Clock Divider Command Timing in Semiconductor Memory Interfaces
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Solution Overview
Problem
As semiconductor devices scale down, there is a need to minimize the number of pads while maintaining stable internal operations using high-frequency external clocks, which requires efficient generation and synchronization of internal commands and addresses.
Innovation Solution
A semiconductor device incorporating a clock division circuit and a valid time determination circuit to generate division clocks and valid signals based on a chip selection signal, allowing for efficient command generation without additional control signals, thereby minimizing pad usage and ensuring stable internal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of pads is minimized to achieve high efficiency and scaling, then device scalability is improved, but the complexity of signal timing control worsens
Solution Approach 1:
The patent combines the chip selection signal function with the command generation enable function. The chip selection signal serves dual purposes: selecting the memory device and enabling command generation in the same timing cycle, eliminating the need for separate control signals and reducing pad requirements while maintaining timing control capability
Solution Approach 2:
The chip selection signal is given multi-functionality by using it both for device selection and for enabling command generation. This universal signal approach reduces the number of dedicated control pads needed, improving scalability while the internal circuitry maintains the necessary timing control complexity
2Speed
If high-frequency external clocks are used for high-speed operation, then operation speed is improved, but internal operation stability worsens
Solution Approach 1:
The patent segments the clock signal into different frequency domains using clock division circuits. The external high-frequency clock is divided into multiple lower-frequency internal clocks that drive different internal operations, allowing high-speed external communication while maintaining stable internal timing
Solution Approach 2:
Clock division circuits act as intermediaries between the high-frequency external clock and the internal operation circuits. These intermediary circuits generate appropriate timing signals for internal operations based on the external clock, isolating internal stability requirements from external high-frequency operation
3Measurement precision
If additional control signals are added to precisely control command generation timing, then timing precision is improved, but the number of control signals increases
Solution Approach 1:
The patent merges the timing enable function into the existing chip selection signal. By using the chip selection signal's timing edge to trigger command generation, the system achieves precise timing control without adding separate enable control signals, maintaining timing precision while reducing control signal count
Data Source
AI summary
A semiconductor device includes a clock division circuit configured to generate division clocks from a clock signal, based on a division enable signal that is activated based on a chip selection signal, and a valid time determination circuit configured to generate a valid signal for setting a generation time of a command, based on the chip selection signal and the division clocks.