PCIe

PCIe Testing Service

Overview

PCI Express (PCIe) is a high-speed serial computer expansion bus standard that is widely used in motherboards, graphics cards, SSDs, network interface cards, and other high-speed communication devices. As data transfer rates have evolved from Gen1 (2.5 GT/s) to the current mainstream Gen5 (32 GT/s) and the emerging Gen6 (64 GT/s), physical layer signal integrity testing has become a critical step to ensure device interoperability and stability.

Common Devices Under Test

The main devices typically tested include:

Device	Properties
Motherboards	Test the onboard PCIe slots and interfaces to ensure they provide stable and reliable connections for various add-in cards and modules.
Graphics Cards (GPUs)	Verify that high-performance graphics cards maintain signal quality at high data rates, which is critical for rendering and data processing.
NVMe Solid-State Drives (SSDs)	Ensure the PCIe-based storage devices meet signal integrity requirements for fast and stable data read/write operations.
Network Interface Cards (NICs)	Evaluate the performance of high-speed Ethernet or other network interface cards that rely on PCIe lanes for fast data transmission.
Server or Industrial Control System Boards	Test server motherboards or industrial system boards with integrated PCIe slots to confirm reliable operation under heavy workloads.
PCIe Expansion Cards and Adapters	Includes various PCIe expansion devices such as additional I/O cards, RAID controllers, or M.2 to PCIe adapters, which must comply with PCIe specifications.
PHY Chips and SerDes Interface Modules	Validate the physical layer components and Serializer/Deserializer (SerDes) modules that enable high-speed PCIe data transfer within or between chips.

PCIe Test Standards

The main test standards for PCIe physical layer testing include:

Standard	Properties
Electrical Characteristics	Such as voltage swing, signal levels, and input/output impedance to ensure that electrical signals meet specification requirements.
Timing Parameters	Including data setup time, hold time, and clock skew to verify that timing relationships between data and clock signals are within acceptable limits.
Signal Integrity	Evaluations such as eye diagram quality, jitter, and crosstalk to ensure high-speed signals maintain integrity over the transmission path.
Environmental Requirements	Assessing how factors like temperature, humidity, and power supply noise may impact signal performance and testing accuracy.

Common PCIe Signal Integrity Physical Layer Test Items

Typical PCIe physical layer signal integrity tests include:

Eye Diagram
Return Loss / Insertion Loss
TDR (Time-Domain Reflectometry) Analysis
Jitter Analysis
Channel Compliance Test
SSC (Spread Spectrum Clocking)
Signal Swing and De-Emphasis Measurement

Commonly Used Test Instruments

When performing PCIe physical layer signal integrity tests, the following instruments are commonly used:

instrument	Properties
High-Speed Oscilloscope (Real-Time Oscilloscope / Sampling Oscilloscope)	Used for time-domain analysis, eye diagram measurements, and jitter testing to evaluate signal quality.
Vector Network Analyzer (VNA)	Used for frequency-domain testing of insertion loss and return loss to assess transmission line performance.
Bit Error Rate Tester (BERT)	Measures bit error rate, jitter tolerance, and performs stress testing to verify link reliability under various conditions.
Pattern Generator / Clock Generator	Generates stimulus signals for compliance tests, including standard test patterns and reference clocks.
TDR Module or Reflectometer	Used to test impedance continuity and locate any impedance mismatches or discontinuities along the signal path.