into VITA 57.4 compliant FPGA carrier boards. (Figure 4B)


With a defined high-density, high band-


SFigure 4A (left). VITA 57.1 module with FMC connector. Figure 4B (right). VITA 57.4 module with FMC+ connector. Photos courtesy of HiTech Global, LLC.


Leveraging a Standardized FPGA Interface Virtually all user-programmable FPGA modules employ external hardware or PHY interfaces that connect to the ex- ternal world or UUT. These interfaces provide a range of capabilities since the FPGA itself has limited I/O capabilities (e.g., current drive, voltage levels, etc.) and is essentially a digital device with very few, if any, analog capabilities. Te table below lists examples of physical in- terfaces that might be supported by an external FPGA interface. Implementation of these PHY interfac-


es requires external interface boards that are custom to a specific vendor’s FPGA module. Figure 3 details an example of an FPGA module which employs a daugh- ter board that is installed on the main board’s assembly. Other implementations involve the use of an external interface module which must be attached to the FPGA module’s front panel interface. An alternative to vendor-specific


PHY interface solutions is the VITA 57 FPGA Mezzanine Card (FMC) stan- dard, which standardizes both the physical and electrical interfaces to FPGAs, resulting in the availability of a portfolio of off-the-shelf mezzanine boards and a standardized method for interfacing to these boards via a de- fined connector interface. The FMC standard is defined by


the VITA 57.1 and 57.4 specifications. Key features and characteristics of the FMC standard include: • Defined PCB dimensions for


20 EVALUATION ENGINEERING JANUARY 2019 WFigure 6. FPGA PXIe Architecture


modules that include connector location and allowance for front panel connections. FMC modules are available in single width (69 mm) and double width (139 mm) variants.


• The VITA 57.x module’s FMC con- nector has fixed locations for serial/ parallel I/Os, clocks, JTAG signals, VCC, and GND.


• The VITA 57.1 (FMC) modules provide access to up to 160 single- ended I/Os (80 LVDS) and/or up to 10 serial transceivers in a 40 x 10 configuration. The FMC modules can be plugged into both VITA 57.1 and VITA 57.4 compliant FPGA car- rier boards. (Figure 4A)


• The VITA 57.4 (FMC+) modules provide access to up to 160 sin- gle-ended I/Os (80 LVDS) and/or up to 24 serial transceivers in a 40 x 14 configuration. Note that the FMC+ modules can only be plugged


width interface, suppliers of user-program- mable FPGA modules are now migrating to the FMC standard, with virtually all of the FPGA evaluation boards supplied by FPGA vendors now incorporating the FMC inter- face. Applications addressed by these FMC modules include: • Analog I/O: ADCs & DACs • High-speed digital parallel I/O: e.g., camera link, LVDS, FPDP


• High-speed serial digital I/O: e.g., fiber optics, serial front panel data port (FPDP), gigabit Ethernet, etc. A PXIe user-programmable FPGA mod-


ule, such as the one detailed in Figure 5, incorporates the 400-pin FMC interface, allowing test engineers to incorporate commercial FMC mezzanine modules which can help realize shorter develop- ment and verification time for designs,


SFigure 5. PXIe user-programmable FPGA module with FMC connector


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