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How do we get Sparamter results with "term" used as input-output in ADS

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Avinash Akotkar

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This is very basic concern which I dont understood.
I have LPF circuit which has term as input and output.
Term.PNGoutput.PNGcircuit.PNG

Here I have below concern:
I define term with default setup. I dont understand how I am getting LPF output s21 if nothing has given.
Is port acting as input source with some power?
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
Is port acting as input source with some power?
Click to expand...
Conceputaly, you may consider like following.
For s11 and s21, port1=hot, port2=cold
For s12 and s22, port1=cold, port2=hot
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

pancho_hideboo said:
Conceputaly, you may consider like following.
For s11 and s21, port1=hot, port2=cold
For s12 and s22, port1=cold, port2=hot
Click to expand...

is their any doucument which can show me how "term" in ADS or "port" from cadence are used to calculate s-paramter?. I went though internet but it only shows me, place port and do connection and you will get this result. I dont want this. I want some simple and clear explanation.
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
I want some simple and clear explanation.
Click to expand...
Too easy thing except for you.

Calculate Y-parameter, then convert it to S-parameter.

Study and learn how to calculate Y or Z parameters.
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

pancho_hideboo said:
Too easy thing except for you.

Calculate Y-parameter, then convert it to S-parameter.

Study and learn how to calculate Y or Z parameters.
Click to expand...

I think you have not got my question. I know about S, Y and Z but here my concern is how "term" is used to calculate it. I mean here I have not define any signal in "term" componant e.g vtg level, power level etc but still I am getting output. As per my knowlege concern, if you dont give nay input to DUT then you should not get any output.
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
I think you have not got my question. I know about S, Y and Z but here my concern is how "term" is used to calculate it. I mean here I have not define any signal in "term" componant e.g vtg level, power level etc but still I am getting output. As per my knowlege concern, if you dont give nay input to DUT then you should not get any output.
Click to expand...
ADS stimulate the circuit with a very low signal level by default s-parameter definition even there is no field for signal spec..That's it you don't understand..
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
I know about S, Y and Z
Click to expand...
You can not understand them at all.

Avinash Akotkar said:
but here my concern is how "term" is used to calculate it.
Click to expand...
It specifies reference impedance.
Reference impedance is required for S-parameter.
On the other hand, Y or Z paramete don’t require reference impedance.

Avinash Akotkar said:
I mean here I have not define any signal in "term" componant e.g vtg level, power level etc but still I am getting output.
Click to expand...
Any stimulus signal is not required for calculating Y or Z parameter.

Avinash Akotkar said:
As per my knowlege concern,
if you dont give nay input to DUT then you should not get any output.
Click to expand...
Surely learn kindergarten level linear circuit theory.
 
Last edited:

Re: How do we get Sparamter results with "term" used as input-output in ADS

BigBoss said:
ADS stimulate the circuit with a very low signal level by default s-parameter definition even there is no field for signal spec..That's it you don't understand..
Click to expand...

That is what I was asking. Do you know what is default value of low signal ADS using to simulate circuit?

- - - Updated - - -

pancho_hideboo said:
You can not understand them at all.

It specifies reference impedance.
Reference impedance is required for S-parameter.
On the other hand, Y or Z paramete don’t require reference impedance.

Got answer on below link
https://www.maximintegrated.com/en/app-notes/index.mvp/id/2866
Click to expand...
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
Do you know what is default value of low signal ADS using to simulate circuit?
Click to expand...
Still you can not understand things correctly.

There is no stimulus signal in S-parameter Analysis in both Keysight ADSsim and Cadence Spectre.

“Term” or “port” define only reference impedance.
No stimulus signal.

Surely learn kindergarten level linear circuit theory.
 
Last edited:

Re: How do we get Sparamter results with "term" used as input-output in ADS

Avinash Akotkar said:
That is what I was asking. Do you know what is default value of low signal ADS using to simulate circuit?
Click to expand...

It is undefined and meaningless, because S-parameters are linear parameters and don't depend on the signal level.
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

S-parameter simulation is a subset/kind of AC Simulation so there is a very low level stimulus but hidden.Otherwise simulation will not run without no source condition.
This is valid also in EM simulations.When you place a Port, in fact you have been placing a generator with a very small voltage level.The EM simulator computes the rest..
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

BigBoss said:
S-parameter simulation is a subset/kind of AC Simulation
so there is a very low level stimulus but hidden.
Otherwise simulation will not run without no source condition.
Click to expand...
Wrong.

There is no stimulus signal in S-parameter Analysis.
Any hidden signal does not exist.

Assume circuit with many ports.
If we do analysis with changing port exciting, it is too uneffective.

Any stimulus signal is not required for calculating Z or Y parameters.
Here we don’t have to calculate any node voltage or branch current.
 
Last edited:

Re: How do we get Sparamter results with "term" used as input-output in ADS

pancho_hideboo said:
Wrong.

There is no stimulus signal in S-parameter Analysis.
Any hidden signal does not exist.

Assume circuit with many ports.
If we do analysis with changing port exciting, it is too uneffective.

Any stimulus signal is not required for calculating Z or Y parameters.
Here we don’t have to calculate any node voltage or branch current.
Click to expand...

spar.png ports.png

All Linear Time Invariant Circuits in this universe ( passive,active,linear or nonlinear) must satisfy this equation below.
state.png
Simulators use these specifications and NO circuit can be simulated without Excitation Source.
 
Last edited:

Re: How do we get Sparamter results with "term" used as input-output in ADS

BigBoss said:
Simulators use these specifications and NO circuit can be simulated without Excitation Source.
Click to expand...
Wrong.
You are misunderstanding.

It is true for DC and Transient Analysis.
But it is not true for small signal linear analysis.

Assume state space formulation.
Matrix A,B,C and D for small signal analysis can be calculated by DC Analysis.
Here small signal stimulus is not used at all.
Y, Z or S matrix can be derived from {A,B,C,D} directly without stimulus.

Evaluation of S-parameters is different between circuit and EM simulation.

If we use same method as EM simulation, it is too ineffective and high computing cost for circuit simulation.

Consider a meaning of “conceptually” in https://www.edaboard.com/showthread.php?383978#2
 
Last edited:

Re: How do we get Sparamter results with "term" used as input-output in ADS

pancho_hideboo said:
Wrong.
You are misunderstanding.

It is true for DC and Transient Analysis.
But it is not true for small signal linear analysis.
Click to expand...

If your hypothesis is correct, this circuit should have been simulated by ADS but gives an error..
AC.PNG

Any circuit which the Sources are not Existing cannot be simulated, it's controversially against the Circuit Theory.
 

Re: How do we get Sparamter results with "term" used as input-output in ADS

BigBoss said:
If your hypothesis is correct, this circuit should have been simulated by ADS but gives an error..
Click to expand...
It is very natural, since you do AC analysis.

AC analysis requires at least one small signal stimulus, since it calculates node voltages and branch current.

BigBoss said:
Any circuit which the Sources are not Existing cannot be simulated,
it's controversially against the Circuit Theory.
Click to expand...
Wrong.
You are completely misunderstanding.

S-parameter Analysis does not require any small signal stimulus.
Rather if you include small signal sources in schematic, S-parameter analysis ignores them.
 

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