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I will pay for the following essay Circuits with Feedback. The essay is to be 6 pages with three to five sources, with in-text citations and a reference page.Download file to see previous pages Deriva
I will pay for the following essay Circuits with Feedback. The essay is to be 6 pages with three to five sources, with in-text citations and a reference page.
Download file to see previous pagesDerivation of Feedback Equation for Inverting Amplifier
Let we consider an inverting amplifier as shown in fig. 2.
Then if ‘A, is the gain then, as vi+ = 0, there fore
vo = A(vin+ – vin¯)
vo = - A vin¯
Also from Ohm’s Law the current is simply the difference in the voltage across R1 divided R1,
i1 = (vin+ – vin¯)/R1 ……(5)
Similarly,if = ( vi¯ – vo)/Rf ……(6)
By Kerchief’s current Law at the inverting input,
i1 = if + i¯ where i¯ is the current entering the amplifier at
it’s inverting point, yet for an idea amplifier it reaches to zero hence,
i1 = if ……… (7)
Substituting the values from equations (5) and (6) we have,
(vin+ – vin¯)/R1= (vi¯ – vo)/Rf ……… (8)
Orvin+/R1 – vin¯/R1= vi¯/Rf – vo/Rf
Solving for ,
= ……… (9)
This is the required voltage gain expression for inverting amplifier with feedback in
terms of open loop gain.
Problem 2: Each of the amplifiers shown below incorporate series feedback. The
gains, input resistances
and output resistances are quoted without feedback. For each amplifier determine: -
a) The feedback fraction.
b) The gain with feedback.
c) The input impedance with feedback.
d) The output impedance with feedback.
Solution: (i) a) If we consider the given cct. then for feedback fraction ‘β, for
given cct. is defined as,
...
terms of open-loop gain A.
Derivation of Feedback Equation for Inverting Amplifier
Let we consider an inverting amplifier as shown in fig. 2 (Bogart, 1997, p. 670).
Then if 'A, is the gain then, as vi+ = 0, there fore
vo = A(vin+ - vin)
vo = - A vin
Fig. 2(a)
Also from Ohm's Law the current is simply the difference in the voltage
across R1 divided R1,
i1 = (vin+ - vin)/R1 (5)
Similarly,if = ( vi - vo)/Rf (6)
By Kerchief's current Law at the inverting input,
i1 = if + i where i is the current entering the amplifier at
it's inverting point, yet for an idea amplifier it reaches to zero hence,
i1 = if (7)
Substituting the values from equations (5) and (6) we have,
(vin+ - vin)/R1= (vi - vo)/Rf (8)
Orvin+/R1 - vin/R1= vi/Rf - vo/Rf
Solving for ,
= (9)
This is the required voltage gain expression for inverting amplifier with feedback in
terms of open loop gain.
Problem 2: Each of the amplifiers shown below incorporate series feedback. The
gains, input resistances
and output resistances are quoted without feedback. For each amplifier determine: -
a) The feedback fraction.
b) The gain with feedback.
c) The input impedance with feedback.
d) The output impedance with feedback.
Solution: (i) a) If we consider the given cct. then for feedback fraction ', for
given cct. is defined as,
= (2ia)
Substituting the values in equation (2ia) from given cct. we have,
=
= 0.175 2ia
Fig.