regarding jumbo loan for home, can I take out second loan from another bank to make up for 20% down payment?

Hello. I am looking into buying home. I heard that jumbo loan ($765000 or more) requires at least 20% down payment. I'm at socal and for nice sized 4 beds house in decent areas can easily go higher than 1M. I am ok with monthly mortgage payment. but I don't have $200K for down payment now. 

I was wondering, if I can get $100k loan from some bank first (as some call it second loan), and then if I apply for jumbo loan from another bank different than the first bank where I got $100k loan, will I be qualified for jumbo loan? or I have to have loan-free money of at least 20% for down payment in order to be qualified as jumbo loan? thank? if anyone can tell me anything eles I need to know regarding jumbo loan, I will appreciate it.