Digitally Calibrated Multiphase Clock Interpolation for CDR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current clock and data recovery (CDR) systems face challenges in generating multiple clock signal phases efficiently, particularly for high-speed serial data streams, as existing methods are costly in terms of power, area, and complexity, and lack the accuracy needed for enhanced data processing.
Innovation Solution
A multiphase clock generator is developed, comprising a first and second clock buffer, and a clock interpolation circuit that generates additional phases by multiplying and integrating input clock signals with adjustable currents, allowing for digital calibration to achieve accurate phase interpolation with lower power consumption and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional methods are used to generate multiple clock signal phases, then the required clock phases can be provided, but power consumption and circuit complexity increase significantly
Solution Approach 1:
The clock generation function is segmented into separate components: a single-phase clock buffer and an interpolation circuit. The interpolation circuit further segments the generation of different phase combinations, creating only the necessary phase pairs rather than all possible phases, thereby reducing overall circuit complexity while maintaining versatility.
Solution Approach 2:
The system dynamically selects which clock phases to generate based on operational requirements. The interpolation circuit can be enabled or disabled, and different input phases can be selected, allowing the system to adaptively provide multiple clock phases only when needed, reducing static complexity and power consumption.
2Adaptability or versatility
If traditional methods are used to generate multiple clock signal phases, then the required clock phases can be provided, but power consumption increases
Solution Approach 1:
Instead of generating all possible clock phases continuously, the system performs partial action by generating only the specific phase pairs required for current operation. The interpolation circuit activates only when phase conversion is needed, consuming power selectively rather than continuously, thus reducing overall power consumption while maintaining the ability to provide multiple phases when required.
3Device complexity
If phase interpolation is implemented without digital calibration, then circuit complexity is reduced, but phase accuracy deteriorates
Solution Approach 1:
A digital calibration mechanism implements feedback to measure and adjust the interpolated phase accuracy. The system monitors the actual phase relationship between input and output clocks and dynamically adjusts the interpolation ratio, ensuring high phase accuracy is maintained despite the simplified circuit architecture. This feedback loop resolves the trade-off by adding only minimal complexity where it directly impacts accuracy.
4Area of stationary object
If a compact design is used, then area is reduced, but the ability to implement accurate phase interpolation and digital calibration is compromised
Solution Approach 1:
The interpolation circuit and digital calibration functions are merged into a single integrated block. The calibration logic, phase detection, and adjustment mechanisms share common circuit elements and control signals, allowing accurate phase interpolation to be achieved within a compact area by eliminating redundant components and optimizing resource utilization.
Data Source
AI summary
Apparatus and methods for multiphase clock generation are provided herein. In certain embodiments, a multiphase clock generator includes a first clock buffer that generates a first output clock signal based on a first input clock signal, a second clock buffer that generates a second output clock signal based on a second input clock signal, and a first clock interpolation circuit that generates a third output clock signal based on interpolating the first input clock signal and the second input clock signal. The first clock interpolation circuit generates the third output clock signal based on multiplying the first input clock signal by a first adjustable current to generate a first multiplied current, multiplying the second input clock signal by a second adjustable current to generate a second multiplied current, combining the first multiplied current and the second multiplied current to generate a combined current, and integrating the combined current.