Lab 5 - ECE 421L
Prelab:
Pre-lab work
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Lab:
To begin this lab we start creating
two CMOS inverters. The CMOS consists of thea PMOS
and a NMOS. The size of the PMOS is 12u/0.6u and the size of the 6u/0.6u.
First we create the schematic for
the CMOS. There is no dc voltage source. Instead we use a supply net.
Figure 1
Next we derive the symbol from
the schematic
Figure 2
Now that we have built the
schematic, we can begin to create the layout for the CMOS. While making the
layout we must pay attention to how we assign our pins. There should be a vdd, A, Ai, and gnd pin added to
the layout to match the schematic pins.
Figure 3
We now extract our layout
Figure 4
After extraction we must DRC and
LVS our design to confirm that there are no errors and that the netlists between the schematic and the extracted view.
Figure 5
Figure 6
After finishing our first CMOS,
we begin to construct our second CMOS. The difference between this CMOS and the
last one that was built is that this CMOS will have its PMOS and CMOS length
and width multiplied by 4.
Figure 7
Next we derive the symbol from
the schematic
Figure 8
Now we can layout our design. The
difference between this and the last CMOS will be the amount of fingers. There
will be four fingers for the amount of multipliers we need. There still needs
to be a vdd, A, Ai, and gnd
pin added to the layout to match the schematic.
Figure 9
Extracted view
Figure 10
DRC to make sure there was
nothing wrong with the design and LVS to confirm the netlists
between schematic and extracted view match.
Figure 11
Figure 12
After we have laid out our design
and extracted our designs, we can now take the symbols and implement them into
a circuit and simulate it with spectre and UltraSim.
The simulations are done with
different values of capacitive loads. The loads that will be used are 100fF,
1pF, 10pF, and 100pF.
First we will be simulating our
12u/6u symbol.
Figure 13
100fF load simulation:
Spectre
UltraSim
1pF load simulation:
Spectre
UltraSim
10pF load simulation
Spectre
UltraSim
100pF load simulation:
Spectre
UltraSim
Next we will be simulating our 4
multiplier symbol implemented in a schematic. The capacitive loads that will be
used are 100fF, 1pF, 10pF, and 100pF.
Figure 14
100fF load simulation:
Spectre
UltraSim
1pF load simulation:
Spectre
UltraSim
10pF load simulation:
Spectre
UltraSim
100kpF load simulation:
Spectre
UltraSim
From all the simulations we can
observe that spectre and UltraSim
output similar results. The spectre state seems to be
a little more accurate for analysis of a circuit over UltraSim.