anybody know about the MOD$$T simulation of e1do rf?

[cqmyg5]

Hi,

I'm studying the MOD$$T simulaiton of e1do rf, there's a question,

Is it possible to run co-sim with eldo and eldo rf? That is to co-sim some RF block(in spice) running in SST simulaiton and some ANALOG block(spice) running in TRAN?

 

[bozzo]

Re: anybody know about the MODSST simulation of eldo rf?

Hello,
Yes you can co-simulate with EldoRF differents blocks running either in .TRAN
or in .MODSST
the syntax to specify how to run in .MODSST the desired blocks is :
.part modsst inst=(name, ...)
so the rest of the circuit will be analyzed in .TRAN

feel free for more questions !
Bozzo.

 

[cqmyg5]

anybody know about the MODSST simulation of eldo rf?

I tried the ".part modsst inst=(name, ...) ", but the simulation result is not correct.

Actually my circuit contains a lna, a mixer and a bpf, if used SST, it can give me right result. But using ".part modsst inst=(Xlna, Xmixer) " for lna and mixer, ant MOD$$T along with two tones SST for whole ciruit, it gave me wrong result.

 

[bozzo]

Re: anybody know about the MODSST simulation of eldo rf?

Hello,

MODSST works for any Ntone simulation but the right way to simulate a 2tone circuit
is to specify a 1tone SST along the LO in order to have the second fundamental frequency
as a modulation of the LO (or one of its harmonics).

for instance if your mixer has LO=910meg and RF=900meg
the correct setup for a MODSST simulation is :

.SST FUND1=910meg NHARM1=10
.param valfund2=900meg
and where you have sources along RF put valfund2 in place of FUND2
So the excitation of the RF sources will be considered as a modulation of FUND1.

Last thing : there are no limitations concerning the type of the blocks in .part modsst

Bozzo

 

[cqmyg5]

Re: anybody know about the MODSST simulation of eldo rf?

Thank Bozzo,

I have tried your solution of MOD$$T with one tone, but it doesn't work.

I am so sad, because I have studied it for 5 days, and still don't know what's the problem. The IF should be 1MHz, two tones SST is OK, but MODSST(.part modsst inst=(XLNA,XMIX)) with one tones SST is failed.

 

[bozzo]

Re: anybody know about the MODSST simulation of eldo rf?

Hello,

I am not sure you use correct syntax to display waveforms at the outputs.
If you want to display nodes in .TRAN block you have to use the following syntax :
.plot tran v(V1I) v(V1Q)

concerning the nodes at the interface between the mixers and the BPFs, you
have to use .plot tmodsst v(IFI) v(IFQ), and in order to have the best representation
for the waveforms, please use .option modsst_full_display=2 (the simulation will be slower).

please post the new .JPG. Which release do you use (ams2006.1, 2, 2a, 2b) ?

Bozzo.

 

[cqmyg5]

Re: anybody know about the MODSST simulation of eldo rf?

Hello bozzo,

I think I plot the right waveform.

Finally, maybe it's not a good version.