With projected savings of $150 million on merger, RFMD's share is $75 million.
With current shares outstanding (282.5 million) this adds approximately $0.265 to bottom line.
At 10 times forward PE this adds about $2.65 to Friday's closing price.
This give us $8.46 current effective price on announcement of the deal.
So we are still under the effective price. Firms downgrading on valuation may have been caught short because the valuation seems to be consistent (or low at present price) with potential cost savings after merger.
Additionally The merger opens up a minimum of $500 million defense market which could not be addressed individually by RFMD or TQNT on their own.