Chapter 4

Question 1

Ideal Diode IV Characteristics

Answer 1

Non-linear over large scale

Question 2

What is Reserve Bias?

Answer 2

VC < 0
iD = 0
Open Circuit
Flows in through the line diode from positive to negative

Question 3

What is Forward Bias?

Answer 3

VC = 0
iD > 0
Short Circuit
Flows in through the triangle diode from positive to negative

Question 4

SLA

Answer 4

Stereolithography
Laser curing of liquid plastic
* Earliest 3D method, based on UV-set polymers.
* Resolution quite good: 0.002” layers.
* Curing needed before part can be used.
Example: COVID 19 Swabs and Celiac Axis Printing

Question 5

SLS

Answer 5

Selective Laser Sintering
Similar with SLA, laser fuses powder

Question 6

LOM

Answer 6

Laminated Object Modeling
Laser cuts paper one layer at a time
* Paper or film is the base material used in this technology
* Layers of adhesive-coated plastic, paper or metal laminates are fused together and cut into shapes with the aid of a knife or laser cutter

Question 7

FDM

Answer 7

Fused Deposition Modeling
A thread of plastic is melted through a moving head
* FDM is one of the most versatile 3D methods
– Many materials can be used: solvent-based or thermo-plastics. e.g., PLA, ABS, etc.
– Requires X-Y-X motion (like a CNC machine).
Example: da Vinci Jr. 1.0w, Respirator Frames, Face Shield Frame

Question 8

Application of Diode Logic Gate

Answer 8

OR Gate (3 Diodes at the top and one resistor connected to ground at the bottom)
AND Gate (3 Diodes at the bottom and one resistor connected to voltage source at the top)

Question 9

Exponential Characteristic

Answer 9

ID = Is [exp (vD/nVt) - 1]

Question 10

Exponential Iterative

Answer 10

VD = 0.736 V
ID = 4.264 mA

Question 11

Piecewise-Linear

Answer 11

VD = 0.735 V
ID = 4.265 mA

Question 12

Constant Voltage

Answer 12

VD = 0.7 V
ID = 4.3 mA

Question 13

Ideal

Answer 13

VD = 0 V
ID = 5 mA

Question 14

Instantaneous Signal Voltage

Answer 14

vD(t) = VD + Vd(t)
Diode Voltage = DC Voltage + AC Voltage

Question 15

Instantaneous Signal Current

Answer 15

iD(t) = ID + Id(t)
iD(t) = Is[ exp (vD(t) / nVt)]

Question 16

Small Signal Model - Effect of vd(t)

Answer 16

iD(t) = ID exp[ vd(t) / nVt)]

Question 17

Forward Biased as Voltage Regulator Purpose?

Answer 17

To provide nearly constant DC voltage at output

Question 18

Forward Biased as Voltage Regulator Independent of?

Answer 18

1 - Load Current
2 - Change in DC Supply “line” voltage

Question 19

Forward Biased as Voltage Regulator rd equation

Answer 19

rd = nVt / ID

Question 20

Forward Biased as Voltage Regulator ID equation

Answer 20

ID = (VDD - 3 * VD) / R

Question 21

Why are forward biased diodes useful in voltage regulation?

Answer 21

Small change in VD with large change in ID
Slope=diD/dvD: large

Question 22

What other characteristic could be useful for voltage regulation?

Answer 22

Reverse breakdown

Question 23

Zener Diode

Answer 23

• Operation at reverse bias
• Iz flows into line from Vz + to -

Question 24

Full Wave Rectifier Definition

Answer 24

• Disadvantages of half-wave rectifier: maximum conduction angle of 180º
• Possible fixes:
• Use two half-wave rectifiers (basic concept of center-tapped transformer approach)
• Bridge rectifier (similar to Wheatstone bridge circuit)

Question 25

Full Wave Rectifier - Bridge Rectifier Approach

Answer 25

Positive Half-Cycle:
Follows the forward bias diode

Negative Half-Cycle:
Follows the reserve bias diode

Question 26

Full Wave Rectifier Equation

Answer 26

PIV = VS - VD

Question 27

SBD

Answer 27

– The Schottky-Barrier Diode
- Schottky diodes can be switched from on to off, and vice versa, much faster than is possible with pn junction diodes

– The forward voltage drop of a conducting SBD is lower than that of a pn-junction diode. e.g. 0.3 V to 0.5V

Question 28

Varactor

Answer 28

voltage-variable capacitors

Question 29

Photodiode

Answer 29

light signals into electrical signals

Question 30

Light-Emitting Diode (LED)

Answer 30

converts a forward current into light