CMOS NOR Gate

Symbol

Information

A CMOS NOR Gate is a fundamental digital logic gate that implements logical NOR operation. The output is HIGH (OH) only when both inputs are LOW (IL); otherwise, the output is LOW (OL).

The gate operates based on voltage thresholds:

• If both inputs are LOW (≤ IL), the output is HIGH (OH).

• If at least one input is HIGH (≥ IH), the output is LOW (OL).

• Intermediate voltages are not handled explicitly in this model.

Ports

• In1: First input terminal

• In2: Second input terminal

• Out: Output terminal

Model

The CMOS NOR Gate model implements standard NOR logic behavior using voltage thresholds.

Attributes:

• Vin1 (signal): Input voltage at In1

• Vin2 (signal): Input voltage at In2

• Vout (signal): Output voltage at Out

• IL (param): Input LOW voltage threshold (default: 0.2V)

• IH (param): Input HIGH voltage threshold (default: 3.2V)

• OL (param): Output LOW voltage (default: 0.0V)

• OH (param): Output HIGH voltage (default: 5.0V)

Methods:

• analog(): Defines the NOR gate behavior based on voltage thresholds.

Logic Table

Vin1	Vin2	Vout
LOW	LOW	HIGH
LOW	HIGH	LOW
HIGH	LOW	LOW
HIGH	HIGH	LOW

Python

from pyams.lib import model, signal, param, voltage

class CNOR(model):
    """
    CMOS NOR Gate model using voltage threshold logic.
    """
    def __init__(self, Out, In1, In2):
        # Signal declarations
        self.Vin1 = signal('in', voltage, In1)
        self.Vin2 = signal('in', voltage, In2)
        self.Vout = signal('out', voltage, Out)

        # Parameter declarations
        self.IL = param(0.2, 'V', 'Input LOW voltage threshold')
        self.IH = param(3.2, 'V', 'Input HIGH voltage threshold')
        self.OL = param(0.0, 'V', 'Output LOW voltage')
        self.OH = param(5.0, 'V', 'Output HIGH voltage')

    def analog(self):
        """Defines the NOR gate behavior using voltage threshold logic."""
        if (self.Vin1 <= self.IL) and (self.Vin2 <= self.IL):
            self.Vout += self.OH  # Output HIGH when both inputs are LOW
        elif (self.Vin1 >= self.IH) or (self.Vin2 >= self.IH):
            self.Vout += self.OL  # Output LOW when at least one input is HIGH

Command Syntax

The syntax for defining a CMOS NOR gate in a PyAMS simulation:

# Import the model
from pyams.models import CNOR

# CNOR instance creation
# Out, In1, In2: Connection points in the circuit
nor_gate = CNOR(Out, In1, In2)