Updated from April 27

RF Micro Devices ( RFMD) took a pounding in after-hours trading after the company said June quarter earnings would come in slightly short of Wall Street expectations.

But the miss mostly reflects costs related to an acquisition, rather than any fundamental weakness at the company.

Shares were recently down 63 cents, or 7.4%, to $7.84.

At Pacific Crest Securities, analyst James Faucette said RF Micro Devices' guidance actually would have been about in line after factoring out increased operating expenses related to its purchase of Silicon Wave, a Bluetooth chip provider.

The apparent shortfall in guidance reflects the fact that most analysts hadn't updated their models to reflect the purchase, he explained. (Bluetooth is a technology that allows for short-range communication between electronic gadgets like computers and personal digital assistants.)

Faucette has a neutral rating on the shares; his firm has no banking relations with RF Micro Devices.

After the bell, RF Micro Devices said revenue for the quarter ended March 31 rose 18% from the prior year's levels to $163.4 million, just above the consensus estimate for $161 million.

The Greensboro, N.C.-based company said sales performance reflected share gains in its core market of power amplifiers used in cell phones, offset by a normal seasonal downtick in the broader handset market.

The company posted a net loss of $900,000, reflecting a $7.7 million noncash asset impairment charge. That marks an improvement over the $13 million loss in the same quarter last year.

On a per-share basis, RF Micro Devices was just at the break-even point based on generally accepted accounting principles. Without the asset impairment charge, it would have posted a pro forma profit of 4 cents, in line with expectations.

Its June quarter sales guidance, which calls for sequential growth of 3% to 5%, implies a revenue range of $168 million to $172 million. The outlook suggests that quarterly revenue could come in below the current consensus estimate for $172 million.

On a GAAP basis, earnings should total 1 penny to 2 cents per share.

But after factoring out a projected write-off of 2 cents for R&D related to an acquisition, RF Micro Devices expects earnings of 3 cents to 4 cents on a pro forma basis, shy of the Wall Street consensus number of a nickel.