Resistance Value for Circuit Design Calculations

design a ckt to provide an output voltage of 2.4 v. assume that diodes available have 0.7 v drop at 1ma ant that v2-v1 = 0.1v/decade change in current.

Hi Ansuman,

I've attached pictures which are almost the same with the problem stated above.

Design the circuit for figure below to provide an output voltage of 2.4V. Assume diodes have 0.7V drop at 1mA and that ∆V=0.1V/decade change in current

Ans: R = 760 ohms

Small Signal Model

•In many circuit applications a diode is biased at an operating point with some small ac signal superimposed on the dc bias

•For this situation a good solution is to find dc bias using one of previous methods and then model small signal variations by resistance equal to 1/slope of diode curve at the operating point.

Hope it helps,

yeah answer is correct but it has nothing to do with small signal analysis becoz there is no time varying signal present in the question actually im getting 7.6 ohm from
v2=v1+0.1log(I2/I1)
where v2 = 2.4v
v1= 3x0.7
I1= 1ma
please rectify if im wrong.