All Questions
Tagged with negative-feedback operational-amplifier
17 questions
25
votes
4
answers
3k
views
Illustrating op amp feedback without control theory
We are teaching op amps in a high school class, before calculus. So we can't use control theory to teach how op amps respond. All the same, I would like to have an intuitive explanation for how a ...
- 1,691
4
votes
5
answers
5k
views
Understanding Op-amp Negative Feedback
Have a look at the diagram above. It shows an op-amp with negative feedback. Ignoring the feedback loop for now, the voltage (pressure) coming from the 5V battery, acting on the inverting pin, ...
- 1,696
2
votes
2
answers
5k
views
Individual Phase shift provided by Op-Amp in Closed loop configuration
When comparing the input and output of the Op Amp alone (Vid1-Vid2 and Vo and not Vsupply and Vo) in a closed loop configuration the phase shift is only 90 degrees? Why it is so?
And the Simulation ...
- 329
5
votes
6
answers
3k
views
How does opamp open-loop gain affect closed-loop gain in a circuit?
The gain of an opamp circuit is basically $$A_v=-\frac{R_f}{R_i}$$
But how come the gain of the opamp itself does not appear in the equation? How is the opamp amplifying anything in the circuit? What ...
- 61
4
votes
5
answers
2k
views
Unity Gain Amplifier Purpose
In layman terms, what is the main use and purpose of unity gain amplifiers? I am reading that it is used to "buffer high impedance sources" but I'm unsure what this means practically.
- 41
0
votes
4
answers
1k
views
How does negative feedback stabilize the output of an op-amp?
I am trying to understand how negative feedback stabilizes the output of op-amps.
It is known that Vout = AOL*((V+)-(V-)), where AOL is the open loop gain of the op-...
0
votes
2
answers
232
views
Understanding Negative feedback loop circuit with an Ideal Op-Amp
The following is given as an example of a negative feedback loop in my textbook, note that the op-amp is assumed to be ideal.
However I do not seem to understand the logic behind this acting as a ...
- 107
6
votes
3
answers
1k
views
How does the op-amp stabilize?
I have a problem understanding one thing in op-amps, namely - when the cycle of stabilizing ends?
For example, when we have simple non-inverting amplifier, firstly the difference equals the amount of ...
- 63
6
votes
5
answers
2k
views
Non-inverting op-amp
Why is resistor R1 connected to the inverting terminal of the op-amp in a non-inverting op-amp configuration? What will happen if we replace it with a short circuit?
- 117
5
votes
4
answers
839
views
OpAmp with common-mode voltages and zero feedback current
Circuit A is a classic non-inverting amplifier with a common-mode DC voltage 1 V to both its inverting and non-inverting input. Since 1 V has to appear at the inverting input, there is no voltage drop ...
- 1,448
4
votes
3
answers
2k
views
What happens to output if OPAMP its supply is tweaked?
Say the above OPAMP is normally operated with supply of +15V and -15V and output is said to swing from +15V to -15V. But I changed -15V power supply {of OPAMP} to -14V and Vi to:
(a)1V
(b)-15V
(...
- 93
1
vote
2
answers
8k
views
How do we explain the common-mode feedback in an intuitive way?
There are such beautiful circuit ideas that make you hold your breath and admire them silently. Such an idea is the common-mode feedback (CMFB) in fully differential amplifiers. I was not familiar ...
- 19.5k
0
votes
1
answer
87
views
How can we confirm whether the op-amp has -ve feedback? [duplicate]
Many text books show an op-amp will have negative feedback when o/p is connected back to -ve input through some discretes and under such condition V+=V- is satisfied for op-amp input terminals.
In the ...
- 3,156
0
votes
6
answers
2k
views
None-inverting op-amp must zero output, why not?
simulate this circuit – Schematic created using CircuitLab
In this circuit, the input is continually summing with its negative through negative feedback, so it must become zero on the output. ...
- 547
0
votes
3
answers
443
views
Unity Gain Buffer Initial Conditions
simulate this circuit – Schematic created using CircuitLab
A typical way of analysing the unity gain buffer is:
Where A is Open Loop Gain
Vout = A(Vin - Vp) and Vp = Vout therefore
Vout = A(Vin ...
- 1,008
0
votes
1
answer
177
views
How to select resistance to cancel offset output voltage due to bias current?
Consider the figure above how Rcomp was choosen. I know for simpler circuits
like inverting amplifier and ideal integrator how Rcomp was calculated but following same procedure (that's using ...
- 475
0
votes
3
answers
536
views
Trouble visualizing voltage-shunt mixing
I'm trying to understand how voltage-shunt feedback works in an inverting op-amp circuit. I can't seem to visualize how the feedback gets mixed in shunt with the input.
NB: Before I tried this, I was ...
- 1,221