Abstract: A method for preventing illicit copying of an application specific integrated circuit (ASIC). The ASIC is defined by a net list which includes a timer circuit for disabling the ASIC. The timer circuit includes a plurality of stages which are distributed in different cores of the ASIC to inhibit detection and removal of the circuit. The timer times out after a period which is set to permit evaluation of the ASIC design. Following the time out period, further use of the ASIC design is inhibited.

Abstract: A logic element for a programmable logic device to implement a global shareable expander. The logic element includes logic modules (P0-P4) for implementing combinatorial logic and a register (445). The combinatorial and registered paths of a logic element may be utilized at the same time. The logic modules may be programmably coupled to the register. The output of the register may be programmably coupled through an output buffer (515) to an I/O pad (520) of the integrated circuit. The logic modules may bypass the register and directly programmably couple through the output buffer to the I/O pad. A logic module may be used as a shareable expander by programmably coupling the module through to a global interconnect with other logic modules in LABs coupled to the global interconnect.

Abstract: An analog-to-digital converter (ADC) is realized in a field programmable gate array (FPGA) without adding special dedicated analog circuitry. In a digital application, a comparator in an interface cell of the FPGA compares an incoming digital signal to a reference voltage. Adjusting of the reference voltage allows the interface cell to support different digital I/O standards. In one embodiment, the comparator is not used for this digital purpose, but rather is used as a comparator in an ADC. A flash ADC is realized by using the comparators of numerous interface cells as the comparators of the flash ADC. Conversion speed is increased by reducing the impedance of the analog signal input path. An on-chip resistor string is provided so that the flash ADC can be realized without external components. In another embodiment, the comparator of the interface cell is the comparator of a successive approximation ADC.

Abstract: A three-state CMOS output buffer (200), having protective circuitry and an output node (OUT) connected to a bus, prevents damage to a connected integrated circuit when the bus voltage exceeds a power supply reference voltage (VCC). A final output stage of the output buffer (200) includes a first pull-up transistor (QP200), a clamping transistor (QN202), and a pull-down transistor (QN204). A half-pass circuit (QN200) blocks the output voltage from propagating through the final output stage to damage the output buffer (200) when the output voltage applied to the output node (OUT) exceeds the supply voltage. The protective circuitry uses a clamping circuit (210), a switching circuit (212) and a backgate bias circuit (206) to prevent a leakage path between the output node (OUT) and the power supply reference (VCC) through the source/bulk junction of biased transistors in the output buffer (200).

Abstract: An adiabatic charging logic circuit includes a logic circuit and a power supply section. The logic circuit is constituted by a plurality of logic elements. The power supply section supplies power to the logic circuit to cause the logic circuit to perform logic processing after an input signal is supplied to the gate of each of the logic elements, and stops supply of the power before a new input signal is supplied to the gate of each of the logic elements after completion of the logic processing.

Abstract: A window pane architecture for FPGAs utilizes spaced subarrays having routing channels therebetween. In one embodiment, at least one routing channel includes segmented and staggered routing wires to minimize current loading and capacitive time delay. Connections between the configurable logic blocks, interconnect, and routing wires may be accomplished with switch matrices and programmable interconnect points.

Abstract: An image processing system uses an FPGA and an external memory to form neighborhoods for image processing. The FPGA is connected to the external memory in a way that reuses address lines, and increases the effective bandwidth of the operation.

Abstract: An programmable logic device has an enhanced embedded array block for the efficient implementation of logic functions including a random access memory and a first-in, first-out memory. A read address register and a write address register are implemented within the embedded array block. The address registers are coupled with a memory array in the embedded array block without using a resources from a programmable interconnect scheme. The first-in, first-out memory may operate as a dual-port FIFO, without cycle-sharing on the interconnect lines.

Abstract: A data input buffer circuit is disclosed.

Abstract: A signal translator circuit for particular use with low level logic signals is designed to accept a low level transitioning signal in a lower voltage range and output a signal transitioning within a higher voltage range. Circuitry is provided to ensure proper operation even at very low voltages. The circuitry which ensures proper operation at low voltages is selectively enabled when low input voltage input signals are used. In addition, the output signal is selectively disabled to allow downstream circuits to conserve energy during power up and power down cycles.

Abstract: The invention discloses an architecture for the input/output buffer section of an FPGA. It provides a convenient and efficient addressing scheme for addressing fuse matrices that are used to configure programmable input/output buffers in the FPGA.

Abstract: Integrated circuit output buffers include pull-down an pull-up circuits and a control circuit that utilizes a preferred feedback circuit to facilitate a reduction in simultaneous-switching noise during pull-down and pull-up operations and also improve the impedance matching characteristics of the output buffers during DC conditions. The preferred feedback circuit also limits the degree to which external noise can influence operation of the control circuit. Each of the pull-down and pull-up circuits may comprise a respective pair of primary and secondary transistors. The pull-down circuit is preferably configured so that the primary and secondary pull-down transistors (e.g., NMOS transistors) are electrically coupled to an output signal line (through an ESD protection resistor) and a first reference signal line (e.g., Vss).

Abstract: In a DCFL circuit, a high-speed operation is conducted in a stable state regardless of its load capacitance. The circuit includes a buffer circuit. Added to the buffer circuit is a pull-up circuit conducting a pull-up operation for a predetermined period of time when an output potential of the circuit changes from a low level to a high level. A first EFET of the pull-up circuit includes a gate electrode connected to an output terminal of a logic stage, a drain electrode coupled with a positive power source, and a source electrode linked with a drain of a second EFET. The second EFET includes a gate electrode connected to a node linked in series to a resistor element. The resistor is coupled with an input terminal. The second EFET includes the drain electrode connected to a source electrode of the first EFET and a source electrode linked with an output terminal.

Abstract: The invention provides a programmable delay element and a programmable slew rate element to allow post-fabrication adjustment and programming of input delay and output slew rate to iteratively alter input delay and output slew rate without redesign and refabrication of the circuit. The invention provides programmable memory cells coupled to a capacitive load via a plurality of switches. The capacitive load is coupled to a signal path and comprises a plurality of capacitors. The programmable memory cells selectively turn on the switches coupled to the capacitive load. In one FPGA implementation, the programmable memory cells are implemented in IOBs and are loaded with appropriate data during a device configuration stage. Delay equalization can be achieved by programming the memory cells such that the delays seen by device I/O pins are equal between IOBs and pads. The invention also provides a slew rate control circuit for an inverter or a buffer to provide an optimal slew rate.

Abstract: A method is provided for precharging a node in an integrated circuit in which the node is precharged a first predetermined delay after the node evaluates and, thereafter, the precharge ceases after a second shorter predetermined delay.

Abstract: A mixed voltage output driver includes an output sensing circuit that senses an output voltage at an output terminal and generates a voltage signal that corresponds to a voltage level at the output terminal. Next, an impedance selection circuit receives the voltage signal and generates a control signal in response to the output voltage having a higher logical uplevel than the mixed voltage output driver. The control signal is then received by an adjustable drive impedance circuit that is also coupled to an input terminal of the mixed voltage output driver and, in response thereto, the adjustable drive impedance circuit modifies an output drive impedance of the mixed voltage output driver. In another advantageous embodiment, the mixed voltage output driver only determines if the output voltage at the output terminal is at a logical uplevel before adjusting the output drive impedance.

Abstract: A single-rail input to dual-rail output conversion circuit suitable for a domino logic hold-time latch. The conversion circuit integrates the two circuit functions in the same circuit block. The circuit involves minimal circuit complexity including a single additional transistor. This circuit eliminates a problem of false output of the prior art.

Abstract: The loop latency compensated PLL filter comprising two additional feedback terms, a delayed phase compensation signal and a state compensation signal, that are provided as input of a PLL filter. Accordingly, the PLL filter input comprises two additional compensation input signals: the delayed phase compensation signal and the state compensation signal in addition to a phase estimated error output from a phase detector that is also coupled to the input of the PLL filter. Consequently, PLL filter thus is able to provide a latency compensated phase error control output that is fedback to control a phase mixer to generate a square waveform used to drive an A/D of the PLL in accordance with the principles of this invention. The loop latency compensated PLL of this invention thus minimizes the jitter of the PLL circuit, provides higher format efficiency, and also has reduced sensitivity to large bursty noises.

Abstract: A method and apparatus are provided for selectively controlling weak feedback in pass gate logic circuits. The pass gate logic circuit includes an intermediate node. A feedback transistor stack is connected between the intermediate node and a voltage supply. The feedback transistor stack includes a pair of transistors. A test signal is applied to a control input of one of the pair of transistors for selectively activating the feedback transistor stack.

Abstract: A 64-bit comparator includes a first stage for receiving a 64-bit number A and a 64-bit number B, and generating first output values. A second stage then receives the first output values from the first stage and outputs second output values, and a third stage receives the second output values from the second stage and outputs greater than, less than, and equivalent values. Thus, the comparator is faster in that it is implemented in three logic stages by making efficient use of compound dynamic gates.