Lecture L

• Mid-term in ~2 weeks. Covers all materials we covered up that date (lectures and labs)

• You can bring one page (letter format), handwritten on one side to the mid-term exam.

• Optional exam review and Q&A session on Thursday Oct. 18, 1-1:50pm in G125.

• Keep thinking about your final projects! (Proposal due in 4 weeks) Check out the guidelines and a list of previous projects on the course web page.

MOSFET:Current is conducted on the surface of the semiconductor.Surface-contamination is an issue (causes current noise.)

JFET:Current is conducted in the (high quality) bulk of the semiconductor lower noise

Our Trusty LF356: Inputs are JFETs (low noise, high impedance), but most gain is provided by BJTs.

Inputs are JFETsgain is provided by BJTs

M1

What is the transconductance gfs for the JFET in the saturated region (VDS > 4V) for VGS biased at 0V?

A) 1 mSB) 2 mSC) 5 mSD) 10 mSE) 15 mS

M2

What is IDSS for this JFET?

A) 3 mAB) 5 mAC) 7.5 mAD) 10.5 mAE) 12 mA

What is Vout for a common source amplifier?

M3

A)VDD - RD ID

B) Vin - RD ID

C) VDD - gfs RD ID

D)Vin - gfs RD ID

E) other

M4

A) 0 VB) 4 VC) 5 VD) 6 VE) 10 V

What is Vout with the gate grounded?

ID

VDS

VGS = 0V

VGS = -0.2V

VGS = -0.6V

VGS = -1.5V

4mA

3mA

2mA

1mA

5V

M5

What is the magnitude of the gain with VGS biased at 0V?

A) 0 B) 0.5 C) 1 D) 5 E) 10

ID

VDS

VGS = 0V

VGS = -0.2V

VGS = -0.6V

VGS = -1.5V

4mA

3mA

2mA

1mA

5V

M6

What is the approximate output impedance of the common source amp?

A) 10 WB) 500 W C) 1000 W D) 2000 W E) 1012 W

M7

Vout of the amplifier is initially 6V. Next, I put a 1000 W resistor to ground on the output. What is Vout now? (Assume gfs is unchanged by this.)

A) 1 VB) 3 VC) 6 VD) 10 VE) 12 V

M8

What is the input impedance of the circuit at DC?

A) 10 WB) 500 W C) 1000 W D) 2000 W E) 1012 W