I have been designing a Wien-bridge oscillator using limiting diodes for amplitude stabilization.
General Circuit can be viewed here.
So I am trying to get this circuit to oscillate at 300 kHz. I was originally using a LM318 op-amp as my oscillator but I decided that I wanted to have the ability to increase my frequency if I so desired. I upgraded to the AD812AN high speed video op amp. My problem is that my calculated frequency is not even close when I use the AD812 to get an oscillation.
F = 1 / (2*pi*R*C) R = 4.7k C = 100pF
F ~= 340kHz
In actuality I am getting an oscillation > 6 MHz. Is this because I am using a video op amp? Is there something I am missing here that would allow me to design for the oscillation frequency instead of randomly swapping resistors and caps until I get where I want to be? Thanks for the help.
Greg
General Circuit can be viewed here.
So I am trying to get this circuit to oscillate at 300 kHz. I was originally using a LM318 op-amp as my oscillator but I decided that I wanted to have the ability to increase my frequency if I so desired. I upgraded to the AD812AN high speed video op amp. My problem is that my calculated frequency is not even close when I use the AD812 to get an oscillation.
F = 1 / (2*pi*R*C) R = 4.7k C = 100pF
F ~= 340kHz
In actuality I am getting an oscillation > 6 MHz. Is this because I am using a video op amp? Is there something I am missing here that would allow me to design for the oscillation frequency instead of randomly swapping resistors and caps until I get where I want to be? Thanks for the help.
Greg