Research On Ka - Band Small Step - By - Band Frequency Source And Hardware Implementation

With the continuous development of communication system technology,System for the frequency of the source of stability and accuracy and spectral purity have higher requirements,Single frequency synthesis technology has been difficult to meet the needs of design.PLL frequennery mature technology,It has a high output frequency and spurious suppression characteristics of system of good.Although DDS technology can obtain the good phase noise and good frequency resolution,But spurious suppression is poor and low output frequency.The purpose of this paper is the advantages of two kinds of frequency synthesis technology combination,to design a Ka band low frequency stepping wideband frequency source.Based on the analysis of DDS and PLL theory, discusses the DDS+PLL technology combined using several scenarios, and analyzes the advantages and disadvantages of each scheme.And then combined with the specific requirements of the indicators, the choice of a suitable plan, and on the basis of the scheme, analysis accord with the selection and index of chip.The last is the design and debugging of the hardware circuit, circuit structure with cavity in modular design, not only simplifies the complexity of the circuit design, and make the circuit debugging more convenient.By adopting the scheme of DDS synthesis with direct excitation of PLL in the circuit design, developed Ka band (27GHz-30GHz) step frequency source.After debugging, realization of 10kHz frequency source frequency interval arbitrary output in this frequency range; phase noise reached -52dBc/Hz@10Hz,-63dBc/Hz@100Hz,-72.8dBc/Hz@1kHz,-80.7dBc/Hz@10kHz,-90.1dBc/Hz@100kHz;Spurious suppression to 68dBc; the output power is not less than 11.8dBm.Meet the design index.