Recent content by yefj

Hello Baluncore,what is the proper way to implement Kramers-Kronig on my s-params which has only 10MHz-67GHz? for causality checking.

Hello , Kramers–Kronig need infinite BW but I measure s-params from 0 to 70GHZ. how do you reccomend to deal with the missing data? Thanks.

Hello , I am frequently using CQMI to see if my s-parameters are casual however I was told the CQMI can give false results. What is the cases where I should not rely on CQMi? https://resources.altium.com/p/ieee-p370-standard-high-speed-pcb-interconnects Thanks.

UPDATE: Hello Baluncore ,I was told the following advice the CQMI is not the ultimate authority to test if the tested s-params is accurate. Could you please reccomend me a better method to know if my s-params are good or not? Thanks. I would compare the time-domain response (TDR/TDT), inspect...

Hello Balucore, Very intresting what you said could you please help me with the following so I will see the situation in more detail? 1.Do you have some good CQMI manual which mathematicakly shows how we process the s-params? 2.Could you recommend me basic EM simulation physical of uneven...

Hello Balun core, this is very intersting.if I understand correctly then CQMI is doing error vector magnitude on the samples of the s-params as shown below. when the dielectric coefficient is not constant then I agree the reflection coeffient get bad so I expect the SDD21 to go bad because of...

How exactly can non stable dielectric constant make the s-params non casual? same thing says Balun core with bad derminations. why impedance discontinuety can do such a thing. impeedance discontinuty makes bad insertion loss. How its linked to CQMI causality? Thanks.

Hello Baluncore the 6 inch line is the one giving better causality. both differential lines are 80 ohms and have two SMA on each end as shown bellow. bad termination will just create reflections ,bad insertion loss. How bad termination can cause causality issue in CQMi? Hello Rive, Why weave...

Hello , I am measuring two differential lines one is 3 inch the other is 6 inch over a span of 70 GHz. one differential line shows 92% percent causality CQMi while the other is 66% CQMicausality.The PNA is well calibrated. why is that ? causality means the quality of the s-params is not good ...

Hello , I did PCB tests in "oven" with long cable like 1m long cable , the causality was very bad like 30% instead of 80%. So first of all I dont know if my calibration got ruined when the cables are at 85C temperature oven connected to DUT. I am trying to think of a strategy. few questions...

Hello sophiecentaur,the main issue is the cables connected to the vnacould be making this causality issue. I am using n2814a cable. How can I test test them to see that they are properly functioning? Thanks...

Hello, I am using VNA with ifbw=3KHz span 10MHz to 70GHZ step 10MHz. I am measuring differential lines SDD11 for TDR uding IFFT. If my IFFT TDR windows is 100ns then an event in 120ns will go to -20ns thus will create causality issue. Anothe cause I know is deembeding creating ringing ,but i...

Hello, I have simulated a situation where we have 3 differential lines as shown below. port 1 has no termination so he has to affter SDD23 . From sdd23 we se resonances spaces 1.23GHz one from another. substrate er=4.1 the traxes are 50mm long. How can I link the distance between the resonance...

Hello, I have tried to implement an open circuit microstrip resonator . I got the microstrip resonating at 5Ghz as shown below. However the S-parameters is very bad. Is there a way to improve the matching so It will have a better dip in 5GHz.

Hello BalunCore 'The impedance is the impedance of the line.the material i think has the same er but different quality.the line impedance I think was simulated that how the PCB trace width was made. is there something more which is needed to have a conclution on the plots at previos post? Thanks.