# Closed loop response not correct

**URL:** <https://forum.plexim.com/t/closed-loop-response-not-correct/738>\
**Category:** PLECS\
**Tags:** multitone-closedloop\
**Created:** [January 25, 2020, 12:23pm UTC](https://forum.plexim.com/t/closed-loop-response-not-correct/738 "2020-01-25T12:23:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Maida](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@Maida](https://forum.plexim.com/u/Maida)\
**Post date:** [January 25, 2020, 12:23pm UTC](https://forum.plexim.com/t/closed-loop-response-not-correct/738/1 "2020-01-25T12:23:12Z")

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Hi,

I am trying to determine the loop gain for LLC converter.I am running Multitone Analysis.The open loop works fine but in closed loop, the response is not right. I have changed the simulation time and even sweeped across amplitude of perturbation.

I am attaching the waveforms and circuit topology so you can guide me better

 ![Screen Shot 2020-01-25 at 9.51.25 PM.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/56ba660c7cfe4923b59f0f658c19fc55757faa93.jpeg)

 ![Screen Shot 2020-01-25 at 9.52.17 PM.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/f17a7c493a5f86d24212e521da3ec22f6ff71bae.jpeg)

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**Author:** ![Kris\_Eberle](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/kris_eberle/32/6_2.png) [@Kris\_Eberle](https://forum.plexim.com/u/Kris_Eberle)\
**Post date:** [February 4, 2020, 6:34pm UTC](https://forum.plexim.com/t/closed-loop-response-not-correct/738/2 "2020-02-04T18:34:29Z")

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Hello, you will need to post your model for anyone to provide help with your question.

Regards,

Kris