A project on 2-bit Full Adder using CMOS Tecchnology. The project contains the CIR file needed to implement the Full Adder using ngspice.
The Full Adder is designed using PMOS and NMOS. Fourteen PMOS and fourteen NMOS are used for designing this circuit. The design was constructed using eSim software and is finally
implemented using skywater 130nm pdk.


/Steps followed to execute the design

*The design of the circuit is made using eSim software. 
*Electrical rules check is done to check for any error in connections. If there is any, error is fixed and then we move further. 
*Now the spice netlist(.cir) is generated in our eSim workspace.
*The spice netlist is modified by adding the sky130 models of the mosfets used in the circuit.
*After that the source voltage, A, B and C_in inputs port are given. Transient analysis is done to get the required waveforms of the full adder. 
*After saving the modified netlist, the CIR file is run using Ngspice software and the final Sum and Cout (Carry out) waveforms are obtained.

/Follow below steps to download sky130 pdk and run ngspice

git clone https://github.com/google/skywater-pdk-libs-sky130_fd_pr
skywater-pdk-libs-sky130_fd_pr-main folder needs to be unzipped and the .cir file should be placed in the same folder where the unzipped sky130 pdk is available.

To run the .cir file ngspice needs to be downloaded: https://sourceforge.net/projects/ngspice/files/ng-spice-rework/ 
and the .cir file should be opened with ngspice

/Problems faced

The only problem I faced was a chain of "fatal error" messages that popped up when I tried to run the spice netlist. But it was resolved once I changed the the type of file from ".txt" to 
"All files".

