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Transient Noise Simulation

Set the following parameters to calculate noise during a transient analysis. (For more detail on the transient noise parameters refer to the Virtuoso Spectre Circuit Simulator User Guide).


Seed for the random number generator (used by the simulator to vary the noise sources internally). Specifying the same seed allows you to reproduce a previous experiment. The default value is 1.

noisefmax=0 (Hz)

The bandwidth of pseudorandom noise sources. A valid (nonzero) value turns on the noise sources during transient analysis. The maximal time step of the transient analysis is limited to 1/noisefmax.


Noise scale factor applied to all generated noise. It can be used to artificially inflate the small noise to make it visible over the transient analysis numerical noise floor, but it should be small enough to maintain the nonlinear operation of the circuit.

noisefmin (Hz)

If specified, the power spectral density of noise sources will depend on frequency in the interval from noisefmin to noisefmax. Below noisefmin, noise power density is constant. The default value is noisefmax, so that only white noise is included and noise sources are evaluated at noisefmax for all models. 1/noisefmin cannot exceed the requested time duration of transient analysis.

noisetmin (s)

Minimum time interval between noise source updates. Default is 1/noisefmax. Smaller values will produce smoother noise signals at the expense of reducing time integration step.

Note: If any of these parameters are not specified, that parameter will not be netlisted.This results in the simulator using its internal default values. Spectre provides both a single run and multiple run method of simulating transient noise. The single run method, which involves a single transient run over several cycles of operation, is best suited for applications where undesirable start-up behavior is present. The multiple run method, which involves a statistical sweep of several iterations over a single period, is recommended for users who are able to take advantage of distributed processing.

Typical Values

(To copy and paste: noiseseed=1,noisefmax=10G,noisescale=1)

how_do_i_simulate_transient_noise.txt · Last modified: 2016/09/17 15:16 (external edit)