Lab 5 - ECE 421L
Authored
by Jovanne Dahan
dahanj1@unlv.nevada.edu
9 October 2018
Post-lab:
·
12u/6u Inverter
The first step I undertook in creating the inverter was to draw the given
schematic. After checking and saving, I created a symbol view for the circuit
and drew the symbol for an inverter; connecting the input to A and output to
Ai. Moving on to the layout part of the design process, I simply followed the
same steps I took in Tutorial
3 for creating the layout of an inverter. After DRCing
showed no errors, I moved on to the last step: LVSing
the extracted view with the schematic. Seen below is the results of the LVS and
the schematic view of my 12u/6u inverter.
·
48u/24u Inverter
The steps to create a 48u/24u inverter was the same as the 12u/6u
inverter except for the fact that the multiplier had to be set to 4 for the
NMOS and the PMOS in the schematic view. Similarly, when laying out the circuit
a multiplier of 4 had to be used for the PMOS and the NMOS cells.
·
Spectre simulations
for 12u/6u inverter
Directly below is the schematic for testing my 12u/6u inverter. As the
lab instruction directed, I simulated the schematic four times using spectre with values of C ranging from 100fF, 1pF, 10pF, to
100pF. The waveforms for each capacitor values are below in the respective
order (left to right, top to bottom).
At 100fF, the inverter works as intended: inverting the value of the
input from logic value “1” to “0” or vice versa. Increasing the capacitance
increases the amount of time it takes to charge/discharge the capacitor
resulting in the following waveforms.
·
Spectre simulations
for 42u/24u inverter
I took the same steps to simulate this circuit as with the previous. I
did a transient analysis from 0 to 20ns with the pulse being 5V.
Similar to the 12u/6u inverter, the increase in capacitance makes the
charge time longer. However, the waveforms below are showing a less drastic
change. This might be due to the fact that the resistivity between drain and
source have decreased due to the larger area of the PMOS.
·
UltraSim simulations
for 12u/6u inverter
Simulating with UltraSim showed no noticeable
difference from the waveforms generated with Spectre.
The simulation speed for UltraSim also did not feel
any faster than Spectre.
·
UltraSim simulations
for 42u/24u inverter
Since the circuits I have simulated are quite small, the simulation speed
and accuracy difference from UltraSim and Spectre are miniscule.
My cells for the content above: lab5.zip