DDS+PLL Frequency Synthesizer Based on AD9858

Phase locked loop and direct digital frequency synthesis technology have their merits and disadvantages respectively,so it is feasible to combine the 2 methods,perform their merits and to overcome their disadvantages,which can generate wideband and super wideband radar signal expected,and it puts up with design scheme and main hardware circuit design. In the design,with AD9858 as the core device,output of DDS is used to stimulate PLL,namely DDS provides the reference signal of PLL,with ADF4107 as the phase detector of PLL. Then FPGA controls conveniently DDS and PLL by procedures. As a result,the output signal has the fast conversion time,phase noise of which is -90 dBc/Hz,and the spur of which is better than -70 dBc. So this system has a high-performance aggregative indicator.