Abstract:
Testing of combinatorial logic in a programmable device is provided by routing input and/or output test values as signals from and back to dedicated logic through programming circuitry in programmable logic. Some embodiments of the present invention provide for a method for testing functional logic block of an application-specific standard product (ASSP) in a programmable logic device, the method comprising: storing an input value into a register; passing the input value from the register to combinatorial logic; producing an output value from the combinatorial logic; passing the output value from the combinatorial logic to the register; saving the output value in the register; and reading the output value out of the register.
Abstract:
An integrated circuit includes a programmable logic device, a dedicated device, and an interface circuit between the two. The interface circuit can be easily modified to accommodate the different interface I/O demands of various dedicated devices that may be embedded into the integrated circuit. In one embodiment, the interface circuit may be implemented using a plurality of mask programmable uni-directional interface buffer circuits. The direction of any desired number of the interface buffer circuits can be reversed based on the needs of a desired dedicated device by re-routing the conductors in the interface buffer circuits in a single metal layer of the integrated circuit. In another embodiment, the interface circuit may be implemented using a hardware configurable bi-directional interface buffer circuit.
Abstract:
An implementation of an apparatus and method to generate a dynamically controlled clock is provided. The resulting clock reduces otherwise produced narrow clock pulses and allows for control from two separate control signals. A first control signal indicates a low power mode, for example a chip-wide low power mode. A second control signal indicates a user-selected mode to shutdown a selected clock.
Abstract:
An antifuse, which has a programmable material disposed between two conductive elements, is programmed using multiple current pulses of opposite polarity. The first pulse has a current that is insufficient to fully program the antifuse, i.e., produce a desired level of resistance. In one embodiment the first pulse is current limited. The first pulse advantageously drives a conductive filament from one conductive element through the antifuse material, which may be, e.g., amorphous silicon. The conductive filament from the first pulse, however, has a limited cross sectional area. A programming pulse having the same voltage with opposite polarity and a current with increased magnitude is used to drive material from the other conductive element into the antifuse material, which increases the cross sectional area of the conductive filament thereby reducing resistance. Additional programming pulses, as well as current limited pulses, may be used if desired. Programming an antifuse in accordance with the present invention results in an antifuse structure with a conductive filament that is in good contact with both conductive elements, which reduces resistance in the antifuse and increases yield. A programming circuitry is provided that includes a current source and a voltage clamp to program antifuses according the described method.
Abstract:
A random access memory (RAM) device includes a buffer in the memory cell to isolate the latching circuit from the read bit line. Consequently, read disturb errors caused by capacitive loading on the read bit line are avoided. Further, the precharge requirements on the write bit line are simplified because the buffer permits optimization of the latching circuit in the memory cell. The RAM device includes a precharge circuit that precharges the write bit line to a ground reference voltage prior to performing write operations. By precharging the write bit line to ground reference voltage, write disturb problems caused by capacitive loading on the write bit line are avoided. Further, by coupling the write bit line to ground reference voltage, little or no power is consumed by precharging the write bit line.
Abstract:
A field programmable gate array has columns of logic modules. A programming conductor used to conduct programming current to program antifuses of the field programmable gate array extends between two adjacent columns of logic modules. First wire segments extend from the programming conductor and toward the logic modules of a first of the two adjacent columns. Second wire segments extend the opposite direction from the programming conductor and toward logic modules of the second of the two adjacent columns. Programming current used to program antifuses disposed along the first wire segments as well as antifuses disposed along the second wire segments can be supplied from the same programming conductor that extends between the two columns of logic modules. The logic modules of the first column are mirrored versions of the logic modules of the second column.
Abstract:
A field programmable gate array includes a programmable routing network, a programmable configuration network integrated with the programmable routing network; and a logic cell integrated with the programmable configuration network. The logic cell includes four two-input AND gates, two six-input AND gates, three multiplexers, and a delay flipflop. The logic cell is a powerful general purpose universal logic building block suitable for implementing most TTL and gate array macrolibrary functions. A considerable variety of functions are realizable with one cell delay, including combinational logic functions as wide as thirteen inputs, all boolean transfer functions for up to three inputs, and sequential flipflop functions such as T, JK and count with carry-in.
Abstract:
An interface cell for a programmable integrated circuit includes a pad, an input buffer, a first routing conductor, a plurality of second routing conductors, and a plurality of antifuses. The input of the input buffer is coupled to the pad and the output of the input buffer is coupled to the first routing conductor so that an input signal from the pad can be supplied onto the first routing conductor without passing through any programmed antifuses. The second routing conductors extend parallel to one another in a direction perpendicular to the direction in which the first routing conductor extends. The second routing conductors cross the first routing conductor and then pass out of the interface cell and into a routing channel of the programmable integrated circuit. One of the antifuses is disposed at each location where one of the second routing conductors crosses the first routing conductor. Accordingly, an input signal from the pad can be supplied onto any desired one of the second routing conductors of the routing channel by programming only one antifuse. The interface cell contains an enablable register, the control inputs of which can be independently driven from any conductor in the adjacent routing channel. Combinatorial and registered outputs of the interface cell can be simultaneously routed to the routing channel and some interface cell outputs have 2.times. drive strength.
Abstract:
Antifuses and gate arrays with antifuses are disclosed that have high thermal stability, reduced size, reduced leakage current, reduced capacitance in the unprogrammed state, improved manufacturing yield, and more controllable electrical characteristics. Some antifuses include spacers in the antifuse via. In some antifuses, the programmable material is planar, and the top or the bottom electrode is formed in the antifuse via. In some gate arrays, the antifuses are formed above the dielectric separating two levels of routing channels rather than below that dielectric.
Abstract:
Antifuses and gate arrays with antifuses are disclosed that have high thermal stability, reduced size, reduced leakage current, reduced capacitance in the unprogrammed state, improved manufacturing yield, and more controllable electrical characteristics. Some antifuses include spacers in the antifuse via. In some antifuses, the programmable material is planar, and the top or the bottom electrode is formed in the antifuse via. In some gate arrays, the antifuses are formed above the dielectric separating two levels of routing channels rather than below that dielectric.