Signal Sampling Circuit for 2T CMD and NT ODT Decoding
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Solution Overview
Problem
In DRAM chips, the 2T CMD and NT ODT CMD signals are easily confused due to differing pulse widths, leading to decoding errors in existing command decoding solutions.
Innovation Solution
A signal sampling circuit with first and second command sampling circuits and a command decoding circuit that performs two-stage sampling and logical operations on chip select signals with different pulse widths to accurately distinguish and decode 2T CMD and NT ODT CMD signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single command decoding solution is used for both 2T CMD and NT ODT CMD signals, then the device complexity is reduced, but decoding accuracy deteriorates due to pulse width confusion
Solution Approach 1:
The command decoding function is segmented into two separate command sampling circuits: a first command sampling circuit for 2T CMD signals and a second command sampling circuit for NT ODT CMD signals. Each circuit is optimized for its specific signal type with appropriate pulse width detection, eliminating the confusion that would occur in a unified decoding approach while maintaining manageable system complexity through functional separation.
2Measurement precision
If pulse width detection is used to distinguish command types, then command decoding accuracy is improved, but the device complexity increases due to additional sampling circuits
Solution Approach 1:
Each command sampling circuit is designed with local quality optimized for its specific command type. The first command sampling circuit has parameters and logic tailored for detecting 2T CMD pulse widths, while the second command sampling circuit has parameters and logic tailored for NT ODT CMD pulse widths. This localized optimization ensures high decoding accuracy for each command type without requiring a single overly complex universal circuit.
Solution Approach 2:
The system dynamically selects which command sampling circuit to use based on the detected pulse width characteristics of the incoming command signal. The command sampling circuit selection logic dynamically routes 2T CMD signals to the first circuit and NT ODT CMD signals to the second circuit, enabling adaptive operation that improves accuracy without permanently increasing the active circuit complexity.
3Adaptability or versatility
If different pulse widths are used for 2T CMD and NT ODT CMD signals, then command type differentiation is enabled, but decoding reliability deteriorates due to signal confusion in existing solutions
Solution Approach 1:
The command sampling circuit selection logic acts as an intermediary that receives the chip select signal, detects its pulse width characteristics, and routes the signal to the appropriate command sampling circuit. This intermediary layer prevents direct confusion between different command types by ensuring that each pulse width variant is handled by its dedicated circuit, thereby maintaining high decoding reliability while supporting multiple command types.
Data Source
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AI summary
A signal sampling circuit and a semiconductor memory are provided according to the embodiments of the application. The signal sampling circuit includes: a signal input circuit, configured to determine a to-be-processed command signal and a to-be-processed chip select signal; a first command sampling circuit, configured to perform a two-stage sampling and a logical operation on the to-be-processed chip select signal according to a first clock signal to obtain a first chip select clock signal; a second command sampling circuit, configured to perform a two-stage sampling and a logical operation on the to-be-processed chip select signal according to the first clock signal to obtain a second chip select clock signal; and a command decoding circuit, configured to perform decoding and sampling processing on the to-be-processed command signal according to be to-be-processed chip select signal and the first chip select clock signal to obtain a target command signal, or perform decoding and sampling processing on the to-be-processed command signal according to the to-be-processed chip select signal and the second chip select clock signal to obtain a target command signal.