Capacitance

Question 1

What are capacitors commonly used for in digital circuits?

Answer 1

Delay elements.

Question 2

What are some applications of capacitors in analog circuits?

Answer 2

1. Signal filtering
2. Timing & phase shift networks
3. Capacitive switching
4. Sensing circuits

Question 3

What are the plates of a parallel-plate capacitor called?

Answer 3

Electrodes

Question 4

What is Farad’s Law?

Answer 4

C = Q/V

Question 5

How do you calculate the capacitance created by overlapping layers?

Answer 5

C = (ε0 * εSiO2 * Area / Distance) Farads

Question 6

How to calculate capacitance of capacitors connected in parallel?

Answer 6

Cab = C1 + C2 + C3…

Question 7

How to calculate capacitance of capacitors connected in series?

Answer 7

1/Cab = 1/C1 + 1/C2 + 1/C3…

Question 8

What are the two main categories of integrated capacitors?

Answer 8

Thin-film capacitors and junction capacitors.

Question 9

Name four types of thin-film capacitors.

Answer 9

1. Gate oxide MOS capacitors
2. poly2 - poly1 (ONO) capacitors
3. Metal-plate
4. Metal-Insulator-Metal (MIM) capacitors

Question 10

Name two types of junction capacitors.

Answer 10

1. Base-emitter junction capacitors

2. Diffusion-bulk capacitors

Question 11

What does ONO stand for?

Answer 11

Oxide-Nitride-Oxide dielectric.

Question 12

What does ILO stand for?

Answer 12

Inter-level Oxide

Question 13

What does MIM stand for?

Answer 13

Metal-Insulator-Metal

Question 14

What does CTM stand for?

Answer 14

Capacitor-Top-Metal

Question 15

What are the two types of capacitance associated with a PN junction?

Answer 15

Sidewall (peripheral) Bottom-wall (areal)

Question 16

What are two layout styles of the Base-Emitter capacitor?

Answer 16

Plate style and comb style.

Question 17

What is “fringe” or “fringing capacitance”?

Answer 17

Capacitance created along edges between poly and diffusion, etc.