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RF Design Forums

Injection lock vco

asrf
9 months ago

Hi all,

Is there any guide that helps me simulate an injection locked vco ?

All I know for now is: run a transient simulation and let my oscillator reach the steady state and then I use a switch to connect the Injection voltage using a varactor and wait for it to lock to finj.

How can I obverse the final fundamental tone using pss ? Can I observe phase noise using pnoise simulation ?

Do pss and pnoise work with switch component ?

This is what I am planning to do. Using a switch to connect the injection signal to VCO using two varactors.

Thank you. I appreciate your time and effort.

Parents
  • 9 months ago

    There's this article which might be useful: Tips for simulating injection locked ring oscillator (thanks to ).

    Yes, you can use the switch component and have it change position during the Transient Assist (tstab) phase of the PSS. You'd need to ensure that the control for the switch is driven by a non-periodic source - so a pulse source without a period specified would suffice. Provded that this has switched before the end of the tstab (and ideally with sufficient time for the oscillator to lock), you would then need to simulate the PSS as a driven circuit because the oscillator is locked to your 4.5G source above (see the article).

    Andrew.

  • 9 months ago in reply to Andrew Beckett

    Thank you for reply. I actually read this before. How can I make a non periodic source. For example using vpwl ?

    For start I have even problem with simple transient simulation. It seems that locking does not happen.

    When I switch in the injection voltage it kind of modulates the signal but it does not change its frequency.

    VCO frequency is around 5.2GHz and injection frequency is 4.8GHz

           

Reply
  • 9 months ago in reply to Andrew Beckett

    Thank you for reply. I actually read this before. How can I make a non periodic source. For example using vpwl ?

    For start I have even problem with simple transient simulation. It seems that locking does not happen.

    When I switch in the injection voltage it kind of modulates the signal but it does not change its frequency.

    VCO frequency is around 5.2GHz and injection frequency is 4.8GHz

           

Children
  • 9 months ago in reply to asrf

    If you have a pulse source with just a delay and a rise time (and no width or period), it will start at val0, stay there for delay, rise to val1 and stay there forever. If you specify a width, it will return back to val0 again after the duration specified by width. In neither case is it periodic - only if a period is specified. Similarly a PWL source is not periodic unless you specify a period.

    Your circuit is not going to work in the PSS analysis since it's not working as an injection locked oscillator; you'll need to fix the circuit, presumably.

    Andrew.

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