Programmable Microcircuit Emulation

Programmable Logic Devices (PLDs) are a popular design solution due to their flexibility and cost. PLDs are manufactured as blank uncommitted microcircuits. Design engineers can program these devices to create the logic function required for the application. Older generation devices used fuse technology for one-time programming. These were followed by second generation devices which could be reprogrammed using an external programmer. Newer generations can be reprogrammed either electrically using non-volatile memory or by downloading and storing binary bit stream data. Examples of PLDs are Programmable Array Logic (PALs), Generic Array Logic (GALs), and Field Programmable Gate Arrays (FPGAs). 

A GEM microcircuit has the capability of emulating multiple types of programmable logic devices. Instead of using fuse, electrical, or software programming methods, the functionality of the digital logic is a hard-coded personalization in the gate array during the wafer manufacturing process. The emulation is an Application Specific Integrated Circuit (ASIC) implementation of the original programmed device. The GEM microcircuit is a form, fit, function, and interface replacement for applications where changes to the programmed data are not required. 

The evolution of the programmable memory device has followed a similar path as PLDs. The uncommitted blank memory devices used similar fuse and electrical programming technology to create non-volatile storage. Examples of these memory devices are Programmable Read Only Memory (PROMs), Erasable Programmable Read Only Memory (EPROMs), and Electrically Erasable Read Only Memory (EEPROM).

A GEM microcircuit can emulate several varieties of programmable memory devices. The memory data is stored using the personalization layers during the wafer manufacturing process. The emulation will be a form, fit, function, and interface replacement with some minor exceptions. For example the lid of the package will be opaque in the case of the emulation of ultraviolet light (UV) erasable PROM. For EPROMs or EEPROMs emulations the programming voltage requirements will not apply. These differences are noted on the procurement specification and will have no effect on how the emulation performs in the application.

GEM microcircuits are a good emulation solution for any programmable device which does not need to be reprogrammed in the application. Programming information is required as part of the technology package. Programmed samples of the original microcircuit are highly desirable. They will be used as part of the reverse engineering process and verification of the programming information.

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