Consider a p-n junction diode having the characteristic `i=i_0(e^(eV//kT)-1)`where `i_0=20(mu)A`. The diode is operated at T=300K. (a) Find the current through the diode when a voltage of 300 mV is applied across it in forward bias, (b) At what voltage does the current double?

Explanation

(a) Given `I_0 = 20xx10^(-6)A`
`T = 300K`
`V = 300mV`
`i =i_0(e^((eV)/(KT))-1)`
` = 20xx10(-6) ((e^(0.3)/(8.62xx300xx10^(-5))-1)`
`= 20xx10^(-5) (e^((100)/(8.62))-1)`
`= 2.18A = 2A`
Since
`rArr 4 = 20xx10^(-6) (e^((v)/(8.62xx3xx10^(-8))-1))`
`rArr (e^(Vxx10^(3))/(8.62xx3)-1 = (4xx10^6)/(20)`
`rArr e^(Vxx10^3)/(8.62xx3) = 200001`
`rArr (Vxx10^3)/(8.62xx3) = 12.2060`
`rArr V = (12.206xx8.63xx3)/(10^3)`
` = 318mV