Research And Implementation Of Ultra-wideband Frequency Agile Source

Frequency source is the key component of most electronic systems such as communication systems and wireless measurement and control equipments,which plays an important role in the fields of communication,wireless measurement and radar.In the field of communication,the frequency source can not only be used as the excitation source of the transmit channel,but also being the local reference oscillation for the receive channel.In the field of test and measurement,almost all of the high-end equipments would employ a high-performance frequency source as the key component,so as to realize high-precision test and measurement.As can be seen,the requiement for high-performance frequency source is especially urgent,which is required to be designed with wider bandwidth,faster speed,shorter frequency hopping time,lower phase noise,smaller size,and lower power consumption.The ultra wideband frequency agile source is designed and implemented in this thesis,along with analysis and comparision of several realization methods for multi-frequency sources,the design and implementation of the ultra wideband frequency agile source is also proposed.The main contents are as follows:First of all,through the analysis and comparison of related literatures,the research direction and hotspot of current wideband frequency agile source technology are summarized in this paper.Then,the theory of three kinds of basic frequency synthesis techniques is introduced in detail,the analysis of various indexes and parameters which affect the performance indexes in the frequency synthesis technology is also given.At the same time,the physical meaning of all parameters,and provides the standard for evaluating the performance of the frequency source is illustrated.Secondly,the analysis and comparision of the implementation schemes of several kinds of complex frequency sources is made through the design requirements,and introduces the implementations of each complex frequency synthesizer.By analyzing and comparing the advantages and disadvantages of each kind of complex frequency synthesizers,the realization scheme which combines DDS,PLL,mixers and frequency multipliers is porposed.This scheme is implemented by using a high speed DDS to generate baseband signal with bandwidth of 750 MHz,then it is mixed with the fixed local oscillator with central frequency of 8.6GHz,after that,a bandpass filter is used to select the signal between 9.25-10 GHz.Finally,the X-band signal is modulated to Ka-band by the active frequency multipliers in order to achieve 37-40 GHz ultra wideband agile signal.Finally,the frequency source is produced according to the proposed design scheme,and the performance of the frequency source is evaluated with experiments.The results show that the design of ultra wideband frequency agile source is completed.To summarize,the output frequency range is 37-40GHz;the bandwidth can reach up to 3GHz;the frequency hopping interval is less than 100ns;the max output power is +7.55 d Bm;the less output power is +4.98 d Bm;the flatness of output signal is 2.57 d B;and the phase noise is better than-91 d Bc/Hz@100k Hz.The performance of this ultra wideband frequency agile source can satisfy the design requirements.