TL074 Open-Loop Gain vs Frequency

Thread Starter

pdunc

Joined Feb 26, 2010
8

t_n_k

Joined Mar 6, 2009
5,455
The unity gain-bandwidth [product] is quoted as 3MHz.

So at the quoted 88dB level the open loop bandwidth would be about 119.4Hz.
 

Ghar

Joined Mar 8, 2010
655
There's an open loop frequency plot in figure 12, page 13 of the datasheet however it shows the typical curve, assuming an open loop gain of 200,000 or 106 dB.
 

rudi

Joined May 3, 2010
2
Hello all,

I have the datasheet and some other information about the TL074 op-amp;

http://focus.ti.com/lit/ds/symlink/tl074.pdf
http://focus.ti.com/docs/prod/folders/print/tl074.html

It states the minimum open-loop gain is 88 dB.

I am interested in finding the frequency where the gain begins to drop off , and at what rate.

I have looked through the datasheet as I thought this would be quoted, but I could not see it.

Am I missing something?

Thanks in advance,


Peter
Hello to all,

I am a newcomer, but if I may, I could try an answer for this question.
The DC Gain, form figure 12 is over 100dB and it begins to drop at the frequency of the first pole, in the transfer function.
This pole, as I can guess from the architecture, is given by the first (input) stage and the time constant associated to it is equal to the total RC from the first stage's output.
If you look at the phase, that drops by 90 degrees around about 40Hz...but the actual w of the pole...that I don't think you can calculate because TI won't specify the actual size of the transistors used in the OpAmp.

Hopefully this helps you a little.
 
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