Shares of Silicon Laboratories Inc. surged more than 8 percent Wednesday after the company posted record fourth-quarter revenue and handily beat analyst earnings estimates. The Austin-based company reported a quarterly profit of $10 million, or 23 cents per share, on revenue of $161.9 million compared with a profit of $10.6 million, or 24 cents per share, on revenue of $146.2 million during the same period the previous fiscal year.