how to simulate phase noise in spice or Hspice

[cici]

I am trying to simulate phase noise of a VCO using Hspice and Spice.
How can I do it? Thank you.

 

[[email protected]]

Because spice can only handle noise simulation for linear circuit.
I don't think it is doable
laomao

 

[Jens Tingleff]

I am trying to simulate phase noise of a VCO using Hspice and Spice.
How can I do it? Thank you.

I should think that you can use the latest Hspice RF, read the manual.

http://www.synopsis.com/products/mixedsignal/hspice/hspice.html

Best Regards

Jens

Key ID 0x09723C12, [email protected]
Analogue filtering / 5GHz RLAN / Mdk Linux / odds and ends
http://www.tingleff.org/jensting/ +44 1223 211 585
"Never drive a car when you're dead!" Tom Waits

 

[Polyonomous]

I am trying to simulate phase noise of a VCO using Hspice and Spice.
How can I do it? Thank you.

The biggest influence in a phase noise measurement is the substrate used in the
semiconductor. Examples are cmos, phemt, gaas, none of the spice variants take
that into account. {afaik}

 

[Steven Swift]

Because spice can only handle noise simulation for linear circuit.
I don't think it is doable
laomao

Use non-linear controlled sources fed with sinwaves into your circuit to
create a semi-discrete implementation of your noise shape. The last guy
I saw do this with spice got almost perfect results-- but he was a "brainiac"
and I never fully understood how he did it. Took him months to get it
right.

Steve.

 

[Subhajit Sen]

I am trying to simulate phase noise of a VCO using Hspice and Spice.
How can I do it? Thank you.

One way that it could be done is to introduce noise current
source PWL data statements at each node of the VCO ring included as a
data file.

The PWL data statements should be generated from a random noise
generator
using C or Matlab progam and each noise source should be uncorrelated
with the other sources. So if you are using a 3 stage differential
ring VCO you need 6 I statements. The RMS value of the noise
current could be obtained by determining the equivalent thermal
noise current from the transistor that switches. Use the
formula for noise from Gray&Meyer book (inoise_thermal=(8/3)k*T*gm)
for a transistor in saturation).

That said, even the above method is approximate/crude, since
the noise current of the transistor is 'time-varying' i.e. depends
upon its operating point. So the RMS noise current value will be
different at each
time-point as the transistor switches from linear to saturation.

Regards,
Subhajit