Diodes

Question 1

What is a diode?

Answer 1

two terminal device whose impedance depends upon the magnitude and polarity of the voltage across the terminals.

Question 2

pn junction diode arises from which equation?

Answer 2

Schrodinger’s wave equation

Question 3

PN diode turns on when forward voltage exceeds what?

Answer 3

0.7 v.

Question 4

Shottky diode turns on when forward voltage exceeds what?

Answer 4

0.4 V

Question 5

A typical reversed bias diode saturation current is 10^-15 amperes, which is a zero in TTL digital logical circuits. The normalizing voltage value is what?

Answer 5

approx 26 millivolts

Question 6

Ln = what?

Answer 6

Diffusion length of an electron (m)

Question 7

gamma n = what?

Answer 7

average lifetime of an electron in free state

Question 8

is = what?

Answer 8

is = ae (n.po Ln/gamma.n+p.no Lp/gamma.p)

Question 9

gamma.p = what?

Answer 9

Average lifetime of a hole in free state

Question 10

L.p

Answer 10

diffusion length of a hole

Question 11

n.po

Answer 11

equilibrium concentration of electrons in p type semiconductors

Question 12

p.no

Answer 12

equilibrium concentration of holes in n type semiductors

Question 13

id=

Answer 13

id=is ((e^x) -1) where x = eVpn/KT = Vpn/26mv)

Question 14

When normalized voltage x is more negative than -4, then

Answer 14

the exponential term is essentially zero and the diode current is constant with value is (i_saturation)

Question 15

Analysis of TTL circuits is easier if you keep in mind that the pn junction diode is off like an open switch when …

Answer 15

the foward voltage falls below 0.7 v