If I want to use a 2-stage opamp for the current to voltage converter application, How should I check for the stability of the circuit? Will it need any kind of stability correction? An uncompensated 2- stage opamp is unstable as voltage amplifier with feedback.enter image description here


closed as too broad by Bimpelrekkie, Harry Svensson, RoyC, Finbarr, Elliot Alderson Jan 21 at 16:31

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    \$\begingroup\$ An uncompensated 2- stage opamp is unstable as voltage amplifier with feedback No it is not, it depends on the design (and external load) if it is stable or not. The answer to your question is: you do a stability analysis, Generally learning this is part of what you would need to learn to become a IC / circuit designer, explaining it here goes too far making this question "too broad". Fortunately there is plenty about that to be found in books and internet, for example: ti.com/lit/an/sloa020a/sloa020a.pdf Also, this is unrelated to "CMOS" nor "VLSI". \$\endgroup\$ – Bimpelrekkie Jan 19 at 12:15
  • \$\begingroup\$ in particular, the noise gain of that stage is ONE, so the transient performance with Av = +1 is important. \$\endgroup\$ – analogsystemsrf Jan 19 at 16:29

If, as you said, an uncompensated 2-stage amplifier is unstable then you have answered your own about whether or not you need compensation.

To check for stability, I would create a circuit simulation at the transistor level that includes all relevant parasitic capacitances and resistances. Then perform an ac simulation out to a few megahertz, looking for changes in gain. You might also want to run transient simulations while slowly sweeping the frequency. Be sure to do this for a range of dc bias conditions.


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