ADS S1P File used in a push-pull simulation - OK?

Hi All,

Somewhat new to ADS so forgive the newbie question. I'm trying to simulate matching networks in a push-pull RF power amplifier. The datasheet for my RF transistor gives Drain-drain impedances. I saw an application note here from Freescale called EB212 with information on how to enter theses into an S1P file ready for simulation....

http://www.nxp.com/assets/documents/...tins/EB212.pdf

I note in figure 10 on page 5 they are calling this an S2P file whereas I think that's a typo and its an S1P file. Is that correct?

Also, in figure 12 on the next page they are using a S1P data block with pins 1 & 2 connected to the matching network and no ground reference.

Is that ok, can you do that? Will the circuit be properly balanced?

My ADS does not show pins 1 & 2 but pins 1 & Ref for a 1-port SNP data block.

Thanks!

You want to present a bunch of load pull data on the gate side of the transistor and design a matching network. Since it's push-pull network the design is symmetrical. You can simplify it but just simulating the upper half or the lower half. In that case, it's just a 1 port file. The better way to do it is by calling a DAC component and load it up the CITI or touchstone file and pass it through the TERM component. This way you have more control over the variable "Zin" for sweeps.

Thanks for the reply.

Are you saying the better way is to halve the drain-drain impedance and simulate everything in a non push-pull circuit, with normal reference to ground? What then happens if I want to simulate the balun (length of coax etc.) as well?

Sorry, but I don't know what a DAC component is.

My real question remains, can you use an S1P data block in a balanced configuration like they do in the app note, not referenced to ground like normal?

Yes, you can use it like in the app note. But you can also use s2p component with a reference ground as well.

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