Variation of Threshold voltage in response to change in source-to-substrate voltage VSB
Figure 2.7 depicts the manner in which the threshold voltage Vth varies as a function of the source-to-substrate voltage VSB . As may be seen from the figure, the extent of the variation of the threshold voltage is nearly 1.3 Volts in this range. In most of the digital circuits, the substrate bias effect (also referred to as the body effect) is inevitable. Accordingly, appropriate measures have to be adopted to compensate for such variations in the threshold voltage.