SPnT

Single pole multiple throw switch

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Libraries:
RF Blockset / Circuit Envelope / Junctions

Description

The SPnT block models a single pole multiple throw switch. This block supports both reflective and absorptive switches. You can specify two to eight output ports for the switch. The control signal is a Simulink^® signal connected to the Ctl port of the block. The control signal specifies which output port transmits the input signal. When the input to the Ctl port is between one and the number of output ports, the Ctl signal value is rounded to the nearest integer. The output port that corresponds to the integer value transmits the data. If the rounded Ctl signal value does not correspond to any of the output ports, then all the output ports are turned off.

Examples

Single Pole Triple Throw Switch

Example for SPnT switch; single pole triple throw.

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Ports

Input

Ctl — Simulink control signal

scalar

Simulink control signal, specified as a scalar.

Data Types: double

Parameters

Main

Insertion loss (dB) — Insertion loss of switch

1 (default) | scalar

Insertion loss value of switch, specified as a finite scalar in decibels. Specify an insertion loss value greater than zero but less than the isolation value of the switch. For the equation, see Insertion Loss.

Isolation (dB) — Isolation value of switch

70 (default) | scalar

Isolation value of switch, specified as a scalar in decibels. Specify an isolation value greater than the insertion loss value of the switch. For the equation, see Isolation.

Loading type — Switch type

Absorptive (default) | Reflective

Switch type, specified as Absorptive or Reflective.

Number of outputs — Number of outputs for switch

2 (default) | scalar

Number of outputs for the switch, specified as a scalar. The number of outputs must be greater than or equal to two or less than or equal to eight.

Port terminations (Ohm) — Port terminations

50 (default) | scalar

Port terminations representing matching required at all input and output ports, specified as a scalar in ohms. If you set the Load type is Absorptive, the impedance seen at all disconnected output ports is the value specified in Port terminations.

Ground and hide reference terminals — Ground RF circuit terminals

on (default) | off

Select this parameter to internally ground and hide the reference terminals. To expose the reference terminals, clear this parameter. By exposing this terminal, you can connect it to other parts of your model.

More About

Reflective and Absorptive SPnT Switches

If there is no internal resistor connected in parallel to the load when the output terminal is turned off, any incident signal at the output side is reflected back to its source. This type of switch is known as reflective switch.

If there is a matching internal resistor connected in parallel to the load when the output terminal is turned off, any incident signal at the output side is absorbed by the switch. This type of switch is known as an absorptive switch.

Insertion Loss

Insertion loss is given by the equation:

$$I_{\text{loss}}(\text{dB})=-10{\log }_{10}\left(\frac{P_{\text{on}}}{P_{\text{in}}}\right)$$

Isolation

Isolation is given by the equation:

$$I_{\text{iso}}(\text{dB})=-10{\log }_{10}\left(\frac{P_{\text{off}}}{P_{\text{in}}}\right)$$

References

[1] Razavi, Behzad. RF Microelectronics. Upper Saddle River, NJ: Prentice Hall, 2011.

Version History

Introduced in R2018a