A weak guidance from cell phone giant Motorola ( MOT) sent the company's shares down 7% Friday and weighed on other technology stocks. Late Thursday, Motorola estimated fourth-quarter earnings of 13 cents to 16 cents a share. Excluding certain items, the company projects earnings of 23 cents to 26 cents a share. Thomson First Call analysts' consensus called for earnings of 39 cents a share. Motorola projects sales of $11.6 billion to $11.7 billion, compared with a $12 billion Wall Street target. Shares were trading down $1.44 to $19.11. The news sent shares of Nokia ( NOK), the world's top mobile-phone maker, down $1.12, or 5.4%, to $19.80 in recent trading. Meanwhile, Skyworks Solutions ( SWKS), Silicon Labs ( SLAB) and RF Micro Devices ( RFMD), which are suppliers to Motorola, also tumbled. Deutsche Bank downgraded the companies, saying that Motorola and Nokia may be shifting toward lower-priced, lower-margin products. Skyworks was down 56 cents, or 7.6%, to $6.78; Silicon Labs fell $2.26, or 6.4%, at $33.08; and RF Micro dropped 49 cents, or 6.9%, to $6.60. Elsewhere, Micrel ( MCRL) dropped 9% after the chipmaker lowered its fourth-quarter projections, citing weakness in demand in the last two weeks of December. The company now expects to report earnings of 9 cents to 10 cents a share, down from its October projection of 11 cents to 13 cents. The company cut its revenue estimate to a range of $64 million to $65 million from a prior view of $67 million to $70.5 million. Shares were down 93 cents to $9.87.