Clock Duty Cycle Calibration Using DC Offset Measurement
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Solution Overview
Problem
Duty cycle distortion in clock signals used in electrical circuit devices leads to reduced timing windows and unreliable performance, especially at high input/output speeds, due to sources like amplifiers and parasitic conductor capacitance, which existing solutions like DLL circuits fail to adequately address due to power consumption and complexity.
Innovation Solution
The implementation of clock distortion calibration circuitry on semiconductor dies that compares and adjusts the duty cycles of differential clock signals, using trim values and biasing to calibrate the clock signal at points closer to electrical circuits, accounting for die-to-die variations and reducing distortion without requiring a warm-up cycle or excessive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DLL circuits are used to calibrate clock signals, then duty cycle distortion is reduced, but power consumption increases and device complexity increases
Solution Approach 1:
The patent extracts the essential calibration function from complex DLL circuits and implements it through a simplified DC component offset measurement approach. By measuring only the DC offset of clock signals at different locations and adjusting delay elements accordingly, the system achieves duty cycle calibration without requiring full DLL circuitry, thereby reducing power consumption while maintaining reliability
Solution Approach 2:
The patent changes the calibration approach from time-domain adjustments in DLL circuits to DC component measurement in the voltage domain. By measuring the DC offset voltage of clock signals and using this information to adjust delay elements, the system achieves calibration with lower power consumption and reduced complexity while maintaining effective duty cycle correction
2Reliability
If DLL circuits are used to calibrate clock signals, then duty cycle distortion is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the essential calibration function from complex DLL circuits and implements it through a simplified DC component offset measurement approach. By measuring only the DC offset of clock signals at different locations and adjusting delay elements accordingly, the system achieves duty cycle calibration without requiring full DLL circuitry, thereby reducing power consumption while maintaining reliability
Solution Approach 2:
The patent uses DC component measurements as a simplified copy or representation of the full clock signal characteristics. Instead of analyzing the complete time-varying clock signal in DLL circuits, the system measures only the DC offset voltage, which serves as a proxy for duty cycle distortion, enabling calibration with much simpler circuitry
3Length of stationary object
If clock signals are transmitted over long distances through amplifiers, then signal reach is extended, but duty cycle distortion increases
Solution Approach 1:
The patent applies preliminary calibration action by measuring DC offsets and adjusting delay elements before actual data transmission occurs. By pre-calibrating the clock signal paths to compensate for expected distortion from long-distance transmission and amplification, the system maintains duty cycle accuracy despite extended signal reach through the clock tree
Solution Approach 2:
The patent implements feedback by measuring the DC component offsets of clock signals at various locations in the clock tree and using these measurements to adjust delay elements. This closed-loop approach continuously compensates for distortion introduced by long-distance transmission and amplification, maintaining duty cycle accuracy across extended signal paths
Data Source
AI summary
Several embodiments of electrical circuit devices and systems with clock distortion calibration circuitry are disclosed herein. In one embodiment, an electrical circuit device includes an electrical circuit die having clock distortion calibration circuitry to calibrate a clock signal. The clock distortion calibration circuitry is configured to compare a first duty cycle of a first voltage signal of the clock signal to a second duty cycle of a second voltage signal of the clock signal. Based on the comparison, the clock distortion calibration circuitry is configured to adjust a trim value associated with at least one of the first and the second duty cycles of the first and the second voltage signals, respectively, to calibrate at least one of the first and the second duty cycles and account for duty cycle distortion encountered as the clock signal propagates through a clock tree of the electrical circuit device.