Re: Frequency Domain and Noise Domain

Amro,

Your question seems to be about the VHDL-AMS language definition related to the concept of 
a domain. 

Quiescent domain, time domain and frequency domains are very general concepts. These 
domains are, as you observed, supported by the language definition. There can be several 
different simulation types in each domain, and simulation types may span domains. For 
example, IEEE Std 1076.1-1999 defines in 12.6 a simulation to start in the Quiescent 
domain and then enter the time domain. In SPICE, this would correspond to transient 
analysis (which in SPICE is preceded by an operating point analysis). Similarly, it 
defines in 12.8 two simulation types that both start in the Quiescent domain, then enter 
the frequency domain: small-signal frequency domain calculation and noise calculation, 
both of which correspond to SPICE analyses. Other simulation types are possible in each of 
the domains.

Conversely, noise is a phenomenon of physical circuits. As such, it can be modeled and 
simulated. I have already discussed the IEEE Std 1076.1-1999 noise calculation, which 
occurs essentially in the frequency domain. However, noise calculation can also be done in 
the time domain, although such a simulation is not as well established as a frequency 
domain (small-signal) noise calculation. Each type of noise analysis requires a different 
way of modeling the noise effects. We conclude that noise is not a domain, but something 
orthogonal to it.

Thanks.
Ernst Christen

On Wed, 15 Mar 2006 05:05:10 -0800, Amr Turk wrote:
> Dear all,
> I'm working on a VHDL-AMS noise source, that can be used in ADMS. As known that ADMS 
doesn't support noise sources in VHDL-AMS tell now. So I - with the help of Joachim Haase- 
created a sin source that generates noise on the original signal. I have posted it before. 
But the problem now, is I want this source to interact with the simulator according to the 
domain of analysis.
> I mean that when working in the Transient Domain, No noise should appear.But when 
working in the Noise_Trans, noise appear. And also, when working in AC domain, no noise 
effects should appear. but in Noise domain, Noise effects should appear.
>  
> The problem is that VHDL-AMS has only three types of domains : QUIESCENT_DOMAIN, 
TIME_DOMAIN, FREQUENCY_DOMAIN.
>  
> So, I don't know how to differentiate between frequency domain and noise domain for 
example.
>  
> Thank you for your support,
> Amro Tork