What happens when injecting a current at different instants in an oscillator?

In summary, the conversation discusses the behavior of an LC tank circuit when a current is injected at different instants. It is observed that injecting the current at t1 causes a change in both the phase and amplitude of the output, while injecting it at t2 only changes the amplitude. The speaker is confused about why the amplitude changes in the first case, and what would happen if a large current is injected. The attached image shows the corresponding points on the dV/dt and V plot.
  • #1
iVenky
212
12
Hi,

I am reading the Hajimiri-Lee phase noise model, and got a question on that. If you have an LC tank circuit that is free-running and I inject a current i(t) (dirac current) at instants either t1 or t2 (shown in the figure), depending on when you inject the phase of the output changes (as shown). If I inject it at t1, then phase of the output changes while if I inject it at t2 only the amplitude changes but not the phase. What I don't understand here is when I inject the current i(t) at instant t1, shouldn't the amplitude also change just by superposition of oscillation waveform and the input i(t) energy? This is the part that's confusing to me. And what happens if I inject a really large i(t) that the resultant voltage exceeds the initial peak voltage to begin with, would the amplitude still change?

In the dV/dt and V plot, t1 corresponds to 'b' and t2 corresponds to 'a'.

Attached the image.
 

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  • #2
I'd say injection of current at t1 should change amplitude as well as phase.
 

1. What is perturbation on an oscillator?

Perturbation on an oscillator refers to the disturbance or external force applied to an oscillator, causing it to deviate from its regular motion. This can be seen as a change in the amplitude, frequency, or phase of the oscillator's oscillations.

2. How does perturbation affect an oscillator?

Perturbation can have various effects on an oscillator, depending on the type and magnitude of the external force. It can cause the oscillator to exhibit chaotic behavior, change in frequency or amplitude, or even lead to the oscillator's complete breakdown.

3. What is the difference between forced and damped oscillations?

Forced oscillations occur when an external force is continuously applied to an oscillator, while damped oscillations occur when the oscillator's energy is gradually dissipated due to friction or other damping mechanisms. Perturbation can affect both types of oscillations, but in different ways.

4. How can perturbation be used in scientific research?

Perturbation on an oscillator is a common phenomenon observed in many natural and man-made systems. It can be used to study the behavior and stability of these systems, as well as to understand the effects of external forces on their dynamics. Perturbation analysis is also a valuable tool in many fields of science, including physics, engineering, and biology.

5. Can perturbation be beneficial for an oscillator?

In some cases, perturbation can have a positive effect on an oscillator. For example, in the field of control systems, perturbation can be used to stabilize an unstable oscillator or to control its behavior. However, in most cases, perturbation is seen as a disturbance that can have negative consequences on the oscillator's performance.

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