Abstract: A method of determining a forced gating function for at least one of a plurality of clocked state-holding elements. The forced gating function compares the input and output of said at least one clocked state-holding element. The method simulates the performance of the element for different implementation conditions; measures the performance of the element for each condition, and determines the implementation of the forced gating function using the measured performances.

Abstract: There is disclosed a clock gating structure for a synchronous circuit comprising a plurality of clocked state holding elements, the clocked gating structure including at least one full-cycle clock gating cell and at least one half-cycle clock gating cell, and a method for designing and controlling such.

Abstract: A method of transforming a first integrated circuit design comprising a plurality of D-type flip-flops each having a clock signal and being associated with an enable signal into a second integrated circuit design using guard-flops, the method comprising: identifying D-type flip-flops in the first integrated circuit design, and transforming each of the identified D-type flip-flops into a guard-flop comprising a transparent catch latch and a transparent pass latch; generating a catch enable signal for controlling the transparent catch latch from the clock signal and enable signal of the D-type flip-flop in the first integrated circuit design; and generating a pass enable signal for controlling the transparent pass latch based on the catch signals of at least some of the guard-flops that take data from the D-type flip-flop in the first integrated circuit design.

Abstract: A programmed computer searches for functional defects in a description of a circuit undergoing functional verification in the following manner. The programmed computer simulates the functional behavior of the circuit in response to a test vector, automatically restores the state of the simulation without causing the simulation to pass through a reset state, and then simulates the functional behavior of the circuit in response to another test vector. A predetermined rule can be used to identify test vectors to be simulated, and the predetermined rule can depend upon a measure of functional verification, including the number of times during simulation when a first state transition is performed by a first-controller at the same time as a second state transition is performed by a second controller. During simulation of the test vectors, manually generated tests or automatically generated checkers can monitor portions of the circuit for defective behavior.

Abstract: A latch is provided which includes: a transparent catch latch having a data input, a data output and a control node arranged to receive a catch signal; a transparent pass latch having a data input connected to the data output of the transparent catch latch at an internal storage node, a data output, and a control node arranged to receive a pass signal; and logic circuitry having an enable input and a clock input connected to provide a gated clock signal to provide one of said catch signal and said pass signal. In another aspect an integrated circuit is provided with input and output guard flops, each including a transparent catch latch and a transparent pass latch, and further including a logic gate with an enable input and a clock input connected to provide a gated clock signal to at least one of the transparent pass latch of the input guard-flop and transparent catch latch of the output guard flop.

Abstract: There is disclosed a method, and apparatus for implementing the method, for determining a gating function for the input to one of a plurality of clocked state holding elements, comprising the step of: for each element determining a first Boolean function corresponding to the variables forming an input to the element; determining a gating function for the plurality of elements; and for each element determining a second Boolean function which provides the same result as the first Boolean function when the gating function has a value 1.

Abstract: There is disclosed a method, and associated apparatus, for optimizing a gating expression for controlling the clock gating to a set of clocked state holding elements, said gating expression comprising at least one variable, the method comprising the step of maximizing the conjunctive form of said at least one variable.

Abstract: There is disclosed a method, and corresponding apparatus, for determining a clock gating function for a set of clocked state-holding elements, comprising the steps of: for each element, determining the conditions under which the element will hold its current value based only on those inputs which are common to all elements; and combining the conditions to form a gating function.

Abstract: There is disclosed a clock gating structure for a synchronous circuit comprising a plurality of clocked state holding elements, the clocked gating structure including at least one full-cycle clock gating cell and at least one half-cycle clock gating cell, and a method for designing and controlling such.

Abstract: There is disclosed a method of determining a forced gating function for at least one of a plurality of clocked state-holding elements, which forced gating function compares the input and output of said at least one element, the method comprising: simulating the performance of the element for different implementation conditions; measuring the performance of the element for each condition, and determining the implementation of the forced gating function in dependence on said measured performances.

Abstract: A method of transforming a first integrated circuit design comprising a plurality of D-type flip-flops each having a clock signal and being associated with an enable signal into a second integrated circuit design using guard-flops, the method comprising: identifying D-type flip-flops in the first integrated circuit design, and transforming each of the identified D-type flip-flops into a guard-flop comprising a transparent catch latch and a transparent pass latch; generating a catch enable signal for controlling the transparent catch latch from the clock signal and enable signal of the D-type flip-flop in the first integrated circuit design; and generating a pass enable signal for controlling the transparent pass latch based on the catch signals of at least some of the guard-flops that take data from the D-type flip-flop in the first integrated circuit design.

Abstract: A latch is provided which includes: a transparent catch latch having a data input, a data output and a control node arranged to receive a catch signal; a transparent pass latch having a data input connected to the data output of the transparent catch latch at an internal storage node, a data output, and a control node arranged to receive a pass signal; and logic circuitry having an enable input and a clock input connected to provide a gated clock signal to provide one of said catch signal and said pass signal.

Abstract: A turnstile FIFO stores data packet from each of a number of separate ordered sets in a generally circular list structure. A select data packet can be dequeued if no older data packet of the same ordered set is stored in the turnstile FIFO. The data packets are stored in the turnstile FIFO in a globally sequential order such that older data packets precede younger data packets regardless of membership in the one or more ordered sets. Turnstile logic determines whether the selected data packet is the oldest data packet of a given ordered set by determining set membership of all older data packets stored in the turnstile FIFO. Older data packets are stored in positions within the turnstile FIFO which precede the position of the selected data packet.

Abstract: A turnstile FIFO stores data packet from each of a number of separate ordered sets in a generally circular list structure. A select data packet can be dequeued if no older data packet of the same ordered set is stored in the turnstile FIFO. The data packets are stored in the turnstile FIFO in a globally sequential order such that older data packets precede younger data packets regardless of membership in the one or more ordered sets. Turnstile logic determines whether the selected data packet is the oldest data packet of a given ordered set by determining set membership of all older data packets stored in the turnstile FIFO. Older data packets are stored in positions within the turnstile FIFO which precede the position of the selected data packet.

Abstract: A portable spot welder includes a hand-held electrode clamp assembly. The hand-held clamp has a fixed electrode and a movable electrode adapted to be moved toward and away from the fixed electrode. A spring loaded toggle is used to pivot the movable electrode to clamp a workpiece between the electrodes to exert a predetermined and repeatable pressure. The invention includes an air cooling system. Air is forced through the electrical cables connecting the hand-held electrode clamp to the welder transformer. At the hand-held clamp, the air escapes to the atmosphere through passageways near the electrodes, thereby enabling heat generated within the cables and at the electrodes to be transferred to the flowing air.