I started with Schmitt Trigger circuit using eSim from scratch.
 Unfortunately, after designing the schematic using eSim 
I could not find any suitable information regarding source details,
 subcircuit reference etc. while converting the file from Kicad to Ngspice.
 So, I tried with a basic design of -CMOS AS AN INVERTER CIRCUIT. 
I got fine waveforms too. 
Then as per the instructions, we were given, I did a concrete research on the theory 
as well as the working principle of inverter circuit.
 I prepared my Literature Survey on the basis of the inverter circuit. 
After completing the survey I watched the full Udemy video to design 2 bit DAC IP.
 At the very first attempt, on designing the switch circuit I got ‘Fatal error’.
 I resolved the error after working on it for a few hours.
 Then I tried to design the main circuit of 2 bit DAC using eSim and 
SKY Water 130nm pdk and it was being displayed that - ‘Make sure that the schematic 
has same number of ports as the switch has’. I also got errors, such as - 
‘Pins are not connected’, ‘unknown subcircuit’, ‘no such vector v(d0)’ etc. 
 I worked on the errors and fixed them anyhow. 
After completing the DAC circuit I changed the eSim_mosfet models by SKY Water 
mosfet models. After this I got fine waveforms.