Impedance Calibration Averaging for DC Ripple Compensation
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Solution Overview
Problem
The ZQ calibration process in semiconductor devices loses accuracy due to inconsistent voltage conditions, particularly when supply voltage exhibits DC ripple or variation, making it challenging to maintain consistent impedance across process, voltage, and temperature changes.
Innovation Solution
Performing multiple impedance calibrations over a period and averaging them to generate a subsequent calibration that reduces calibration error caused by DC ripple in the supply voltage, using a system with a controller and semiconductor devices that include a code generator and relay circuit to adjust output impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single impedance calibration is performed, then the calibration process is fast and simple, but the calibration accuracy deteriorates due to DC ripple in supply voltage
Solution Approach 1:
The patent applies periodic action by performing multiple impedance calibrations at different phases of the supply voltage cycle. The calibration is executed repeatedly across multiple periods of the DC ripple, capturing measurements at various voltage levels. This periodic sampling approach allows the system to average out the ripple effects and obtain a more accurate representative impedance value, resolving the contradiction between measurement precision and time loss.
2Measurement precision
If multiple impedance calibrations are performed and averaged, then calibration accuracy improves, but the calibration process becomes more complex
Solution Approach 1:
The patent merges multiple individual calibration measurements into a single averaged result. By combining the calibration data from multiple periods and phases, the system produces one consolidated impedance calibration value that represents the overall behavior across varying voltage conditions. This merging approach improves accuracy while managing complexity through systematic data aggregation rather than requiring separate calibration routines for each condition.
3Reliability
If impedance calibration is performed frequently to maintain accuracy across voltage changes, then impedance matching improves, but the productivity of the system decreases
Solution Approach 1:
The patent performs preliminary action by conducting multiple calibrations in advance across different voltage phases before operating conditions stabilize. This upfront calibration work establishes a robust baseline impedance value that remains valid across subsequent voltage variations, reducing the need for frequent recalibration and thereby maintaining productivity while ensuring reliability.
Data Source
AI summary
A semiconductor device also includes programmable termination components and a calibration circuit. The calibration circuit generates impedance calibration codes. The calibration circuit also calibrates impedance of the programmable termination components based on an average impedance calibration code of the impedance calibration codes. The semiconductor device further includes an averaging circuit that determines the average impedance calibration code of the impedance calibration codes.