3-Input NAND Gate

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Description

This MicroSim provides an interactive demonstration of a 3-input NAND gate. The simulation displays the standard NAND gate symbol (AND shape with an inversion bubble at the output), three clickable input toggles, and a complete eight-row truth table.

The 3-input NAND gate outputs 0 only when all three inputs are 1. For every other input combination, the output is 1. This is the complement of the 3-input AND gate. As you toggle inputs, the truth table highlights the current row in real time.

Key Features

  • ● Standard NAND gate symbol with inversion bubble and three input wires
  • ● Three clickable toggle buttons for inputs A, B, and C
  • ● Eight-row truth table with real-time row highlighting
  • ● Live output display showing the Boolean expression NOT(A AND B AND C) = Y

How to Use

  1. Click the toggle button next to input A to switch it between 0 and 1
  2. Click the toggle button next to input B to switch it between 0 and 1
  3. Click the toggle button next to input C to switch it between 0 and 1
  4. Observe the gate output update in real time
  5. Watch the truth table highlight the row matching the current input combination
  6. Verify that the output is 0 only when all three inputs are 1

Learning Objectives

Bloom Level: Understand (L2)

After using this MicroSim, students will be able to:

  • ✓ Extend the 2-input NAND gate concept to three or more inputs
  • ✓ Predict the output of a 3-input NAND gate for any input combination
  • ✓ Explain the relationship between NAND and AND gates (NAND = NOT AND)
  • ✓ Recognize that NAND is a universal gate capable of implementing any Boolean function

Lesson Plan

Before the Simulation (5 minutes)

  • ● Review the 2-input NAND gate and its truth table
  • ● Remind students that NAND is the complement of AND
  • ● Introduce NAND as a universal gate and discuss its importance in CMOS design

During the Simulation (15 minutes)

  1. Start with all inputs at 0 and verify the output is 1
  2. Toggle inputs systematically to explore all eight combinations
  3. Find the single combination that produces output 0 (A=1, B=1, C=1)
  4. Compare the NAND truth table with the AND truth table row by row
  5. Count how many rows produce 1 versus 0 (seven vs. one)
  6. Discuss why NAND outputs are the exact complement of AND outputs

After the Simulation (5 minutes)

  • ● Discuss why NAND gates are preferred in CMOS technology
  • ● Show how any gate can be built from NAND gates alone
  • ● Connect to De Morgan's theorem: NOT(A AND B AND C) = NOT A OR NOT B OR NOT C

References