Abstract: Distributed RAM in a logic array. A single, customizable, logic array fabric provides both gate array logic and RAM functionality simultaneously while substantially maximizing the amount of configurable metal for routing. The extra semiconductor area in the cells of a metal limited device is used to implement general purpose RAM. Common select lines and read/write lines for the RAM are embedded in the base cells so that the configurable metal (whether via or actual metal layer) over the RAM can be used for routing logic.

Abstract: In a programmable logic device having dedicated multiplier circuitry, some of the scan chain registers normally used for testing the device are located adjacent input registers of the multipliers. Those scan chain registers are ANDed with the input registers, and can be loaded with templates of ones and zeroes. This allows, e.g., subset multiplication if the least significant bits are loaded with zeroes and the remaining bits are loaded with ones. The multipliers preferably are arranged in blocks with other components, such as adders, that allow them to be configured as finite impulse response (FIR) filters. In such configurations, the scan chain registers can be used to load filter coefficients, avoiding the use of scarce logic and routing resources of the device.

Abstract: Disclosed is an improved register circuit of an extended mode register set. The register circuit comprises a first mode register block reset by a reset signal and outputting a predetermined level of signal in the input of an extended mode register set signal; a logic block for generating an output signal by OR operation of the reset signal and the mode register set signal and masking the mode register set signal when the predetermined level of signal is inputted from the first mode register block; and a second mode register block reset by output signal of the logic block.

Abstract: A technique to implement functions requiring fewer pins of an integrated circuit to serially transfer data into the integrated circuit for multiple logic blocks. By reducing the required pins, this permits downbonding of the integrated circuit into a package with fewer pins. This technique may be used to implement test functions in a programmable logic device. Test data may be serially input using a test pin (310) for two or more columns (320) of logic blocks. The test data is stored in an A register (330), and may be later transferred into a B register (335).

Abstract: A signal control circuit includes a set of signal lines that form a data bus. A set of three-state driver columns is connected to the data bus; each three-state driver column is connected to each signal line of the set of signal lines. A programmable synchronous three-state control circuit is connected to the set of three-state driver columns. The programmable synchronous three-state control circuit responds to a control signal and select signals to produce a three-state output enable signal which is applied to a selected three-state driver column of the set of three-state driver columns so as to control data signals on the data bus.

Abstract: A programmable I/O element for an I/O terminal of a logic array is suitable for operating according to high speed I/O modes such as double data rate and zero bus turnaround. The I/O element may include an input block with two registers for registering input signals from the terminal upon alternate clock edges. In addition or alternatively, it may include an output block with two registers that separately register output signals from the array on the same clock edge and a multiplexer that alternately outputs those signals. For bidirectional terminals, the multiplexer output is connectable to the I/O terminal via an output buffer, and an output enable block provides an enable signal to a gating input of the output buffer. Programmable delays may be included in the input, output, and output enable paths, in particular to provide a slower turn-on time than turn-off time for the output buffer.

Abstract: An FPGA architecture has top, middle and low levels. The top level of the architecture is an array of the B16×16 tiles arranged in a rectangular array and enclosed by I/O blocks on the periphery. On each of the four sides of a B16×16 tile, and also associated with each of the I/O blocks is a freeway routing channel. A B16×16 tile in the middle level of hierarchy is a sixteen by sixteen array of B1 blocks. The routing resources in the middle level of hierarchy are expressway routing channels M1, M2, and M3 including groups of interconnect conductors. At the lowest level of the semi-hierarchical FPGA architecture, there are block connect (BC) routing channels, local mesh (LM) routing channels, and direct connect (DC) interconnect conductors to connect the logic elements to further routing resources. Each B1 block includes four clusters of devices. Each of the four clusters includes first and second LUT3s, a LUT2, and a DFF.

Abstract: In a mask-programmable logic device having embedded memory blocks, which device cannot be reconfigured for testing like a full programmable logic device, the embedded memory blocks are tested by forming scan chains from the input-side registers of a plurality of embedded memory blocks, and from the output-side registers of a those embedded memory blocks. Test vectors are clocked into the input-side scan chain and the results are clocked out from the output-side scan chain. The test vectors can be made by concatenating multiple copies of a test vector for one block when the blocks are identical. The method works even where one or more embedded memory blocks are configured as read-only devices, as long as the contents of the read-only devices are known so that one knows what test output to expect.

Abstract: A Programmable Logic Device providing reduction in power consumption for sequential logic and data storage functions, including at least one circuit arrangement configurable to function as a dual-edge-triggered flip-flop operating on a selected one or both edges of the circuit clock.

Abstract: A lookup table (LUT) for a field programmable gate array (FPGA) is designed to operate reliably at low voltage levels. The low-voltage LUT uses CMOS pass gates instead of unpaired N-channel transistors to select one memory cell output as the LUT output signal. Therefore, no voltage drop occurs across the pass gates. While this modification significantly increases the overall gate count of the LUT, this disadvantage can be mitigated by removing the half-latches required in current designs, and by removing initialization circuitry made unnecessary by the modification. Some embodiments include a decoder that decreases the number of pass gates between the memory cells and the output terminal, at the cost of an increased delay on the input paths that traverse the decoder.

Abstract: A configuration memory array for a programmable logic device includes an array of configuration memory cells arranged in rows and columns. Initially, each of the configuration memory cells is reset to a reset state. Each row of configuration memory cells is coupled to a corresponding data line and data line driver. During configuration, each data line driver drives a configuration data value having a first state or a second state onto the corresponding data line. A configuration data value having the first state has a polarity that tends to flip the reset state of a configuration memory cell. A repeater cell is connected to an intermediate location of each data line. Each repeater cell improves the drive of configuration data values having the first state.

Abstract: A programmable array logic circuit macrocell using ferromagnetic memory cells. More particularly, the present invention uses a non-volatile ferromagnetic memory cell to temporarily store binary data. It is an advantage of the invention to have the ferromagnetic memory cells or bits to store data even when there is no power provided to the circuitry, thus saving power during operation of the programmable logic circuitry, and ensuring that there is no loss of the data should there be a temporary power shutdown. Additionally, the ferromagnetic cells provide for indefinite number of switching actions on the data without degradation to the capacity to store data therein, thus eliminating “write fatigue”. The invention provides an integrated circuit, comprising a programmable OR array (24), a programmable AND array (28), coupled to the programmable OR array, and a macrocell output circuit (22).

Abstract: A programmable logic device or field programmable gate array includes an on-chip clock synchronization circuit to synchronize a reference or system clock signal. The clock synchronization circuit is a delay-locked loop (DLL) circuit in one implementation and a phase-locked loop (PLL) circuit in another implementation. The DLL or PLL circuits may be analog or digital. The clock synchronization circuit generates a synchronized clock signal that is distributed throughout the programmable integrated circuit. The synchronized clock signal is programmably connected to the programmable logic elements or logic array blocks (LABs) of the integrated circuit. The clock synchronization circuit reduces or minimizes clock skew when distributing a clock signal within the integrated circuit. The clock synchronization circuit improves the overall performance of the programmable logic integrated circuit.

Abstract: A programmable interconnect circuit comprising a plurality of I/O cells arranged into I/O blocks includes a routing structure for each I/O block, wherein each routing structure may have a partially populated first level for programmably routing signals from the I/O cells into a first set of output signals. A second level of the routing structure programmably routes signals from the first set of output signals to I/O cells in the routing structure's I/O block.

Abstract: A gate array in accordance with the invention includes a matrix of function blocks capable of being configured to implement combinational, sequential, and memory modes of operation, as well as providing tri-state drivers and buffers in useful numbers. The function block includes a logic circuit with a first bit storage unit, which is selectively configurable to behave as combinational logic or to store a first bit, and a second bit storage unit, which is also selectively configurable to behave as combinational logic or to store a second bit. The matrix of function blocks in accordance with the invention is also useful to properly distribute clocks throughout the gate array.

Abstract: A general-purpose logic cell used in a general-purpose logic cell array for a logic circuit, includes a plurality of kinds of logic circuit elements, each of which has a plurality of terminals with no connection. The plurality of kinds of logic circuit elements includes a flip-flop and a first inverter set. In this case, each of first inverters of the first inverter set is possible to be connected with an input of the flip-flop in parallel or as one of a series connection of at least two of the first inverters. Also, each first inverter is possible to be connected with an output of the flip-flop in parallel or as one of a series connection of at least two of the first inverters.

Abstract: Distributed RAM in a logic array. A single, customizable, logic array fabric provides both gate array logic and RAM functionality simultaneously while substantially maximizing the amount of configurable metal for routing. The extra semiconductor area in the cells of a metal limited device is used to implement general purpose RAM. Common select lines and read/write lines for the RAM are embedded in the base cells so that the configurable metal (whether via or actual metal layer) over the RAM can be used for routing logic.

Abstract: A programmable logic device may include a programmable interconnect structure and a plurality of configurable logic elements including data latches interconnected by the interconnect structure. At least one of the configurable logic elements may be configurable as both a shift register and a lookup table. Also, the shift register may be enabled to operate as a bi-directional shift register by the inclusion of a first circuit for configuring the data latches either as series-connected inverters during a shift operation or as data latches after each shift operation. A second circuit for selecting a direction of shifting may also be included, as well as a third circuit for supplying data to the input of the shift register as determined by the direction of shifting.

Abstract: An FPGA architecture has top, middle and low levels. The top level of the architecture is an array of the B16×16 tiles arranged in a rectangular array and enclosed by I/O blocks on the periphery. A B16×16 tile in the middle level of hierarchy is a sixteen by sixteen array of B1 blocks. The B16×16 tile is a nesting of a B2×2 tile that includes a two by two array of four B1 blocks. The routing resources in the middle level of hierarchy are expressway routing channels M1, M2, and M3 including groups of interconnect conductors. The expressway routing channels M1, M2, and M3 are segmented, and between each of the segments in the expressway routing channels M1, M2, and M3 are disposed extensions that can extend the expressway routing channel M1, M2, or M3 an identical distance along the same direction. The expressway routing channels M1, M2, and M3 run both vertically through every column and horizontally through every row of B2×2 tiles.

Abstract: A programmable logic device has logic array locks (“LABs”) and interconnection resources. For interconnecting signals to, from, and between the LABS, the global interconnection resources may include switch boxes, long lines, double lines, single lines, and half- and partially populated multiplexer regions. The LAB includes two levels of function blocks. In a preferred embodiment, there is one four-input second-level function block for every four-input first-level function blocks. At least one tri-state buffer is provided in each LAB. Each tri-state buffer may receive a data signal either from one or more function blocks in the associated LAB or from one or more interconnection conductors adjacent to the LAB. The tri-state buffer may buffer one of the received data signals and apply the resulting buffered signal to one or more of the interconnection conductors adjacent to the LAB.

Abstract: A novel architecture for a multi-scale programmable logic array (MSA) to be used in the design of complex digital systems allows digital logic to be programmed using both small-scale blocks (also called gate level blocks) as well as medium scale blocks (also called Register Transfer Level or RTL blocks). The MSA concept is based on a bit sliceable Arithmetic Logic Unit (ALU). Each bit-slice may be programmed to perform a basic Boolean logic operation or may be programmed to contribute to higher-level functions that are further programmed by an ALU controller circuit. The ALU controller level in this new approach also allows the primitive logic operations computed at the bit-slice level to be combined to perform complex random logic operations. The data shifting capability of this new programmable logic architecture reduces the complexity of the programmable routing needed to implement shift operations including multiplier arrays.

Abstract: A programmable logic integrated circuit device has at least one function-specific circuit block (e.g., a parallel multiplier, a parallel barrel shifter, a parallel arithmetic logic unit, etc.) in addition to the usual multiple regions of programmable logic and the usual programmable interconnection circuit resources. To reduce the impact of use of the function-specific block (“FSB”) on the general purpose interconnection resources of the device, inputs and/or outputs of the FSB may be coupled relatively directly to a subset of the logic regions. In addition to conserving general purpose interconnect, resources of the logic regions to which the FSB are connected can be used by the FSB to reduce the amount of circuitry that must be dedicated to the FSB.

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 read decoder includes a multiplexing circuit made up of a series of multiplexers that are directly controlled by the input signals received from the interconnect resources of the PLD. In one embodiment, a configurable logic block is provided with a single write decoder that is shared by a first LUT and a second LUT.

Abstract: A semiconductor device malfunction preventive circuit S is disposed in a macrocell logic cell 1 of a semiconductor device 50 used in an electronic device 100. A signal in an output pin 3 or in a signal line 6 is returned to the semiconductor device malfunction preventive circuit S as a pin feedback and monitored. When a predetermined state is detected, an abnormality detecting signal SIGAB for resetting the operation of the electronic device 100 is outputted.

Abstract: Dynamic PLAs are used as the basis of constructing a new class of programmable devices called field-programmable dynamic logic arrays (FPDLAs). Unlike existing programmable devices that use static logic, the FPDLAs use reprogrammable, reconfigurable, and fixed-function dynamic PLAs in programmable modules that provide both programmable logic and interconnect structures. A system of micro clocks is used to ensure that each dynamic PLA operates correctly by allowing it to start the evaluate phase after all of its inputs have become valid. Since dynamic PLAs with large number of inputs can be built in a small area due to its regular circuit structure, and they produce the outputs in a time independent of the number of inputs affecting the outputs, FPDLAs can operate at a higher speed and require a smaller area than programmable devices built using static logic.

Abstract: A configuration memory for storing information which is in-system programmable. The programming of the configuration memory may be performed using JTAG (IEEE Standard 1149.1) instructions. Furthermore, the configuration of a programmable logic device using the configuration data in the configuration memory may be initiated with a JTAG instruction. Pull-up resistors are incorporated within the configuration memory package.

Abstract: An apparatus comprising an input/output circuit and a programmable logic device. The input/output circuit may be configured to (i) connect to an end of a bus and (ii) operate in one or more modes in response to one or more control signals. The programmable logic device may be configured to generate said one or more control signals.

Abstract: A method and a structure provide in a programmable logic device wide multiplexers without increasing delay and the number of interconnections in an input routing resource over corresponding multiplexer with less number of input signals. In one embodiment, each of a number of 8-input multiplexers shares both common input signals and common selection signals with a neighboring multiplexer. Even wider multiplexers can be achieved by cascading the multiplexers in a conventional manner.

Abstract: A programmable logic configuration device is disclosed having a configuration memory accessible by a controller of the configuration device and by a second device. Arbitration circuitry is provided for arbitrating access to the configuration memory between the configuration controller and the second device.

Abstract: Systems and methods for programmable logic arrays having depletion mode, non volatile p-channel floating gate transistors with ultra thin tunnel oxides are provided. The programmable logic arrays of the present invention can be programmed with voltages of 2.0 to 3.0 Volts and the normal operating voltages on the control gates are of the order 1.0 Volt. The depletion mode, non volatile p-channel floating gate transistors the present invention, include a range of floating gate potentials over which charge can not leak on to or off of the floating gate. The non volatile p-channel floating gate transistors in the programmable logic array include an oxide layer of less than 50 Angstroms (Å) which separates the floating gate from a p-type doped channel region separating a source and a drain region in a substrate.

Abstract: A programmable logic integrated circuit device has at least one function-specific circuit block (e.g., a parallel multiplier, a parallel barrel shifter, a parallel arithmetic logic unit, etc.) in addition to the usual multiple regions of programmable logic and the usual programmable interconnection circuit resources. To reduce the impact of use of the function-specific block (“FSB”) on the general purpose interconnection resources of the device, inputs and/or outputs of the FSB may be coupled relatively directly to a subset of the logic regions. In addition to conserving general purpose interconnect, resources of the logic regions to which the FSB are connected can be used by the FSB to reduce the amount of circuitry that must be dedicated to the FSB.

Abstract: A high-performance programmable logic architecture has embedded memory (608). arranged at the peripheries or edges of the integrated circuit. This enhances the performance of the programmable logic integrated circuit by shortening the lengths of the programmable interconnect (748). In a specific embodiment, the memory blocks (703) are organized in rows along the top and bottom edges of the integrated circuit. The logic elements (805) can be directly programmable routed and connected to driver blocks (809) of the logic block in adjacent rows and columns. This permits fast interconnection of signals without using the global programmable interconnect resources (815, 825). Using similar direct programmable interconnections (828, 830, 835), the logic blocks can directly programmable connect to the memory blocks without using the global programmable interconnect resources. The present invention also provides technique of flexibly combining or stitching multiple memories together to form memories of a desired size.

Abstract: In a programmable logic device having dedicated multiplier circuitry, some of the scan chain registers normally used for testing the device are located adjacent input registers of the multipliers. Those scan chain registers are ANDed with the input registers, and can be loaded with templates of ones and zeroes. This allows, e.g., subset multiplication if the least significant bits are loaded with zeroes and the remaining bits are loaded with ones. The multipliers preferably are arranged in blocks with other components, such as adders, that allow them to be configured as finite impulse response (FIR) filters. In such configurations, the scan chain registers can be used to load filter coefficients, avoiding the use of scarce logic and routing resources of the device.

Abstract: A configurable crossbar switching circuit within a programmable logic device capable of efficient, large scale switching and for cascading for implementing much larger switching functions. In one embodiment of the invention, the crossbar switch is integral to a programmable logic device. In one embodiment, the crossbar switching circuit is bus based, switching all of the conductors constituting a data bus substantially simultaneously and in their entirety as a bus unit. In one embodiment, the crossbar switching circuit performs switching operations unidirectionally. For the implementation of larger scale switching functions, one embodiment of the present invention exploits the cascadable character of the crossbar switching circuit. Cascading crossbar switches enables switching between differing numbers of inputs and outputs, even exceeding capacities of individual crossbars.

Abstract: A ramp-up circuit on an integrated circuit receives a relatively high program (erase) voltage for changing the program state of a memory cell. The ramp-up circuit gradually raises the program (erase) voltage to prevent damage to the memory cell. The ramp-up circuit includes a pass gate and associated control circuitry that provides a controlled, ramped-up version of the program (erase) voltage to the memory cell without raising internal circuit nodes above the program (erase) voltage.

Abstract: A bypassable latch circuit consumes less power in the bypass mode than it does in the latched mode. The circuit includes a flip-flop whose output is routed to an input of a multiplexer. The other input of the multiplexer is the input of the flip-flop as well. The multiplexer is used to select as the latch output either the registered or latched flip-flop output, or the flip-flop input. The flip-flop is modified by replacing the inverter at the flip-flop clock input with a logic gate that accepts as inputs both the clock input and a control input. The control input can cause the flip-flop to ignore the clock, preventing switching that consumes power by charging and discharging capacitive elements in the flip-flop.

Abstract: A semiconductor device and method of testing the device having a plurality of logic cells interconnected using vias to connect routing tracks that are disposed among a plurality of layers in the device. The logic cells in the device including at least two three-input look-up tables, one two-input look-up table and a flip-flop. The components in the logic cell are connected so that any look-up table can drive at least one input of any other look-up table and where the flip-flop is connected to the look-up tables so that any look-up table can drive an input of the flip-flop.

Abstract: There is disclosed a field programmable gate array (FPGA) that performs bit swapping functions in the interconnects rather than in the configurable logic blocks of the FPGA.

Abstract: A method and apparatus for enabling individual cells in a Cell Matrix to detect when they have been configured to act as a simple wire, and to bypass their internal logic accordingly. Such bypass conditions result in faster data transmission from input to output. When sets of adjacent cells are each configured to act as a wire, significantly faster transmission of data through the cells can be achieved by this bypass routing. Also disclosed is a means for selectively disconnecting unused inputs from internal logic, thereby further increasing switching speed across cells utilizing this bypass routing.

Abstract: A one transistor, non-volatile programmable switch includes uni-directional and in some embodiments, bi-directional, states. The programmable switch is used in an integrated circuit, and comprises a first node and a second node coupled with corresponding circuit elements in the integrated circuit. A non-volatile programmable transistor having a drain coupled to one of the first node and second node, a source coupled to the other of the first node and second node, gate coupled to an energizing conductor, and a data storage structure constitute the programmable switch. The non-volatile programmable transistor used in the switch is a charge programmable device (e.g. SONOS cell), in which the data storage structure comprises a nitride layer, or other charge trapping layer, between oxides or other insulators.

Abstract: A bifurcation circuit uses dynamic asP* protocol. to exchange data among three or more FIFOs. Each FIFO contains a plurality of places containing data and a plurality of paths that exchange data between neighboring places. The bifurcator circuit generally comprises a control FIFO, two subordinate FIFOs and a bifurcation path coupled to all three FIFOs. The bifurcator circuit further comprises a chain of data latches coupled to all three FIFOs at the bifurcation path. A data value carried in the control FIFO determines which of the subordinate FIFOs exchanges data with the control FIFO. Each place in the FIFOs contains a set reset flip-flop in which the state of each place is held by a single wire and stabilized by a keeper. A single transistor sets or resets the state of the place. The pulse that changes the state of the control flip-flops also makes the data latches momentarily transparent. The bifurcator circuit is generally capable of a branch or join operations.

Abstract: Described are programmable logic systems and methods in which programmable logic devices receive configuration data. In some embodiments, one or more input/output blocks of a programmable logic device are adapted to store a value identifying a remote memory space as a source of reconfiguration data. In other embodiments, external memory spaces for storing configuration data are adapted to store the value.

Abstract: A programmable logic device architecture. This programmable logic architecture includes a first logic block (425) containing programmable logic elements for performing logic functions. The architecture may also include a diagnostic block interface (415), which interfaces with the first logic block (425), for performing JTAG functions, configuring the first logic block (425), initializing the first logic block (425), interfacing with off-chip diagnostic and test devices and equipment, and performing other similar functions. The first logic block (425) may be programmably coupled to other components on the integrated circuit using a first programmable interconnect network (511). The first logic block (425) includes a plurality of second logic blocks (505) which may be programmably coupled using a second programmable interconnect network (521). The second programmable interconnect network (521) may be programmably coupled to the first programmable interconnect network (511).

Abstract: A Field Programmable Gate Array (FPGA) core cell with one or more Look-Up Tables (LUTs) and a selectable logic gate is presented as a space-efficient alternative to the conventional LUT-based FPGA core cell. An algorithm based upon the familiar FlowMap algorithm for LUT-based FPGA core cells implements the mapping of a Boolean logic network into the disclosed FPGA core cell.

Abstract: In a programmable logic device having dedicated multiplier circuitry, some of the scan chain registers normally used for testing the device are located adjacent input registers of the multipliers. Those scan chain registers are ANDed with the input registers, and can be loaded with templates of ones and zeroes. This allows, e.g., subset multiplication if the least significant bits are loaded with zeroes and the remaining bits are loaded with ones. The multipliers preferably are arranged in blocks with other components, such as adders, that allow them to be configured as finite impulse response (FIR) filters. In such configurations, the scan chain registers can be used to load filter coefficients, avoiding the use of scarce logic and routing resources of the device.

Abstract: A programmable logic circuit is provided that solves glitch problems associated with asynchronous logic operations associated with conventional look-up tables by utilizing a preset dominant transparent latch element to replace a conventional look-up table. Since latch elements are normally present in programmable logic circuits (e.g., FPGAs) no additional circuitry is necessary to implement the approach of the present invention. In one exemplary embodiment, an FPGA is provided which includes an array of programmable latch elements, and an array of programmable flip-flop elements generating flip-flop output signals. One or more of the latch elements are programmed to form a preset dominant transparent latch (PDTL) such that the data signals are coupled to the data inputs and preset inputs of the latch. In this manner, the latch operates to replace conventional look-up tables by operating as a primitive OR or NOR gate to generate a desired output.

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 read decoder includes a multiplexing circuit made up of a series of multiplexers that are directly controlled by the input signals received from the interconnect resources of the PLD. In one embodiment, a configurable logic block is provided with a single write decoder that is shared by a first LUT and a second LUT.

Abstract: In this invention, three schemes of nonvolatile FPLD structures are proposed using a latch that has been disclosed herein. In the first proposed scheme the latches, which can be designed using either GMR or SDT devices, will work as interconnects in a conventional Programmable Logic Array (PLA). In the second proposed scheme, the latches will constitute the look-up table for a standard PLA. In the third proposed scheme, the latch itself will work as a nonvolatile Programmable Logic Device (PLD) structure. This FPLD latch will have 2n GMR or SDT resistors, instead of just 2, for an n-input logic gate. By programming the resistors differently, in each scheme, numerous different logic functions from the same logic gate can be achieved.

Abstract: A multi-threshold flip-flop circuit having an outside feedback is disclosed. The multi-threshold flip-flop circuit comprises a master latch and a slave latch. Coupled between an output of the slave latch and an input of the master latch, a switchable feedback path is utilized to retain logical values of the slave latch during a sleep mode of the flip-flop circuit.

Abstract: A technique to implement functions requiring fewer pins of an integrated circuit to serially transfer data into the integrated circuit for multiple logic blocks. By reducing the required pins, this permits downbonding of the integrated circuit into a package with fewer pins. This technique may be used to implement test Functions in a programmable logic device. Test data may be serially input using a test pin (410) for two or more columns (320) of logic blocks. The test data is stored in an A resister (330), and may be later transferred into a B register (335).