Research On Key Technologies Of Optoelectronic Oscillators Microwave Circuit Integration

As a new type of microwave signal source,Optoelectronic Oscillator(OEO)can output high quality signal with very low phase noise,which has broad application prospects.However,most of the current OEOs are composed of discrete optical and microwave device modules,which results in unsatisfactory performance in terms of size and power consumption.Through the integration of OEO microwave circuit,it is helpful to reduce the size and power consumption of OEO,which is of great significance to realize its miniaturization and practicality.Based on the characteristics of the microwave circuit in the OEO system,this paper studies the substrate integrated waveguide(SIW)narrow-band filter,high-frequency microwave signal coupling interaction structure,low-noise amplifier integration method and so on.This paper also proposes a high gain and narrow-band microwave circuit integration scheme,which can integrate OEO microwave circuits on a single board.The main contents of this paper are as follows:(1)A SIW filter with narrow bandwidth and easy integration is designed and implemented.In view of the problem that the filter loss increases due to the narrow bandwidth of SIW filter,a solution is proposed to optimize the performance of SIW filter by selecting the appropriate laminate material and bonding material,bonding multiple laminates to form a thicker dielectric substrate,in order to improve the unloaded quality factor of SIW resonator.Using this method,when the dielectric constant and dissipation factor of the laminate material and the bonding material are the same,the original SIW structure remains unchanged,and the insertion loss of the narrow-band filter can be optimized to a certain extent only by adding the laminate.(2)The board level microwave signal interconnection structure is optimized to eliminate the influence of discontinuity in the integration of OEO microwave circuits.In order to solve the discontinuity problem caused by abrupt change of signal reference plane in integration,this paper proposes two optimized structures for interconnection between microstrip lines with different reference grounds.The first structure reduces the field path mutation of the interconnection circuit by using the forward extension form of the inner reference ground,which has the characteristics of small board size,excellent loss performance.In the second structure,the parallel coupled microstrip filter is used to bridge the discontinuity structure,which effectively suppresses the parasitic passband of SIW filter,and uses its DC open circuit characteristics to avoid the influence of current short circuit of SIW structure.Both of the above-mentioned structures are verified by simulation and experiment.(3)Completed the single-board integrated design and verification of the OEO microwave circuit.The board level integration and layout optimization design of low noise amplifiers and SIW filters are realized,and the signal integrity problem in the integration is avoided by methods such as trapezoidal transition and optimal miter of microstrip bend.At the same time,in response to the bias requirements of the p HEMT microwave amplifier,a low-cost,easy-to-integrate,high-performance microwave amplifier bias network is designed and implemented.