By analyzing relation between BEMF of the hard disk spindle motor and the rotate speed. This paper presents a new method of following the motor rotate speed by PLL to lock BEMF.

通过对硬盘主轴马达的反电动势与马达转速之间关系的分析，提出一种利用马达的反电动势信号跟踪马达转动速度变化，产生系统伺服写入时钟信号的方法。

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One of the main challenges in reducing the thickness of current 7mm hard disk drives by almost 30% without compromising on its performance and stability is its spindle motor design.

ENGADGET: A*STAR unveils 5mm-thick hybrid hard drive, touts affordability and improved energy efficiency