Possible Mezz-Blade Connectors

• Samtec ET60T/ET60S (60A power, up to 24 low-speed signals)
• Samtec ERF8/ERM8 (edge-rate diff pair up to 58Gbps)

Meetings:

• ​https://indico.cern.ch/event/738681/ (2018-06-20)

2018-05-31

Thinking about a common blade for ATLAS L0MDT and CMS IT-DTC.
Issues with the current ATLAS design:

• FMC stacking height at 8.5mm is too high

Issues with the current CMS design (Cornell one):

• Really don't like the interposer concept with metal plates, springs etc
• Prefer stand-alone mezzanine card operation

Plus, there are two different blade designs for no obvious reason.

First, looking at low stack height connectors, but not Z-ray. (See Samtec ​guide) Samtec families with low stack heights:

Family	Series	Stack Height	Notes
Sea-Ray	​LPAM/​LPAF	4mm
Edge Rate	​EDM6/​EDF6	5mm
Q Series	​QTH/​QSH	5mm?	28 Gbps+, pairs, power
	​QTE/​QSE	5mm	25A GND plane
Ultra-Micro	​EDM6/​EDF6	5mm
	​LSS/​LSEM/​LSHM	5mm
	​ST4/​SSR	4mm

Below is a figure with dimensions excerpted from the ATCA standard.

Seems as if we can find a 4mm or 5mm solution. This gives us about 15.7mm above a mezzanine board for components.

Next, thinking about the logic. Is it really that hard to make a common blade? Here are some thoughts:

• Build a blade to accommodate 3 mezzanine cards
• Plan for only "low speed" mezz-to-mezz communications
  (SelectIO or < 10Gbps SERDES)
• Mezzanine cards would have the optics on board along with DC/DC converters and regulators
• Split the CMS IT-DTC into 3 parts
• Eliminate the "blade FPGA" from the ATLAS design and designate one mezz card as "master"
  (this could be a different design).

ATLAS requirements

• Sector logic