AC Response of Diodes, BJTs and FETs

Question 1

The diode law (aka Shockley Equation) tells us what?

Answer 1

-The shockley equation relates current applied in the forward bias of a semiconductor diode.
-where I(s) is the reverse saturation current.

Question 2

What is thermal voltage?

Answer 2

Describes the voltage in the PN Junction at a certain temperature
-At room temperature this is approx 26mV

Question 3

How do Zener diodes work?

Answer 3

-Zener diodes breakdown in a way similar to forward bias in reverse.

Question 4

What is meant by an equivalent circuit?

Answer 4

A method of modelling a circuit in a simpler way to make calculations easier

Question 5

How do we find small signal resistance

Answer 5

rd = ∆Vd / ∆ Id

Question 6

Define transconductance

Answer 6

The ratio of change in current at the output terminal to the change of voltage at the input terminal
gm =∆Id/∆Vds
gm is the gradient at the Q-point of the transfer characteristic