Receiver Calibration Joint Reference Voltage and Equalizer Coefficients
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Solution Overview
Problem
Accurately and efficiently calibrating multiple parameters in a receiver, such as reference voltage and equalizer coefficients, to optimize the operation of dynamic random access memory (DRAM) devices is challenging due to the complexity of optimizing overall receiver performance.
Innovation Solution
A calibration module jointly calibrates the reference voltage and equalizer coefficients by learning parameters that optimize specific criteria related to signal timings, such as maximizing the right eye boundary and eye width of an eye diagram, through a process involving pre-calibration, training, and adjustment of coefficients to achieve low bit error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple parameters (reference voltage and equalizer coefficients) are calibrated separately, then the calibration process is simpler, but the overall receiver performance is not optimized
Solution Approach 1:
The patent combines the calibration of reference voltage and equalizer coefficients into a single joint calibration process. The calibration module simultaneously adjusts both parameters based on eye diagram measurements, rather than calibrating them separately. This merging approach optimizes overall receiver performance by considering the interaction between these parameters, resolving the contradiction between achieving robust operation and maintaining calibration simplicity.
2Reliability
If joint calibration of reference voltage and equalizer coefficients is performed, then receiver performance is optimized, but the calibration process becomes more complex
Solution Approach 1:
The calibration module performs self-calibration by automatically measuring eye diagram parameters and adjusting reference voltage and equalizer coefficients without manual intervention. The system uses feedback from eye width and eye boundary measurements to iteratively optimize parameters, making the complex joint calibration process operate autonomously. This resolves the contradiction by making the complex calibration process easy to operate through automation.
3Reliability
If calibration focuses on maximizing eye width, then signal timing robustness is improved, but other performance parameters may be compromised
Solution Approach 1:
The calibration module simultaneously optimizes multiple parameters including reference voltage, equalizer coefficients, and sampling timing based on eye diagram measurements. By changing multiple parameters jointly rather than focusing on a single parameter, the system achieves balanced optimization of eye width, eye boundary, and bit error rate, resolving the contradiction between improving signal timing robustness and maintaining overall performance adaptability.
Data Source
AI summary
In a receiver having at least a first equalizer and a sampler, a calibration module jointly calibrates a reference voltage and one or more equalizer coefficients. For each of a set of test reference voltages, an equalizer coefficient for the first equalizer may be learned that maximizes a right eye boundary of an eye diagram of a sampler input signal to a sampler of the receiver following the equalization stage. Then, from the possible pairs of reference voltages and corresponding optimal equalizer coefficients, a pair is identified that maximizes an eye width of the eye diagram. After setting the reference voltage, the first equalizer coefficient may then be adjusted together with learning a second equalizer coefficient for the second equalizer using a similar technique.