-> i choosen 2:1 mux usig pass transistor logic..
->start with the diagram and the working procedure of mux.
->then start doing schematic diagram usim esim open source EDA tool.
-> here i used 1 pmos and 3 nmos to make a 2:1 mux.
-> after completed the schematic diagram generate a netlist file.
-> then starts main thing ,need to replace the nmos and pmos with sky130 pdK
   that was the learnable thing.
->then finaly i ran succesfully but the output wave form was not accurate as the output requires.
->learned about pwl command for random digital sequence like if want A=1100 so, command will be like
             vdn A 0 pwl(0 5 10u 5 10.001u 0 20u 0) 1 as logic high=5v
                                                    0 as logic low=0v
          if your sequnce is pulse like A=1010 then we can use pulse command 
                 vdn A 0 pulse(0 5 0s 0s 0s 5us 10us)
-> in my case i observed that inputs should not change their state at the same time
-> if you decrease the fall time then state change will be faster.

i faced most of the error in the output wave form, i successfully recovered it and obtain a perfect waveform as 2:1 mux should give.
   ## it can also be used as a switch circuit. if give vin1= 3v and vin2=1v, if s=0 the vout=3v and if s=1 vout =1v..