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Unformatted text preview: ECE 255 ELECTRONIC ANALYSIS AND DESIGN Fall 2011 S PICE D ESIGN P ROJECT #1 Due Friday, September 30, 2011 5:00 p.m. Room MSEE 180 Drop Box Development of D.C. and Hybrid models for a 2N3904 Bipolar Transistor. (Based on ECE 208 Experiments #9A and #11 using a 2N3904 in place of the 2N3704) This exercise will use the PSpice model Q2N3904 which is available in most simulation packages. Below are the model parameters used by the Cadence PSpice program. .model Q2N3904 NPN(Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4 Ne=1.259 + Ise=6.734f Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1 + Cjc=3.638p Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75 + Tr=239.5n Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb=10) 1. To verify that your transistor model is correct, plot the input characteristics @ V CE = 2 V and the output characteristics for I B = 40, 80, 120, 160, and 200 A for CE V 10 V to obtain the plots shown below. 2. The model for the forward biased BaseEmitter junction consists of a series D.C. voltage source, V , and series resistor, R BB connected between the Base and Emitter terminals. Using your plot of the transistor input characteristics determine and list appropriate values for both V and R BB at operating points characterized by I B = 50 A and 100 A. I B V BE R BB V 50 A 150 A NOTES: Remember that the d( ) operator can be used to find the derivative of a PSpice curve. Additional copies of the tables appear on the last page for use in your report. Base Current Collector Current I B = 200 A I B = 160 A I B = 120 A I B = 80 A I B = 40 A 3. Plot the VI characteristics of your models ( using the function Add Trace from the Trace menu in the probe window) on the input characteristics as shown below. 4. The output characteristics are modeled by the parallel combination of an independent current source, I CEO , a dependent current source, dc I B , and a resistor, R d . In this case, the independent current source, I CE0 , can be considered unimportant. Determine and list values for the control of the independent source, dc , and the parallel resistor, R d . I B dc R d 40 A 80 A 120 A 160 A 200 A 5. Using the equation, C dc B CE d I I V R = + , plot the characteristics of the models you have created (using Add Trace in the plot window) on the output characteristics of the transistor as shown below. 6. On a second plot, extend the sweep to negative voltages and show that your model characteristics converge to a single point; then using the cursor, mark that point, ( V A ). Early Voltage = V A . Base Current Collector Current Collector Emitter Voltage Base Emitter Voltage Collector Current Collector Emitter Voltage NOTE: This example uses a DIFFERENT transistor Your plot will show a different value of V A Vcc R2 100k Rs 33k Vbb Vcc Rc MPS3704 Vcc 5Vdc R1 22k Vs 1Vac 0Vdc Vce Vbb Vbb MPS3704 Vbb Rc Vref 2Vdc Vbb Rs 33k Vcc Vce + + E E Vs 1Vac 0Vdc Vcc...
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 Fall '08
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 Transistor

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