Critical Path Monitoring With Clock Shift Compensation
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Solution Overview
Problem
Conventional monitoring devices in digital integrated circuits are affected by programmable multiplexers, which can falsify the detection of propagation time in critical paths, leading to inaccurate monitoring and potential failures due to aging-related degradation of the real time margin.
Innovation Solution
A monitoring device with a replica of the critical path using programmable delay means and a sequencing module that generates secondary clock signals with mutual time delays to account for propagation times inherent to multiplexers, allowing for precise adjustment and cancellation of delays, thereby improving monitoring accuracy and avoiding failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If programmable multiplexers are used to generate fixed or programmable initial delay, then the monitoring device can be configured flexibly, but the propagation time inherent to the multiplexers falsifies the detection of propagation time
Solution Approach 1:
The patent extracts and separates the harmful propagation time inherent to the multiplexers from the measurement process. By delivering secondary clock signals to sequential elements with time shifts that compensate for these inherent delays, the invention removes the distortion caused by multiplexer propagation time, allowing accurate measurement of the critical path delay without the multiplexer interference.
Solution Approach 2:
The invention changes the timing parameters of the clock signals delivered to sequential elements. By introducing specific time shifts between secondary clock signals based on the inherent propagation times of multiplexers, the system compensates for the delay distortion and enables accurate propagation time measurement while maintaining the flexibility of programmable delay configuration.
2Measurement precision
If the monitoring device is disposed directly on or close to the critical path, then the real time margin can be monitored accurately, but the device complexity increases
Solution Approach 1:
The monitoring device uses the same multiplexers and sequential elements that are part of the critical path structure for both their original function and for monitoring purposes. The multiplexers serve dual roles: configuring delay values and providing the clock distribution network. This multi-functionality allows accurate monitoring without adding separate dedicated monitoring infrastructure, thereby limiting the increase in device complexity.
3Measurement precision
If secondary clock signals with time shifts are delivered to sequential elements, then the propagation time inherent to multiplexers is compensated, but the sequencing complexity increases
Solution Approach 1:
The sequencing module pre-calculates and pre-applies the necessary time shifts to the secondary clock signals before delivering them to the sequential elements. By anticipating the inherent propagation delays of the multiplexers and compensating for them in advance through predetermined time shifts in the clock signal distribution, the system achieves accurate delay measurement without requiring complex real-time adjustment mechanisms.
Data Source
AI summary
A device for monitoring a critical path of an integrated circuit includes a replica of the critical path formed by sequential elements mutually separated by delay circuits that are programmable though a corresponding main multiplexer. A control circuit controls delay selections made by each main multiplexer. A sequencing module operates to sequence each sequential element using a main clock signal by delivering, in response to a main clock signal, respectively to the sequential elements, secondary clock signals that are mutually time shifted in such a manner as to take into account the propagation time inherent to the main multiplexer.