CMOS NAND Gate

Symbol

Information

A CMOS NAND Gate produces a LOW (OL) output only when both inputs are HIGH (IH). Otherwise, the output remains HIGH (OH).

The gate operates based on voltage thresholds:

• If at least one input is LOW (≤ IL), the output is HIGH (OH).

• If both inputs are 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 NAND Gate model implements standard NAND 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 NAND gate behavior based on voltage thresholds.

Logic Table

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

Python

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

class CNAND(model):
    """
    CMOS NAND 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 NAND gate behavior using voltage threshold logic."""
        if (self.Vin1 <= self.IL) or (self.Vin2 <= self.IL):
            self.Vout += self.OH  # Output HIGH when at least one input is LOW
        elif (self.Vin1 >= self.IH) and (self.Vin2 >= self.IH):
            self.Vout += self.OL  # Output LOW when both inputs are HIGH

Command Syntax

The syntax for defining a CMOS NAND gate in a PyAMS simulation:

# Import the model
from pyams.models import CNAND

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