| Electronics > Projects, Designs, and Technical Stuff |
| Active Integrator Circuit |
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| aldanisvigo:
So I have a question. When creating op-amp integrator circuits, how do you choose the components attached to the op-amp so that you end up with the correct desired triangle wave? For example, say I put a 1KHz square wave into the inverting input, how do I choose the capacitor and resistors so that I will get a 1KHz Triangle Wave on the output? Example circuit below. R2 |------/\/\/\------| | | ---------||--------| | C1 | | _ | R1 | | \ | -------\/\/\/\--------| - \ | | | \_____|___ /\/\/\/\/\/\/\/\ (1VPk-Pk 1KHz) Triangle wave | --------| + / (1VPk-Pk 1KHz ) | | / _|‾|_|‾|_|‾|_ | |_ / _|__ GND So really what I am after is any tricks or tips on how do I figure out R1, C1 and R2 so that the conditions are satisfied and I get a 1KHz 1VPk-Pk wave on the output pin of the op-amp? Any help you guys can provide me will be greatly appreciated. Thanks. |
| magic:
Frequency is of course the same in and out. Pick some sensible R1, like 1k. The current through C1 is C1·dV/dt, where dV/dt is the output rise/fall rate in V/s, and it is essentially equal to the current through R1, which you calculate easily. Pick C1 such that you get the dV/dt it takes to reach the desired amplitude in each half of the signal period. Pick R2 such that R2·C1 is greater than 10x the period in seconds, i.e. 10·0.001 for 1kHz. Increase for less distortion, reduce for better output centering around zero. If unpractically large, try again with lower R1. |
| aldanisvigo:
Hey thanks so much for your reply. I will give this a go and post what I come up with. Thanks you so much. |
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