Dynamic Clock Pulse Insertion for Low-Power IC Responsiveness
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Solution Overview
Problem
Integrated circuits face challenges in reducing power consumption while maintaining responsiveness to high-priority transactions, as entering and exiting a sleep state can incur significant performance overhead, leading to undesirable power management strategies.
Innovation Solution
A power management circuit monitors activity levels and reduces the clock signal frequency by inhibiting N-1 pulses for every N pulses of the full frequency clock signal, while allowing inserted pulses for high-priority transactions, allowing functional circuit blocks to remain active and responsive without full power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If functional circuit blocks are placed into a sleep state to reduce power consumption, then power consumption is reduced, but performance overhead increases due to state saving and restoration overhead
Solution Approach 1:
The patent applies dynamics by making the clock signal frequency variable rather than fixed. The clock gating circuit dynamically adjusts the clock frequency to functional circuit blocks based on their activity level, transitioning between full frequency (active state) and reduced frequency (sleep-like state) without requiring actual state saving/restoration overhead. This dynamic frequency adjustment resolves the contradiction by providing power savings with minimal performance penalty.
Solution Approach 2:
The patent changes the clock frequency parameter of the functional circuit blocks to control their power consumption. By monitoring activity levels and adjusting the clock frequency accordingly (from full frequency to 1/N frequency), the system achieves power savings similar to sleep states but without the state saving/restoration overhead, thus resolving the performance-penalty contradiction.
2Productivity
If functional circuit blocks remain in an active state to maintain responsiveness, then performance is maintained, but power consumption increases
Solution Approach 1:
The patent implements periodic action by providing clock pulses at reduced frequency (1/N of original frequency) to functional circuit blocks with low activity levels. This periodic clocking maintains the circuits in a functional state capable of responding to stimuli while consuming less power than continuous full-frequency operation, thus resolving the contradiction between responsiveness and power consumption.
Solution Approach 2:
The system dynamically adjusts clock frequency based on real-time activity monitoring. Functional circuit blocks that need responsiveness maintain full clock frequency, while those with low activity receive reduced frequency (1/N), optimizing the balance between responsiveness and power consumption for each block individually.
3Use of energy by moving object
If clock signal frequency is reduced by gating N-1 pulses for every N pulses, then power consumption is reduced, but response time to transactions increases
Solution Approach 1:
The clock gating circuit incorporates activity monitoring and automatic frequency adjustment, allowing the system to self-regulate clock frequency based on actual functional needs. When activity is detected, the circuit automatically restores full clock frequency, ensuring timely response without manual intervention, thus resolving the contradiction between power savings and response time.
Solution Approach 2:
The system uses feedback from activity level monitoring to dynamically adjust clock frequency. The power management circuit monitors activity levels and feeds this information back to the clock gating circuit, which adjusts the clock frequency accordingly. This feedback mechanism ensures that clock frequency is reduced only when appropriate, maintaining response time while achieving power savings.
4Speed
If inserted clock pulses are provided for high priority transactions during reduced frequency operation, then responsiveness to high priority transactions is improved, but clock signal timing complexity increases
Solution Approach 1:
The patent introduces an intermediary mechanism (the clock gating circuit with activity monitoring) that mediates between the source clock signal and the functional circuit blocks. This intermediary intelligently inserts clock pulses when needed for high-priority transactions while maintaining reduced frequency operation otherwise, managing the timing complexity within the clock gating logic itself rather than requiring complex external timing control.
Data Source
AI summary
A method and apparatus for saving power in integrated circuits is disclosed. An IC includes functional circuit blocks which are not placed into a sleep mode when idle. A power management circuit may monitor the activity levels of the functional circuit blocks not placed into a sleep mode. When the power management circuit detects that an activity level of one of the non-sleep functional circuit blocks is less than a predefined threshold, it reduce the frequency of a clock signal provided thereto by scheduling only one pulse of a clock signal for every N pulses of the full frequency clock signal. The remaining N−1 pulses of the clock signal may be inhibited. If a high priority transaction inbound for the functional circuit block is detected, an inserted pulse of the clock signal may be provided to the functional unit irrespective of when a most recent regular pulse was provided.