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Designing the opamp using cmos (pmos and nmos) to construct RC phase shift oscillator using opamp with the help of opamp (constructed using cmos.)

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  • \$\begingroup\$ Is this is a 3-stage phase shift oscillator? \$\endgroup\$ – jonk Apr 27 at 5:39
  • \$\begingroup\$ If you intend to use opamps it does not matter if it is CMOS-based or a BJT-based opamp.. You can use any of the known phase shift topologies. \$\endgroup\$ – LvW Apr 27 at 7:32
  • \$\begingroup\$ @jonk Yes but i don't know how to design it using cmos \$\endgroup\$ – rakshit ks Apr 27 at 9:09
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    \$\begingroup\$ Can you design it without CMOS? If so then post your schematic and you'll get help to convert it. \$\endgroup\$ – Andy aka Apr 27 at 9:31
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    \$\begingroup\$ @rakshitks You might look here and here for some thoughts to consider. \$\endgroup\$ – jonk Apr 27 at 17:03
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This should give you a good starting point although it doesn't actually oscillate in Circuit Wizard simulations. Might oscillate if it was actually built.

Phase Shift Oscillator

EDIT

This shows the op amp operating on its own. I've changed the output stage to make it symmetrical which it'll probably need to be for the oscillator to work. The output stage could probably be improved perhaps by adjusting the value of R7.

Discrete op amp simulation

EDIT

This simulates well.

I'm using the op amp as a comparator which doesn't load the RC network.

The sine output should be taken from the output of the filter network. The comparator output bangs up and down between the rails keeping the loop gain at unity.

Modifier Oscillator

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  • \$\begingroup\$ thank you ..i will try it out \$\endgroup\$ – rakshit ks Apr 27 at 10:04
  • \$\begingroup\$ W/L value for cmos? \$\endgroup\$ – rakshit ks Apr 27 at 10:53
  • \$\begingroup\$ @rakshit ks See edit \$\endgroup\$ – James Apr 29 at 9:26
  • \$\begingroup\$ thanks it worked \$\endgroup\$ – rakshit ks Apr 30 at 10:59

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