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R&D (FilterCavity)
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NaokiAritomi - 15:26, Tuesday 21 December 2021 (2758)Get code to link to this report
Realizing CCFC+green OLTF with green only

To realize the CCFC+green OLTF with green only, we need the following green filter.

1 + G_CCFC/G_green = 1 + P_CCFC/P_green*G_f*P_f 

where G_CCFC, G_green are the OLTF of CCFC and green, P_CCFC, P_green are the cavity pole of CCFC and green, and G_f = 1000, P_f are gain and pole of the CCFC filter. The pole P can be written as

P = 1/(1+i*f/f_p)

where f_p is the pole frequency. f_p for P_CCFC, P_green, P_f are 57 Hz, 1450 Hz, 30 Hz, respectively.

This ideal filter is complicated to realize with combination of zeros and poles. Instead, we can use a simple filter which is the combination of 2 poles and 2 zeros. The pole and zero frequency are 30 Hz and 1000 Hz, respectively, and gain is 1000. As you can see in the attached figure, the simple filter is similar to the ideal filter. 

Images attached to this report
2758_20211221081215_greenfilter.png