Differential Data Strobes for Wider Memory Data Capture Windows
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Solution Overview
Problem
Integrated circuit memories face challenges in accurately capturing data due to variations in data skew, particularly when interpreting logic ones and zeros, which leads to a reduced data capture window and performance issues under skewed conditions.
Innovation Solution
The solution involves inputting differential strobes into individual buffers compared against a reference voltage, with outputs maintained separate until data latching, where data ones are latched based on rising edge signals and zeros on falling edge signals, ensuring equal skew cancellation and widening the data capture window. This approach ensures that external data and strobes are transmitted simultaneously, allowing for better skew factor cancellation and programmable delays to optimize system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential input strobes are used in true differential mode, then the internal strobe signal tracks the external strobes well, but the data capture window is reduced due to data skew variations
Solution Approach 1:
The patent segments the strobe signal processing into two separate paths: one for strobe signal conditioning and another for data signal conditioning. Each path is processed independently through separate amplifiers and delay circuits, allowing individual optimization of each signal path to maintain both strobe tracking accuracy and adequate data capture window.
Solution Approach 2:
The patent introduces an intermediary delay circuit between the strobe input and the data latching circuitry. This delay circuit acts as a mediator that can be independently adjusted to compensate for data skew variations, thereby maintaining the data capture window without compromising strobe tracking accuracy.
2Duration of action of moving object
If single-ended data input amplifiers are used, then data capture window is increased, but data skew variations cause reduced measurement precision
Solution Approach 1:
The patent applies local quality by using different amplifier configurations for different signal paths. The strobe path uses differential amplifiers for high precision tracking, while the data path uses single-ended amplifiers with independent delay adjustment, optimizing each path for its specific function rather than using a uniform approach.
Solution Approach 2:
The patent introduces dynamically adjustable delay circuits in the data path that can be programmed to compensate for varying data skew conditions. This dynamic adjustment capability allows the system to maintain both adequate data capture window and high measurement precision under different operating conditions.
3Reliability
If data ones and zeros are detected differently by differential amplifiers, then strobe tracking is maintained, but uniform delay throughout the capture process is lost
Solution Approach 1:
The patent applies preliminary action by introducing programmable delay circuits in the data path before the latching stage. These delay circuits are configured in advance to compensate for expected data skew variations, ensuring that both data ones and zeros arrive at the latch with uniform timing, thereby maintaining both reliability and productivity.
Data Source
AI summary
A data capture circuit includes strobes that track input data even when conditions arise that cause the differences in skew from interpreting data state ones and zeros. This is accomplished whether these skews arise from reference voltage variation, data pattern loading, power supply droop, process variations within the chip itself, or other causes. The differential input strobes of the data capture circuit are input into individual input buffers, each compared against a reference voltage individually, as well as a data input pin. The outputs from these buffers are maintained separate from each other all the way to the point where the input data is latched. In latching the input data, data ones are latched entirely based on input signals derived from a rising edge (both strobes and data), and zeros are latched entirely based on input signals derived from a falling edge (both strobes and data).