Given a linear Vin, what frequency to assume as a differentiator input?

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atferrari

Joined Jan 6, 2004
4,672
All PID control loops have to be tuned. So it depends on the 's' domain 'plant' it is controlling. You can accomplish both the integral and proportional gain with one amplifier you drop remove Cin to accomplish that the P gain is Rf/Rin and the I gain is determined by Cf and Rin. If you want a differentiator you need only Cin and Rf. To implement complete PID control loop send the D and the PI to a final summing amplifier stage.
For tuning, start with a system that is all proportional only, increase P gain until you start to get oscillations, reduce it back some so that a step function has no overshoot. Next add I gain to eliminate following error. Finally add D gain for stabilization. Not all PID control loops require the D part. (Differentiator part).

If this is for a new circuit design for PID control I would recommend an ADC / Microcontroller or FPGA followed by DAC. Then do all the P I and D gains in software/firmware. This is much more flexible than using fixed parts tuned to the system.
Hola dcbing
Pity you did not reply my question which is more or less suggested in the title.
Tuning, I have some experience but my question was on what frequency I could assume to design a differentiator.
Gracias anyway.
 
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