Ring oscillators with 3 integrators inversor op-amp

[alberto1990]

Hy i have a very large problem:First i put a schematic ring oscillators:View attachment untitled.bmp
It-s formed by cascading 3 inversor op-amp.the reaction has a resistance and a capacitor in parallel.I don't know how dimension ther capacitance and resitance to have 390khz.Can u help me please????

 

[godfreyl]

You need to choose the parallel R and C values so that there is a phase shift of 60 degrees between the voltage across them and the current through them at 390KHz.

p.s. Here's the circuit for anyone who doesn't want to download a 1.5MB bitmap:

 

[Audioguru]

Very few opamps have enough slew rate to have an output as high as 390kHz. Their phase shift will also add too much and affect the frequency.
The faint lines on the black background looks awful.

 

[alberto1990]

Very few opamps have enough slew rate to have an output as high as 390kHz. Their phase shift will also add too much and affect the frequency.
The faint lines on the black background looks awful.

TI understand,but the oscillator is part of a project given by my teacher,and i need to make it.I don't know how,but i try.:grin:Through several simulations with those values ​​of capacitor and resistance,i managed to make 390khz,but i don't know how prove mathematical,teoretical these values of capacitance and resistance.:-(.Anyway, I have a high request:You know where i can find tutorials(videos or documents pdfs) where explain in more detaill how determine Op-Amp Parameters(offset,PSRR,CMRR,CMFB,aplification,the pole and zerous,Slew-Rate...)?What source we use,what analyse we mast to do,whou we read the result waveform,some ecuation....i meen somthing where explein better these thing and give some real exaple.Please you know?:-(

 

[Audioguru]

Why didn't your teacher teach any of these important things?

 

[alberto1990]

Why didn't your teacher teach any of these important things?

My teacher is a young teachear.He have 26-27 years.He just finished the master and make medicine in electronic.He just know from him this thing.He explain something but not soo good,just some theoretical,nothing simulating and exercices.Moore exactly how it's make and determine
this parametter from simulating in cadence or other programs.And the internet i don't find moore things.Just theoretical.I don't have a soo good theacher.He don't really care soo much us,he just want to finish his medicine and go somewhere.He is just an asistant and the tutore theacher is gone in irlanda.He come at the end of this year.

 

[LvW]

Alberto,

what I am missing is the following: A clear description of your task.

OK - I know that a frequency of 390 kHz is required.
Which amplitude? Which wave form? Dual or single supply voltages?
Are you free to choose any circuit or are you required to use the shown topology?