EEL3304: SPICE 1 Assignment

The summary sheet is available as a word file at: spicesummary.doc and as a html file at: spicesummary.htm

Design a single-transistor amplifier that provides a nominal gain of 10 (within 5%) when driving a load resistance of 5k . Assume a source resistance of 5k . You may use a 15-Volt power supply ( 15V) and a single Q2N222 transistor. You must use resistors with standard values (see appendix F in Sedra & Smith ) but you can use large coupling capacitors (1GF) to avoid dealing with the frequency effects that we will discuss in Chapter 7. Your design goal is to minimize the variation of the gain over the temperature range 0 C to 125 C. Compute (max-gain - min-gain)/nominal-gain Use the microsim PSPICE model for the Q2N2222 npn transistor for all of your simulations:

.model Q2N2222  NPN(Is=14.34f Xti=3 Eg=1.11 Vaf=74.03 BF=255.9 Ne=1.307
+		Ise=14.34f Ikf=.2847 Xtb=1.5 Br=6.092 Nc=2 Isc=0 Ikr=0 Rc=1
+		Cjc=7.306p Mjc=.3416 Vjc=.75 Fc=.5 Cje=22.01p Mje=.377 Vje=.75
+		Tr=46.91n Tf=411.1p Itf=.6 Vtf=1.7 Xtf=3 Rb=10)

You must hand in each of the following parts:

1. A summary sheet showing all of the key numerical results of your simulations. (A blank sheet will be provided to you in class)
2. Briefly describe your design process, i.e. how you decided which amplifier configuration to use, how you went about setting the component values, etc.
3. DC Analysis: Derive the DC operating point voltages and currents for your design. Compare these hand calculated values with those given by spice. Compute and for this operating point. Compare these values with those given by spice.
4. AC analysis: Derive the expressions for gain, input impedance and output impedance for your amplifier. Numerically calculate these values for your design and compare them to those generated with spice.
5. Transient analysis: What is the largest sine wave your circuit can amplify without distortion? Use spice to plot vs. time of the largest distortionless output.
6. Temperature analysis: Finally use spice to show how the gain changes through the range 0 C to 125 C. Calculate the percent variation from the nominal value (at 27 C). Hint: use the ``.TEMP 125'' card to compute the gain at 125 C. Make sure to include a temperature coefficient for your resistors such as in :

   RC 1 2 100K TC=1200u

   This gives a linear change in resistance. The spice model already accounts for temperature changes in the bipolar transistor.

Hand in all of your SPICE input decks and output files. Clearly mark the numerical answers you calculate and mark with a colored pen the relevant answers from SPICE.