You need to be aware that not everyone uses LTSpice; many people use other simulation packages, and posting only an LTSpice .asc file doesn't allow them to see your circuit.I have done some theoritical design for opamp based colpit oscillator.
Could anybody me know the reason why output is strange ?
Thanks,You need to be aware that not everyone uses LTSpice; many people use other simulation packages, and posting only an LTSpice .asc file doesn't allow them to see your circuit.
You'll likely get a lot more help if you also post a screen capture image of your schematic and waveforms, preferably in .png format.
Thanks for your reply !The op-amp output is very low impedance and the inverting input is a virtual earth, so both of these load down the tuned circuit.
Try the attached.
Your principle error is that you have transferred the feedback circuit from a transistor (acting as a current source) to an opamp (which is a voltage source).Thanks,
Below circuit i used for simulation !
Many Thanks,Your principle error is that you have transferred the feedback circuit from a transistor (acting as a current source) to an opamp (which is a voltage source).
As a consequence, the capacitor C2 acts as a load to the active device - thats all, but it is not part of the feedback circuit anymore.
Hence, we need a resistor between the opamps output and the feedback path.
Hi ,@mishra87, you can mesaure/simulate nearly everything.
However, at first we need the definition of the parameter you want to measure.
What is the "bandwidth of an oscillator"?
Perhaps you mean the bandwidth of the lowpass in the feedback path?
In this case - display magnitude and phase of the loop gain function versus frequency.
The question i had was -So - you think, that he wants to see the result of phase noise? I am not sure....
OK - I think, the question concernes the bandwidth of the open-loop (loop gain). This is a 3rd-order lowpass - and all you have to do is to open the circuit at the node Vout and perform an AC analysis. The magnitude of the lowpass function gives you the bandwidth.The question i had was -
"how can you find the Bandwidth of this circuit using the LTSpice? What is the formula of Bandwidth for this oscillator?
I am trying to find the answer of these questions what all i have is LT Spice design file attached post#12.
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