S-band Frequency Synthesizer Of Research And Application

Frequency synthesizer is the key component in electronic systems, whose performance directly affects the capability of various systems such as radar, navigation system, etc. Nowadays, by the development of modern electronic communication technology, higher requirement has been presented. Synthesizers with low cost, low phase noise, wide band and high resolution have dominating development direction of the frequency synthesis technology. The paper was based on the goal of low cost, low phase noise, high resolution to study and analyze the wideband frequency source.The difficult of this project is realizing low cost, wide frequency range and fine resolution sweep frequency synthesizer. In order to realize high resolution, we can adopt fractional-N PLL or DDS technology. But the former technology is more complex, bigger size and worse spur. Due to the development of LSI, we can use single chip DDS to realize fine resolution and fast frequency hopping time. PLL can filter out DDS's spurious.This paper analyzed DDS and PLL technique, and then combined them together, developed a type of fine resolution, low cost, wide band sweep source, which output 2100MHz~2400MHz sweep signal with 5Hz frequency resolution. System include two main parts: one generating 1400MHz const frequency and the other make use of DDS+PLL technology realizing 2100MHZ~2400MHz phase lock signal with 5Hz resolution. Two signal mix to generate 2100MHz~2400MHz signal.