I need to design astable, monostable and bistable multivibrators using cmos logic . Actually first i had to design these circuits using opamp but now i had to design these corresponding circuits using cmos logic and simulate it on multisim. Is it enough to simply replace the opamp portion of the circuit with its equivalent cmos design or do i need to make some other changes in circuit like voltage levels etc.?

 

Likely there would be some changes. Without seeing your circuits that's only a guess.