Command Path Delay Mechanism for Memory Timing Alignment
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Solution Overview
Problem
In semiconductor memory, achieving proper timing of internal command and clock signals is challenging due to high clock frequencies and varying propagation delays, which can result in incorrect or incomplete data capture, especially in multi-data rate memories where data rates exceed clock frequencies and timing domains need to be crossed.
Innovation Solution
A system that includes a command path delay mechanism to align internal command signals with data strobe signals, utilizing a delay-locked loop to provide variable delays based on process, voltage, and temperature changes, ensuring synchronization across clock and command paths, and a data strobe generator circuit to control data capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clock frequency is increased to enhance productivity, then the data transfer rate is improved, but the timing precision deteriorates due to smaller error margins and varying propagation delays
Solution Approach 1:
The patent adjusts the timing parameters of internal command signals dynamically. A delay mechanism is introduced to the write command signal, allowing its timing to be shifted relative to the DQS signal. This parameter adjustment compensates for propagation delay variations and enables precise timing alignment even at high clock frequencies where error margins are minimal.
Solution Approach 2:
The patent employs a feedback mechanism where the timing relationship between the DQS signal and internal command signals is continuously monitored and adjusted. The delay amount is programmed based on observed timing deviations, creating a closed-loop system that maintains accurate timing synchronization despite variations in propagation delays and high clock frequencies.
2Reliability
If delay circuitry is added to align command and DQS signals, then timing synchronization is improved, but the device complexity increases
Solution Approach 1:
The patent applies delay compensation in advance by programming the appropriate delay amount before the actual data transfer operation begins. The delay value is determined based on expected propagation delay characteristics and is pre-configured in the delay mechanism, allowing the system to achieve timing synchronization without requiring complex real-time adjustment circuitry during operation.
3Reliability
If the propagation delay is increased to accommodate timing alignment, then the timing margin is improved, but the speed of operation deteriorates
Solution Approach 1:
The patent implements a dynamic delay adjustment mechanism that can be programmed to provide different delay amounts based on operating conditions. Rather than using a fixed, conservative delay that would slow down all operations, the system dynamically adjusts the delay to the minimum amount needed for timing alignment, thereby maintaining high operation speed while ensuring sufficient timing margin when required.
Data Source
AI summary
An apparatus or method may include provision of a command to a data block. An example apparatus includes a command circuit configured to provide a command signal in an internal clock time domain based at least in part on a memory access command received in an external clock time domain. The example apparatus further includes a command path delay configured to delay the command signal. The example apparatus further includes a data strobe generator circuit configured to receive the command signal and a data strobe signal. A plurality of clock edges of the data strobe signal correspond to received data bits associated with the memory access command. The data strobe generator circuit is configured to control input circuitry to capture the data associated with the memory access command based at least in part on the data strobe signal and the command signal.