Apple Inc.

Harsha Krishnamurthy

Rajat Goel

Muthukumaravelu Velayoudame

Shingo Suzuki

Mridul Agarwal

Rohit Kumar

Suparn Vats

Shyam Sundar Balasubramanian

Christopher S Thomas

Manoj Gopalan

Edvin Catovic

Ram Subramaniam Gandhi

In one embodiment, an integrated circuit may be designed using a library of clocked circuits that have programmable clock delays that may be inserted on the clock input to the clocked circuits. During the design process, timing paths which are challenging due to significant variations across operating states, process corners, and/or temperature may be met by using the clocked circuits with programmable delays and inserting a delay control circuit that programs the delays based on the current operating state, process corner used to manufacture the integrated circuit, and/or temperature. That is, different delays may be selected by the delay control circuit depending on inputs that identify the operating state, the process corner, and/or the temperature. Because the clock delay is intentionally skewed, the timing of the path may be different at different operating states, temperatures, or process corners and thus may meet timing by changing the clock skew during operation.

Programmable clock skewing for timing closure

Systems, apparatuses, and methods for efficiently implementing clock gating circuitry. A multi-bit clock gating cell is placed on the die of an integrated circuit and replaces at least two single-bit clock gating cells that were to be placed on the die. Each single-bit clock gating cell receives a single clock enable signal and generates a single gated clock signal. Each multi-bit clock gating cell receives multiple clock enable signals and generates multiple gated clock signals based on a single common received clock signal. Conditions for determining whether two or more single-bit clock gating cells are replaced by a multi-bit clock gating cell include a distance between two single-bit clock gating cells, a load driven by any one of the two single-bit clock gating cells and an activity level of a common single clock received by at least two single-bit clock gating cells is above a respective threshold.

Multi-bit clock gating cell to reduce clock power

Techniques are disclosed relating to reducing dynamic power consumption in integrated circuits. In some embodiments, simulation is performed at one or more stages of a circuit design to identify portions of the circuit with relatively high average clock switching activity, based on an amount of clock gating during the simulation by one or more clock gaters. In some embodiments, sequential circuit elements in the identified portions are specified as candidates for implementation using low-power sequential circuitry. Examples of low-power sequential circuitry include multibit flip flops and flip flops with low clock pin input capacitance. The disclosed techniques may allow automated design tools to significantly reduce dynamic power consumption while still meeting other design parameters such as timing constraints.

Switching-activity-based selection of low-power sequential circuitry

A method and apparatus for forcing equivalent outputs at start-up for replicated sequential circuits is disclosed. An integrated circuit (IC) includes first and second clocked logic circuits each coupled to receive a clock signal common to both, and each configured to produce equivalent logical outputs based on a common set of logic inputs. The IC further includes an equivalence circuit coupled to the outputs of each of the first and second clocked logic circuits. During a system start-up (e.g., power on) and before the clock signal has been applied, the equivalence circuit may detect if the outputs of the to first and second clocked logic circuits originally come up in different states. Responsive to determining that the outputs of the first and second clocked logic circuits are different, the equivalence circuit may cause the outputs to be forced to the same logical state.

Apparatus and method to force equivalent outputs at start-up for replicated sequential circuits

In some embodiments, a register file circuit design process includes instructing an automated integrated circuit design program to generate a register file circuit design, including providing a cell circuit design and instructing the automated integrated circuit design program to generate a selection design, a pre-decode design, and a data gating design. The cell circuit design describes a plurality of selection circuits that have a particular arrangement. The selection design describes a plurality of replica circuits that include respective pluralities of selection circuits having the particular arrangement. The pre-decode design describes a pre-decode circuit configured to identify a plurality of entries identified by a portion of a write instruction. The data gating design describes data gating circuits configured, in response to the pre-decode circuit not identifying respective entries, to disable data inputs to respective write selection circuits connected to the respective entries.

Register file circuit design process

In an embodiment, an integrated circuit may include one or more power gated blocks and a power manager circuit. The power manager circuit may be configured to generate a block enable for each power gated block and a block enable clock. The power gated block may generate local block enables to various power switch segments in the power gated block. In particular, the power gated block may include a set of series-connected flops that receive the block enable from the power manager circuit. The power gated block may include a set of multiplexors (muxes) that provide the local block enables for each power switch segment. One input of the muxes is coupled to the block enable, and the other input is coupled to another enable propagated through one of the other power switch segments. Accordingly, the muxes may be controlled to select the propagated enables or the input block enable.

Power switch ramp rate control using selectable daisy-chained connection of enable to power switches or daisy-chained flops providing enables

A process utilized in an integrated circuit design methodology may be used to assess and organize individual bits (e.g., flip-flops) within multi-bit clocked storage devices (e.g., multi-bit flip-flops) for use in the integrated circuit design. The process may include assessing timing slacks of the bits, sorting and/or assigning the bits based on the assessed timing slacks, and remapping the multi-bit clocked storage devices using the sorted and/or assigned bits. One or more timing corrections may be applied to the remapped multi-bit clocked storage devices. The timing corrections may include useful clock skewing or resizing (e.g., upsizing or downsizing) of the remapped multi-bit clocked storage devices.

Multi-bit flip-flop reorganization techniques

In some embodiments, a method may be directed towards contextual based spare cell assignment for integrated circuits. The method may include reserving a plurality of spare cell areas in which to position spare cells on an integrated circuit. The method may include positioning standard cells as defined by an integrated circuit design for the integrated circuit. In some embodiments, the method may include determining the spare cells to be positioned in the plurality of spare cell areas based upon a population of a plurality of types of cells in a predetermined area. The method may include ensuring that each of the plurality of spare cell areas may include a minimum number of predetermined cells. The method may include positioning a predetermined cell in at least one of the plurality of spare cell areas if the type of predetermined cells is absent in the population of areas adjacent to the predetermined area.

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San Jose, CA, United States of America

Harsha Krishnamurthy