Test Logic Timer for IC Signal Correlation
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Solution Overview
Problem
Integrated circuits face challenges in acquiring a large number of internal operational signals for testing due to the limitations of test multiplexer hierarchies and crosspoint switches, which restrict the number of signals that can be simultaneously analyzed, making it difficult to fully test the circuit's response to events while maintaining reasonable costs.
Innovation Solution
A method and structure that utilize a test multiplexer hierarchy and a test logic timer with a clock signal to generate a common time base, allowing internal operational signals from multiple iterations of an event to be correlated in time, enabling the acquisition and analysis of a greater number of signals by resetting and incrementing counter values upon event detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a test multiplexer hierarchy is used to select internal operational signals, then the cost and size of the circuit are reduced, but the number of signals that can be simultaneously acquired is limited
Solution Approach 1:
The patent transitions from acquiring signals simultaneously in space (limited by MUX output channels) to acquiring signals sequentially in time (unlimited by MUX channels). The time dimension is introduced through multi-trigger operation and timestamp correlation, allowing any number of signals to be acquired across multiple triggers without adding hardware channels.
Solution Approach 2:
The system uses periodic triggering to acquire different sets of signals in different cycles. Each trigger event activates a specific MUX configuration, and by repeating triggers with different MUX settings, the system periodically samples different signal groups, ultimately building a complete picture through temporal aggregation.
2Adaptability or versatility
If a crosspoint switch is used to address signal exclusion, then signal selection flexibility is improved, but the total number of selectable signals remains limited
Solution Approach 1:
The system pre-configures multiple MUX hierarchies with different signal selections before triggering. Each MUX hierarchy is prepared in advance with specific signal routes, and the controller selects which pre-configured hierarchy to activate based on the triggering event, enabling flexible signal selection without requiring a large crosspoint switch.
3Quantity of substance
If multiple iterations of event triggering are performed to acquire more signals, then the number of acquirable signals increases, but the complexity of correlating signals from different iterations increases
Solution Approach 1:
Timestamps serve as an intermediary that bridges signals acquired in different trigger iterations. Each signal is tagged with a timestamp indicating its position in the trigger sequence, and this timestamp intermediary allows the controller to automatically correlate signals from different iterations without complex manual synchronization, reducing correlation complexity.
Data Source
AI summary
Methods and structure for correlating multiple sets of test output signals in time are provided. The structure includes an integrated circuit comprising a block of circuitry that generates internal operational signals. The circuit also comprises a test multiplexer (MUX) hierarchy that selects subsets of the internal signals and applies the subsets to a testing element. A clock generator generates a clock signal for the selected signals. A test logic timer receives the clock signal and increments a counter value, and applies the counter value to the testing element. An event detector resets the counter value upon detection of an event, such that a first subset of the internal signals acquired from the test MUX hierarchy acquired responsive to detection of a first instance of the event may be correlated in time with a second subset of the internal signals acquired responsive to detection of a second instance of the event.