Design for Signal Integrity


Signal integrity is crucial for maintaining the integrity of signal waveforms during transmission along physical mediums, such as copper traces on a printed circuit board (PCB). In modern board-level and system hardware designs, high-speed interconnects and networking pose significant challenges to signal integrity due to transmission effects caused by high-speed signaling.

Different Types of Signal Integrity Problems

Common Problems


Reduce stubs and uncessary test points.

ESD pads introduce additional capacitance, which can cause impedance discontinuity. To minimize impedance changes, it is recommended to reduce the mounting capacitance of ESD diodes by incorporating a ground void directly underneath the signal pad. Additionally, selecting ESD diodes with low intrinsic capacitance is advisable. 

For connector pins, one can consider voiding the signal ground or using differential signaling, which exhibits lower dependence on ground layers.

High-Speed Interfaces

Type C USB (data transfer), Display Port (DP) (display), embedded Display Port (eDP) (display), MIPI CSI (Camera), PCIE (WiFi), DDR3/DDR4/LPDDR4/4x (DRAM), UFS3.0/eMMC5.1 (Flash Memory), etc.


Signal integrity is critical for ensuring the proper transmission of signal waveforms along physical mediums like copper traces on a PCB. High-speed interconnects and networking pose challenges to signal integrity due to reflection, crosstalk, and signal attenuation. Impedance discontinuity, one common problem, can be mitigated by controlling the impedance of high-speed traces. Signal attenuation can be addressed by adhering to trace length limits and employing techniques like preemphasis. Performing signal integrity simulations helps verify waveform quality.

For high-speed interfaces such as Type C USB, Display Port, MIPI CSI, PCIE, DDR3/DDR4/LPDDR4/4x, UFS3.0/eMMC5.1, maintaining signal integrity is crucial. Mitigation strategies include minimizing impedance changes caused by ESD pads, selecting diodes with low intrinsic capacitance, and utilizing techniques like ground voiding and differential signaling.

By understanding and effectively mitigating signal integrity problems, designers can ensure reliable and high-quality signal transmission in modern high-speed electronic systems.