DLL Thermometer Code Correction for High-Speed Bit-Flip Protection
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Solution Overview
Problem
Conventional dual interlocked storage cell latches (DICE latches) are not suitable for high-speed applications in semiconductor memory due to their low speed and weak robustness against meta-stability, particularly in coarse delay lines where soft errors like bit flips occur, necessitating a more effective countermeasure for high-speed correction of multiple bit flips.
Innovation Solution
A thermometer code correction mechanism is implemented in the shift register circuit of the DLL circuit, using adjacent bits to correct bit values, ensuring synchronization with external clock signals and enhancing robustness against soft errors like neutron-induced bit flips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DICE latches are used to protect against bit flips, then reliability is improved, but speed deteriorates
Solution Approach 1:
The invention divides the protection mechanism into two distinct parts: a simple flip-flop circuit for high-speed operation and a separate correction circuit for reliability. The flip-flop captures the thermometer code at high speed without the complexity of DICE latches, while the correction circuit processes the captured code to detect and correct bit flips, thus achieving both high speed and high reliability independently.
Solution Approach 2:
The invention introduces a correction circuit as an intermediary between the flip-flop and the delay line control. This correction circuit acts as a mediator that receives the potentially erroneous thermometer code from the flip-flop, processes it through correction logic, and outputs a corrected code to control the delay line, thereby protecting against bit flips without slowing down the main high-speed flip-flop operation.
2Ease of manufacture
If simple thermometer protection is implemented, then ease of manufacture is improved, but reliability deteriorates when bit 1 is erroneous
Solution Approach 1:
The correction circuit implements feedback logic that continuously monitors the thermometer code for errors and applies corrections based on detected patterns. When a bit flip is detected in the flip-flop output, the correction circuit uses feedback mechanisms to identify the error and restore the correct thermometer code, thereby improving reliability while maintaining the simplicity of the overall system architecture.
Data Source
AI summary
Apparatuses and methods for correcting a code used for delay adjustment are disclosed. An example method includes providing a bit of a thermometer code responsive, at least, to a shift direction signal; and adjusting an amount of a delay responsive to the thermometer code. Providing the bit comprises correcting the bit using one or more adjacent bits on one side of the bit in the thermometer code and one or more adjacent bits on another side of the bit in the thermometer code.