Security antifuse that prevents readout of some but not other information from a programmed field programmable gate array
First Claim
1. A field programmable gate array, comprising:
- a plurality of modules;
a plurality of first antifuses of a programmable interconnect structure, selected ones of said first antifuses being programmed, said first antifuses being programmable to interconnect selected ones of said logic modules;
a plurality of second antifuses, selected ones of said second antifuses being programmed, said second antifuses not being programmable to interconnect said logic modules and not being part of the programmable interconnect structure; and
means for preventing first data indicative of which ones of said first antifuses are programmed from being extracted from said field programmable gate array while second data indicative of which ones of said second antifuses are programmed is extracted from said field programmable gate array.
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Accused Products
Abstract
A field programmable gate array has a security antifuse which when programmed prevents readout of data indicative of how the interconnect structure is programmed but which does not prevent readout of data indicative of which other antifuses are programmed. In some embodiments, the programming control shift registers adjacent the left and right sides are the field programmable gate array are disabled when the security antifuse is programmed but the programming control shift registers adjacent the top and bottom sides of the field programmable gate array are not disabled. A second security antifuse is also provided which when programmed disables a JTAG boundary scan register but does not disable a JTAG bypass register. Information can therefore be shifted through the JTAG test circuitry without allowing the JTAG circuitry to be used to extract information indicative of how the interconnect structure is programmed. Logic module and interface cell scan paths are provided and special test instructions are supported which allow test vectors to be loaded into the logic module and interface cell scan paths.
51 Citations
19 Claims
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1. A field programmable gate array, comprising:
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a plurality of modules; a plurality of first antifuses of a programmable interconnect structure, selected ones of said first antifuses being programmed, said first antifuses being programmable to interconnect selected ones of said logic modules; a plurality of second antifuses, selected ones of said second antifuses being programmed, said second antifuses not being programmable to interconnect said logic modules and not being part of the programmable interconnect structure; and means for preventing first data indicative of which ones of said first antifuses are programmed from being extracted from said field programmable gate array while second data indicative of which ones of said second antifuses are programmed is extracted from said field programmable gate array. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A field programmable gate array, comprising:
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a boundary scan register; and a boundary scan disable circuit preventing information in said boundary scan register from being shifted out of said field programmable gate array when a security antifuse of said boundary scan disable circuit is in a programmed state. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A field programmable gate array, comprising:
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a bypass register; a logic module scan path extending through a plurality of logic modules; a terminal; a security antifuse not usable to interconnect logic modules; and means for preventing, when said security antifuse is in a programmed state, information in said logic module scan path from being shifted out of said field programmable gate array onto said terminal but not preventing information in said bypass register from being shifted through said bypass register and out of said field programmable gate array onto said terminal. - View Dependent Claims (19)
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Specification