Voltage-Controlled Switch

Symbol

Information

A Voltage-Controlled Switch is an electronic component that changes its resistance based on a control voltage (Vc). The switch consists of an internal resistor (Rs) whose resistance dynamically changes between Ron (low resistance) and Roff (high resistance) depending on the control voltage.

The switching behavior is defined as:

\[ \begin{align}\begin{aligned}R = R_{on}, \quad \text{if } V_c \geq V_{on}\\R = R_{off}, \quad \text{if } V_c \leq V_{off}\end{aligned}\end{align} \]

Where:

\(R\) is the resistance of the switch
\(V_c\) is the control voltage
\(V_{on}\) is the voltage threshold to turn ON the switch
\(V_{off}\) is the voltage threshold to turn OFF the switch
\(R_{on}\) is the resistance when the switch is ON
\(R_{off}\) is the resistance when the switch is OFF

Ports

pc, nc: Control voltage input terminals
p, n: Switch terminals

Model

The Voltage-Controlled Switch model simulates a switch using a variable resistor.

The switch operates based on the control voltage (Vc) and uses an internal resistor model (Rs) to represent its resistance.

Attributes:

Vc (signal): Control voltage input that determines switch state.

Rs (Resistor): Internal resistor model representing switch resistance.

Von (param): Voltage threshold to turn the switch ON (default: 5V).

Voff (param): Voltage threshold to turn the switch OFF (default: -5V).

Ron (param): Resistance value when the switch is ON (default: 10Ω).

Roff (param): Resistance value when the switch is OFF (default: 1MΩ).

Rint (param): Initial resistance value (default: 10Ω).

Methods:

sub(): Initializes the internal resistor model. analog(): Dynamically updates resistance based on control voltage.

from pyams.lib import model, signal, param
from pyams.lib import voltage, current
from pyams.models.Basic.Resistor import Resistor

class Switch(model):
    """
    Voltage-Controlled Switch Model
    """

    def __init__(self, pc, nc, p, n):
        # Signal declarations
        self.Vc = signal('in', voltage, pc, nc)

        # Resistor model
        self.Rs = Resistor(p, n)

        # Parameter declarations
        self.Von = param(5.0, 'V', 'Voltage for switch ON')
        self.Voff = param(-5.0, 'V', 'Voltage for switch OFF')
        self.Ron = param(10.0, 'Ω', 'ON-state resistance')
        self.Roff = param(1e+6, 'Ω', 'OFF-state resistance')
        self.Rint = param(10.0, 'Ω', 'Initial resistance value')

    def sub(self):
        """Initializes the internal resistor model with default resistance."""
        self.Rs.R = self.Rint
        return [self.Rs]

    def analog(self):
        """Updates the resistance value based on control voltage."""
        if self.Vc >= self.Von:
            self.Rs.R = self.Ron  # Switch ON

        if self.Vc <= self.Voff:
            self.Rs.R = self.Roff  # Switch OFF

Command syntax

The syntax for defining a Voltage-Controlled Switch model in a PyAMS simulation:

# Import the model
from pyams.models import Switch

# Sname: is the name of the switch instance
# pc, nc: Control voltage input terminals
# p, n: Switch terminals in the circuit
Sname = Switch(pc, nc, p, n)