Semiconductor Memory Gear-Down Clock Segmentation
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Solution Overview
Problem
Semiconductor memory devices face challenges in maintaining operation stability during high-speed gear-down mode due to difficulties in coordinating the timing between internal and external clock signals, leading to issues with setup and hold margins and mass production efficiency.
Innovation Solution
A semiconductor memory device design that includes a clock signal generation unit to divide the external clock signal into odd and even period internal clock signals, with an operation control unit enabling specific input units during gear-down mode to adjust the clock signals and ensure stable operation, allowing for flexible operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the external clock signal frequency is increased to achieve higher operation speed, then the data transmission rate is improved, but the setup and hold margin between the external clock signal and command/address signals deteriorates
Solution Approach 1:
The patent divides the input units into multiple separate units (first input unit, second input unit, etc.), each receiving commands and addresses at different clock phases. This segmentation allows the system to maintain proper timing margins by distributing the loading across multiple clock cycles rather than requiring all inputs to be ready simultaneously at a single high-frequency clock edge.
Solution Approach 2:
The patent implements gear-down mode where command and address signals are received periodically at intervals of two external clock periods (2tck) instead of one period (1tck). This periodic action with extended timing allows the high-frequency external clock to operate while maintaining adequate setup and hold margins by accepting inputs only at specific phased intervals.
2Reliability
If gear-down mode is implemented to improve operation stability, then the setup and hold margin is improved, but the frequency coordination between internal and external clock signals becomes more complex
Solution Approach 1:
The clock signal generation unit is segmented to produce multiple internal clock signals (first internal clock signal, second internal clock signal) with different phase relationships to the external clock. Each input unit is assigned a specific internal clock, simplifying the timing coordination for each unit while achieving overall gear-down mode stability through the collective phased approach.
3Adaptability or versatility
If multiple input units are enabled simultaneously to receive commands and addresses, then the operation flexibility is improved, but the current consumption increases
Solution Approach 1:
The operation control unit dynamically enables or disables specific input units based on the current operating mode (normal mode vs. gear-down mode). This dynamic control allows the system to maintain operational flexibility by enabling only the necessary input units for the current mode, thereby reducing current consumption compared to having all input units continuously enabled.
Data Source
AI summary
A semiconductor memory device includes a clock signal generation unit suitable for dividing an external clock signal to generate a first internal clock signal corresponding to odd number periods of the external clock signal and a second internal clock corresponding to even number periods, a first input unit suitable for receiving an external command signal and an external address signal in response to the first internal clock signal, a second input unit suitable for receiving the external command signal and the external address signal in response to the second internal clock signal, and an operation control unit suitable for enabling one of the first input unit and the second input unit and disabling the other of the first input unit and the second input unit, during a gear-down mode.