Die Stack Access Control for Signal Timing Accuracy
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Solution Overview
Problem
As semiconductor devices are miniaturized and stacked, signal transition windows become shorter, and increased capacitances and inductances between connections delay signal transitions, leading to propagation delays that complicate signal timings across die stacks, preventing reductions in signal transition windows.
Innovation Solution
A die stack architecture with a master die and slave dies, utilizing a common die-external signal for coordination, including a coordination buffer and internal-bus access circuit, to manage signal timings and increase tolerance to PVT variations, allowing for longer die-external paths and higher circuit density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit density is increased and devices are miniaturized, then productivity and integration are improved, but signal transition delays increase due to higher capacitances and inductances
Solution Approach 1:
The patent segments the signal path into multiple controlled segments by introducing access control circuits at different levels (die level and stack level). These circuits divide the signal transition management into discrete controllable stages, allowing optimization of each segment to mitigate overall delay while maintaining high density.
Solution Approach 2:
The access control circuits perform preliminary actions by pre-managing signal transitions and propagating control signals before main data signals need to traverse the full path. This preliminary control prepares the signal paths in advance, reducing actual transition delays during critical operations.
2Productivity
If die stack height is increased to improve density, then productivity is improved, but signal timing accuracy deteriorates due to varying propagation delays
Solution Approach 1:
The patent implements feedback mechanisms where access control circuits monitor and adjust signal timing based on propagation delay variations. Control signals are dynamically adjusted according to the specific die position and path characteristics, ensuring timing accuracy is maintained despite increased stack height and varying delays.
Solution Approach 2:
The system changes control parameters (signal timing, voltage levels, enable states) based on the specific die configuration and position in the stack. By dynamically adjusting these parameters, the system compensates for propagation delay variations and maintains precise timing control across different stack heights.
3Manufacturing precision
If additional delay modules are added to compensate for propagation delays, then signal timing accuracy is improved, but device complexity increases
Solution Approach 1:
The access control circuits perform multiple functions simultaneously: they manage signal transitions, control access to memory arrays, propagate timing signals, and compensate for propagation delays. This multi-functionality eliminates the need for separate dedicated delay compensation modules, reducing overall circuit complexity while maintaining timing accuracy.
Solution Approach 2:
The patent merges the delay compensation function with the existing access control logic. The same control circuits that manage normal memory access operations also handle timing compensation, combining multiple functions into unified circuitry rather than adding separate complexity-increasing modules.
Data Source
AI summary
Methods, apparatuses, and systems related to die-to-die communications are described. An apparatus may include an interfacing die and at least one additional die communicatively coupled to each other through an internal bus. The interfacing die may be configured to provide a combined external interface for the coupled dies. For the die-to-die communications, a target die may coordinate transfer of communicated data to the internal interface according to a timing signal generated by a source external to the at least one additional die.