Differential Pair Impedance Calculator

Maintaining precise impedance is the cornerstone of high-speed digital design. This calculator allows you to determine the exact trace width and spacing required to meet differential impedance targets for critical protocols like USB (90Ω), Ethernet (100Ω), and HDMI (100Ω).

By selecting from common industry stackup presets and defining your layer location, you can minimize signal reflections and ensure peak data integrity for your most critical high-frequency nets without needing to manually hunt for complex dielectric data.

Description

This utility simplifies the translation of high-speed protocol specifications into physical PCB layouts by focusing on the parameters engineers use most:

• Layer-Aware Calculations: Choose between External (Microstrip) or Internal (Stripline) layers to account for the significant differences in electromagnetic environments and propagation speeds.
• Simplified Input Parameters: Skip complex permittivity (epsilon_r) searches by using Stackup Presets for standard 2-layer and 4-layer boards.
• Protocol-Specific Matching: Instantly verify if your geometry meets the 90Ω standard for USB or the 100Ω requirement for Ethernet, HDMI, and DisplayPort.
• Real-Time Design Guidance: Receive immediate “Match Status” feedback advising whether to increase or decrease spacing to hit your target impedance.
• Copper Weight Integration: Select standard copper weights (0.5 oz, 1.0 oz, or 2.0 oz) to automatically account for finished trace thickness (T) in your impedance model.

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