Abstract: A bit-serial multiplier and an infinite impulse response filter implemented therewith, both implemented on an FPGA, are described in various embodiments. The bit-serial multiplier includes function generators configured as a multiplicand memory, a multiplier memory, a product memory, a bit-serial multiplier, and a bit-serial adder. The function generators are arranged to perform bit-serial multiplication of values in the multiplier and multiplicand memories.

Abstract: System and method for configuring a programmable logic device (PLD) using an automatically generated configuration control file. A control file contains directives for configuring a PLD with a configuration bitstream, wherein the directives are in a selected language. A configuration control file generator is programmed to automatically create the control file with the directives in the selected language. In another embodiment, the particular directives and sequence of the directives that are generated are dependent on a selected configuration mode for the PLD. In performing the directives, configuration control signals are applied to the PLD, and the configuration bitstream is provided to the PLD.

Abstract: Mask-alignment detection structures that measure both the direction and extent of misalignment between layers of an integrated circuit using resistive elements for which resistance varies with misalignment in one dimension. Measurements in accordance with the invention are relatively insensitive to process variations, and the structures using to take these measurements can be formed along with other features on an integrated circuit using standard processes. One embodiment of the invention may be used to measure misalignment between two conductive layers. Other embodiments measure misalignment between diffusion regions and conductors and between diffusion regions and windows through which other diffusion regions are to be formed. A circuit in accordance with one embodiment includes row and column decoders for independently selecting mask-alignment detection structures to reduce the number of test terminals required to implement the detection structures.

Abstract: A sense amplifier (10) is disclosed comprising: a connecting node (12) connectable to a plurality of logic cells (13) for reading the logic states thereof; at least one output (16, 18, 20); circuitry (14) for transferring the read logic states from the connecting node (12) to the at least one output; and a circuit (50) dynamically operative to limit the voltage at the connecting node (12) substantially to a predetermined voltage. In one embodiment, the circuit (50) includes a pass transistor (46) coupled between the connecting node (12) and the transferring circuit (14) and operative to conduct the logic states read from the logic cells to the transferring circuit; and a capacitive divider circuit (54, 56) coupled to a voltage source (Vdd) for producing at a node (52) thereof the predetermined voltage as a fraction of the voltage of the source, the node (52) being coupled to the pass transistor (46) to limit the voltage at the connecting node (12) substantially to the predetermined voltage.

Abstract: A structure and method for operating an asynchronous first in, first out (FIFO) memory system in which the full or empty condition of the memory is determined by comparing a currently-generated write address with a currently-generated read address and a next-to-be-used read address. The current write address and current read address are transmitted from a write address counter and a read address counter, respectively, to a flag control circuit. The flag control circuit includes registers for storing Gray-code versions of the current write address, the current read address, and the next-to-be-used read address, which is determined from the current read address. The flag control circuit generates intermediate ALMOST_EMPTY and ALMOST_FULL signals when the FIFO memory is one data value from being “empty” and “full”, respectively.

Abstract: A method of forming a bond pad area for an integrated circuit provides FSG in the dielectric layer while at the same time minimizes bond pad lift off. The method includes forming a first dielectric layer of fluorinated silicon glass (FSG) on a substrate, then forming an FSG barrier layer on the first dielectric layer. A second, non-FSG dielectric layer is formed on the FSG barrier layer. A barrier metal layer is then formed on the second dielectric layer. Finally, a metal layer is formed on the barrier metal layer. This metal layer provides the surface for adhesion to the bonding wire. The FSG barrier layer absorbs the atoms of fluorine diffused from the first dielectric layer. In this manner, fluorine is prevented from penetrating the second dielectric layer, thereby minimizing bond pad lift off between the second dielectric layer and the barrier metal layer. In one embodiment, the FSG barrier layer includes titanium and/or aluminum.

Abstract: A method and system for demonstrating simulation of a communications bus. In various embodiments, methods and systems are described which support recording a simulation of a system having a communications bus and playback of the recorded simulation. Bus signal vectors are recorded by recorder logic during the simulation, and player logic reads the recorded signal vectors and provides the appropriate bus signals at the appropriate times during playback of the simulation.

Abstract: A structure and method for testing a failed integrated circuit device includes a ball grid array substrate with its heat sink removed to form a cavity where a failed bare die is to be placed. An adhesive tape is attached to the lower surface of the ball grid array substrate covering the cavity, and the die is placed into the cavity against the sticky side of the adhesive tape. Wire bonds are formed from necessary pads on the die to electrical conductors on the substrate and the cavity and bond wires are covered with epoxy. When the epoxy is cured, the adhesive tape is removed, thus exposing the back side of the die for visual inspection while under test.

Abstract: A clock routing circuit is coupled to receive a primary clock signal, a secondary clock signal, and a select signal, all of which may be asynchronous with respect to one another. When the select signal is in a first state, the clock routing circuit passes the primary clock signal as an output clock signal. When the select signal transitions to a second state, the clock routing circuit waits for the primary clock signal to transition in a predetermined direction (i.e., rising edge or falling edge). Upon detecting the transition of the primary clock signal, the clock routing circuit holds the state of the output clock signal. The clock routing circuit then waits for the secondary clock signal to transition in the predetermined direction. Upon detecting the transition of the secondary clock signal, the clock routing circuit passes the secondary clock signal as the output clock signal.

Abstract: An integrated circuit receives an external clock signal and generates therefrom a clock signal that is supplied to a plurality of external devices. A delay-locked loop (DLL), a balanced clock tree, and a plurality of interface cells on the integrated circuit function together to supply the clock signal to the plurality of external devices such that the clock signal at each of the external devices is deskewed with respect to the external clock signal. Board level design is simplified because no balanced clock tree is needed to route the clock signal from the integrated circuit to the external devices, rather each external device is coupled to a corresponding one of the interface cells via a separate external connection. Each of these external connections has an equal propagation delay. One of the interface cells supplies the clock signal back to a reference signal input of the DLL via an external connection.

Abstract: A method is provided for structured layout of design objects in a hardware description language (HDL). Standard features of the HDL are used to specify a first-level design object and the placement of other design objects in the first-level design object. A first-level design object is declared, wherein the first design object has no input or output ports and has one or more slots available for one or more second-level design objects. Values are assigned to attributes of the first-level design object to indicate placement for the second-level design objects within the first-level design object. The second-level design objects are declared as elements within the first-level design object, and the first- and second-level design objects are thereafter compiled.

Abstract: A bus interface circuit for a programmable logic device (PLD) including an interface multiplexer connected between two or more external communication circuits and a configuration memory array. The interface multiplexer coordinates communication between a selected one of the external communication circuits and a packet processor. The packet processor interprets command/data information transmitted in a bit stream from the selected external communication circuit. In a default state, the interface multiplexer connects dual-purpose input/output pins of the PLD to the packet processor. In an alternative state, the interface multiplexer connects a JTAG interface circuit to the packet processor to facilitate configuration operations through the JTAG pins of the PLD.

Abstract: An output driver on an integrated circuit (IC) includes at least one transistor that has a thicker gate oxide than other standard transistors in the IC. In one embodiment, the output driver includes two pull-up transistors. A first pull-up transistor has a thicker gate oxide than standard transistors on the IC to provide a wide range of output voltages on the pad. A second pull-up transistor has a standard, i.e. thin, gate oxide thickness to ensure a fast low-to-high voltage transition on the pad. The other transistors in the output driver have standard gate oxide thicknesses. Illustrative thicknesses include 150 Angstroms for the first pull-up transistor and 50 Angstroms for the second pull-up transistor.

Abstract: A system and method for evolving configuration bitstreams for a programmable logic device are disclosed. A plurality of data structures having respective sets of data are established. From the sets of data, respective configuration bitstreams are generated, wherein the sets of data are mapped to positions in the bitstreams. The configuration bitstreams are then evaluated for relative suitability to meet predetermined criteria when deployed on a progammable logic device. From the relative suitability of the configuration bitstreams, next-generation data for the data structures are generated using a genetic algorithm applied to sets of data. In the various embodiments, the configuration bitstreams eliminate resource contentions, selectively eliminate asynchronous behavior, include built-in test circuits, and are relocatable. Multiple populations of configuration bitstreams can evolve in parallel over a network.

Abstract: A system for controlling the impedances of circuits on an integrated circuit chip is provided. At least one circuit is selected to operate as a p-channel reference circuit, and at least one circuit is selected to operate as an n-channel reference circuit. Other circuits are selected to operate as circuits and/or line termination circuits. A digitally controlled impedance (DCI) circuit controls the p-channel reference circuit to determine a desired configuration of p-channel transistors for use in the circuits. The DCI circuit further controls the n-channel reference circuit to determine a desired configuration of n-channel transistors for use in the circuits. The DCI circuit takes into account such factors as resistances of p-channel transistors in the p-channel reference circuit, resistances of n-channel transistors in the n-channel reference circuit, as well as temperature, voltage and process variations.

Abstract: Described are mask-alignment detection structures that measure both the direction and extent of misalignment between layers of an integrated circuit. Each structure includes one or more MOS transistors, each of which exhibits a threshold voltage that varies with misalignment in one dimension. The test structures are configured in mirrored pairs, so that misalignment in one direction oppositely affects the threshold voltages of the paired structures. The threshold voltages of the paired structures can therefore be compared to determine the extent and direction of misalignment. Measurements in accordance with the invention are relatively insensitive to process variations, and the structures using to take these measurements can be formed along with other features on an integrated circuit using standard processes. One embodiment of the invention may be used to measure misalignment between active implants and the windows in which active regions are formed.

Abstract: An improved CLB architecture, wherein the use of dedicated AND gates to generate a carry chain input signal facilitates low latency multiplication and makes efficient use of four-input function generators. In one embodiment of the invention, when multiplication using a binary addition tree algorithm is used, AND gates to implement single-bit multiplication are provided within the available function generators and duplicated in a dedicated AND gate accessible outside the corresponding function generator as a carry-chain input signal. In another embodiment, carry chain multiplexers can be selectively configured as AND or OR gates to facilitate certain arithmetic or comparison functions for the outputs of a plurality of function generators.

Abstract: A system and method for reading back data from a programmable logic device (PLD). A clock offset table having one or more clock offset values is constructed. Each clock offset value indicates a relative clock cycle at which a selected bit read from the device is saved and sent to a host computer. The data is read from the PLD at a rate of one bit per readback clock cycle, and the readback clock cycles are counted as the bits are read from the device. When the count of readback clock cycles equals an offset, the bit is selected and saved.

Abstract: An FPGA configuration provides a virtual instruction. In a generic computation, the output pattern of a first instruction is compared to the input pattern of a second instruction. If the input and output patterns of the first and second instructions do not match, then a pattern manipulation instruction is inserted between the first and second instructions. At this point, the input and output patterns of the first and second instructions should match and the computation task can be completed. The method of providing virtual instructions is applicable to any FPGA. In a standard FPGA, the data stored in the storage elements of the FPGA, such as flip-flops, is retained for the next configuration of the FPGA. In this manner, successive configurations can communicate data using the patterns of the storage elements, thereby allowing standard FPGAs to implement virtual instructions. Alternatively, a standard FPGA could write out data to an external memory using a predetermined pattern of addresses.

Abstract: A handler interface apparatus for low-temperature semiconductor device testing that includes a bracket and a handler board. The bracket including an outer frame, an inner frame connected to the outer frame by one or more arms, and a cover plate positioned over a central opening of the inner frame. When the handler board is mounted onto the bracket, conductors extending through the handler board from a device contactor pad are enclosed in a chamber formed by the handler board, the inner frame and the cover plate. The handler board is then mated to the test pins of a device tester, which extend through openings located between the inner frame, the outer frame, and the arms of the bracket. During low temperature testing, dry gas is pumped into the chamber through conduits formed in the arms of the bracket to prevent the condensation of moisture on the conductors located in the chamber. In a second disclosed embodiment, a cover plate is attached directly to a handler board.