Issue link: https://resources.pcb.cadence.com/i/1534337
2. Isolate Sensitive Components: f Analog and digital components often require different routing strategies. Isolate sensitive analog components from high-speed digital signals to reduce interference. f Use ground planes or shielding to separate noisy sections, such as switching regulators, from high-speed data lines. 3. Minimize Crosstalk with Component Spacing: f Maintain adequate spacing between components with high-speed signals, reducing the risk of signal interference and crosstalk. f Consider arranging components in functional blocks for easier routing and reduced noise. High-Level Routing Techniques Routing high-speed signals requires attention to proximity rules, differential pair routing, and controlled impedance. These techniques help maintain signal quality and minimize reflections. 1. Signal Proximity Rules: f Purpose: High-speed signals routed too closely to other signals can induce crosstalk. Maintain a consistent distance between high-speed traces to minimize coupling. f Implementation: Define minimum spacing constraints within the Constraint Manager to ensure critical traces are isolated from each other. 2. Differential Pair Routing: f Purpose: Differential pairs are commonly used for high-speed signals, such as USB and Ethernet, because they reduce susceptibility to noise. f Implementation: ɢ Route differential pairs with consistent trace width and spacing to maintain impedance. ɢ Keep pairs as close as possible along their entire route and avoid sudden changes in spacing or width that could introduce reflections. ɢ Set up constraints to help maintain spacing and length matching for improved signal integrity. 3. Controlled Impedance Routing: f Purpose: High-speed signals require consistent impedance to reduce signal reflections and maintain signal integrity. f Implementation: ɢ Define impedance values in Constraint Manager for critical nets and use routing tools to ensure these values are met throughout the design. ɢ Avoid abrupt changes in trace width or layer transitions, as these can disrupt impedance control. Signal Return Paths and Via Design Signal return paths and via design are key considerations in high-speed layouts. Proper return path management and via design prevent noise, signal distortion, and EMI issues. 1. Signal Return Paths: f Purpose: High-speed signals should have a clear, continuous return path to minimize loop area and reduce electro- magnetic interference. f Implementation: ɢ Place high-speed signal traces over a solid ground plane to provide a low impedance return path, reducing potential EMI and crosstalk. ɢ Avoid routing high-speed signals over split planes, as this can disrupt the return path and introduce impedance variations. 19 www.cadence.com OrCAD X High-Speed Digital Design Guide