Ripple Majority Detector for Receiver Offset Voltage Calibration
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Solution Overview
Problem
Data receivers, such as DRAM data receivers, face challenges in accurately discerning bits at high frequencies due to sensitivity to input referred offset caused by device mismatch, leading to errors in data interpretation.
Innovation Solution
A compact sequential majority detect circuit based on a ripple architecture is implemented, comprising two ripple counters and a ripple comparator, which counts 'ones' and total bits, allowing for precise calibration of the offset voltage by adjusting the reference voltage until a transition is achieved, thereby determining and correcting for device mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data receiver operates at high frequencies, then productivity increases, but measurement precision deteriorates due to sensitivity to input referred offset
Solution Approach 1:
The patent applies preliminary action by performing offset calibration before normal data reception operations. The calibration process determines the offset voltage in advance using a calibration voltage and majority detector, then stores this information for use during high-frequency operation. This preliminary characterization of the offset allows the receiver to compensate for it during actual data reception, enabling high-speed operation without sacrificing accuracy.
2Measurement precision
If offset correction circuit is added, then measurement precision improves, but device complexity increases
Solution Approach 1:
The calibration circuit performs self-service by automatically determining its own offset voltage without requiring external calibration equipment or complex adjustment mechanisms. The majority detector compares the calibration voltage with the variable voltage (which includes the offset) and automatically identifies when they are equal, thereby self-calibrating the system. This self-service approach reduces complexity compared to manual or externally-assisted calibration methods.
3Measurement precision
If calibration process is made more accurate, then measurement precision improves, but loss of time increases
Solution Approach 1:
The calibration process implements continuity of useful action by continuously monitoring the relationship between calibration voltage and variable voltage across multiple clock edges. Rather than taking a single measurement, the system observes the output over many clock cycles, continuously accumulating data to determine the offset. This continuous observation approach improves accuracy through statistical averaging while minimizing calibration time by utilizing every available clock edge during the calibration window.
Data Source
AI summary
Apparatus, methods, and systems are disclosed, including, for example, a data receiver to receive a calibration voltage and a reference voltage to calibrate the data receiver. The output of the data receiver is provided to a first ripple counter that counts the outputs from the data receiver and provides an output count. The ripple counter may count either ones or zeros. A second ripple counter counts the number of a clock signals over the same period of time. The output count is either multiplied by two or the count of clock signals is divided by two. A ripple comparator may then compare the outputs and adjust the reference voltage based upon the comparison results.