Cmos Transistor Designs with Magic VLSI- Part 1: Nand Gate

Cmos transistor design environment is the key factor to design any kind of IC. For this project we choose MAGIC VLSI (Very Large Scale Integration) to design layout of the IC. You can download and install MAGIC VLSI from here.

After installation you are ready to design an IC as you wish. For an example there is a tutorial video that can be the best start;

For our first part project, we designed the layout of Nand gate;

After designing this layout, we produce netlist of this specific layout. For each different layout design, different netlist code produced by the MAGIC VLSI. Netlist codes defines connections between metals and defines parasitic capacitors depending on your design.

After completing transistor design, you need to follow these steps;

1_"save nandgate"

2_"extract all"

3_"ext2spice"

After all you produced netlist of your design as "nandgate.spice" and you can open it with "Notepad++". For final you we are suggested to use LTSpice. This program allows us to edit netlist document of MAGIC VLSI. Open LTSpice and follow these steps

1_Click File-new schematic

2_View-Spice Netlist

3_Right Click and Edit as Indp. Netlist

4_Give a name for LTSpice Netlist

5_Copy MAGIC VLSI netlist and paste LTSpice documents 

6_Modify as shown below;

Change;

nfet to NMOS

pfet to PMOS

gnd to 0

gnd! to 0

and obtain netlist as;

* SPICE3 file created from nandv2.ext - technology: scmos

.model NMOS NMOS

.model PMOS PMOS

M1000 Vout Va Vdd Vdd PMOS w=12 l=2

+ ad=84 pd=38 as=120 ps=68

M1001 Vdd Vb Vout Vdd PMOS w=12 l=2

+ ad=0 pd=0 as=0 ps=0

M1002 a_n4_n24# Va 0 0 NMOS w=6 l=2

+ ad=42 pd=26 as=36 ps=24

M1003 Vout Vb a_n4_n24# 0 NMOS w=6 l=2

+ ad=30 pd=22 as=0 ps=0

C0 Vdd Va 2.6fF

C1 Vdd Vb 2.6fF

C2 0 0 7.9fF

C3 Vout 0 3.5fF

C4 Vb 0 8.7fF

C5 Va 0 7.3fF

*1 MHZ

V1 Va 0  PULSE(0 5 0 0 0 0.0000005 0.000001 100)

V2 Vb 0  PULSE(0 5 0 0 0 0.0000005 0.000001 100)

V3 Vdd 0 5 Rser=0

.tran 0.00001

.backanno

.end

And right click to the modified netlist and run, by adding trace you can observe your results.