*From*: "Andrew Byers" <abyers@xxxxxxxxxx>*To*: <codymiller@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>*Date*: Wed, 19 Dec 2007 16:42:06 -0800

Hi Cody, It seems there are two methods you could use to turn measured S11 data into TDR-like data: 1 - Directly translate the S11 data (frequency-domain) to a time-domain representation 2 - Simulate a transient waveform interacting with the S11 data block in a circuit simulator The first method is usually a built-in function found in VNAs or EM-extraction programs. The fundamental procedure used is an inverse fast fourier transform (IFFT). Application of the IFFT to the frequency-domain data can yield a time-domain step-response and even a TDR-waveform. Given complex s-parameter data, an IFFT-based procedure can also be implemented in standard mathematical packages like Matlab. The second method is to perform a transient circuit simulation with the measured S-parameter block. Here you can define a step-source and series resistance connected to the s-parameter block, run the simulation, then calculate and plot the TDR response. The pitfalls here include passivity issues (yes, measured s-parameters can sometimes come over as "non-passive"), implementation method (pole-zero or convolution), DC-extrapolation, and high-frequency content. The transient simulation of s-parameters seems to be what some of the other posts refer to - this is where you'll see the differences between technologies that the EDA industry offers. If all you require is a TDR waveform from the measured S-parameter block alone, then method 1 above is probably sufficient. However, if other circuit elements, models or stimuli are to be included (as in a channel or system), then you're probably going to be looking at method 2. If you'd like to talk more about what Ansoft offers with respect to either of these methods, please feel free to contact me offline and I'd be glad to help. Regards, Andrew Byers abyers@xxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of codymiller@xxxxxxxxxx Sent: Wednesday, December 19, 2007 10:15 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] S parameter to time domain signal All, Does anyone in the group know of any available software packages that can take post measurement S11 data and convert it to a time domain reflected signal? Thanks, Cody Miller ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu

**References**:**[SI-LIST] internal time step too small error in transient analysis***From:*boli sudha

**[SI-LIST] Re: internal time step too small error in transient analysis***From:*vuk_borich

**[SI-LIST] S parameter to time domain signal***From:*codymiller

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