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ECE 335
PROJECT II
Due Nov. 28, 2005.
ASSIGNMENT:
(a) Characterize a MOSFET and a BJT, extract their dc models, and use SPICE to simulate the
transistor characteristics and compared with measured characteristics.
(b) Design, build, and test current mirror circuits using either MOSFETs or BJTs.
Procedure example using a 2N7000 MOSFET:
(1) Use HP 4145B to plot transfer function (ID~VGS) and output characteristic (ID~VDS) curve of
the transistor, and estimate VTH, Kn, etc. for the subsequent PSPICE simulation.
(2) Test circuits
(a) Maintain a constant gate-source voltage for approximately 15 mA IDS (except linear region) as
VDS is carefully varied over a 0-1 0V range. Carefully record IDS and VGS for every VDS point.
Repeat this step for IDS=10 mA and 5 mA.
(b) Obtain the transfer characteristic with VDS held contact at 5V and vary the VGS as required to
cover 0-60 mA range of IDS. Carefully record IDS for each VGS data point.
(c) Plot both sets of measurements (HP4145 and test circuits) to extract appropriate SPICE
modeling parameters (KP, VTO, LAMBDA) for your transistor. Use these parameters to obtain
the same characteristics curves using SPICE and compare with the plotted experimental curves.
Save the characterized transistor.
(3) Design, build, and test a simple current mirror circuit with a maximum of three resistors. The
current must be 10mA ± 10% when the voltage to the current source is 10 V (i.e. Vo=VDS2=10V).
You may select a separate fixed power supply of +12 V to power the gate bias circuit. Carefully
measure and plot the current as the applied voltage is varied for 0-12 V. Compare the results with
SPICE simulation.
(4) The reports should be submitted along with the current sink circuits. All experimental
measurements should be supported by design calculations. SPICE output must be included in the
report (either attached as an appendix or pasted in the main body of the report). A summary of
SPICE results must be included in the report. The report should also include complete circuit
diagrams clearly showing all component values.
(5) The grading of the report will be based on the technical content as well as the writing and
organization of the report.