How to simulate a subharmonic mixer in ADS?

[mfarhan1]

Dear all
I want to simulate an ideal (or real) subharmonic mixer in ADS. I could nt find any model for subharmonic mixer in ADS library and ADS toolbars that i can use.
The hardware component i have is XLD-X3 subharmonic mixer from synergy.

Can any one guide me how can i simulate subharmonic mixer? I dont want to design it.

Thanks, your help is really appreciated

 

[RF-OM]

Re: Subharmonic Mixer

May be Synergy can give you a model or S-parameter file?

 

[mfarhan1]

Subharmonic Mixer

hmmm i could not find any s parameter file on the web site of synergy. Now i am thinking of measuring S parameter by myself and put them into ADS.

any suggestion for alternative?
thanks

 

[RF-OM]

Re: Subharmonic Mixer

I think you can do it. There may be a couple of problems. First of all S-parameters defined for certain impedance and all three ports must be terminated with this the same impedance. This is often not the case for mixers, moreover mixer often have different impedance during the single period of LO signal. You may try to use VNA and measure the S-parameters, but what VNA will actually measure it is hard to say. Next problem may be with different relation between input and output signals compare with normal mixers. You need to check what your particular VNA requires for mixer measurements. There are some application notes on Agilent web site about mixer measurements with VNA. If you will not find them let me know and I may check my library.

 

[khouly]

Subharmonic Mixer

i don't know, if u inculded the S pam of the mixer ADS will take the mixing action into account or not.

u can make it by using freq multipier and mixer. this will be a system block.

khouly

 

[toonafishy]

Re: Subharmonic Mixer

subhamonic mixing is a non linear process. i doubt S parameters will capture the performance

 

[khouly]

Re: Subharmonic Mixer

please check the document i have attached
it is a very simple system models in ADS i have created from the frequency multiplier and mixer a subharmonic mixer

wish this helps u

khouly

 

[RF-OM]

Re: Subharmonic Mixer

To toonafishy,

Yes, usage of S-parameters for mixer measurement and analyzes is not easy task. But it is possible. May be not for any case, but at least for some of them. By the way, I afraid that some of EDAboard members will fight to this opinion, but this is the true that linear mixer is possible. I mean mixer that made from linear (from RF point of view) elements. I invented such circuits, built them, tested and used a lot. They performed excellent, but I am sure many of university professors will bite me immediately. The beauty of these mixers is that they provide very high quality mixing and for some of them no LO currents practically flow through the mixer. These circuits may be considered as a kind of subharmonic when IF is not equal to n*RF+/-m*LO and they may be well described with standard S3P files. Therefore at least for some cases it is possible to use S-parameters file for mixer analyzes.

 

[khouly]

Subharmonic Mixer

RF-OM

do u mean by the linear mixer is the mixer based on time variant linear element. like the resistive FET mixer and so on. yeah this is possible , even i have designed and tested one.

if you mean other circuit would u please give a link for it or give a paper.

thanks
Khouly

 

[RF-OM]

Re: Subharmonic Mixer

You are right: such a mixer is one of an examples for mixer built with linear element. But in this case impedance is variable and usually we may consider it as geometric means from min and max values. At least for noise calculations. In previous post I mean another circuits. There are no links and papers because I did not publish the results due to the special purpose of these developments. It is still closed for a while. It is interesting that today you practically immediately mentioned at least one example of such a circuits. Long time ago I spent about two years until I found the mathematical prove that linear mixer is possible into one of rare and very old book that was publish in 1964.

 

[khouly]

Subharmonic Mixer

i worked with mixers alot during my master work , which is have finished very soon. my main reference was Steve Maas work.

khouly

 

[RF-OM]

Re: Subharmonic Mixer

Oh, I know Steve and his books. He is one of the best authors about mixers and noise. Good luck with your masters!

 

[khouly]

Subharmonic Mixer

thanks RF-OM

yeah Steve Maas is great author. i studied his book about nonlinear microwave circuits it is amazing.

khouly

 

[RF-OM]

Re: Subharmonic Mixer

Yes, he is nice to talk too and he is definitely knows all these subjects well.

 

[mfarhan1]

Re: Subharmonic Mixer

First of all
Thanks to all of you for your expert advice.
The file uploaded by khouly is really helpfull and very interesting way of simulating Subharmonic mixer. I agree with toonafishy and RF-OM that S paramter is not that stright as they are for filters etc, I dont want to put myself in that trouble of calculating S parameters. RF-OM i did look on agilent application notes they are really helpful when measuring mixers.
Very amazing to know about mixer with linear elements. Stev maas has written excellent books on mixers and nonlinear elements i read them. I am working on mixers with Prof. I.D Robertson and would seek your help further

By the way is any of you working on LTCC!
Cheers all.

 

[khouly]

Subharmonic Mixer

i am trying to find information about it , and how to design microwave circuits using LTCC. but LTCC is design is always a process dependent so u need to have a design kit fot it

if u have any resorses about it please share

Khouly

 

[RF-OM]

Re: Subharmonic Mixer

As far as I know LTCC is make sense on frequencies higher than 10 GHz. Below 10 GHz it is too expensive and may provide too low yield. This is very old technology, but surprisingly there is almost no changes for so many years. I considered LTCC for several times and always regular PCB won.

 

[khouly]

Subharmonic Mixer

what about think film technology , i saw many RF FEMs and PAM's are designed using thin film

also this technology is used in RF SIP

khouly

 

[RF-OM]

Re: Subharmonic Mixer

I did not use this technology yet. Could you please tell a bit more about it and give some link(s) to find the information?

 

[khouly]

Subharmonic Mixer

check this
**broken link removed**
http://eesof.tm.agilent.com/pdf/rf_sip_module_design_verification.pdf
http://www.thin-film.com/web/TFT.nsf/+view+/A4FB30ADCDB0C7F8862573F6007E6160/$FILE/tft_custom_electrical_filter_designs.pdf

khouly