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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> feedback topolgy https://designers-guide.org/forum/YaBB.pl?num=1365699001 Message started by aman gupta on Apr 11th, 2013, 9:49am |
Title: feedback topolgy Post by aman gupta on Apr 11th, 2013, 9:49am What is the feedback topology in the given circuit ?? At the input i can see that input and feedback currents are mixing, but what quantity is being sampled at the output here. Is it voltage because i am getting If = -Vo / Rf or is it current because i am also getting Io= -If......... ?? pls help i am confused |
Title: Re: feedback topolgy Post by raja.cedt on Apr 11th, 2013, 12:08pm @ o/p voltage sampling and @ input current mixing. Feedback current depends on the o/p voltage rather o/p voltage as matter of fact i donno how to define o/p current. Thanks, Raj. |
Title: Re: feedback topolgy Post by Vladislav D on Apr 11th, 2013, 1:20pm Hi, Nothing is mixing. If case of an ideal amplifier, source current equal exactly to feedback current. Since voltage at the inverting input is a virtual ground, it is equal to DC, whatever current your apply to it i.e input impedance is zero. Consequently, input for this configuration should be a current. Voltage does not make sense, since it would be similar to connecting voltage source to ground. Output of the amplifier is the only way for current to flow. So output voltage is defined by Rf and input current. If you apply a current source to the output you will see that this does not affect the output voltage. Therefore the output impedance is zero, i.e there is a voltage at the output. So, this is a current input- voltage output amplifier. |
Title: Re: feedback topolgy Post by aman gupta on Apr 12th, 2013, 3:11am tell me what kind of feedback is there in the new figure ? |
Title: Re: feedback topolgy Post by raja.cedt on Apr 12th, 2013, 3:31am voltage sampling at the o/p and voltage mixing at the i/p. please have a look into razavi basic micro-electronics. Thanks, Raj. |
Title: Re: feedback topolgy Post by buddypoor on Apr 25th, 2013, 6:34am aman gupta wrote on Apr 12th, 2013, 3:11am:
It is "current-controlled voltage feedback". (A clear indication of the fact that the BJT is a voltage-controlled device). |
Title: Re: feedback topolgy Post by loose-electron on Apr 26th, 2013, 10:23am time to buy a few textbooks! |
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