Query about LED driver

Hi All!
I had seen some LED driver circuits (specially more then 90W); in which After EMI filter+Rectifer section their is Power Factor/Boost circuit and then Half wave inverter and then buck circuit or Forward converter.

I want to know why designer uses Boost and then Inverter section.

Thanks in Advance!

alok1982 said:

I want to know why designer uses Boost and then Inverter section.

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Because that's how the PFC (Power Factor Correction) works - same in TV's.

Then waht's need of Resonant circuit?

alok1982 said:

Then waht's need of Resonant circuit?

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What resonant circuit?.