Interstage matching-LNA-Cadence error
I have a 2 stage LNA and I am trying to do inter-stage matching.I found 1st stage output impedance and 2nd stage input impedance. I created 2 ports with conjugate of these impedance in a separate schematic and found the matching network using ADS.But when I am running SP analysis I am getting an error "Arithmetic exception in analysis `sp' ".
I attached error and the inter-stage network.
I want to know whether this is the correct way to do inter-stage matching and how to resolve the error.Thanks in advance.
But Zxx parameters are not used for matching if s-parameters have been used because Zxx parameters are open circuit parameters and they don't give input/output impedances when the other ports are terminated.You do it wrong..
Second, Complex conjugate impedances are very close so you don't need a matching circuit.
I am sorry ,yes they are Sparameter values .I wrote it wrongly on the paper. They are S11 and S22.
Your matching circuit is not correct.A simple 52.35pH inductor in series can be used for optimum matching but I have mentioned above, this circuit does not need a matching circuit because impedances are very close.
Exactly, one inductor can do the job,but what If I want broadband matching?
and you mentioned "Complex conjugate impedances are very close so you don't need a matching circuit." what if they are not close, then this way of doing is correct?
-Question: How much broadband matching you need ?
The technique is correct ( I presume that you did a typo about Zxx instead of Sxx ) but this is valid at one single frequency and since the impedances are very close broadband matching-especially in that region of Smith Chart- is pretty difficult.If the impedances are not very close, you will need a matching at that frequency.( Wavelength is relatively short )
More than 10Ghz but I am targeting for 20GHz ,from 50GHz to 70GHz ,centered at 60GHz.
Forget about Broadband Matching.
Connect two circuits directly.No matching is necessary..
Describe correctly using correct terminologies.
This thread title is "Interstage matching-LNA-Cadence error".
I don't know what you want to mean by Cadence.
Show me netlist.
Generally, we use Short-Probe for evaluation of interstage impedances.
Show me netlist.
Do you surely think so ?
Their magnitude are far bigger than 1.0.
I think Z22 is Zleft and Z11 is Zright.
Describe correctly using correct terminologies.
Now I gave different resistance and reactance values in the ports
When I run the SP analysis for the above circuit, I got the below error.
Warning from spectre at freq = 70 GHz during SP analysis `sp'.
WARNING (SPECTRE-16518): Arithmetic exception in analysis `sp' .
Could you tell more about it.I have not used this before.
I got those values from Smith chart after running SP analysis for 1st stage(at the output side-->54+j231 ohm) and 2nd stage (at the input side-->59.64-j254 ohm) at my frequency of interest.
No.
Same warning surely appered before.
Show me netlist.
Show me simulator correct name and version which you use.
There is no simulator whose name is ADS or Cadence.
So they are not S11 and S22.
https://www.edaboard.com/showthread.php?t=376172#3 is completely wrong.
They are not S11 or S22, they are just un-normalized Input Impedances.@50 Ohm Zc.
I understood that it's not an error ,it's just a warning. So it didn't effect my work.