Abstract: A digital frequency synthesizer (DFS) circuit adds little additional delay on the clock path. True and complement versions of an input clock signal are provided to a first and second passgates, respectively. Under the direction of a control circuit, the passgates pass selected rising edges of the true clock signal, and selected falling edges of the complement clock signal, to an output clock terminal of the DFS circuit. When neither the true nor the complement clock signal is passed, a keeper circuit retains the value already present at the output clock terminal. In some embodiments, both passgates can be disabled and a ground or power high signal can be applied to the output terminal. Other embodiments include PLDs in which the DFS circuits are employed to allow individual clock control for each programmable logic block.

Abstract: After a delay lock loop synchronizes a reference clock signal with a skewed clock signal, a digital phase shifter can be used to shift the skewed clock signal by a small amount with respect to the reference clock signal. The tap/trim settings of a delay line in the main path of the delay lock loop can be transmitted to the digital phase shifter, thereby informing the digital phase shifter of the period of the reference clock signal. In response, the digital phase shifter provides a phase control signal that introduces a delay, which is referenced to the period of the reference clock signal, to either the reference clock signal or the skew clock signal. The phase control signal is proportional to a predetermined fraction of the period of the reference clock signal. The digital phase shifter can be controlled to operate in several modes. In a first fixed mode, the digital phase shifter introduces delay to the skew clock signal.

Abstract: A method of providing a constant current drive to a driver circuit (40) in a compensating bias circuit (10) includes the steps of providing a constant current source insensitive to process, supply voltage, and temperature variations and mirroring the constant current source to the driver circuit while adding no sensitivity to process, supply voltage, and temperature variations.

Abstract: A programmable integrated circuit is disclosed that includes a nonvolatile memory cell programmed to represent a configuration bit associated with a special purpose function. A volatile memory cell is associated with the nonvolatile memory cell. The integrated circuit includes a logic gate for logically combining states of the volatile and nonvolatile memory cells to selectively enable the special purpose function, even before the volatile memory cell is initialized. In this way, the predetermined function can be executed prior to a complete initialization of the integrated circuit.

Abstract: Method and apparatus for an insertable block tile is described. More particularly, a reserved area in an integrated circuit layout is removed, and terminated conductive line information is extracted from a layout database affected by the removal. The terminated conductive line information is used to create extensions or pins of the conductive lines terminated, as well as to identify signals associated with those terminated conductive lines. These physical or layout names and coordinates are mapped and then translated to logic names and coordinates for placement and routing to create the insertable block tile.

Abstract: Optimal routing line segments and associated buffers are pre-engineered for each family of ASIC chips by simulating wires segments of various lengths using distributed resistance and capacitance wire models, and by estimating crosstalk from neighboring line segments. During ASIC design, space is reserved on the ASIC substrate for fabricating the buffers, which are selectively connected by local metal and diffusion structures to form long distance interconnections. Signals are passed from an ASIC circuit structure to a selected long distance interconnection by connecting an output terminal of the ASIC structure either to the input terminal of a buffer located at one end of the interconnection, or by connecting the output terminal directed to a line segment of the interconnection.

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 form 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 multiplexer that can be used, for example, in a programmable logic device (PLD). The multiplexer includes a plurality of pass transistors passing a selected one of several input values to an internal node, which drives a buffer that provides the multiplexer output signal. The pass transistors can be controlled, for example, by values stored in memory cells of a PLD. The pass transistors have a first oxide thickness and are controlled by a value having a first operating voltage. The buffer includes transistors having a second and thinner oxide thickness, and is operated at a second and lower operating voltage. Where memory cells are used to control the pass transistors, the memory cells include transistors having the first oxide thickness and operate at the first operating voltage. Some embodiments also include transistors of varying gate length for each of the pass transistors, buffer transistors, and memory cell transistors.

Abstract: A structure that can be used, for example, to implement a lookup table for a programmable logic device (PLD). The structure includes configuration memory cells, pass transistors, and a buffer. The pass transistors pass the output of a selected configuration memory cell to the buffer, and are controlled by data input signals of the structure. The pass transistors have a first oxide thickness and are controlled by a value having a first operating voltage. The memory cells and buffer include transistors having a second oxide thickness thinner than the first oxide thickness, and operate at a second operating voltage lower than the first operating voltage. The data input signals are provided at the first operating voltage. Some embodiments include data generating circuits that include transistors having the first oxide thickness. Gate lengths can also vary between the memory cell transistors, pass transistors, buffer transistors, and data generating circuits.

Abstract: A clock recovery circuit that operates at a clock speed equal to one-half the input data rate is presented. The clock recovery circuit uses dual input latches to sample the incoming serial data on both the rising edge and falling edge of a half-rate clock signal to provide equivalent full data rate clock recovery. The clock recovery circuit functions to maintain the half-rate clock transitions in the center of the incoming serial data bits. The clock recovery circuit includes a phase detector, charge pump, controlled oscillation module and a feedback module. The phase detector produces information on the phase and data transitions in the incoming data signal to the charge pump. Generally, the circuit is delay insensitive and receives phase and transition information staggered relative to each other.

Abstract: A buffer employs an input stage with an active, LC load. The active load includes integrated inductors that combine with the parasitic gate capacitances of a pair of transistors in a negative-transconductance (−Gm) booster configuration. The resulting active load emphasizes a desired frequency, improving the quality, or “Q,” of the input stage, and consequently of the entire buffer.

Abstract: Method and apparatus is described for interconnect routing. More particularly, an integrated circuit may be thought of as a network with a plurality of resources that are interconnected. These resources may be blocks of circuitry or individual circuit elements. By first routing in a resource mode, critical connections are identifiable. After that routing, a deterministic approach to delay mode routing is described using logic level information. Connections within a logic level are independent, thereby allowing multiple connections for a logic level to be routed together without any need for timing update.

Abstract: Method and code for dedicated resource placement enhancement is described. More particularly, a local area of a network is obtained for determining placement options of logic blocks to increase availability of dedicated resources within the local area. Each placement option is scored. This scoring may be based in part on whether a signal is to be propagated over a dedicated resource, and whether this signal is presently meeting a slack or target delay. Logic blocks, and therefore the dedicated resources, are placed after scoring.

Abstract: Probe points can be inserted (430) into an FPGA-based embedded processor SoC (305a) while specifying hardware and software cores with a design automation tool. This tool then aids the user (via high level GUI) in imbedding logic analysis functions in the SoC and connecting selected monitor signals to the logic analyzer. The design automation tool provides the necessary support files for the logic analysis software suite for naming and formatting of monitor signals on the waveform display. Trigger and trace information can be captured for the probe points and waveforms representing the captured information can be displayed (450) for analysis. An integrated logic analyzer core can be downloaded (440) into the FPGA-based embedded processor SoC to facilitate insertion of the probe points and capture of information. A software application can receive the captured information and translate it into a format suitable for display.

Abstract: A method for using an FPGA to implement a crossbar switch is described. Rather than using signals routed through the general FPGA routing resources to control connectivity of the crossbar switch, the input signals only carry crossbar switch data, and the connectivity is controlled by FPGA configuration data. The crossbar switch is implemented in two parts: a template of basic and constant routing to carry input signals through the switch array in one dimension and output signals from the array in another dimension, and a connectivity part controlled by a connectivity table or algorithm to generate partial reconfiguration bitstreams that determine which of the input signals is to be connected to which of the output signals.

Abstract: A VDD power-up detection circuit is provided having a p-channel transistor having a source coupled to a VDD voltage supply terminal and a gate coupled to a ground supply terminal. A first resistor or a diode element is coupled between the drain of the p-channel transistor and the ground supply terminal. An n-channel transistor has a source coupled to the ground supply terminal and a gate coupled to the drain of the p-channel transistor. A second resistor is coupled between a drain of the n-channel transistor and the VDD voltage supply terminal. A trigger circuit is coupled to the drain of the n-channel transistor. As the VDD supply voltage increases during power-up, the p-channel and n-channel transistors are both turned on. At this time, the trigger circuit asserts a control signal that enables an associated circuit to operate in response to the VDD supply voltage.

Abstract: An active inductance circuit for ESD parasitic cancellation is described. A feedback circuit on a transconductance amplifier is utilized to transform and reflect the impedance of an active inductor to minimize effects of parasitics produced by ESD circuitry. The active inductance circuit may be programmably implemented, allowing tunable component values.

Abstract: A phase detector employing asynchronous level-mode sequential circuitry is described. The phase detector includes edge detection circuitry for generating a first edge detection signal and a second edge detection signal. The first edge detection signal is indicative of an edge in a first clock signal, and the second edge detection signal is indicative of an edge in a second clock signal. The phase detector further includes a state machine that is asynchronously responsive to level changes in the first and second edge signals. The state machine generates a control signal indicative of which of the first and second clock signals is leading the other of the first and second clock signals.

Abstract: The present invention provides a method for breakpoint stepping a multi-bus device. The multi-bus device includes a breakpoint unit capable of detecting bus events on multiple busses. The breakpoint unit is originally programmed to break on the detection of a specified bus event on a bus selected from multiple busses. After the specified bus event has been detected and the device has entered one of several possible frozen states, the breakpoint unit may be programmed to detect a new bus event on a bus selected from multiple busses. The method is repeated as needed to achieve breakpoint stepping, including single stepping.

Abstract: A die assembly contains multiple stacked dice bonded together by a large number of metal posts. A first die has a plurality of metal posts oriented orthogonally to a planar surface of the first die. The metal posts protrude from the first die out beyond the surface. Similarly, a second die also has a plurality of metal posts protruding from a surface. The first die is coupled to the second die in an oxygen-free atmosphere such that each protruding metal post of the first die contacts a protruding metal post of the second die. By applying pressure, cold welds are formed between corresponding metal posts of the first and second dice. The first die and the second die are held together by the metal posts without an adhesive. In one embodiment, some of the metal posts do not conduct signals between the first and second dice.