SPST
Single pole single throw switch
- Library:
RF Blockset / Circuit Envelope / Junctions
Description
The SPST block models a single pole single throw switch. This block
supports both reflective and absorptive switches. The control signal is a Simulink® signal connected to the Vctl port of the block. The control
signal specifies when the output port, Out, transmits the input signal at
the input port, In.
Ports
Input
Vctl — Simulink control signal
scalar
Simulink control signal, specified as a scalar.
Data Types: double
Parameters
Threshold voltage — Threshold voltage
0 (default) | positive scalar
Threshold voltage of the switch, specified as a positive scalar in volts.
Characterization — Characterization
Resistance (default) | Insertion loss
Characterization of the switch, specified as Resistance
or Insertion loss.
On resistance — On resistance
10 (default) | positive scalar
On resistance value of the switch, specified as a positive scalar in ohms.
On resistance is available when you set
Characterization to Resistance.
Off resistance — Off resistance
1e-6 (default) | positive scalar
Off resistance value of the switch, specified as a positive scalar in ohms.
Off resistance is available when you set
Characterization to Resistance.
Insertion loss (dB) — Insertion loss
1 (default) | scalar
Insertion loss value of the switch, specified as a positive scalar in decibels.
Insertion loss (dB) is available when you set
Characterization to Insertion
loss.
Isolation (dB) — Isolation value
70 (default) | scalar
Isolation value of the switch, specified as a scalar in decibels.
Isolation (dB) is available when you set
Characterization to Insertion
loss.
Loading type — Loading type
Reflective (default) | Absorptive
Loading type of the switch, specified as Reflective or
Absorptive.
Port terminations (Ohm) — Port terminations
50 (default) | scalar | vector of size 1-by-2
Port terminations that match the impedance conditions of the SPDT
switch, specified as a scalar in ohms or a vector of size 1-by-2 with each element unit
in ohms. If the value is a scalar, then the input port and the output port impedances
are the same. If the value is a vector, the first value is the matching required at the
inport of the block and the second values is the matching required at the output
port.
Note
Port terminations is available when you set the
SPST switch Characterization to
Insertion loss or when you set Loading
type to Absorptive.
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 these terminal, you can connect them to other parts of your model.
More About
Resistance Characterization
If the control voltage is less than the threshold voltage, then the block attenuates the signal using the resistance value specified in Off resistance. The block places the resistor between the positive input and output terminals.
If the control voltage is greater than or equal to the threshold voltage, then the block attenuates the signal using the resistance value specified in On resistance.
When the switch loading type is absorptive, and the control voltage is less than the threshold voltage, the block places internal shunt resistors at the input and output ports. The shunt resistor values provide matching terminations at the input and output ports.
Insertion Loss Characterization
If the control voltage is less than the threshold voltage, calculate the off resistance value using the Isolation (dB) value.
If the control voltage is greater than or equal to the threshold voltage, calculate the on resistance value using the Insertion loss (dB) value.
When the switch loading type is absorptive, and the control voltage is less than the threshold voltage, the block places internal shunt resistors at the input and output ports. The shunt resistor values provide matching terminations at the input and output ports.
Voltage–Current Relationship
The voltage–current relationship at the terminals depends on the relationship between control voltage, Vctl, and the threshold voltage, Vthreshold.
If Vctl < Vthreshold
If Vctl ≥Vthreshold
Gon, Goff — On and off path conductances
GZ01, GZ02 — Shunt port conductances
See Also
Potentiometer | SPDT | Switch