The Design Of1.1GHz Frequency Synthesis Module

The frequency synthesizer is a RF signal source, which takes high stabilityoscillator as standard and uses frequency synthesis techniques to form the desiredfrequency. It has extremely high output frequency and accuracy, and its signalcharacteristic parameters are controllable. It is widely used in product design anddevelopment and debugging of the circuit system.This subject derives from some project of “1.1GHz frequency synthesis sweepingsource”. The specific task of this subject is to generate a sine wave frequency signal of5kHz~1.1GHz, and use it as carrier to achieve AM, FM, pulse modulation function.Frequency of5kHz~1.1GHz is synthesized with the method of direct DDS output andDDS+PLL+frequency mixing output. The way of analog to digital and then processingis adopted to realize AM, FM, pulse modulation function.Firstly, this dissertation introduces the development of the frequency synthesizertechnology at home and abroad, as well as the main frequency synthesis technology.Then considered with the system index, it designs and improves a set of system schemeand analyzes the feasibility of the scheme. Then according to the scheme design, itintroduces the design and debugging of the low frequency synthesis part, highfrequency synthesis part as well as the signal modulation part. According to the scheme,low frequency synthesizer uses DDS output directly, high frequency synthesizer usesthe output of the DDS and PLL frequency mixing after removing the up-convertingfrequency, and modulation uses digital modulation mode. More details are discussedespecially for very low frequency harmonic suppression of low frequency synthesis part,third-order intermodulation suppression of mixer of high frequency synthesis part, therealization of the digital FM and AM and other technical difficulties.Finally, the actual results of frequency synthesizer module is given. Someimprovements are proposed after summarizing the experience in the project.