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

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

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

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?

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

Originally Posted by Avinash Akotkar
Is port acting as input source with some power?
Conceputaly, you may consider like following.
For s11 and s21, port1=hot, port2=cold
For s12 and s22, port1=cold, port2=hot

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

Originally Posted by pancho_hideboo
Conceputaly, you may consider like following.
For s11 and s21, port1=hot, port2=cold
For s12 and s22, port1=cold, port2=hot
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.

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

Originally Posted by Avinash Akotkar
I want some simple and clear explanation.
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.

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

Originally Posted by pancho_hideboo
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.
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.

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

Originally Posted by Avinash Akotkar
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.
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..

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

Originally Posted by Avinash Akotkar
I know about S, Y and Z
You can not understand them at all.

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

Originally Posted by Avinash Akotkar
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.
Any stimulus signal is not required for calculating Y or Z parameter.

Originally Posted by Avinash Akotkar
As per my knowlege concern,
if you dont give nay input to DUT then you should not get any output.
Surely learn kindergarten level linear circuit theory.

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8. ## Re: How do we get Sparamter results with &quot;term&quot; used as input-output in ADS

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

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[QUOTE=pancho_hideboo;1648212]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.

https://www.maximintegrated.com/en/a...ex.mvp/id/2866

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

Originally Posted by Avinash Akotkar
Do you know what is default value of low signal ADS using to simulate circuit?
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.

10. ## Re: How do we get Sparamter results with &quot;term&quot; used as input-output in ADS

Originally Posted by Avinash Akotkar
That is what I was asking. Do you know what is default value of low signal ADS using to simulate circuit?
It is undefined and meaningless, because S-parameters are linear parameters and don't depend on the signal level.

11. ## 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..

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

Originally Posted by BigBoss
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.
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.

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

Originally Posted by pancho_hideboo
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.

All Linear Time Invariant Circuits in this universe ( passive,active,linear or nonlinear) must satisfy this equation below.

Simulators use these specifications and NO circuit can be simulated without Excitation Source.

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

Originally Posted by BigBoss
Simulators use these specifications and NO circuit can be simulated without Excitation Source.
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

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

Originally Posted by pancho_hideboo
Wrong.
You are misunderstanding.

It is true for DC and Transient Analysis.
But it is not true for small signal linear analysis.
If your hypothesis is correct, this circuit should have been simulated by ADS but gives an error..

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

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

Originally Posted by BigBoss
If your hypothesis is correct, this circuit should have been simulated by ADS but gives an error..
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.

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