I am constructing 10kHz , 30kHz and 50kHz sine waves using wien bridge oscillator design with LM358 OP-Amp. I have a few problems with the circuits that i could not figure out. Thank you for all your helps.
1)The output sine waves are getting distorted as the frequency increases. It is OK for 10kHz but when i increase the frequency more to 30kHz or to 50kHz I am getting the following distortions on my waves. I have tried changing the Op-Amp, (not the model), changing the source changing the values for resistors but could not fix it.
2) And secondly I want to amplify the waves but non-inverting amplifier or inverting amplifier with only resistors aren't working. I've read the data sheet of LM-358 there is an example amplifier circuit for AC signals. However I couldn't figure out what component does what. Do I have to use that circuit or is there a simpler solution.
Again Thank you for all your kind help.