Lecture K

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

Ener

gy

Momentum

n-doped

p-doped

un-doped(“intrinsic”)

Electrons carry the current.

“Holes” carry the current.

Traffic jam! Current cannot flow.

Based on the VCE vs. IC plot on the board, what is the current gain hfe?

L1

A) 1B) 10C) 100D) 200E) 1000

What is Vout for an emitter follower?

L2

A) IB RE

B) Vin

C) 10 V - 0.6 VD) Vin + 0.6 VE) Vin – 0.6 V

What is Vout for a common emitter amplifier?

L5

A) Vcc- hfe RC IB

B) Vin - hfe RC IB

C) Vcc- RC IB

D) Vin - RC IB

E) I donno.

21

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?

22

Vin is a 1 kHz signal with peak-to-peak amplitude of 1 V.

A) A > B > C

B) B > A > C

C) B > C > A

D) B > A = C

E) C > A > B

Rank the three circuits according to the peak-to-peak amplitude of Vout.

23

For Vin as shown, rank outputs 1, 2, and 3 according to peak-to-peak amplitude from largest to smallest

A) 1 > 2 > 3

B) 1 > 2 = 3

C) 2 = 3 > 1

D) 2 > 3 > 1

E) 3 > 2 = 1

24

Suppose a 1-kΩ resistor is added to the circuit as shown at right.

A) Increase

B) Decrease

C) Remain the same

D) Not enough information

When the resistor is added, the peak-to-peak amplitude of output 1 (for the same input signal) will:

25

Vin is a 1 kHz signal with peak-to-peak amplitude of 1 V.

A)A > B > C

B)B > A > C

C)B > C > A

D)B > A = C

E)C > A > B

Rank the three circuits according to the peak-to-peak amplitude of Vout.