UPDATE 2-Silicon Labs Q3 results top Street, outlook in-line

* Q3 adj shr $0.67 beats est by $0.07

* Q3 rev $125.9 mln vs est $123.8 mln

* Sees Q4 adj shr $0.60-$0.63 vs est $0.60

* Sees Q4 rev $124-$129 mln vs est $126.3 mln

* CEO says looking to buy private firms (Adds CEO comments, share buyback, updates stock movement)

By Sudipto Ganguly

BANGALORE, Oct 28 (Reuters) - Silicon Laboratories (SLAB.O) posted better-than-expected quarterly results helped by strong demand for its FM radio tuner chips, especially for handsets made by a key customer, Samsung (005930.KS).

Silicon Laboratories also forecast fourth-quarter results in line with Wall Street expectations, reflecting the expected moderation in demand in the current quarter at Samsung. [ID:nBNG533420]

The expected fall in demand at Samsung was the main reason for the forecasted sequential fall in its radio frequency (RF) chips sales in the current fourth quarter, Chief Executive Necip Sayiner told Reuters in an interview.

However, in the third quarter, revenue soared at five out of its eight product lines -- audio, video, short-range wireless, timing and micro-controllers -- led by a 40 percent surge in its RF business.

"These five product lines along with the power business will continue to support our growth in the near future," Sayiner told Reuters.

The company, whose competitors include Texas Instruments (TXI.N), Analog Devices (ADI.N) and Broadcom (BRCM.O), was also looking at strategic acquisition opportunities, he said.

"We're primarily looking at the late stage private companies that we can help grow faster, than they can on their own, Sayiner told Reuters.

The company, whose customers also include Huawei [HWT.UL], LG Electronics (066570.KS) and Motorola (MOT.N), also said it will buy back up to $150 million shares through the end of 2010.

QUARTERLY RESULTS BEAT

Third-quarter profit rocketed to $22.4 million, or 47 cents a share, from $1.2 million, or 2 cents a share, a year ago.