Design And Experimental Research Of The GHz Signal Source Based On ADF4350

Our aim is to design and manufacture a portable GHz signal source to drive thehigh-speed optical switch. The research work carried out in this paper comes from theNational Natural Science Foundation of China whose name is “research on spectralflattening and failure mode of polymer optical switch array in S+C+L wide-band of(61107021).We have designed and made the circuits and written the software program, suchas GHz signal generating circuit, a loop filter circuit, a control circuit with ARM7,high-speed signal amplifying circuit based on chip AD8351, a parameter settingcircuit and a LCD display circuit. The software programs of the GHz signal sourcemainly include ADF4350register configuration program, button scanning programand LCD display program. Since the PLL frequency synthesizer technology has someadvantages such as good output signal frequency spectrum and high frequency, theintegrated PLL chip is chosen to generate GHz signal.We integrate the software and hardware components of the signal source anddevelop a prototype. And then we test and analysis its function. Experimental testinclude test of the characteristic impedance, test of the signal generating circuit andamplifier circuit and test of spectrum analysis. The test of characteristic impedance isto measure the characteristic impedance of microstrip line on printed circuit boardwith a vector network analyzer. This is to verify feasibility and correctness ofcontrolling characteristic impedance with HFSS simulation. The test of the signalgenerating circuit and amplifier circuit is to measure the signal wave forms with thedigital oscilloscope. This is to test the performance of circuits. The test of spectrumanalysis is to measure output signal spectrums of the GHz signal source withspectrum Analyzer. This is to determine frequency range of the signal source andsignal spectral purity. These results above show that he characteristic impedance of the microstrip linereaches50Ohm. The magnification of the high frequency amplifier circuit reachesabout20dBm. The signal frequency range is0.2GHz-1.5GHz. And its frequency isadjustable. The output power range is-17.41--4.788dBm and the noise level isat-55dBm. All of them have reached the design target.