公开(公告)号：US06806746B1

公开(公告)日：2004-10-19

申请号：US10633225

申请日：2003-07-31

Applicant: Wing J. Mar

Inventor： Wing J. Mar

IPC: H03B2100

CPC classification number: H03L7/16 ,  H03B21/02 ,  H03L2207/12

Abstract: A direct frequency synthesizer provides an output signal derived from a high frequency reference signal that is frequency divided and mixed to satisfy the coarse step synthesis requirements of an offset loop synthesizer. The absence of a VCO within the direct frequency synthesizer, provides the direct frequency synthesizer with lower phase noise than a typical PLL-based coarse step synthesizer. Though applicable to a variety of types of synthesizers and signal generators, the direct frequency synthesizer provides especially advantageous noise performance when used to generate an offset signal for an offset loop synthesizer of the first local oscillator of a spectrum analyzer, where the second local oscillator of the spectrum analyzer provides the reference signal for the direct frequency synthesizer.

Abstract translation: 直接频率合成器提供从频率分频和混合的高频参考信号导出的输出信号，以满足偏移环路合成器的粗略步骤合成要求。 在直接频率合成器内不存在VCO，为典型的基于PLL的粗步合成器提供了具有较低相位噪声的直接频率合成器。 尽管适用于各种类型的合成器和信号发生器，直接频率合成器在用于为频谱分析仪的第一本地振荡器的偏移环路合成器生成偏移信号时提供特别有利的噪声性能，其中第二本地振荡器 频谱分析仪为直接频率合成器提供参考信号。