Overcoming Design Constraints in 3U VPX Form Factors: Modularity and Scalability

Engineers working with 3U VPX architectures face a familiar challenge: modern applications continue to scale in demand for processing capability, storage, and bandwidth, but the form factor stays the same. As size and weight constraints remain fixed, meeting higher performance demands requires smarter strategies. Modularity and scalability — often achieved through mezzanine cards — can expand what 3U VPX systems can do, but only with the right framework in place.

3U VPX Mezzanine Cards

Mezzanine cards offer a modular, plug-and-play solution for 3U VPX systems that essentially shrinks two slots into one. They’re ideal for upgrades such as new optical interfaces, additional memory, or enhanced processing for AI algorithms, GPUs, or CPUs.

Mezzanine cards enable engineers to add functionality and use more of the full 3D volume allocated by the VITA standard without increasing overall size. Consider these strategies for mezzanine cards:

• Use third-party modules for flexibility. An FPGA mezzanine card, such as XMC (defined by VITA 42.3) can sit on another supplier’s SBC, or any 3U or 6U VPX “carrier,” to save space — including potentially saving a slot in the chassis that could be used for another function in the system.
• Upgrade capabilities. In I/O intensive applications, mezzanine cards can connect directly to the backplane, enabling low-latency data ingest support for many different protocols. In compute-intensive applications, they can offer dedicated FPGA co-processing and the ability to add optical I/O interfaces to the backplane when needed. In both cases, functionality is added via a single slot instead of requiring another VPX slot to be consumed by this capability.
• Facilitate legacy designs. Products can utilize mezzanine cards to add legacy protocol support to a new VPX module without modifying the base card. This allows for a platform to upgrade the sensor processor without necessarily needing to upgrade every sensor. The mezzanine card provides a way for the new processor to interface with the legacy sensor and introduce new or upgraded capabilities without impact to the backplane or base 3U VPX card.

Evolving VITA Standards

As processing demands grow, engineers are approaching the physical limits of the 3D mechanical envelope defined by the 3U VPX form factor and VITA 46. It’s critical for standards like VITA to keep up with and support the latest advances in technology to allow designs to continue to push the limits of what is possible and enable data architects to achieve more in the same volumes.

The VITA 100 standard is currently in development, a significant step forward that represents the next generation of VPX. VITA 100 is expected to provide an option to expand the footprint and volume of embedded computing modules to include a 4U form factor. This offers more vertical space than 3U VPX, allowing for larger silicon chips with increased I/O counts to support the large amounts of data moving in, and through VPX-based embedded computing systems today.

Modular and scalable VPX designs help engineers meet future demands and requirements, but they also require careful balance. Engineers must successfully manage trade-offs between modularity and system integrity to ensure seamless performance and uncompromisable quality. In the right hands and with the right plan, constraint becomes capability.