Research On Dual Frequency Oscillator Based On Filter Integration Technology

From the early analog communication to the present digital communication,the carrier frequency of transmission signal has developed from low frequency to high frequency.Due to the increasing demand for high-speed communication,users can meet the needs of high-speed communication by increasing the signal bandwidth.The system with dual frequency or multi frequency can effectively expand the communication bandwidth,but the traditional multi-channel structure improves the complexity of the system,and also results in the increase of power consumption.In order to simplify the system structure and process multi frequency signals at the same time,multiple frequency signals can be transmitted and processed through one signal channel at the same time.In this kind of single channel system,two kinds of local oscillation signals with different frequencies are needed at the same time.Aiming at the shortcomings of traditional dualfrequency oscillators with complex structure and high power consumption,this thesis proposes a new dual-frequency oscillator with filter fusion.Not only reduces the complexity of the dual-frequency oscillation circuit,but also improves the isolation between the dual-frequency.The main work of this thesis is divided into four parts:Firstly,after analyzing the research background and potential application value of the dual frequency oscillator,the dual frequency oscillator with research value and potential application scenarios is proposed,and the existing research results are analyzed.In this thesis,the theory related to the design of dual frequency oscillator is studied.The parameter index and design method of filter and oscillator are mainly studied.Then,the theory is applied and the comb filter is used to design the oscillator.A single frequency oscillator based on filter integration technology is realized.The output signal frequency is 2.4GHz,the output power is 7.588 dbm and the phase noise is-120dbc/Hz@100kHz and-140dbc/Hz@1MHz.Then,the open end of the comb filter is connected to the varactor to realize the change of the passband frequency with the reverse bias of the varactor.It is integrated into the amplifying circuit to design the VCO.The practical test results show that the output frequency tuning bandwidth of the VCO is 81.6%,the signal power is more than-1dbm,and the phase noise is less than-113.00dbc/Hz @ 100 kHz and-118.00dbc/Hz @ 1MHz.Finally,based on the single frequency oscillator,the circuit of dual frequency oscillator is designed.Using only a single transistor and a single feedback loop to design a dual frequency oscillator has the advantages of low circuit complexity and low DC power.In the design of the filter,two kinds of narrow band dual frequency filters are selected.Two kinds of dual frequency filters are integrated into the feedback loop of the transistor.Two kinds of oscillators with dual frequency output at the same time are designed and simulated in the software.The results show that the dual frequency oscillator has the same signal power and phase noise as the VCO designed in this thesis.At the end of this thesis,the main work of this thesis is summarized,and the future research work is prospected.