Transcript LectureKx

Lecture K
• No lectures on Thursdays anymore! Yeah!
• Mid-term in ~3 weeks. Covers all materials we
covered up that date (lectures and labs)
• Start thinking about your final projects!
(Proposal due in 5 weeks)
Our Trusty LF356 contains about a dozen transistors
(BJTs and FETs)
Modern CPUs and GPUs contain well over 1 billion
transistors. Some memory chips even several 10
billions (mostly FETs)!
(Sorry. No circuit diagram for this one…)
Moore’s Law
Curve shows ‘Moore’s Law’:
Transistor count doubling
every two years
Analogy of current in n and p-doped semiconductors
Electrons
carry the
current.
n-doped
Traffic jam!
Current
cannot
flow.
un-doped
Energy
(“intrinsic”)
“Holes”
carry the
current.
p-doped
Momentum
L1
Based on the VCE vs. IC plot on the board,
what is the current gain hfe?
A) 1
B) 10
C) 100
D) 200
E) 1000
L2
What is Vout for an emitter follower?
A) IB RE
B) Vin
C) 10 V - 0.6 V
D) Vin + 0.6 V
E) Vin – 0.6 V
L5
What is Vout for a common emitter amplifier?
A) Vcc- hfe RC IB
B) Vin - hfe RC IB
C) Vcc- RC IB
D) Vin - RC IB
E) I donno.
For the (properly biased) input voltage
signal shown below, which of the
following choices best represents the
output voltage signal for the circuit at
right?
Vin
VCC= +20V
RC = 10k
B
C
Vout
E
RE = 1k
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Vin is a 1 kHz signal with peak-to-peak amplitude of 1 V.
+15V
A)
56k
+15V
B)
680
0.33mF
56k
Vout, A
Vin
+15V
C)
6.8k
0.33mF
56k
Vout, B
Vin
6.8k
0.33mF
Vin
Vout, C
5.6k
6.8k
5.6k
680
5.6k
680
A) A > B > C
B) B > A > C
Rank the three circuits according
to the peak-to-peak amplitude of
Vout.
C) B > C > A
D) B > A = C
E) C > A > B
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For Vin as shown, rank
outputs 1, 2, and 3
according to peak-topeak amplitude from
largest to smallest
Vcc = +10.0 V
1k
7k
B) 1 > 2 = 3
3k
C) 2 = 3 > 1
D) 2 > 3 > 1
E) 3 > 2 = 1
Vout, 1
E
1k
Vout, 2
B
Vin
A) 1 > 2 > 3
C
Vin (V)
Vout, 3
3k
1.0
t
–1.0
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Vcc = +10.0 V
Suppose a 1-kΩ resistor
is added to the circuit as
shown at right.
When the resistor is
added, the peak-topeak amplitude of
output 1 (for the same
input signal) will:
1k
1k
7k
Vin (V)
3k
1.0
B) Decrease
Vout, 1
E
1k
Vout, 2
B
Vin
A) Increase
C
t
Vout, 3
3k
–1.0
C) Remain the same
D) Not enough information
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Vin is a 1 kHz signal with peak-to-peak amplitude of 1 V.
+15V
A)
56k
+15V
B)
680
0.33mF
56k
Vout, A
Vin
+15V
C)
6.8k
0.33mF
56k
Vout, B
Vin
6.8k
0.33mF
Vin
Vout, C
5.6k
6.8k
5.6k
680
5.6k
680
A)A > B > C
B)B > A > C
Rank the three circuits according
to the peak-to-peak amplitude of
Vout.
C)B > C > A
D)B > A = C
E)C > A > B
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