Lab 8 - EE 420L 

Authored by: Roman Gabriele Ocampo
Email: ocampor5@unlv.nevada.edu
Date: May 2, 2014
  

Characterization of the CD4007 Transistor Array


Prelab:
Lab Description and Goals:


NMOS:
ID vs VGS (0<VGS<3V) with VDS=3V

 
ID vs VDS (0<VDS<5V) for VGS varying from 1V to 5V

 
ID vs VGS (0<VGS<5V) with VDS=5V for VSB varying from 0 to 3V

 
PMOS
ID vs VSG (0<VSG<3V) with VSD=3V

 
ID vs VSD (0<VSD<5V) for VSG varying from 1V to 5V

 
ID vs VSG (0<VSG<5V) with VSD=5V for VBS varying from 0 to 3V

 
From this measured data, VTO, GAMMA, KP, and TOX can be obtained.
Assume L=5u, W=500u, and Cox=5p.
 
Tox= eo*er/C'ox = 8.85E-18*3.75 / (5p/(5u*500u)) = 175.7E-10 for both NMOS and PMOS
VTO: Based on the first ID vs VGS (VSG) results, the threshold voltage for NMOS and PMOS is 1V and 1.5V respectively.
KP = 2*ID / VDSSAT^2: Based on the first ID vs VGS results, and the VTO above, the KP values for both NMOS and PMOS vary greatly. When the average is taken, KPn = 600E-6 and KPp = 1000E-6.
GAMMA: Gamma was approximated by taking the change in threshold voltage divided by the change in body voltage. Body voltage has a high effect on NMOS, while it has a negligible one on the PMOS. For an initial estimate, NMOS =0.7 PMOS = 0.2.
 
The following SPICE Level=1 model assumes these values: CD4007_models.txt
 
The following circuits and waveforms were obtained:
NMOS
ID vs VGS (0<VGS<3V) with VDS=3V


 
ID vs VDS (0<VDS<5V) for VGS varying from 1V to 5V


 
ID vs VGS (0<VGS<5V) with VDS=5V for VSB varying from 0 to 3V


 
PMOS
ID vs VSG (0<VSG<3V) with VSD=3V


 
ID vs VSD (0<VSD<5V) for VSG varying from 1V to 5V


 
ID vs VSG (0<VSG<5V) with VSD=5V for VBS varying from 0 to 3V


It is worth noting that the final 2 PMOS sims are reversed because, the calculation for varying VSG, VS was held constant while VG was decreased, allowing for a subtraction.
 
For the next part of the experiment, the delay of an inverter is obtained. The following AC test circuit was built (found on the third page of the datasheet).

Rise time, fall time, tPHL, tPLH, tTHL, tTLH are to be obtained experimentally, and in simulations.
 
From the experiment:
Input:

Output:

From the above:
tr = 20.8ns
tf = 20.8ns
tTHL = 24.4ns
tTLH = 37.6ns
tPHL = 22.0ns
tPLH = 28.8ns
 
From LTspice:



tTHL = 46.15ns
tTLH = 35.78ns
tPHL = 29.6ns
tPLH = 25.9ns
 
From all the simulated data, we can conclude that CD4007_models.txt is a decently accurate Level=1 model. However, the body effect plots are not as accurate as the others, so improvements to the GAMMA measurement and calculation should be made.
 
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