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Layout sketches - for communication only as I can't put sketches in comments, illustrating both how the Rs and Cs are configured a third order section, and how a buffer might be put in the feedback (something I would not suggest for a real design, only for an interesting experiment)

schematic

simulate this circuit – Schematic created using CircuitLab

Layout sketches

Layout sketches - for communication only as I can't put sketches in comments, illustrating both how the Rs and Cs are configured a third order section, and how a buffer might be put in the feedback (something I would not suggest for a real design, only for an interesting experiment)

schematic

simulate this circuit – Schematic created using CircuitLab

8 added 23 characters in body
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Layout sketches

Layout sketches

7 deleted 1 character in body
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CouldGood catch from LvW, and his analysis that feedforward from the small capacitor was getting directly onto the output. This shows another non-ideality of opamps, their finite output impedance. The better result with the higher impedances shows that this is a contributing cause.

Could catch from LvW, and his analysis that feedforward from the small capacitor was getting directly onto the output. This shows another non-ideality of opamps, their finite output impedance. The better result with the higher impedances shows that this is a contributing cause.

Good catch from LvW, and his analysis that feedforward from the small capacitor was getting directly onto the output. This shows another non-ideality of opamps, their finite output impedance. The better result with the higher impedances shows that this is a contributing cause.

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