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Entry  Sun Mar 28 17:28:26 2010, matt, kiwamu, Update, Green Locking, frequency discriminator for green PLL 6x
    Reply  Mon Mar 29 15:19:33 2010, mevans, Update, Green Locking, frequency discriminator for green PLL 
       Reply  Wed Mar 31 02:57:48 2010, kiwamu, Update, Green Locking, frequency counter for green PLL FCnoise.png
          Reply  Wed Mar 31 12:30:31 2010, rana, Update, Green Locking, frequency counter for green PLL 
          Reply  Thu Apr 1 15:21:12 2010, rana, Update, Green Locking, frequency counter for green PLL 
Message ID: 2728     Entry time: Mon Mar 29 15:19:33 2010     In reply to: 2718     Reply to this: 2737
Author: mevans 
Type: Update 
Category: Green Locking 
Subject: frequency discriminator for green PLL 

Thanks for the great entry!

In order to make this work for higher frequencies, I would add Hartmut's suggestion of a frequency dividing input stage.  If we divide the input down by 100, the overall range will be about 200MHz, and the noise will be about 20Hz/rtHz.  That might be good enough... but we can hope that the commercial device is lower noise!

Quote:

Last Friday, Matt made a frequency discriminator circuit on a bread board in order to test the idea and study the noise level. I think it will work for phase lock acquisition of Green locking.

As a result a response of 100kHz/V and a noise level of 2uV/rtHz @ 10Hz are yielded. This corresponds to 0.2Hz/rtHz @ 10Hz.

The motivation of using frequency discriminators is that  it makes a frequency range wider and easier for lock acquisition of PLLs in green locking experiment.

FD.png

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