The sizing of the transistor can be done using RC delay approximation. The RC Delay Model helps in delay estimation CMOS circuit. The RC delay model treats the non-linear transistor current-voltage I-V and capacitor voltage C-V characteristics with their equivalent resistance and capacitance model. This RC delay model approximates a transistor as a switch with a series of resistance or effective resistance R (Which is the ratio of the average value of Vds to Ids). The size of a unit transistor is approximated as 4/2 lambda. The RC circuit equivalent models for the PMOS and NMOS transistors are shown below. Here the k width of both PMOS and NMOS transistors is contacted to Source S and drain D. Since the holes in