Switch Sample

Symbol

Information

A SwitchSample is a voltage-controlled switch that changes its resistance based on a control voltage. It operates with two states:

ON state: When the control voltage exceeds a defined threshold (Von), the switch has a low resistance (Ron).
OFF state: When the control voltage falls below another threshold (Voff), the switch has a high resistance (Roff).

This model is useful in circuits that require dynamic switching behavior.

Ports

c: Control voltage input
p: Positive terminal
n: Negative terminal

Model

The SwitchSample model simulates a voltage-controlled switch by varying the resistance dynamically.

The switch behavior is controlled by the voltage applied at the control terminal (c). It switches between a high and low resistance state based on the threshold voltages.

Attributes:

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

Rs (Resistor): Internal resistor model that simulates switch resistance.

Von (param): Voltage threshold for turning the switch ON (default: 5V).

Voff (param): Voltage threshold for turning the switch OFF (default: -5V).

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

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

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

Methods:

sub(): Initializes the internal resistor model with the default resistance.

analog(): Updates resistance dynamically based on the control voltage.

\[\begin{split}R = \begin{cases} R_{\text{on}}, & \text{if } V_c \geq V_{\text{on}} \\ R_{\text{off}}, & \text{if } V_c \leq V_{\text{off}} \\ R_{\text{int}}, & \text{otherwise} \end{cases}\end{split}\]

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

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

    def __init__(self, c, p, n):
        # Signal declaration
        self.Vc = signal('in', voltage, c)

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

        # Parameter declaration
        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 switch in a PyAMS simulation:

# Import the model
from pyams.models import SwitchSample

# Sname: is the name of the switch instance
# c, p, n: The connection points in the circuit
Sname = SwitchSample(c, p, n)