CPU current ripple and OCV effect mitigation
First Claim
1. A method of reducing transient variations in power supplied to a processor comprising a plurality of functional processing units, comprising:
- generating at least first and second clock signals, the second clock signal having the same frequency, but a phase offset, relative to the first clock signal;
clocking a first functional unit of the processor with the first clock signal;
clocking a second functional unit of the processor with the second clock signal;
synchronizing data transfer between the second functional unit and a circuit, other than the first functional unit, that is clocked by the first clock signal by interposing a clock phase synchronization circuit on a data path between the second functional unit and the circuit clocked by the first clock signal; and
suspending at least one of the first and second clock signals when the associated functional unit of the processor is placed in an inactive state.
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Accused Products
Abstract
High frequency current transients, due to logic switching inside the CPU, are reduced by applying clock signals having different relative phases to different parts of the CPU. This reduces the amplitude of current variations, and hence noise induced onto the power supply voltage. In some embodiments, different CPU cores within multi-core CPUs are clocked with a different clock phases. Additionally a method and circuit for low-latency communication in the presence of large OCV effects is provided. The low-latency communication may be based on a FIFO. Strobes are used to indicate safe points in time to update and read signals between transmitter and receiver. The strobes are generated in a central clock generation module. The strobe mechanism is used to transfer the read and write pointers between the transmitter and receiver, while the payload data is transferred using a FIFO data array that allows data writes to be asynchronous to corresponding data reads.
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Citations
26 Claims
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1. A method of reducing transient variations in power supplied to a processor comprising a plurality of functional processing units, comprising:
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generating at least first and second clock signals, the second clock signal having the same frequency, but a phase offset, relative to the first clock signal; clocking a first functional unit of the processor with the first clock signal; clocking a second functional unit of the processor with the second clock signal; synchronizing data transfer between the second functional unit and a circuit, other than the first functional unit, that is clocked by the first clock signal by interposing a clock phase synchronization circuit on a data path between the second functional unit and the circuit clocked by the first clock signal; and suspending at least one of the first and second clock signals when the associated functional unit of the processor is placed in an inactive state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A processor, comprising:
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a clock generator circuit operative to generate at least first and second clock signals, the second clock signal having the same frequency, but a phase offset, relative to the first clock signal; a first functional unit of the processor clocked with the first clock signal; a second functional unit of the processor clocked with the second clock signal; and a clock phase synchronization circuit interposed on a data path between the second functional unit and a circuit, other than the first functional unit, that is clocked by the first clock signal and operative to synchronize data transfer between the second functional unit and a circuit clocked by the first clock signal; wherein the clock generator circuit is further operative to suspend at least one of the first and second clock signals when the associated functional unit of the processor is placed in an inactive state. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An On-Chip Variation (OCV) mitigation First In First Out (FIFO) memory circuit operative to synchronize data between clock phase domains wherein clock signals have the same frequency but different relative phases, and further operative to mitigate the effects of OCV in clock signals, comprising:
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in a first clock phase domain, inputs operative to receive a first clock signal and a plurality of first strobe signals, each first strobe signal operative to qualify a cycle of the first clock signal; a plurality of data storage registers; source pointer logic operative to generate write pointers into the data storage registers and to output a plurality of write pointers; a plurality of write pointer registers, each associated with and qualified by a first strobe signal and operative to receive a write pointer from the source pointer logic and output a write pointer to a second clock phase domain of the OCV mitigation FIFO; and a read pointer multiplexer operative to receive the plurality of first strobe signals and a plurality of read pointers from the second clock phase domain of the OCV mitigation FIFO and output an active read pointer to the source pointer logic based on the first strobe signals; and in a second clock phase domain wherein clock signals have the same frequency as, but different relative phases than, clock signals in the first clock phase domain, inputs operative to receive a second clock signal having a phase offset from the first clock signal and a plurality of second strobe signals, each second strobe signal operative to qualify a cycle of the second clock signal associated with a corresponding cycle of the first clock signal; target pointer logic operative to generate a plurality of read pointers; a plurality of read pointer registers, each associated with and qualified by a second strobe signal and operative to receive a read pointer from the target pointer logic and output a read pointer to the first clock phase domain of the OCV mitigation FIFO; and a write pointer multiplexer operative to receive the plurality of second strobe signals and a plurality of write pointers from the first clock phase domain of the OCV mitigation FIFO and output an active write pointer to the target pointer logic based on the second strobe signals; and a data multiplexer operative to receive data from the first clock phase domain of the OCV mitigation FIFO and output data based on a read pointer received from the target pointer logic. - View Dependent Claims (26)
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Specification