Model variable resistor
RF Blockset / Circuit Envelope / Elements
The Variable Resistor block controls the output of RF Blockset™ feedback circuits using Simulink® controlled resistance in ohms. The minimum value of the resistance (Rmin) is an RF Blockset defined constant independent of the Simulink control signal. The block has two electrical terminals. One terminal is for the Simulink control signal and one terminal is for the RF Blockset signal.
Variable Resistor block mask icons are dynamic and show the current state of the applied noise parameter. This table shows you how the icons on this block vary based on the state of the Simulate noise parameter on the block.
|Simulate noise: ||Simulate noise: |
R — Simulink control signal
Simulink control signal, specified as a scalar.
Simulate noise — Simulate thermal noise
on (default) |
Select this parameter, to simulate thermal noise in the variable resistor. Then, in the Configuration block dialog box, also select the Simulate noise check box. By default, both Simulate noise check boxes are selected.
This parameter inserts a current noise source with the single-sided power density of 4 kT/R A2/Hz, where:
k is the Boltzmann constant
T is the value of the Temperature parameter, in degrees Kelvin. (Also located in the Configuration block.)
Version HistoryIntroduced in R2017b
R2021b: Variable Resistor block icon updated
Behavior changed in R2021b
Starting in R2021b, the Variable Resistor block icon is now updated. The block icons are now dynamic and show the current state of the noise parameter.
When you open a model created before R2021b containing a Variable Resistor block, the software replaces the block icon with the R2021b version.