Calculating Diode Current with Is=50nA and Vd=0.6V | Homework Help

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Discussion Overview

The discussion revolves around calculating the diode current given specific parameters, including saturation current (Is) and forward bias voltage (Vd). Participants explore the application of the diode current equation and address issues related to constants and calculations. The context is primarily homework-related, focusing on understanding the diode equation and its application in different scenarios.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents the diode current equation and attempts to apply it using Is=50nA and Vd=0.6V, expressing uncertainty about the constants used.
  • Another participant corrects the exponential term in the equation, emphasizing the need to include the charge of an electron (e) and Boltzmann's constant (k) in the calculations.
  • A participant recalculates the diode current and arrives at a value of 10.077nA, indicating a sense of resolution but also expressing confusion about the constants.
  • Further discussion introduces a second part of the homework involving a silicon diode with different parameters, where participants continue to apply the same principles but express uncertainty about the results.
  • Another participant reiterates the importance of including e and k in the calculations for the second part of the question.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of their calculations, with ongoing corrections and challenges to earlier claims. There is a general agreement on the need to include specific constants in the calculations, but individual results and interpretations vary.

Contextual Notes

Participants express uncertainty regarding the application of constants and the accuracy of their calculations, indicating potential limitations in their understanding of the diode equation.

HebrewHammer
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Homework Statement



Determine the diode current with Is=50nA and an applied forward bias of 0.6V

Homework Equations



Id = Is ( e ^ (kVd/Tk) - 1)

The Attempt at a Solution



So my teacher is horrible and this is what I have been able to collect on my own.

Is = 50 and Vd = 0.6v
I'm pretty sure k is referring to Boltzmann’s constant k = 1.38 x 10^-23 J.K-1.
I'm pretty sure Tk is the room temperature in kelvin so that would be 298.

Plugging it all in I get
Id = 50 ( e ^ (((1.38 x 10^-23)(.6))/298)-1)

This gives me an answer of 1.389*10^-24
Something seems really off, if one of those constants I figured out is wrong please let me know.
 
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The exponential term should actually be

e ^ [e·Vd / (k·T)]​

where e is the charge of an electron, k is Boltzmann's constant, and T is absolute temperature. (Vd is the diode voltage, of course.)

Also, you seem to be using 50 Amps for Is, when it is actually 50 nA.
 
Ok so I figured out how to do it.

50nA(e^(.6/298)-1) =

50nA(.002015) =

10.077nA

Seems like I was overthinking it. Now there's a part 2 to this question that I am really lost on.


Determine the diode current at 20 degrees C for a silicon diode with Is=0.1uA at a reverse bias potential of -10v.

Further help would be awesome.
 
HebrewHammer said:
Ok so I figured out how to do it.

50nA(e^(.6/298)-1) =

50nA(.002015) =

10.077nA

Seems like I was overthinking it.
There's still a problem. You have completely left e and k out of your calculation!

Now there's a part 2 to this question that I am really lost on.

Determine the diode current at 20 degrees C for a silicon diode with Is=0.1uA at a reverse bias potential of -10v.

Further help would be awesome.
You are given Vd and the temperature, so just apply the same equation. (Don't forget about e and k.)
 
ok i got the answer i think

.1(e^(-10/293)-1) =

= -.00335nA

Seems off to me but its the same procedure.
 
There's still a problem. You have completely left e and k out of your calculation!

The exponential term should actually be
e^[e·Vd / (k·T)]​
where e is the charge of an electron, and k is Boltzmann's constant.
 

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