Abstract: A security circuit for an IEEE Standard 1149.1 compliant PLD that is controlled by a security bit or bits programmed when the PLD is incorporated into a final product. The security circuit includes a switch connected directly or indirectly into the Boundary-Scan Register (BSR) chain of the PLD. The security bit applies a control signal to the switch such that test data signals generated during INTEST procedures are either passed through the switch, or blocked by the switch. For example, when the Boundary-Scan architecture of the PLD is set for INTEST procedures when the security bit is set in a first programmed state, the logic gate passes test data from an input terminal to an output terminal. Conversely, when the security bit is set in a second programmed state, the logic gate masks the test data values received at the input terminal (i.e., the shifted test data is blocked).

Abstract: A clock enable control circuit for controlling flip flops on a programmable logic device. The clock enable control circuit either passes an original data signal to the input terminal of a flip flop, or feeds back an output signal from the output terminal to the input terminal of the flip flop in response to a clock enable control signal. The clock enable control signal is selected from one of a set control signal and a reset control signal that are otherwise provided on the programmable logic device to selectively control set and reset functions of the flip flop. In one embodiment, the set and reset control signals are generated as product-term signals that are programmably routed by a product-term allocator circuit to a macrocell including the flip flop and the clock enable control circuit.

Abstract: A fast, space-efficient lookup table (LUT) for programmable logic devices (PLDs) in which the write decoder, read decoder and memory block of the LUT are modified to improve performance while providing a highly efficient layout. Both the write decoder and the read decoder are controlled by LUT input signals, and data signals are transmitted directly to each memory circuit of the memory block (i.e., without passing through the write decoder). The write decoder includes NOR gates that generate select signals used to address individual memory circuits during write operations. For dynamic latching during reading or shifting, each memory circuit includes an inverter circuit connected between the memory cell and the output terminal of the memory circuit. The read decoder includes a multiplexing circuit made up of a series of 2-to-1 multiplexers that are directly controlled by the input signals received from the interconnect resources of the PLD.

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 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.

Abstract: A system and method for operating an asynchronous first in, first out (FIFO) memory system in which the amount of data stored in a FIFO memory is determined by re-synchronizing a binary read address from a read clock signal to a write clock signal, then subtracting the write-synchronized read address from the binary write address. The FIFO memory system includes the FIFO memory, read and write address counters for generating the binary read address and binary write address, respectively, and a write synchronization circuit. The binary read address is converted into a Gray-code value which is then synchronized to the write clock signal. The write-synchronized Gray-code read address value is then re-converted to binary to form the write-synchronized read address.

Abstract: A reticle that is modified to prevent bridging of the masking material (e.g., chrome) between portions of the lithographic mask pattern during an integrated circuit fabrication process. According to a first aspect, the modification involves electrically connecting the various portions of the lithographic mask pattern that balance charges generated in the portions during fabrication processes. In one embodiment, sub-resolution wires that extend between the lithographic mask pattern portions facilitate electrical conduction between the mask pattern portions, thereby equalizing dissimilar charges. In another embodiment, a transparent conductive film is formed over the lithographic mask pattern to facilitate conduction. In accordance with a second aspect, the modification involves separating the various portions of the lithographic mask pattern into relatively small segments by providing sub-resolution gaps between the various portions, thereby minimizing the amount of charge that is generated on each portion.

Abstract: A semiconductor device tester and handler interface includes tester and handler boards with a coplanarity plate between them. The handler board includes a central area adapted to mount semiconductor devices to be tested by a tester. The tester board has tester contacts located to interface with a tester. During cold testing, to avoid condensation on the side of the handler board away from the devices being tested, dry gas is applied to the region formed by the coplanarity plate. During hot testing, flowing dry gas prevents the hot handler board from excessively heating the tester board and associated tester.

Abstract: A voltage regulator circuit in an integrated circuit (IC) device such as a Complex Programmable Logic Device (CPLD) comprises a reference voltage generator, a tuning circuit, and an output driver circuit. The reference voltage generator converts an external supply voltage provided to the IC device into a stable reference voltage. The tuning circuit converts the stable reference voltage into a desired internal supply voltage, such as the reduced voltage required by deep sub-micron transistors. The output driver circuit provides the desired internal supply voltage with sufficient current to properly power the circuits of the IC device. The tuning circuit includes an op-amp and resistive elements configured in a voltage divider configuration in the negative feedback loop of the op-amp. The output of the op-amp can be set to the desired internal supply voltage by properly sizing the resistive elements.

Abstract: During the development of process parameters for fabricating an integrated circuit, a test circuit is provided on the wafer that provides rapid identification of process problems (i.e., before failure analysis), detects defects down to a part-per-million (PPM) level, and identifies the precise location of any defects, thereby facilitating rapid failure analysis during the development and refinement of IC fabrication processes used to fabricate an integrated circuit (IC). In a first embodiment, the test circuit includes parallel conductive paths that are selectively connected to a signal source by pass transistors. Open circuits are identified by sequentially connecting one end of the conductive paths to the signal source and measuring the current at the other end. In a second embodiment, the test circuit includes perpendicular sets of overlapping conductors. Short conductive segments extend in parallel with a first set of conductors that are electrically connected to a second set of conductors.

Abstract: A logic/memory circuit (LMC) utilized in a configurable logic block (CLB) of a programmable logic device (PLD) that implements an eight-input lookup table (LUT) using an array of programmable elements arranged in rows and columns. A decoder is used to read bit values from one column (e.g., sixteen programmable elements) of the array. In one embodiment, a separate read bit line is provided to facilitate faster read operations. A sixteen-to-one multiplexer/demultiplexer circuit is used to pass selected bit values to an output terminal. The array of programmable elements is programmable both from configuration lines during a configuration mode, and by data transmitted on the interconnect resources through the multiplexer/demultiplexer circuit. In one embodiment, the programmable elements of the array are connected in pairs to product term generation circuitry, and input signals to the array are routed onto bit lines that are also connected to the product term generation circuitry.

Abstract: An FPGA configuration circuit including a bus interface for applying a bit stream from either a JTAG interface or an input/output block (IOB) interface onto a bus. The bus interface parses a header word from the bit stream into an address field and an operand field. Several registers are connected to the bus including a frame data register, a frame address register, a control register, a command register, and an optional data check register. The bus interface generates control signals in response to the address field and the operand field that cause one or more registers to perform predefined operations according to subsequent data words in the bit stream. For example, during configuration write operations, the bus interface enables the frame data register to receive data signals that are subsequently transferred to a configuration memory array.

Abstract: A cyclic redundancy check (CRC) register is connected to the bi-directional bus and a packet processor in a configuration circuit of an FPGA. The CRC register performs transmission error detection functions based on the command/data transmissions to various registers connected to the bus, and based on the address information transmitted from the packet processor to an address/operand decoder used to enable the various registers to receive subsequent command/data words. The CRC register calculates a check-sum value in accordance with a predetermined equation. At any time during the transmission (e.g., halfway through configuration or at the end of configuration), a pre-calculated check-sum value is transmitted to the CRC register that represents an expected check-sum value at the selected time. The pre-calculated check-sum value is then compared with the check-sum value currently stored in the CRC register.

Abstract: A logic/memory circuit (LMC) utilized in a configurable logic block (CLB) of a programmable logic device (PLD) that implements an eight-input lookup table (LUT) using an array of programmable elements arranged in rows and columns. A decoder is used to read bit values from one column (e.g., sixteen programmable elements) of the array. In one embodiment, a separate read bit line is provided to facilitate faster read operations. A sixteen-to-one multiplexer/demultiplexer circuit is used to pass selected bit values to an output terminal. The array of programmable elements is programmable both from configuration lines during a configuration mode, and by data transmitted on the interconnect resources through the multiplexer/demultiplexer circuit. In one embodiment, the programmable elements of the array are connected in pairs to product term generation circuitry. Product terms generated by the product term circuitry are passed to a macrocell circuit to perform programmable array logic (PAL) logic operations.

Abstract: An output driver circuit including a first path from an output pad to ground through a first switch, and a second path from the output pad to ground through series-connected second and third switches. The first switch is directly connected to a pull-down signal source, and one of the second and third switches is connected to the pull-down signal source through a one-shot circuit. In a pull-up state, the first and second switches are opened, and the one-shot circuit generates a stabilized output signal which closes the third switch. When the output driver circuit switches to a pull-down state, the first switch is closed, thereby connecting the output pad to ground via the first path. The signal change also closes the second switch. In addition, due to a propagation delay of the second signal through the one-shot circuit, the third switch initially remains closed, thereby also connecting the output pad to ground via the second path.

Abstract: A semiconductor device tester and handler interface includes a tester and handler board. The board includes multiple test sites and has multiple layers of metallization traces. The handler side of the board includes a central area adapted to mount multiple semiconductor devices to be tested by a tester. The tester side of the board has tester contacts located to interface with a tester. Vias connect metallization traces in one metallization layer to metallization traces in another layer. The traces and vias are arranged to form paths from a tester contact to a test socket. The test sites are placed close to and sometimes superimposed on the tester contacts receiving the test signals. Thus delay is minimized and with multiple test sites, throughput is increased.

Abstract: A method and structure for testing static signal levels on an integrated circuit device using an electron beam deflection device. Each static signal is applied to a first terminal of a switch, such as an AND gate, an OR gate, or a pass transistor. An alternating control signal of approximately 1 MHz is transmitted to a second terminal of the switch such that the switch generates an output signal that is either constant (if the static signal is at a first level), or has a frequency equal to that of the alternating control signal (if the static signal is at a second level). The output signal is transmitted to a pad located on an exposed surface of the integrated circuit, where an electron beam deflection device is utilized to determine the static signal level by detecting the presence or absence of an alternating signal. A method for determining the voltage level of a signal includes applying the signal to the gate of a transistor and an alternating control signal to an input terminal.

Abstract: A post-placement residual overlap removal process for use with core-based programmable logic device programming methods that is called when an optimal placement solution includes one or more overlapping cores. Horizontal and vertical constraint graphs are utilized to mathematically define the two-dimensional positional relationship between the cores of the infeasible placement solution in two separate one-dimensional (i.e., horizontal and vertical) directions. Next, the constraint graphs are analyzed to determine whether they include a feasible solution (i.e., whether the overlaps existing in the placement solution can be removed simply by reallocating available resources to the overlapping cores). If one of the constraint graphs is not feasible, then the infeasible constraint graph is revised, and then the feasibility of both graphs is re-analyzed for feasibility. The feasibility analysis and constraint graph revision steps are repeated until both constraint graphs are feasible.