ECE3424 Lab.
After 2 semesters plus one summer of rebuilding and refitting the ECE3424 lab is now fixed. It is no
longer the kit (which was essentially a joke). It is anything but an automatic 25%. In fact (Yaroslav will
like this) they may need the lecture grade to pull up their lab grade..
It is now a (didactic) measurements lab for (1) device characteristics and (2) circuit performance
characteristics. Synopses of the experiments are on the next page.
It requires a $25 parts kit instead of the $85 FM radio kit. As long as discrete parts are available the lab
will be good.
Caveat #1: Almost all lab experiments require use of pSPICE. And almost all lab experiments require
use of Excel curve-fitting techniques (example attached). So it is strongly recommended that you assign a
pSPICE homework exercise the first week - with solutions given. One such is attached (attachment #2).
The exercise will (1) bring them up to speed quickly on pSPICE, (2) acquaint them with the method of
electronic submissions and (3) give them a clean readable format and template.
Caveat #2: All labs make use of the opamp, primarily as a means to measure current. So you need to
give the first week of lecture class to opamp basics. The ECE3413 instructor often does not cover
opamps. Regrets.
And you will need to give coverage to CMOS logic.
And you will need to give coverage to parasitic capacitances of the BJT and FET.
Most everything else is familiar. There is a Big emphasis on measurement of device characteristics and
device model parameters. Out of the eleven labs five are on device characteristics. The rest are a mix of
known circuit topologies and application circuits.
There are a total of eleven lab experiments beginning with week 1 and spaced unevenly through the
semester at about one experiment/week.
All lab experiments include figures of a protoboard template with suggestions for placement and routing.
All lab experiments include one or more photos of the protoboard layout.
All lab experiments have an instructor protoboard with mounted test circuit and are kept in the lab.
Students may look at ‘the instructor solution’ but not touch.
Many lab experiments also include photos of O-scope screenshots so they know what to expect.
My favorite lab is the measurement of the CMOS transfer characteristics since it shows the skew of the
transfer curve for different logic inputs of the NAND gate (causes sneak faults in logic functions.)
Students have 24/7 access to the lab if they need extra time or make-up time. Even so you will probably
have students coming to you with questions about the lab experiments.
My apologies for taking so long to get this damn lab fixed.
The Experiments:
Experiment 1x: Getting started. Measurement of opamp characteristics. Get acquainted with the
instrument cluster. Measure Rin and Rout for 741C opamp vs frequency. Compare to pSPICE
simulations.
Experiment 2x: Junction diode forward conductance characteristics. Measure reverse saturation current
IS and emission coefficient n for 1n4148 junction diode, 1n4732 Zener, and LED by use of Excel curve
fitting. Compare to device model parameters of the same and compare to pSPICE simulations.
Introduction to curve-fitting using Excel.
Experiment 3x: Junction diode reverse-bias characteristics. Measure junction capacitance CJ vs reverse
bias VR for the 1n4148 junction diode and extract zero-bias capacitance CJ0, built-in potential PB and
grading coefficient exponent MJ by means of Excel curve fitting. Compare to device model parameters
and to pSPICE simulations.
Experiment 4x: AC-DC Converters and Charge-pump circuits. Measure V(ripple) and VDC level as a
function of R(load) and with two different capacitance sizes. For the charge pump also vary the
frequency and measure the rise time constant. Compare to pSPICE simulations.
Experiment 5x: I-V characteristics of the bipolar junction transistor. For the 2n3904 and 2n3906 (npn
and pnp) transistors measure measure Early voltage VA and forward current gain  F vs collector current.
Compare to device model parameters and compare to pSPICE simulations. Introduction to pSPICE
performance analysis and goal functions.
Experiment 6x: Optimization of Single-transistor BJT amplifiers. Evaluate CE topology for distortion
as a function of resistance bias frame. Use pSPICE to design a CE amplifier with Vout of amplitude +5.0V and THD < 5%.
Experiment 7x: (Application circuit) Phase-splitter/phase-shifter. Measure phase-shift vs tuning
resistance and compare to pSPICE simulations.
Experiment 8x: Conduction characteristics of the junction field-effect transistor. For the 2n5457 nJFET
extract  and VP from I vs VGS using Excel curve-fit techniques. From I vs VDS extract Early voltage
VA. Compare to device model parameters and compare to pSPICE simulations.
Experiment 9x: Transfer characteristics of CMOS logic gates. For the CD4069UBE (CMOS) hex
inverter evaluate inverter threshold VIT and transition current maximum IMAX vs VDD. From loading
measurements extract VTN, VTP, KN and KP using Excel curve-fit techniques. For the three realization
of an inverter using a NAND gate evaluate VIT vs VDD and identify logic skew.
Experiment 10x: (Application circuits) Mixed applications with both JFETs and BJTs. Measure (1)
performance characteristics of linearized voltage-controlled gain circuit and (2) Rin for high input
impedance (100M) voltage-follower circuit. Compare to pSPICE simulations. Introduction to log-log
data plots and log-log performance characteristics.
Experiment 11x: Measurement of the parasitic capacitances of BJTs and FETs. Extract CJC, CJE and
F for 2n3906 (npn BJT). Extract CGD and CGS for 2n5457 (nJFET). Compare to device model
parameters and compare techniques to pSPICE performance analysis simulations. This is a tricky
experiment since the frequencies are at the limit of the test instrumentation and the protoboard parasitic
capacitances are of the same magnitudes as those of the transistors and have to be subtracted out by
comparison measurements.