What are the values of Rf and V2 for the given circuit?

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Homework Help Overview

The discussion revolves around calculating the resistance Rf and the voltage V2 in a circuit involving a logarithmic operational amplifier (op-amp) connected to a differential op-amp. The original poster mentions that both op-amps follow the Golden Rules and expresses uncertainty about obtaining the necessary equations for their calculations.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to derive equations from the circuit setup but feels they need additional equations to solve for the unknowns. Some participants suggest providing a clearer image of the circuit diagram to facilitate understanding.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the circuit diagram and the problem statement. There is an indication of attempts to enhance the visual representation of the circuit for better comprehension.

Contextual Notes

There is a mention of specific parameters for the diode in the circuit, including reverse saturation current, device factor, and operating temperature, which may influence the calculations but are not fully explored in the discussion.

Aprtaenl
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Homework Statement


Hello,

I am trying to Calculate The Resistance Rf and the value of the Voltage V2. The setup is a logarithmic Op amp connected to a differential Op amp. Both Op amps obey the Golden Rules.

Attached below is my attempt at the solution and the question.

Currently, I have an equation with three variables, and so i think i need potentially two more equations but do not know how to obtain these.

Any help would be appreciated

28907016_612090565801533_1525825119_n.jpg
 

Attachments

  • 28907016_612090565801533_1525825119_n.jpg
    28907016_612090565801533_1525825119_n.jpg
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Perhaps you could provide a closeup image of the circuit diagram oriented in the correct way?

Edit: Also type out the problem statement. The text is all but unreadable in your image.
 
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Likes   Reactions: berkeman
I'll try rotating it and enhancing the contrast a bit...

Forum Opamp Logamp Circuit 01.jpg
Forum Opamp Logamp Circuit 01.jpg
 

Attachments

  • Forum Opamp Logamp Circuit 01.jpg
    Forum Opamp Logamp Circuit 01.jpg
    22.6 KB · Views: 662
  • Forum Opamp Logamp Circuit 01.jpg
    Forum Opamp Logamp Circuit 01.jpg
    22.6 KB · Views: 491
The text says

' In the Circuit below, the diode has a reverse saturation current Is= 10fA, a device factor n=1 and is operated at a temperature of 300K . Find values of resistance Rf and voltage V2 which will produce an output voltage.

Vout = ln (Vin)'
 

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