| An X, Ku-band frequency synthesizer developed in the subject, is consitituted bytwo separate frequency synthesizer output signal source, which be installed in analuminum cavity with volume of109mm×106mm×30mm, and the output frequenciesare respectively8GHz~12GHz and12GHz~18GHz, and the stepper is50MHz.This paper proposes a scheme that first synthesize local oscillator signal oflow-frequency and then through the multiplier to get high-frequency signal indirectly.Design includes three major parts that the local oscillator, frequency multiplier, andfilter. Local oscillator signal generated by the PLL chip, two-channel output frequencyto require a quarter of the frequency of the external DIP switch through the parallel portof the microcontroller to control the frequency stepping, stepping to12.5MHz;frequency multiplier using twice frequency doubling method, and choosed three kindsof multiplier chip to design circuit; the filter using parallel-coupled microstrip line toproduce, and using ADS software to assisted design. In addition, design of thecorresponding amplifying circuit match the attenuation network, and the ESCattenuating circuit to ensure that the components of the output power stability in therange of12±1.5dBm. Next discuss the physical structure of the component and thesize of each part of the circuit, and to design a suitable cavity. Finally, the article givesthe assembly process of debugging and test result.The experimental results show that the output power, frequency accuracy, phasenoise indicators of the two-channel synthesizer has overall reached the designrequirements, but there is still room for improvement. The article points out thecontradiction between the design and production process of broadband parallel coupledmicrostrip lines is a major factor affecting the performance of components, and alsoanalyzes the system structure, cavity layout, microstrip-waveguide adapter and otherfactors on the performance of components, and presents an improved program. |
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