Effect of the BFMOAT to the oscillator frequency

[jwonoh]

Hi all!

I'm designing an mm-wave oscillator and simulating it through ADS Momentum.
I drew the high resistivity substrate, the BFMOAT layer, under the inductor to decrease the substrate noise contribution.
However, the simulation doesn't support the BFMOAT layer and its effect was ignored.
So I have an uncertainty whether the BFMOAT affects the oscillation frequency of the oscillator and the tank Q.

What do you think about it? Does the BFMOAT layer affect the frequency characteristic or Q of the tank?
Thanks.

 

[dick_freebird]

The stray capacitance (with its inherent series
access resistance in the lightly doped silicon)
will pull frequency, and eddy currents in that
layer will degrade Q as a "burdened winding"
below.

Ideally (or less non-ideally) the resistance will
tamp down the effects of these actors at the
frequencies of interest. But observing that, is
where you'd like accurate models.

So you're probably facing the task of adding
any realism which you may notice the lack.
That might be generic components informed
by measurement or literature, placed sensibly.

 

[BigBoss]

ADS Momentum supports all kind of layers since they are well defined.