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Define system simulation settings

  • Library:
  • SimRF / Circuit Envelope / Utilities


Use the Configuration block to set the model conditions for a circuit envelope simulation. The block parameters define a set of simulation frequencies, solver attributes, and thermal noise.

Connect one Configuration block to each topologically distinct SimRF™ subsystem. Each Configuration block defines the parameters of the connected SimRF subsystem. To see an example of the Configuration block in a model, enter simrfV2_noise in a MATLAB Command Window.

For an introduction to RF simulation, see Simulate High Frequency Components.


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Select this parameter to choose Fundamental tones and Harmonic order parameters automatically when you update the model. Automatic selection does not always return the smallest possible set of simulation frequencies.

To manually set the Fundamental tones and Harmonic order, clear this paramter. A smaller set of simulation frequencies decreases simulation time and decreases memory requirements. However, a decrease in simulation frequencies can reduce accuracy.

Fundamental tones of a set of simulation frequencies, specified as a vector of positive integers in Hz.


To enable this parameter, clear Automatically select fundamental tones and harmonic order.

Harmonic order for each fundamental tone, specified as a vector of positive integer. You can also specify a scalar and this value is applied to each Fundamental tones.


To enable this parameter, clear Automatically select fundamental tones and harmonic order.

Click View to open dialog box containing additional information about the simulation frequencies in your system. The Configuration block displays the number of simulation frequencies for a nonlinear model. For linear models, the actual number of frequencies are automatically optimized during simulation. Because the solver computes a solution to the network at each simulation frequency, computation time scales according to the size of this value.

By clicking a listed simulation frequency, you can see which linear or multiple combinations of fundamental tones represent that frequency. From the dialog box, you can also plot the simulation frequencies on a number line.

The block parameters define a set of simulation frequencies as combinations of fundamental tones: [m*f1 + n*f2 + …]. In this case, represented as [f1,f2,…], and the integers m and n are bounded by the corresponding Harmonic order, |m| ≦ h1, |n| ≦ h2, etc. Only positive frequencies are considered.

For example, suppose that you have a single fundamental tone f1 = 2 GHz and corresponding harmonic order h1 = 3. The set of simulation frequencies [0, f1, 2f1, 3f1] = [0GHz, 2 GHz, 4 GHz, 6GHz].

As a second example, suppose you have a circuit with two fundamental tones [f1 = 2 GHz, f2 = 50 MHz] and corresponding harmonic orders h1 = h2 = 1. This setup results in five simulation frequencies with values [0, f2, f1-f2, f1, f1+f2].

The set of simulation frequencies must include all carrier frequencies specified in the SimRF subsystem such as the carrier frequencies inside Inport, Outport, and source blocks.

Select this option to normalize the carrier power such that the average power of the signal is:


In this case, the equation gives the corresponding passband signal at ω:



  • I(t) am the in-phase part of the carrier signal.

  • Q(t) is the quadrature part of the carrier signal.

  • fk are the carrier frequencies.

Clear this option so the average power of the carrier signal is:


In this case, the corresponding passband signal at ω represented by the equation


0 carrier frequency is a special case. Its passband representation is always I and average power I2

Fixed-step solver of SimRF environment, specified as one of the following:

  • Auto: Set this parameter to Auto, when you are not sure which solver to use.

  • NDF2: Set this parameter to NDF2 to balance narrowband and wideband accuracy. This solver is suitable for situations where the frequency content of the signals in the system is unknown relative to the Nyquist rate.

  • Trapezoidal Rule: Set this parameter to Trapezoidal Rule for narrowband simulations. Frequency warping and the lack of damping effects make this method inappropriate for most wideband simulations.

  • Backward Euler: Set this parameter to Backward Euler to simulate the largest class of systems and signals. Damping effects make this solver suitable for wideband simulation, but overall accuracy is low.

The SimRF solver is an extension of the Simscape™ local solver. For more information on the Simscape local solver, see the Solver Configuration block reference page.

Time step for fixed step solver configuration, specified as a vector of integers in seconds. The default is sufficient for modeling envelope signals with bandwidths of up to 1/h, or 1 MHz. But simulation accuracy is reduced when simulating close to the maximum bandwidth. Reduce the step size to model signals with a larger bandwidth, or improve accuracy.

When the noise is simulated, the noise bandwidth for each simulation frequency is equal to 1/h.

Select this parameter to globally enable noise modeling in SimRF circuits. When this check box is selected:

  • Amplifier and Mixer blocks use the value of their respective Noise figure (dB) parameters.

  • Amplifier and Mixer blocks simulate with thermal noise at the temperature specified by the Temperature parameter.

  • Resistor blocks model thermal noise using the Temperature parameters.

  • Noise blocks model a specified noise power as a voltage or current source.

To disable noise modeling globally, clear this parameter.

Select this parameter to retain the default pseudorandom noise stream for SimRF sources. Clear this option to specify an independent pseudorandom number stream for the SimRF topological subsystem and determine the stream's seed


To expose this parameter, select Simulate noise.

Seed of the independent pseudorandom number stream, specified as a scalar positive integer.


To expose this parameter, clear Use default random number generator.

Global noise temperature, specified as a scalar integer in kelvin.

See Also


Introduced in R2013a

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