Propagation Delay

Propagation Delay Visually

Interactive visualization of propagation delay in digital circuits. Learn about signal propagation, setup and hold times, and timing analysis with real data and simulations.

Propagation Delay Signal Integrity Setup Time Hold Time Timing Analysis Circuit Simulation
Circuit Visualization
Propagation Delay Steps
1
Input Signal Transition

An input signal changes from one logic level to another (e.g., 0 to 1 or 1 to 0).

2
Gate Processing Time

The logic gate processes the input signal internally. This takes a finite amount of time.

3
Output Signal Transition

The output signal begins to change after the propagation delay time (tpd).

4
Signal Stabilization

The output signal stabilizes at its final value after transition time (tr or tf).

Circuit Parameters
Timing Analysis
Propagation Delay (tpd): 5.0 ns
Setup Time (tsu): 2.5 ns
Hold Time (th): 1.0 ns
Maximum Frequency: 66.7 MHz
Timing Margin: 8.3 ns
Timing Violation Status:
No timing violations detected
Multiple Simulations
Results:
Total delay: 25.0 ns
Critical path delay: 25.0 ns
Estimated frequency: 40.0 MHz
Theory and Concepts
What is Propagation Delay?

Propagation delay is the time taken for a signal to travel from the input of a logic gate to its output. It is a critical parameter in digital circuit design as it determines the maximum speed at which a circuit can operate.

Types of Propagation Delay
  • tPHL: Time for output to change from HIGH to LOW
  • tPLH: Time for output to change from LOW to HIGH
  • tpd: Average propagation delay = (tPHL + tPLH) / 2
Setup and Hold Time
  • Setup Time (tsu): Minimum time before the clock edge that the data must be stable
  • Hold Time (th): Minimum time after the clock edge that the data must remain stable
Timing Constraints

To ensure reliable operation, the following condition must be met:
Tclk ≥ tpd + tsu
Where Tclk is the clock period.