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Variable Attenuator

Model variable attenuator

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  • Variable Attenuator block

Libraries:
RF Blockset / Circuit Envelope / Elements

Description

The Variable Attenuator block attenuates the signal power by a given factor known as Insertion Loss in dB. Using the Variable Attenuator block, you can vary the attenuation of the input Simulink® signal during simulation. Commonly, the block matches the impedance of the RF circuit at the input and output ports. You can use attenuators to dampen the power of the incoming signal to protect RF circuits.

Variable Attenuator 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: onSimulate noise: off

Variable Attenuator block icon with Simulate noise is set to on.

Variable Attenuator block icon with Simulate noise is set to off.

Examples

Vary Attenuation of Signal During Simulation

Vary Attenuation of Signal During Simulation

Use the Variable Attenuator block to attenuate a 20 dB constant signal. Use the Repeating Sequence Stair block as a Simulink control signal to vary the attenuation of the signal. In this model, the signal attenuation varies between 5 and 10 dB during simulation. To see the variation in attenuation, open and run the model.

Ports

Input

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Simulink control signal, specified as a scalar. This control signal is an Insertion Loss in dB.

Data Types: double

Parameters

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Lowest value of insertion loss or attenuation to apply to the signal, specified as a scalar in dB.

Highest value of insertion loss or attenuation to apply to the signal, specified as a scalar in dB.

Input impedance of the attenuator, specified as a scalar in ohms.

Output impedance of the attenuator, specified as a scalar in ohms.

Select this parameter to simulate thermal noise in the attenuator. You must select Simulate noise in the Configuration block.

This parameter inserts a current noise source with the single-sided power density of 4 kT/R A2/Hz, where:

  • T is the value of the Temperature parameter in the Configuration block. Units are in degrees Kelvin.

  • k is the Boltzmann constant.

Select this parameter to ground and hide the negative terminals. To expose the negative terminals, clear this parameter. By exposing these terminals, you can connect them to other parts of your model.

Version History

Introduced in R2016b

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See Also

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