Abstract: Approaches for processing a circuit design include determining pin slack values for pins of the circuit elements in the circuit design. A processor selects a subset of endpoints based on pin slack values of the endpoints being in a critical slack range and determines startpoints of the circuit design that are in respective critical fanin cones. For each endpoint of the subset, the processor determines an arrival time from each startpoint in the respective critical fanin cone and determines for each startpoint-endpoint pair, a respective set of constraint values as a function of the respective arrival time from the startpoint. The processor generates a graph in the memory circuit from the startpoint-endpoint pairs. First nodes in the graph represent the startpoints and second nodes in the graph represent the endpoints, and values in the respective set of constraint values are associated with edges that connect the nodes.

Abstract: Improving timing of a circuit design may include determining, using a processor, critical feed-forward paths of the circuit design, determining, using the processor, a sequential loop having a largest loop delay within the circuit design, and iteratively cutting, using the processor, the critical feed-forward paths and feed-forward paths parallel to the cut critical feed-forward paths until a stopping condition is met. The stopping condition may be determined according to the largest loop delay. The circuit design may be modified by inserting a register at each cut feed-forward path.

Abstract: A device includes a multiplexer circuit with a plurality of input circuits. Each input circuit is connected to a respective input node and a shared output node. The input circuits are configured to pass, in response to a respective control signal, a signal between the respective input and shared output node. An output circuit is configured to store data from the shared output node in a latch mode and to act as a buffer in a pass-through mode. A control circuit is configured to switch, in response to a configuration signal, the output circuit between the latch mode and the pass-through mode.

Abstract: Disclosed approaches for processing a circuit design include identifying duplicate instances of a module in a representation of the circuit design. A processor circuit performs folding operations for at least one pair of the duplicate instances of the module. One instance of the duplicates is removed from the circuit design, and a multiplexer is inserted. The multiplexer receives and selects one of the input signals to the duplicate instances and provides the selected input signal to the remaining instance. For each flip-flop in the remaining instance, a pipelined flip-flop is inserted. Connections to a first clock signal in the remaining instance are replaced with connections to a second clock signal having twice the frequency of the first clock signal. An alignment circuit is inserted to receive the output signal from the first instance and provide concurrent first and second output signals.

Abstract: A circuit for reducing duty-cycle distortion in an integrated circuit implementing dual-edge clocking is described. The circuit also comprises a plurality of circuit elements that enable the routing of data generated at outputs of the circuit elements; a plurality of register circuits that store data at outputs of the plurality of circuit elements; a clock circuit routing a clock signal to clock inputs of the plurality of register circuits; and a pulsed-controlled register circuit coupled to an output of a circuit element and generating a pulsed output coupled to a clock input of a register of the pulse-controlled register circuit; wherein the pulsed output is coupled to the clock input of the register to enable the pulse-controlled register circuit to store data at a time that is different than an edge of the clock signal. A method of reducing duty-cycle distortion in an integrated circuit implementing dual-edge clocking is also described.

Abstract: Methods and apparatus for generating multiple phase-shifted clock signals from a base clock signal using programmable delays at the leaf level in a clock distribution network are described. One example method for generating and distributing multiple phase-shifted clock signals in a programmable integrated circuit (IC) generally includes generating a base clock signal, routing the base clock signal through a clock distribution network in the programmable IC to a leaf node, and applying one or more programmable delays to the base clock signal received from the leaf node to generate the multiple phase-shifted clock signals.

Abstract: In an example implementation, a circuit includes first and second latch circuits. A circuit coupled to the first and second latch circuits is configured to provide a first clock signal to the clock input node of the second latch circuit and provide a second clock signal that is an inversion of the first clock signal to the clock input node of the first latch circuit. The circuit includes a first multiplexer having a first input node coupled to a data output node of the first latch circuit, a second input node coupled to a data input node of the first latch circuit, and an output node coupled to a data input node of the second latch circuit. The circuit also includes a second multiplexer having a first input node coupled to the data output node of the first latch circuit and a second input node coupled to a data output node of the second latch circuit.

Abstract: Processing a circuit design includes determining that an operating frequency for a first placement and routing for the circuit design does not exceed a target operating frequency, distinguishing between loop paths and feed-forward paths in the circuit design, and, responsive to determining that the operating frequency does not exceed the target operating frequency, relaxing timing constraints of the feed-forward paths using a processor. A second placement and routing is performed on the loop paths and the feed-forward paths of the circuit design.

Abstract: A programmable delay circuit block includes an input stage having a cascade input and a clock input, wherein the input stage passes a signal received at the cascade input or a signal received at the clock input. The programmable delay circuit block further may include a delay block configured to generate a delayed signal by applying a selected amount of delay to the signal passed from the input stage and a pulse generator configured to generate a pulse signal having a pulse width that depends upon the amount of delay. The programmable delay circuit block also includes an output stage having a cascade output and a clock output. The output stage is configured to pass an inverted version of the pulse signal or the delayed signal from the cascade output and pass the signal received at the clock input, the inverted version of the pulse signal, or the delayed signal from the clock output.

Abstract: A circuit for routing signals in an integrated circuit is disclosed. The circuit comprises a path having a plurality of registers coupled in series and including a source register, a destination register and at least one intermediate register; a clock generator generating a clock signal; and a delay element coupled to receive the clock signal and generate a delayed clock signal, wherein the delayed clock signal is coupled to a clock input of the at least one intermediate register. A method of routing signals in an integrated circuit is also disclosed.