Research And Design On X-band Wideband Small Step Receiver

With the rapid development of the modern communication systems, the frequency resources became urgent, RF channel is becoming more and more valuable, which is the performance of a modern receiver system made high demands; at the same time, in order to ensure effective battlefield received signal under the complex electromagnetic environment, as a dedicated radar receiver system, broadband receiver conversion function has become its most basic design requirements; this thesis studied those two core issue of radar system, designed a X-band radar system receiver with ultra-small stepping reception and broadband function.To solve the problem of resource utilization of RF channel, the receiver system designed in this paper includes ultra-small stepping reception, the received signal frequency step is 0.0005 Hz, the paper carried out a detail analysis of this design; by comparing different schemes, comprehensive direct digital frequency synthesis(DDS) and phase-locked loop frequency synthesis scheme(PLL), the innovative design a "PLL + DDS + PLL " frequency source system, not only to achieve a minimal 0.0005 Hz step function, but also have excellent phase noise and spurious performance.Multifunctional broadband conversion receive is a major feature of this X-band wideband small step receiver, it is another focus of this paper design. this receiver not only have broadband RF input but also have broadband IF output. The output intermediate have choosable of 5MHz, 10 MHz, 20 MHz. The selectable gain mode can be manual gain control(MGC) and automatic gain control(AGC) to switch between; the entire frequency channel modules feature-rich to meet the receiver system for use in different environments. To achieve this wideband frequency channel module, this thesis use ADS simulation software to design this module. After component selection and optimizing design of the communication link, the author implemented this broadband frequency channel module.