Abstract: A single-electron tunneling (SET) element used as a logic or memory element includes at least one tunneling junction with a minute metal-insulator-metal sandwich structure, and a biasing power source which is connected in series to the at least one tunneling junction and whose ON/OFF operation is controlled by an external control input. SET oscillations are generated in the at least one tunneling junction and the generated oscillations are phase-locked to subharmonics of a pump signal supplied from an AC power source, to thus exhibit a plurality of stable phase states. Also, a plurality of gates, each including the SET element, are constituted in the form of a logic network to realize a predetermined logic operation in a computer. In the logic network, an input signal with a frequency half that of the pump signal is continually applied to a specified gate among the plurality of gates, while the biasing power sources of all of the gates are kept in ON state.

Abstract: A circuit utilizes a toggle flip-flop, a D flip-flop and combinatorial logic to generate a clock signal which can be enabled or disabled without creating spikes or shortened pulses in the clock signal. The circuit receives an input clock signal and an input clock enable signal. The circuit generates an output clock signal which is an enabled/disabled version of the input clock signal, controlled by the input clock enable signal. The circuit thus provides the operational advantages of enabling or disabling, with a single control signal, groups of logic circuits triggered by a common clock signal.

Abstract: An architecture is provided for field programmable gate army (FPGA) devices which implement relay ladder logic in PLC systems. Once the device is programmed, the implemented logic is executed in rung parallel fashion at electronic speeds. A direct correspondence of these devices in detail to relay ladder logic assures that technology mapping software for the FPGA device will run sufficiently fast for use in PLC systems. A reversible device programming method is required, so that the device can be reprogrammed conveniently to different relay ladder models. The architecture scales to families of devices of differing sizes and resources. A basic relay ladder logic is implemented, which supports various relay ladder logic dialects.

Abstract: In a voltage level shift circuit, a load device L11, a P-channel type MOS transistor P12 and N-channel type MOS transistors N12 and N11 are connected in series in the cited order between a high voltage source Vpp and GND. Voltages VMP and VMN having a level close to Vpp/2 are applied to the respective gates of the transistors P12 and N12 in order to suppress the level of the voltage to be applied to the gate oxide films of the MOS transistors.

Abstract: An improved tri-state output buffer having an emitter-follower output stage clamps the reverse-bias voltage across the base-emitter path of an emitter-follower to limit the output leakage current and thereby extending the operating life of an integrated circuit (IC). A current sensitive voltage device such as a bipolar transistor or diode clamps the reverse-bias voltage of the base-emitter path. Voltage clamping prevents the bipolar transistors from activating while the buffer is disabled. The output leakage current that occurs when the junction is forward biased is minimized. This results in low output load capacitance that improves the propagation delay particularly when multiple buffers are used.

Abstract: A logic gate circuit includes a logic gate stage to which an input signal is supplied, for outputting a signal depending on a state of the input signal, an output driver stage having an enhancement-type transistor for pull-up and a pull-down circuit, the enhancement-type transistor having a drain connected to a power supply line, a gate to which the signal output from the logic gate stage is supplied and a source connected to the pull-down circuit, the pull-down circuit being connected to the ground line and controlled by the input signal, and a clamping circuit for clamping a gate voltage of the enhancement-type transistor of the output driver stage at a constant voltage so that a node at which the source of the enhancement-type transistor and the pull-down circuit are connected has a high level, the node being an output terminal of the logic gate circuit.

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: A termination network in an integrated circuit, and a control circuit for controlling the impedance of the termination network is described. The termination network comprises transistors for matching the impedance of the termination network with the characteristic impedance of a transmission line, which is connected to the termination network. The control circuit comprises a reference transistor which is integrated on the same integrated circuit as the termination network. The control circuit senses the impedance of the reference transistor and controls the reference transistor and the transistors in the termination network in such a way that the impedance is not affected by variations in temperature and in the manufacturing process of the integrated circuit.

Abstract: A 4.times.1 multiplexer for an electrically configurable device uses novel logic gates to logically combine outputs from two SRAM memory cells to control pass gates between the multiplexer signal inputs and a multiplexer output. Each logic gate has three transistors. A complementary NMOS/PMOS pair of transistors defines a transmission gate. The gate of the NMOS transistor defines a first logic-gate input, while the gate of the PMOS transistor defines a second logic-gate input. Their sources are coupled and cooperatively define a third logic-gate input. Their drains are coupled and cooperatively define the logic-gate output. A third transistor, with its gate tied to the third input, couples the logic-gate output to ground when the transmission gate is OFF. The first and second logic-gate inputs are respectively coupled to complementary outputs of one memory cell, while the third logic gate input is coupled to an output of the other memory cell.

Abstract: A reduced power programmable logic array is disclosed. The circuit includes an AND array, coupled through product term lines to an output OR array. Pull-up devices in the OR array are gated to one of the active product term lines. Also disclosed is method for choosing a product term line for gating pull-up devices such that power consumption in the pull-up devices is minimized.

Abstract: An output buffer is disclosed for an integrated circuit having a varying number of simultaneously switching outputs. As fewer outputs on the integrated circuit are simultaneously switching, the output conductance of certain logic gates within each of the output buffers on the integrated circuit is increased by sharing intermediate nodes between each of the output buffers. Consequently, the speed of the output buffer increases as fewer of the outputs simultaneously switch and internally generated noise is small. Conversely, as additional outputs simultaneously switch, the output conductance of certain logic gates within the output buffer is decreased, resulting in reduced speed of the output buffers and a corresponding reduction in internally generated noise.

Abstract: An improved programmable logic device (PLD) comprises a programmable AND first array to which a set of PLD input lines are selectively connectable and providing a set of outputs which are selectively connectable to a set of inputs to a programmable OR second army which drives a second set of output lines, in combination with a programmable AND third array having a set of inputs that are selectively connectable to the set of input lines and having a set of outputs that are fixedly connected as a set of inputs to a fixed OR fourth array providing a set of PLD outputs, with the set of outputs from the OR second array also connected in a fixed manner as inputs to the OR fourth array. This arrangement overcomes some of the weaknesses in both the conventional PAL and PLA architectures while retaining most of their strengths.

Abstract: A data qualification circuit (11) comprises a comparator (28), a first threshold circuit (33), and a second threshold circuit (41). A differential input signal is applied to the data qualification circuit (11). A first threshold circuit (33) is enabled by a zero logic state at the output of comparator (28). The first threshold circuit (33) sets a one logic state threshold voltage which the differential input signal must overcome for the comparator (28) to generate a one logic state. A second threshold circuit (41) is enabled by a zero logic state at the output of comparator (28). The second threshold circuit (41) sets a zero logic state threshold voltage which the differential input signal must overcome for the comparator (28) to generate a zero logic state.

Abstract: An improved local clock driver for locating critical speed paths within a integrated digital circuit. Highly integrated digital circuits have many local circuits and each local circuit has a local clock driver. The local clock driver strengthens and distributes a clock signal within the local circuit. The improved local clock driver introduces a controllable delay circuit in all the local clock drivers of the digital integrated circuit. By selectively delaying each local clock driver, critical speed paths can be located. To compensate for critical speed paths, the delay circuit can be turned on in the receiving local block circuit.

Abstract: The present invention provides a device for terminating a data bus. The present invention provides the proper termination without the use of external discrete components. The device can be programmed, at the chip level, to produce particular termination resistances that are commonly used. The present invention termination device uses a minimum of power dissipation which may be useful in applications that require minimum power consumption.

Abstract: A current source varies the bias current to a differential amplifier according to fluctuations in the supply voltage. In this manner, the operating point of the differential amplifier is automatically adjusted to compensate for variations in the supply voltage. Adjusting bias current in this manner provides for a reduction in power dissipation. The current supply is coupled to the differential amplifier in such a manner that a current mirror is not required to be connected between the differential amplifier and the inverter. Eliminating the need for such a current mirror is advantageous in reducing the number of gate delays and thereby increasing the speed of a level translator to which the current source is coupled.

Abstract: An apparatus and method is provided for precharging a conductor within a bus containing a plurality of conductors. The apparatus comprises a precharge circuit which drives an intermediate voltage between VDD and ground upon respective conductors. The precharge driver maintains the intermediate voltage within a range between a first voltage level and a second voltage level, the second voltage level being higher in magnitude than the first voltage level. The precharge voltage defined within an intermediate voltage range is chosen to consume minimal power within the precharge driver. An isolation device can be provided on each conductor for isolating the intermediate, precharged value from a receiver circuit input so as to minimize power consumption of the overall circuit. Precharging to an intermediate value causes logic-driven transitions within the bus to occur at a faster frequency than if the bus were precharged to full rail.

Abstract: In an FPGA having a hierarchical routing structure, additional routing lines are provided which have different destinations for different cells within a block. A pattern is chosen which allows signal lines to turn corners conveniently. In one embodiment having cells arranged into 4.times.4 blocks, cells on the diagonal of a block generate signals which are provided to switches which form one boundary of the block.

Abstract: A technique is provided for signaling to a first data processing circuit that an output of a second data processing circuit is ready for processing by the first data processing circuit. An occurrence of a logic transition at an input of the second data processing circuit is detected, and a latch circuit is used to produce a detection signal indicative of the occurrence. In response to the logic transition, the output of the second data processing circuit is produced, and this output is provided to the first data processing circuit. In response to production of the detection signal, and after delaying for an amount of time adequate to permit the second data processing circuit to produce its output, a done signal is sent to the first data processing circuit.

Abstract: A clock signal generator inputs a main system clock signal and timing signals to indicate optimum timings for selecting and outputting data, respectively, in an integrated circuit to be accessed which performs based on a specified clock signal with respect to the main clock signal. The clock signal generator outputs clock signals having different duty ratios of the main clock signal according to the timing signals for a precharge operation and a readout operation for the integrated circuit. A precharge type integrated circuit including the clock signal generator outputs data therein correctly according to an address signal and the timing signals from the clock signal generator.