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Unformatted text preview: 1. (6 points) Construct a truth table for the output of the following digital circuit (3
points) and then express the output of the circuit in the canonical sum—of—products form (3 points). ﬁfe Meal 3—0,? W ‘9;
meb): ail: + 0J3+ (Lb: (An «M W Jm xmﬁé;
“POL/h) : 0' + E) 2. (4 points) An Exclusive—OR (XOR) gate takes two Boolean inputs (4 and b) and
produces an output of 1 when exactly one of the inputs is 1.
a. (2 points) What is the truth table for the XOR operation? What is the
canonical sum—of—products expression for an XOR gate? The standard bol for an XOR ate is: .
gym g Fulan c. 0., l3 mil” ,1le
O .—
4 ii” i?“ O o l l CW 1 9—0": W
\ 0 l l o
b. (2 points) In the following circuit, What values of CO through 03 would
a cause the output to be the XOR of A and B? 3. (8 points) Simplify the Boolean function f = A E(C+ l—))+A E ED (3 points) and draw
a CMOS zgflte for realizing this function with no more than 6 transistors (5 points)?
(Hint: X+ X Y = P) 36:. Recess") *RE ED
: $015+?” =— HE ("D + w>
’, p96 CEﬁerD) Cake—Aw :: 9:93 (c+1>+x> 3 p WC RE Cc—rL) == REC'1') .—
r 4. (6 points) Consider the following circuit built from NMOS and PMOS ﬁeld
effect transistors. Can the circuit be used as a CMOS gate? Explain why or why
not. Ifit can be used as a CMOS gate then what function does it compute? rubric. 5. (6 points) Al Digit is struggling to design his ﬁrst CMOS logic gate. He has
implemented the following circuit: M4 [sea
“4 tag a. (2 points) Al has fabricated 100 test chips containing this circuit, and has a
simple testing circuit that allows him to try out his proposed gate statically
for various combinations of the A and B inputs. He has burned out 97 of
his chips, and needs your help before destroying the remaining three. He is
certain he is applying only valid input voltages, and expects to ﬁnd a valid
output at terminal C. Al also keeps noticing a very faint smell of smoke. A.
What is burning out Al's test chips? Give a speciﬁc scenario, including input
values. b. (2 points) Are there input combinations for which Al can expect a valid
output at C? Explain. ‘ euipuat akC. ' LWVWcﬁL . DOM—MN
a, mint
(JPr5) c. (2 points) One of Al's test chips has failed by burning out the pullup
connected to A as well as the pulldown connected to“ B. Each of the burned
out FETs appears as an open circuit, but the rest of the circuit remains
functional. Can the resulting circuit be used as a combinational device?
Explain its behavior for each combination of valid inputs. m MW coMeM 4—D A Xr‘lebb
Nahum acme/EA, .L—o ‘3 W5?”
OCH/weds. ...
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This note was uploaded on 02/28/2010 for the course ECE 311 taught by Professor Leon during the Spring '10 term at UNBC.
 Spring '10
 Leon

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