Sensitivity

Question 1

What is the sensitivity equation ?

Answer 1

X/Y* dy/dx = (dy/Y)/ (dx/X)

Question 2

What ideally do you want the sensitivity of IO in comparision to Vcc (input line )

Answer 2

0 as you want them to be completely independent

Question 3

Work out the sensitivity of IO in comparision to Vcc (input line ) for a widlar current sink( look up )

Answer 3

check revsion book

Question 4

What is the equation and units for TCf

Answer 4

TCf= (1/Io)*dIo/dT

Question 5

Work out TCf for widlar current sink

Answer 5

check revision book

Question 6

what is Vt in terms of kt Q

Answer 6

Vt = kt /Q

Question 7

Draw a Vbe reference current sink and explain whats its problem still

Answer 7

Not totally supply indendant since Vbe1 change with Vcc via Iin

Question 8

current mirror above

Draw a self baised Vbe reference current sink and what conditions do they meet

Answer 8

Io= Iin
Io=(Vt/R)*ln(Iin/Is)

Question 9

what is main problem with this circuit (self baised Vbe reference current sink)

Answer 9

It has a stable state at Io = 0 so there for we need to give it a kick

Question 10

diode

draw the start up circuitry (self baised Vbe reference current sink) and explains the disadvantage of this circuit

Answer 10

Has a large tempreture coefficient and a large R

Question 11

3 diodes

Draw the PTAT and explain why its better than self baised Vbe reference current sink , work out the tempreture coefficient for the circuit for n =2

Answer 11

tempreture coeffeient is a lot smaller