一种改善杂散的DDS频率合成器

DDS Frequency Synthesizer with Reducing Spur

相位舍位及量化噪声引起的杂散问题一直是数字频率合成器研究的重点。针对杂散问题,使用了修正频率控制字和相位抖动两种技术,再结合延迟叠加方法,很好地降低了幅度量化杂散和相位舍位杂散,提高了系统的信噪比。最终经由仿真验证了此方法能够有效抑制离散的杂散并且能够很好地改善由于相位抖动所引起的底部噪声过多的问题。

Spurious issue has been a focus issue in the study of digital synthesizer because of ignoring of low bits of phase and qnantization noise. This paper presents a method combined the amended frequency control word technology with phase jitter to reduce the spur of DDS. With delayed superposition method, discrete phase jitter in the half of frequency root is improved, but also reduces the frequency edge for the inhibition is reduced and finally SNR of the system is improved. All of this has been simulated. The results prove that this method can reduce spur and improve the problem of spur because of phase jitter.