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78 Threads found on Open Loop Voltage Gain
A loudspeaker has a strong resonance. It causes sounds to be "boomy". Therefore modern audio amplifiers use a fairly high open-loop voltage gain and a lot of negative feedback to reduce the gain to a useable amount, reduce distortion a lot, increase the bandwidth and reduce the output impedance a lot. The (...)
i think things going to be very complicated here, so here is the exact question AND i will thank anyone who could help me out with this! consider this LM741 in open loop with the specifications attached:(LTspice) 124544 measure the rise and fall time of the output voltage with pulses with given amplitudes: +-5mv , +-5v ,
For a good understanding of the feedback principle it is necessary, I think, to realize that the voltages at both inputs are NOT equal (due to negative feedback). This is because the opamp always needs an input voltage difference to produce an output voltage. However, due to the large open-loop (...)
Hi all, As virtual short exists in opamp (with -ve feedback,open loop gain=infinite), Is output of this opamp is always zero? And also why virtual short not valid in positive feedback? Thanks.
please explain me whether the opamp(two stage) i have used can drive the resistors as shown You can answer the question yourself if you calculate open loop voltage gain and output impedance of your opamp. Of course the answer also depends on the resistor values. But in case of a wideband amplifier, the resistors need to (...)
This 1mV offset is caused by finite open loop gain. For source follower V_{out}=V_{in}/(1+K^{-1})
Why we are using RC network in the negative feedback to measure the op-amp open loop gain?
If R2=R3 , I recall it is Av = R2/R1 is the open loop gain. External Closed loop would lower the output impedance and reduce the gain.
Hi,all In op-amp the band and openloop voltage gains are equal to infinity, what is the advantage of keeping both infinity
WHat is not shown is a gain control pot for the 1k resistor in the bottom right corner to ground. The 1st stage has ● HIGH open-loop gain: 160dB ● LOW INPUT BIAS CURRENT: 10nA max ● LOW OFFSET voltage: 75?V max The cap added tends to improve the phase margin and cuts lower than the (...)
Stability is usually analyzed with unity gain step response or open loop gain-phase or closed loop gain-phase. Which case did you have in mind?
does this have to do with the input stage of the opamp. Not necessarily. Common mode rejection is also related to supply voltage rejection. If you assume the supply crosstalk located in the second or output stage, the open loop gain frequency characteristic would already explain the CMRR drop. In practice, expect a (...)
Hi, Why in the simulation of the open loop gain of an operational amplifier I have to use a voltage source AC 1V ? I know that AC 1 means that the output will plot correctly in db as gain. If I plot volts in the output versus volt in the input, I will have really big values of the gain (...)
Hi !!!! I would like to know how can I measure the open loop gain of an operational amplifier CMOS. REgards, Joak
That's a nice thing to mention and the answer depends on what you are trying to do, as always. If you are going to implement this thing as an open loop amplifier, you have serious problems. You need to find a method to ensure that the output voltage will be at the desired DC bias. Since your gain is 42 dB, if you have a 1 (...)
The input voltages of a linear opamp are almost the same because its open-loop voltage gain is very high. The (+) input voltage is 0v so the (-) input is also 0V. 1) You want the output to be -5V when the input is 0V so R2 has 5mA in it. 2) You want an offset resistor to also have 5mA in (...)
Phase = 0 and mag = 1 is what I do. But you need to "sniff" the input difference voltage to get the right basis for loop gain (open or closed) - not the magnitude of the stimulus source.
Depends on your understanding of "linear range". The datasheet specification refers to Aol=100dB. If you need to guarantee this open loop gain in the respective operation point, 100 mV are valid. If you can accept a lower gain, you can calculate with a smaller output voltage. Seriously, you never get all (...)
No real OP has infinite CMRR or SR. It has high (open loop) voltage gain by design, according to it's working principle.
keith1200rs is quite right. An LM386 cannot possibly give a gain of 200dB. The open loop gain of an op-amp is only about 100dB, so where did you get the figure of 200dB from?