Hello all, i made an op amp to generate a triangular wave, the circuit should integrate the square wave and generate a triangular wave at its ouput, as u can see from the pictures for the part of generating the square wave i could do that, but for the part of triangular wave i think i made a mistake or so.

First of all i chose a common value of R9, which is 10k then i calculated the capitance for having an integration at 10khz, i found out C=1/2 πR*F what i obtained is a capacitance of C= 1,6nF at this point i calculated R4 in order to have fc=fmin/10 and i obtained that R2>10/2 π C1*fmin where fmin is 1KHz
What i obtained is R2 needs to be atleast 1MegaOhm, which is the value i chose. Now as last i chose the gainbandwidth to be atleast 10 times the fmaxso its 100KHz (the op amp i chose has 550 kHz to 650 kHz.

I cant understand the mistake i made, calculations side seem to be right, then why i get that wave from in output?

 

hi 089,
When post an asc file with models of your own creation, it helps if you also post the *.asy & *.sub file.

E

 

hi 089,
When post an asc file with models of your own creation, it helps if you also post the *.asy & *.sub file.

E

i forgot sorry, here u go

 

hi 089,

Those files are ones you have downloaded from some other source, they do not include the asy file or either the net or sub files.
The asy resides in your Alternate sym folder.

E

 

hi 089,

Those files are ones you have downloaded from some other source, they do not include the asy file or either the net or sub files.
The asy resides in your Alternate sym folder.

E

thats actually what i downloaded, but i will check

 

Plot the voltage across the capacitor, not vout1.

 

a

hi 089,

Those files are ones you have downloaded from some other source, they do not include the asy file or either the net or sub files.
The asy resides in your Alternate sym folder.

E

The LT1006 exists on LTSpice, while i dont know but i imported that component from the file i gave ya , no idea why it doesnt work with u , btw u can do the simulation by using a wave generator ( the square wave one ) instead of having that put a pulse generator, i tried rn and it shows distorted wave still ( anyways my issue is the integrator only rn )

 

Plot the voltage across the capacitor, not vout1.

across the capacitor i got this wave

 

If you put the integrator in the feedback loop for the square-wave generator then you don't need to add a resistor across the integration capacitor, which makes a leaky integrator with less then a flat-slope triangular waveform (LTspice sim of example circuit below):

 

If you put the integrator in the feedback loop for the square-wave generator then you don't need to add a resistor across the integration capacitor, which makes a leaky integrator with less then a flat-slope triangular waveform (LTspice sim of example circuit below):


View attachment 355029

so what i could do on my circuit? removing that 1Meg resistor?

 

If you put the integrator in the feedback loop for the square-wave generator then you don't need to add a resistor across the integration capacitor, which makes a leaky integrator with less then a flat-slope triangular waveform (LTspice sim of example circuit below):


View attachment 355029

Mhh but in my circuit then i gotta connect the output from the integrator and feed it back to the inverting pin? of my circuit? right? so i put it in feedback loop

 

Mhh but in my circuit then i gotta connect the output from the integrator and feed it back to the inverting pin? of my circuit? right? so i put it in feedback loop

Yes. Just follow how my circuit is connected.

 

You must connect the + input of LT1006 to V+ instead of GND. Additionally you should connect a capacitor with about 10 uF in parallel to R2. So V+ gets a stable virtual GND. Your integration time constant is R9×C2.

 

Yes. Just follow how my circuit is connected.

Yeah but how like u know that this would happen? Its ur experience on op amps or pure theory?

 

Yes. Just follow how my circuit is connected.

I followed ur circuit, i connected via a 10k the output of the integrator to the non inverting pin, but thats what i get now, its shifted, why so?

 

I followed ur circuit, i connected via a 10k the output of the integrator to the non inverting pin, but thats what i get now, its shifted, why so?

You don't need the feedback to the (-) comparator input.
Just connect the (-) input of U2 and the (+) input of U1 to the Ref voltage and use the feedback resistors at the (+) input as shown below.
(I didn't have the TLV3201 comparator model, but it should work the same as the one I used.)