ECE 2212

PROBLEM SET 10

S. G. Burns

Due:  Friday, 19 April 2013

 

Note:  I will be at the SME Conference Tuesday All Day and Wednesday morning (16 and 17 April) of next week. To provide additional opportunities to ask questions and for office hour consultations, I am scheduling Quiz 10 for Friday, 19 April, rather than Wednesday, 17 April.  By the way, students are invited to attend. http://www.d.umn.edu/ce/learningopportunities/conferences/sme/   

 

1.     Text 5.83.  Part (a) only and Text 5.84

2.     Refer to Text Figure P5.26 given below.  Modify the default BJT SPICE model to generate a set of curves that are a reasonable match to the characteristics shown in Figure P5.26.  Save this model because you will need it in Problems 3 and 4.    Submit the BJT non-default model  parameters and a copy of the characteristic curves that you obtained.   Key parameters to change will be β and VAF.

 

ProblemSet10Support1 

 

3.     Text 5.94 and compare your Q-Point analytical results with a SPICE simulation using the BJT SPICE model results from Problem 2.  Depending upon your version of SPICE, the Q-Point could also be called the Operating Point, OP,  or the Bias Point.  You select this from the Setup Menu. 

 

4.     Text 5.97. Observe that you will have to derive an equation for the base current by summing current at the collector node. Again, compare your Q-Point analytical results with a SPICE simulation using the BJT SPICE model results from Problem 2.

 

5.     This is a circuit of a two-stage npn-npn cascade amplifier operating between two power supplies, VCC and a -VEE. Assume that for BJTs Q1 and Q2, IC1 = 1 mA and IC2 = 2 mA, b1 = 100 and b2 = 150, and both Early voltages are 75 volts.

 

(a)     Draw and label a small-signal, frequency-independent, model. By frequency-independent I mean that the you should assume capacitive reactances are very small at the frequency of interest.

(b)     Using your small-signal model, derive an algebraic equation for the voltage gain defined by          Av = Vout/Vs.

(c)              Compute numerical values for gm, ro, and rp for both the npn BJTs.

(d)             Using your small-signal model, derive an algebraic expression for the input resistance Rin1 and Rin2.

 

 

Q2
 

Q1
 

 

I have a collection of these!