Research On Novel SOLT Calibration Substrates Based On 12-Term Error Model

With microwave and millimeter wave integrated circuits are moving towards multi-functional chips on the wafer level,related manufacturing processes,testing and measurement technologies are also constantly developing and improving.As a high-precision measurement tool,the design and processing of RF probe,as well as the research on related calibration theories and calibration components,have also become one of the current research hotspots in the field of testing.This thesis presents a SOLT calibration method based on 12 error models,as well as the development of broadband,high-precision,and low-cost calibration substrate.The main content of this thesis is as follows:1)The development history of vector network analyzer,RF probe and matching calibration parts in the probe platform test system is described in detail,and the applicable scenarios,advantages and disadvantages of various calibration methods are analyzed.On the basis of establishing a test signal flow diagram and system error model,the Mason formula is used to derive the analytical expressions for the relationship between the measured values and the true values of the 12-term error model and 8-term error model.The advantages,disadvantages,and application scenarios of the two error models are analyzed,laying a theoretical foundation for the design of calibration substrate in the following text.2)Based on the 12-term error model theory,a low-cost SOLT calibration module is designed with the Coplanar waveguide structure.Firstly,model and simulate the short circuit kit,open circuit kit,matched load kit,and thru kit.Based on this,program to convert the measured value of the deviceunder-test(DUT)to the true value,the calibration is completed.Then,using software testing methods,a 20 d B attenuator and a 3.5 mm transmission line are used as DUT,and the parameters obtained from the simulation of the DUT with a 10 mm line added to the two ports are used as the measured values.The parameters obtained from the simulation of the DUT without line added is used as the true values to verify the calibration effect of the SOLT calibration component.In 10 GHz-40 GHz frequency band,the measured values of the two DUT have been calibrated by the designed SOLT calibration piece software,and the consistency with the true values is high.The difference in transmission coefficient amplitude is less than 0.1 d B,and the difference in transmission phase is less than 1 °.3)In response to the issues of process accuracy and matching load assembly of calibration substrate,the structural design scheme of SOLT calibration substrate has been optimized,and three new low-cost calibration substrates,namely curve,step,and through.Firstly,the parasitic parameters of calibration kits are extracted by means of software simulation,development and measurement of calibration kits,and they are input into the vector network analyzer as calibration kit parameters.Then two methods are used to verify the calibration effect of the new SOLT calibration substrate.One is the software testing method,where a 3.5 mm transmission line is used as the test piece.The results showed in the 10 GHz to 40 GHz frequency band,the calibration results of the measured values of the DUT are compared with the true values,and the difference in transmission coefficient amplitude is less than 0.18 d B,and the difference in transmission phase is less than 1 °;The second is the actual circuit testing method,which uses the same set of RF probes and uses the calibration substrate designed in this thesis and commercial calibration substrate to calibration before the test.Measurement and comparative analysis of the two-port thru kit show that the two sets of measurement results have good consistency.