全数字导航接收机中的频率合成器

为在直扩接收机中实现高精度的频率合成器，提出了一种改进的坐标旋转数字计算机（CORDIC）算法，通过预迭代的方式将传统的CORDIC算法的工作范围扩展到了全角度范围，并且加入的预迭代可以统一到流水线结构中.该算法避免了采用传统查表方法耗费大量ROM资源，从而不利于芯片实现小型化和低功耗化的缺点，通过加法和移位操作计算基本的超越函数，可以采用迭代算法实现高精度的频率合成，在保证高速、高精度频率输出的同时节省了硬件资源.硬件平台仿真结果表明，该算法占用很小的硬件资源，能够产生高速、高精度的频率输出，可以应用于直扩接收机中.

Frequency synthesizer applied to digital navigation receiver

An improved coordinate rotational digital computer(CORDIC) algorithm was proposed to realize high accuracy frequency synthesizer on direct spread receiver.Traditional look-up table(LUT) scheme spends lots of ROM resources and is not good for chip miniaturization and low power realization.The CORDIC approach could be used to compute transcendental functions through simple addition,shift and table looking-up operations.The improved CORDIC algorithm extended the effective domain of the traditional CORDIC algorithm to the full angle domain,and the additive pre-iterative arithmetic could be easily practiced to the pipeline architecture.The CORDIC approach takes the advantage of iterative arithmetic to realize high accuracy frequency synthesizer and saves hardware cost.Hardware implementation shows that the approach requires little hardware resource,accurately gives out high frequencies and can be applied to direct spread receivers.