ee102_midterm1_Sp2005.fm
4/1/05
EE102L Midterm #1 - Spring 2005
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C Copyright 2005 Gandhi Puvvada
Spring 2005
EE102L
Instructor: Gandhi Puvvada
Midterm Exam (15%)
Date: April 1, 2004, Friday
Open-Book Open-Notes Exam
Time: 4:05 - 6:00PM in SGM124
Name:
Total points:
155
Perfect score:
145
1
( 4+6+10+5+6+4+6=41 points)
35 min.
Combinational logic, etc.:
1.1
A _________________ (10 Kohm / 330 ohm) resistor is usually employed as
current-limiting
resistor
in series with
an LED. The sinking capability at the ___________ (output/input) of a
__________________________________________ (totem-pole out put / open-collector output)
gate is a better choice compared to the sourcing capability to drive an LED. In such cases, you
produce a ____________ (0 / 1) to light up the LED.
1.2
It is
NOT
desirable that __________ (
VIH/VOH)
is close to
5V
. Similarly it is
NOT
desirable
that ____________ (
VIL/VOL
) is close to
0V
. We want _________ (
VIH/VIL
) to be
higher
than _________ (
VOH/VOL
) because _____________________________________________
____________________________________________________________________________
____________________________________________________________________________
1.3
Given below are Shannon’s Expansion Theorems (covered in EE101 ?).
F(X
1
, X
2
, .
...,X
n
) = X1. F(1,
X
2
, .
...,X
n
) + X1’. F(0,
X
2
, .
...,X
n
)
F(X
1
, X
2
, .
...,X
n
) = [X1+ F(0,
X
2
, .
...,X
n
) ] . [X1’+ F(1,
X
2
, .
...,X
n
)]
Now consider the Carry-Out from a full-adder. Cout is a function of (X, Y, Cin)
Cout = F(Cin, X, Y) = X . Cin
+ Y . Cin + X . Y = Cin . (X + Y) + X . Y
If Cin = 0, then Cout = X . Y
and if Cin = 1, then Cout = X + Y
Based on the above, produce Cout by completing as many of the four logics as possible.
4
pts
6
pts
FA
X
Y
Cin
Cout
S
10
pts
Cout
Cin
Cout
Cin
Cout
Cin
Cout
Cin