SRAM Feedback Oscillation for Critical Path Delay Measurement
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Solution Overview
Problem
The efficient determination of critical path time delays in devices with SRAM elements is challenging, particularly in forming an oscillation loop for accurate measurement.
Innovation Solution
An apparatus is provided with a static random access memory (SRAM) element, a logic cell arrangement, and a feedback path to create an oscillation loop, allowing for the measurement of critical path delay time by generating feedback clock and address signals to form an oscillation loop and using a frequency measurement element to determine the critical path delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oscillation loop is established to determine critical path time delay, then measurement capability is provided, but device complexity increases due to additional feedback path components
Solution Approach 1:
The patent implements a feedback path that takes the output of the logic cell arrangement and feeds it back to the SRAM element's address input and clock input. This feedback mechanism enables the formation of an oscillation loop that allows critical path time delay measurement by creating a self-sustaining oscillating signal that traverses the critical path repeatedly, enabling precise timing measurement without permanently altering the device structure.
Solution Approach 2:
The patent employs dynamic mode switching between normal operation mode and oscillation measurement mode. The feedback path is selectively activated only during measurement, allowing the system to transition from static functional operation to dynamic measurement state. This dynamic approach enables measurement capability without permanently increasing device complexity, as the feedback components remain dormant during normal operation.
2Measurement precision
If the feedback path is activated for oscillation mode, then critical path measurement is enabled, but normal operation is disrupted
Solution Approach 1:
The system implements dynamic mode switching between normal operation and oscillation measurement modes. Control logic selectively enables or disables the feedback path based on the operational state. During normal operation, the feedback path is deactivated or isolated, ensuring stable functional performance. During measurement, the feedback path is activated to create the oscillation loop, enabling critical path timing measurement without affecting normal operational reliability.
Solution Approach 2:
The patent separates the measurement function from the functional operation by using distinct operational modes. The feedback path components are isolated during normal operation and only engaged during measurement phases. This segmentation ensures that measurement activities do not interfere with normal system operation, maintaining reliability while enabling precise timing measurements when needed.
3Measurement precision
If measurement mode is used to form oscillation loop, then timing accuracy is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic oscillation rather than continuous operation for measurement. The feedback path creates an oscillating signal that periodically traverses the critical path, allowing timing measurement over multiple cycles. This periodic action enables accurate averaging of timing measurements while consuming power only during measurement intervals, rather than continuously, thereby reducing overall power consumption while maintaining measurement precision.
Solution Approach 2:
The system dynamically transitions between low-power normal operation mode and measurement mode. The oscillation loop and feedback path are activated only during measurement periods and deactivated during normal operation. This dynamic power management ensures that the additional power consumption associated with the measurement function is minimized, occurring only when timing measurements are actually performed rather than continuously.
Data Source
AI summary
An apparatus includes a SRAM element having a clock input, an address input, an SRAM output, and a first and second address space A clock signal causes the SRAM element to output the logic value stored in a designated address space. A logic arrangement couples the SRAM output to a register A feedback path receives an output of the logic arrangement and provides a feedback clock and address signal. In an oscillation mode, a one is stored in the first address space and a zero in the second address space, and the feedback path provides the output of the logic cell arrangement to the address input and provides the feedback clock signal to trigger the output of the logic value stored in the currently designated address space, Thereby the feedback path, the SRAM element, and the logic cell arrangement form an oscillation loop.