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Circuit Envelope Simulator Question - RF Cafe Forums

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Post subject: Circuit Envelope Simulator Question..
Unread postPosted: Fri May 21, 2004 11:55 am

hello everyone,
I use ADS to simulate a PA (modeled by a .p2d file) feedforward linearizer.
Anyone knows if in circuit envelope simulations the group delay of the amplifier is actually evaluated?or should i include it as an external delay element?
tnx in advance :wink:


Post subject:
Unread postPosted: Sat May 22, 2004 2:35 am

I think you may add the group delay option in the HB simulation engine. When you simulate a linearizer you use HB or LSSP engines to view the non-linear S-parameter results. There should be an option to view the group delay of the circuit as you do it with linear simulation. I should also check this option myself. If not, then try to use the S-parameter engine only and check the group delay option.

BTW Feedforward is not trendy nowadays, there are Pre-distortion techniques which are more popular. If you need information I will be keen to help you.

Good luck,
Itay :mrgreen:


Post subject:
Unread postPosted: Wed May 26, 2004 5:03 am

tnx for the reply.. :)
i need to use envelope simulation to see the behaviour of the linearizer when fed with complex signals, in the controller there is no any group delay option. as long as i remember it is peculiar of s-parameter controller, and is used to store in a variable called "delay" the group delay calculated from s-parameter phase.
anyway i am almost sure it is not evaluated in simulation and so am using an external delay element. if someone has a final ansewer on the subject i am listening ;-)



Post subject:
Unread postPosted: Thu May 27, 2004 3:13 pm

Are you using the Ptolmy tool for envelope simulation or another tool?

You said that you use an external element for delay, Are you using it as a constant reference delay at the input and by that derive the the delay that your system contributes?

There must be a delay option that as you said is calculated from the delay of the S-parameters: delta phase/frequency, and from that the group delay is derived. I used it myself not long ago to find a group delay of a filter.



Post subject:
Unread postPosted: Fri May 28, 2004 10:31 am


i am using envelope inside the RF/Analog simulator, not ptolemy.

i introduced a delay element after the amplifier to simulate the effect of the group delay, because i didn't see the effect of the group delay on the previous simulations results.

i couldn't find any option related to group delay in envelope controller, i looked in the hidden parameters (the ones in the display tab) but found nothing.



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