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

AI Thread Summary
The discussion focuses on calculating the resistance Rf and the voltage V2 in a circuit involving a logarithmic operational amplifier and a differential operational amplifier, both adhering to the Golden Rules. The user has derived an equation with three variables but needs additional equations to solve the problem. They request assistance in obtaining these equations and ask for a clearer image of the circuit diagram, as the current one is unreadable. The problem statement specifies that the diode has a reverse saturation current of 10 fA, a device factor of 1, and operates at 300K. The goal is to find Rf and V2 to achieve an output voltage defined by Vout = ln(Vin).
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
 

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  • 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 berkeman
I'll try rotating it and enhancing the contrast a bit...

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

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