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Problem with this opamp

I don't find correct Req value in this opamp configuration:

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If i don't consider Ib and define:

1)Va=voltage across R2 2)eo=Ip*Req Va=RfT*Ip=(R2/(R2+R1))eo, so e0=Ip*(RfT*(1+R1/R2)) This result is right if Rft>>R1, but in general Req=Rft+R1+(Rft*R1)/ R2: so it is wrong...can you help me? I have another question:i'm looking for a good book about systematic methods for the study of networks with active and passive components...i'm looking for a book that give to me ability of analyze electrical circuits in simple and quickly way... Thanks
Reply to
silusilusilu
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silusilus, The exact equation is Rfeq =3D Rft + R1 + (RftR1/R2). No assumptions are necessary. A classic book on circuit theory is "Introductory Circuit Theory" by Ernst A Guilleman. It's long out of print, but is readily available used. A quick Google search will provide lots of sources. I got mine on Ebay. Regards, Jon

Reply to
jd_lark

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