About the sources of RF_layout

[jktheone]

Hi,there.
I'm a student in doing LNA,and now my research has come to the point of drawing the RF layout,but I have been researching on the schematic design, and my colleagues have no experience in drawing the RF layout,neither do we have the resources about the RF layout.
It's hard to find the resources in my country,neither can I find on the restricted website, so can anyone introduce some resources or some suggestions to me ?Thanks a lot.

 

[BigBoss]

First of all, you may look some layout examples to be inspired.I believe there should be few..

 

[jktheone]

First of all, you may look some layout examples to be inspired.I believe there should be few..

I am doing this kind of job.But you know,because I am worried about the performance that the actual layout may not satisfy the pre-simulation performance,and my colleagues are designing some low frequency ckts,(<1 GHz)they have no idea how to make such a high frequency,so could you give me some more constructive suggestions?

 

[mkhogely]

It's hard to find the resources in my country,neither can I find on the restricted website, so can anyone introduce some resources or some suggestions to me ?Thanks a lot.

What you mean by restricted website,,
it's restricted by who?? your country or website owner.

 

[Abao.lin]

You should know what kind of layout stack you choose.To draw the RF layout trace,you could use one simulation tool to find out the RF trace impedance based on the layout stack.
The tool ,AppCAD,could be a good and free tool to do that.

 

[jktheone]

my country,actually.

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Thanks. I am using the Candance for simulation and do the post-sim, but the performance deteriorates badly in the high frequency domain, I do not know the effect cause I do not know how to determine with the help of parastic parameters because they are so many.So can I use AppCAD for simulation?I only have the library in Candance.I do not know whether I have say it clearly.Thanks a lot

- - - Updated - - -

Thanks. I am using the Candance for simulation and do the post-sim, but the performance deteriorates badly in the high frequency domain, I do not know the effect cause I do not know how to determine with the help of parastic parameters because they are so many.So can I use AppCAD for simulation?I only have the library in Candance.I do not know whether I have say it clearly.Thanks a lot

- - - Updated - - -

Thanks. I am using the Candance for simulation and do the post-sim, but the performance deteriorates badly in the high frequency domain, I do not know the effect cause I do not know how to determine with the help of parastic parameters because they are so many.So can I use AppCAD for simulation?I only have the library in Candance.I do not know whether I have say it clearly.Thanks a lot

- - - Updated - - -

Thanks. I am using the Candance for simulation and do the post-sim, but the performance deteriorates badly in the high frequency domain, I do not know the effect cause I do not know how to determine with the help of parastic parameters because they are so many.So can I use AppCAD for simulation?I only have the library in Candance.I do not know whether I have say it clearly.Thanks a lot

 

[Darktrax]

AppCAD is a useful collection of calculators, with enough to figure out a LNA design, and decide on microstrip line-widths and substrate type and thickness.
It is not a full simulator! The famous simulators are like those derived from ex Hewlett-Packard, now Agilent ADS, AWR Microwave Office, Ansoft Designer & Nexxim. There are more. Several have free student versions.

I would not try and specify a layout directly, and then make an EM simulator fight through it. First use S-Parameters to decide the matching sections and interconnect features. Then you implement them in a mixture of transmission-line and lumped components as may be appropriate to their function. Decide on a substrate, and its thickness, and the AppCAD too will let you discover the line widths and lengths. At this point, you start on how much of the lines are taken up in bends, tees, etc. Now is when you need to build it into a simulation model. Even the inductance of via holes may be important. Using a program like Ansoft Designer has all the schematic and layout tools built-in. Be aware that all these tools take considerable attention to learn, and some are reputed to be more "difficult" than others, requiring much training.

If you run Linux, there is at least one free full Spice + Harmonic Balance simulator called qucs, and for layout, there is a free full featured schematic capture and PCB layout tool called gEDA. eg. On a Ubuntu installation, all these will download and install automatically if selected from the software package manager. Again, a full EDA layout tool is not a one-day play to learn. These too will have a learning curve, but fortunately, there are lots of documentation, examples, and thousands of users.

I have no experience of Cadence, but it sounds as if it was not built for true RF work. Are we wrong?

 

[jktheone]

AppCAD is a useful collection of calculators, with enough to figure out a LNA design, and decide on microstrip line-widths and substrate type and thickness.
It is not a full simulator! The famous simulators are like those derived from ex Hewlett-Packard, now Agilent ADS, AWR Microwave Office, Ansoft Designer & Nexxim. There are more. Several have free student versions.

I would not try and specify a layout directly, and then make an EM simulator fight through it. First use S-Parameters to decide the matching sections and interconnect features. Then you implement them in a mixture of transmission-line and lumped components as may be appropriate to their function. Decide on a substrate, and its thickness, and the AppCAD too will let you discover the line widths and lengths. At this point, you start on how much of the lines are taken up in bends, tees, etc. Now is when you need to build it into a simulation model. Even the inductance of via holes may be important. Using a program like Ansoft Designer has all the schematic and layout tools built-in. Be aware that all these tools take considerable attention to learn, and some are reputed to be more "difficult" than others, requiring much training.

If you run Linux, there is at least one free full Spice + Harmonic Balance simulator called qucs, and for layout, there is a free full featured schematic capture and PCB layout tool called gEDA. eg. On a Ubuntu installation, all these will download and install automatically if selected from the software package manager. Again, a full EDA layout tool is not a one-day play to learn. These too will have a learning curve, but fortunately, there are lots of documentation, examples, and thousands of users.

I have no experience of Cadence, but it sounds as if it was not built for true RF work. Are we wrong?

Thanks,buddy.I'm very thankful for your advice,honestly there are some hints that may be not very clear to me cause in our lab no one has used them,so if it is kind of you to address some wondering I gave below:
1.Cadence Spectre is kinda a simulator which can be used for RF simulation,our colleagues are using it for designing the PLL,(about 1GHz),that works,but I am required to do the designing of LNA in more high frequency domain where sufficient simulation about high frequency characteristics are required.But we do not know if spectre can do the same job well as before.But we only have the foundry tech files in Cadence.
My procedures are as follows:first I design the schematic,determine the value of lumped components,and do the simulation to verify the function.But the first question is,when extracting the parastic parameters, I can not extract the line's inductance's parameters,besides,I do not know how to determine the width of line and I only have the experience of analog layout that the current should not be large 1mA per um's wide.
So there is a huge uncertainties because I can only judge the lump components value,but I can not find the other impacts.Can I transfer the layout to ADS if I have the foundry licence in ADS?

2.Can AppCAD tool decide the length and width of the input line between the antenna and LNA?If it can do this job,so how?And can the line's layout be made on AppCAD?
3.You said the vias of inductance can be huge,so what platform should I use to simulate the layout of my LNA design?
4.You said we can decide the substrate's thickness,so does this mean the thickness of PCB?what about the thickness of subtrate (silicon)?
5.The last question,how can I put all the layout and schematic tools in the Ansoft Designer?(This question might be silly......sorry,our resources are scarce...)

Hope for your reply,thank you.

 

[jktheone]

Thank you very much on your help, it's very helpful to me!!!!