How to test a matching circuit

[kellyza]

Hi all...

Just would like to know how to test a matching circuit? I mean how to determine that the matching circuit either at the input or output port is done correctly and under expectation? One more is which is better either we test the matching using lumped element circuit or using distributed circuit?

Thanks in advance,
-Kellyza-

 

[bubuta77]

I guess if you below 3-5GHz it's preferable to use lumped element circuit because you always can change things if you find a mistake.
If matching supposed to be a conjugate matching you must measure the maximum gain something near to spec. measuring s11 and s22 must give you a negative peak at desired frequency or at least something that looks like.
For maximum output power you must see the imroved linearity charachteristics (OIP3/P1DB/ACPR... whatever) close to the datasheet. s11 still must have a negative peak, but s22 no.

 

[mkonca]

bubuta, how did you even understand kellyza was asking about an amplifier? And wouldnt it be better to use a VNA for measuring matching? (assuming kellyza has one since you are talking about "OIP3/P1DB/ACPR... whatever".

 

[kellyza]

Hi all...

Actually I'm designing an up-conversion mixer at 12.4 GHz. I designed using distributed network with input and output matching. My concern is how to determine that my matching circuit was done correctly for the desired frequency and how to test it. I've tried getting the S11 at input port and S22 at the output port and I did not exactly get the negative power drop at the desired freq as been told by bubuta77. Then what I did, I just tuned my distributed circuit to get the power drop at the desired frequency. I just want to make sure that am I doing it correctly using the distributed circuit or I need to test using the lumped circuit?

Thanks for the concern.
-Kellyza-

 

[johnnykhor]

hi everyone, i have quite similar question as kellyza mentioned.
However, I'm my question is: how to convert a matching circuit (microstrip-open circuited stub) into lump element.
my purpose in doing this is because of saving space.

thx in advance for replying.