Electrical Engineering 40, Fall '05
Introduction to Microelectronic Circuits
Professor Andy Neureuther, EECS

HOMEWORKS













Version 09/27/05   EE 40 Homework Feedback from Readers in PDF Fall 05 

HW 3

statistics:
Mean 7.59
Std. Dev. 2.09
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1 a-c. were difficult to grade.  If we saw that you had a couple of correct currents and/or voltages you probably got credit.  

a. 1pt.

b. 1pt.

c. 1pt.

d. Not graded

e. 0.5 each for Vth and Rth

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2

a.  1pt.  All or nothing, just had to get Vout correct.

b.  You got credit if you had at least 3 voltage nodes that were correct.  Otherwise 0.6 off for each missing.

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3.

a. 0.5

b. 1

c. 0.5

d. 1

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For problem 1, errors simply came from mixing up your references! Pick ANY direction for your currents, if the current is negative that means it goes the other direction.  When current travels through a resistor, there is a voltage drop across the resistor in the direction of the current.  

Many of you had incorrect signs for 2a, 3b, and 3d.  Remember, the sign for voltage is based on how the element is referenced in the circuit diagram. 

When asked to identify voltages at ALL nodes, that means all the wires between any two circuit elements.  Not just nodes where more than one wire intersects. 

To find the input or output resistance, simply apply a test voltage, and see what test current appears.  Then the input or output Resistance is simply = Vtest/Itest. 

Many people did not calculate the thevenin voltage when told to find the thevenin equivalent.

Many seemed confused by 3d.  A source resistance is a resistance connected in series to the source.  A load resistance is connected across Vout, the output port.  With those added into the circuit, find Vout in terms of Vs, then divide by Vs to find Vout/Vs.




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