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The 'sparam_to_tf' utility is useful when fitting a single chosen port-to-port transfer function from an S-parameter file. I even managed to build a four-port transmission line model by extracting the transmission and crosstalk transfer functions individually and then combining the fitted results. However, the task gets overwhelming as the number of ports increases. Is there an automated way to extract an entire transmission line model including all the port-to-port transfer functions from an S-parameter file?
Yes, there is! The XMODEL 2021.06 release introduced the 'sparam_to_tline' utility, which can extract an entire transmission line model including all the port-to-port transfer functions from an S-parameter file.
Here is a basic usage of the 'sparam_to_tline' utility. The command below will fit all the transmission transfer functions (i.e. the transfer functions with non-zero DC gains) stored in an S-parameter file named 'channel.s4p' with the accuracy suitable for 16Gb/s data rate and store the results in a parameter description file named 'channel.dat':
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --plotwave
To fit the crosstalk transfer functions as well, you can add the '--xtalk' option:
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --plotwave --xtalk
Now with the extracted parameter description file 'channel.dat', you can instantiate an 'stline' primitive to add a transmission line model to your simulation:
stline #(.num_port(4), .filename(“channel.dat”)) ST (.pos(sig[4:1]), .neg(gnd[4:1]));
There is also a symbol available for this 'stline' primitive in GLISTER.
One key feature of the 'sparam_to_tline' utility and 'stline' primitive is that they can deliver much faster simulation speed if the source and load termination conditions are known in advance. For instance, if both the source and load sides of the transmission lines are terminated with a parallel combination of 50-ohm resistance and 1pF capacitance, extracting the model with the following '--Z0' option can significantly reduce the number of simulation events and hence improve the simulation speed:
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --Z0 "R50||C1p" --plotwave --xtalk
The attached application note describes this 'sparam_to_tline' utility in more detail, with a simple exercise example.
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XMODEL에 포함되어 있는 'sparam_to_tf' 유틸리티는 S-파라메터 파일에 포함되어 있는 하나의 선택된 포트-대-포트 전달함수를 추출하는데 유용합니다. 저는 이 유틸리티를 사용해 개별 전달함수들을 하나씩 추출하고, 그 결과들을 조합해 4-포트 전송선 모델을 만들어보기도 했습니다. 하지만, 포트의 수가 증가하면 개별적으로 추출해야 하는 전달함수가 너무 많아지는 것 같습니다. S-파라메터 파일에 정의된 모든 전달함수들을 추출하여 하나의 온전한 전송선 모델을 만드는 좀더 쉬운 방법이 있을까요?
Yes, there is! The XMODEL 2021.06 release introduced the 'sparam_to_tline' utility, which can extract an entire transmission line model including all the port-to-port transfer functions from an S-parameter file.
Here is a basic usage of the 'sparam_to_tline' utility. The command below will fit all the transmission transfer functions (i.e. the transfer functions with non-zero DC gains) stored in an S-parameter file named 'channel.s4p' with the accuracy suitable for 16Gb/s data rate and store the results in a parameter description file named 'channel.dat':
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --plotwave
To fit the crosstalk transfer functions as well, you can add the '--xtalk' option:
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --plotwave --xtalk
Now with the extracted parameter description file 'channel.dat', you can instantiate an 'stline' primitive to add a transmission line model to your simulation:
stline #(.num_port(4), .filename(“channel.dat”)) ST (.pos(sig[4:1]), .neg(gnd[4:1]));
There is also a symbol available for this 'stline' primitive in GLISTER.
One key feature of the 'sparam_to_tline' utility and 'stline' primitive is that they can deliver much faster simulation speed if the source and load termination conditions are known in advance. For instance, if both the source and load sides of the transmission lines are terminated with a parallel combination of 50-ohm resistance and 1pF capacitance, extracting the model with the following '--Z0' option can significantly reduce the number of simulation events and hence improve the simulation speed:
sparam_to_tline channel.s4p -r 16e9 –o channel.dat --Z0 "R50||C1p" --plotwave --xtalk
The attached application note describes this 'sparam_to_tline' utility in more detail, with a simple exercise example.
Please login or Register to submit your answer