Kirk Jensen

PCIe® 6.0: The Next Evolution of PCIe

2022-04-21 | 3 min read

Background

Peripheral Component Interconnect Express (PCIe®) is a core technology that many types of computer servers and endpoint devices use. Advances in this technology allow users to drive innovation in 5G, cloud computing, hyperscale data centers, and beyond. The PCI Special Interest Group (PCI-SIG®) defines specifications and compliance tests that guarantee the interoperability of PCIe systems. Evolving from PCIe® 1.0 in 2003 and supporting 2.5 gigatransfers per second (GT/s), the current PCIe standard, PCIe 6.0, came out in 2022 and supports 64 GT/s.

A Significant Upgrade

PCIe 6.0 technology is the first PCI Express® standard to use pulse amplitude modulation 4-level (PAM4) signal encoding, enabling PCIe 6.0 devices to achieve twice the throughput of PCIe 5.0 devices while maintaining the same channel bandwidth, low power, and backward compatibility with previous generations. The PCIe 6.0 standard uses the same high-level approach for transmitter (Tx) and receiver (Rx) testing while adding new transmitter measurements that are specific to PAM4 encoding. Like previous generations, PCIe 6.0 devices employ Tx and Rx equalization along with requiring forward error correction (FEC). Because FEC causes a latency increase, PCIe 6.0 introduces flow control unit (FLIT) encoding. PCIe FLITs eliminate the need for extra packet overhead, thus reducing overall latency by offsetting the increase from FEC.

Compliance Testing

The PCI-SIG requires vendors to conduct compliance testing for interoperability that includes a list of preset or transmitter equalization settings which must be electronically verified. You must conduct three categories of testing to reach official PCI-SIG approved compliance: the physical layer, the data link layer, and general interoperability. When reviewing the standard, you will notice that the PCIe specification framework consists of multiple specifications: Base, Card Electromechanical (CEM), and Test. These specifications define what you need to understand, and test, to comply with the PCIe standard.

Test Solutions

Regardless of which generation of the PCIe specification you are working on, you need a test solution the PCI-SIG aligns with to ensure that your products comply with the standard and get to market faster. Keysight provides a total-solution approach to test all generations of the PCIe specifications so you can focus on your next design, rather than spending time learning the details of the test procedures and requirements.