Switchable Logic for IC Short Circuit Recovery
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Solution Overview
Problem
Current integrated circuit testing methods often incorrectly identify shorts in logic blocks controlled by power switches, leading to the discarding of potentially viable ICs, as they apply voltage directly to power switches and declare an ohmic short based on ohmic curves.
Innovation Solution
A system and method that use a power switch control circuit on a different voltage rail to isolate and test individual logic blocks, applying varying power levels to identify shorts and deactivate nonviable blocks, ensuring only viable logic blocks are used, with a Test VDD to fully turn on or off power switches and apply low voltages to detect ohmic responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If voltage is applied directly to power switches during testing, then testing speed is improved, but measurement precision deteriorates due to false ohmic short identification
Solution Approach 1:
The patent segments the integrated circuit into individual logic blocks that can be tested independently. By isolating each logic block and controlling its power switches separately, the system can apply voltage to specific blocks without affecting others, enabling faster parallel testing while maintaining accurate short detection through controlled voltage application and current measurement sequences
Solution Approach 2:
The patent implements preliminary actions by first establishing known good states for power switches before applying test voltages. The control circuit pre-configures switch states and performs preliminary checks to ensure accurate baseline measurements, preventing false ohmic short identifications while maintaining efficient testing progression
2Productivity
If all logic blocks are tested simultaneously, then productivity is improved, but device complexity increases due to need for isolated control circuits
Solution Approach 1:
The patent divides the control function into separate control circuits for different voltage rails. Each control circuit manages power switches for logic blocks on its specific rail, enabling simultaneous independent testing of multiple blocks across different rails while keeping each control circuit relatively simple and focused on its designated voltage domain
Solution Approach 2:
The control circuits are designed with multi-functionality to handle various testing scenarios across multiple logic blocks. Each control circuit can independently control power switches, apply test voltages, measure currents, and determine viability for multiple logic blocks on its voltage rail, reducing overall system complexity through standardized reusable control units
3Measurement precision
If high voltage is applied to detect shorts, then measurement precision is improved, but object-generated harmful factors increase due to potential damage to logic blocks
Solution Approach 1:
The patent applies preliminary low-voltage tests before high-voltage testing. The control circuit first establishes baseline current measurements at safe voltage levels, then progressively increases voltage only when necessary and only for brief measurement intervals. This preliminary action sequence enables accurate short detection while minimizing damage risk by limiting exposure to high voltages
Solution Approach 2:
The patent uses periodic voltage application with controlled duty cycles. High voltage is applied in short periodic bursts rather than continuously, allowing current measurements to be taken at peak voltage while minimizing total energy exposure to logic blocks. The periodic switching between test and safe states enables sensitive short detection without sustained harmful stress
4Reliability
If nonviable logic blocks are discarded, then reliability is improved, but loss of substance increases due to discarding potentially viable ICs
Solution Approach 1:
The patent changes the testing parameters by applying controlled voltage sequences and measuring current responses under specific switch configurations. By analyzing current characteristics under multiple parameter conditions rather than single static tests, the system can distinguish between true shorts and other anomalies, reducing false positives and preventing discarding of potentially viable ICs while maintaining high reliability standards
Solution Approach 2:
The patent implements a recovery mechanism where logic blocks initially flagged as nonviable are not immediately discarded. Instead, the control circuit performs additional verification tests and analyzes test patterns to confirm actual shorts. Blocks that pass verification are recovered and marked as viable, reducing unnecessary discards while ensuring that truly defective blocks are identified and discarded to maintain reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the identification and isolation of nonviable logic blocks, preventing shorts during normal use and enabling the use of ICs that would otherwise be discarded, by determining viability through controlled power switching and current measurement.
Implementation Method 1
If the result is an ohmic curve, the conclusion is nearly always that there is an ohmic short in the logic controlled by the power switch
Implementation Method 2
If the result is an ohmic curve, the conclusion is nearly always that there is an ohmic short in the logic controlled by the power switch
Data Source
AI summary
In some embodiments, a system and/or method may test logic blocks for an integrated circuit. To alleviate problems associated with current methods of integrated circuit testing, a system may include a power switch control signal on a different voltage rail. In some embodiments, a Test VDD may be used to isolate the power switches from the rest of the logic cells in an integrated circuit. During testing, each logic block may be powered individually using the Test VDD to control the power switches to the logic blocks. When a logic block short is identified, the nonviable logic block may be isolated to such that the nonviable logic block is not used during the future and only viable logic blocks are used in the integrated circuit. This allows for use of logic within an integrated circuit that might otherwise have been discarded or destroyed because of one or more shorts.