Chip Select Signal Training Using Dual DQ Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chip select (CS) signal training methods in memory devices, particularly in high-speed DDR and LPDDR, face challenges such as increased complexity due to higher data rates and frequencies, leading to issues like inter-symbol interference, cross-talk, and voltage noise, with existing methods failing to accurately align CS signals with clock signals.
Innovation Solution
Implementing enhanced CS signal training by using multiple DQ pins to provide separate outputs for high and low pulses of the CS signal, allowing for accurate alignment with the clock signal, and employing a defined sampling window and low-frequency entry/exit to improve training efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If higher data rates and frequencies are used in CS signal training, then data transfer speed is improved, but signal alignment accuracy deteriorates due to inter-symbol interference, cross-talk, and voltage noise
Solution Approach 1:
The patent segments the CS signal training process into distinct phases: a training sequence phase where training sequences are transmitted and sampled, and a data transmission phase. It also segments the sampling process into multiple sampling points within a sampling window, allowing independent analysis of signal characteristics at different times. This segmentation enables the system to optimize for both speed and accuracy by separating training operations from data operations and by analyzing signal quality at multiple discrete points.
Solution Approach 2:
The patent performs preliminary CS signal training operations before actual data transmission begins. Training sequences are transmitted at reduced frequencies to establish proper signal alignment and timing relationships in advance. This preliminary action ensures that the sampling window and sampling points are properly configured before high-speed data transfer starts, preventing signal alignment issues during high-speed operation.
2Device complexity
If traditional CS signal training methods are used, then device complexity is kept low, but training accuracy and reliability deteriorate at high data rates
Solution Approach 1:
The patent implements feedback mechanisms where the sampled training sequences are analyzed to determine signal quality and alignment accuracy. The system uses this feedback information to adjust sampling window parameters, sampling point timing, and training sequence characteristics. This feedback loop enables the system to automatically optimize training accuracy without significantly increasing device complexity, as the feedback processing occurs within the existing signal processing architecture.
3Measurement precision
If a defined sampling window with multiple sampling points is used, then signal alignment accuracy is improved, but processing time increases
Solution Approach 1:
The patent uses periodic sampling within the sampling window, where multiple sampling points are distributed at regular intervals during the training sequence transmission. This periodic sampling pattern allows efficient use of processing time by sampling at optimal moments in the signal cycle rather than continuously. The sampling points are strategically positioned to capture critical signal characteristics while minimizing total processing time compared to continuous or random sampling approaches.
Data Source
AI summary
In some aspects, a host device may transmit a clock signal having a first frequency to a memory device and, for a chip select training operation, transmit a chip select signal having a pattern including high pulses and low pulses. The host device may initiate, for a sampling window, a chip select training operation with the memory device using the clock signal and the chip select signal, the sampling window including a quantity of pulses of the chip select signal. The host device may obtain from the memory device, via a first data in or out (DQ) pin, an indication of a first result of the chip select training operation for the high pulses of the chip select signal, and obtain, via a second DQ pin, an indication of a second result of the chip select training operation for the low pulses of the signal. Numerous other aspects are described.