Multi-Phase Clock Generator for Duty-Cycle-Tolerant Phase Locking
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Solution Overview
Problem
Conventional multi-phase clock signal generators face difficulties in maintaining accurate phase relationships due to duty cycle distortion in incoming clock signals, leading to inefficient locking processes and limited range in delay lines, especially as speeds increase and timing requirements tighten.
Innovation Solution
The proposed solution involves a multi-phase clock signal generator with a delay line having multiple delay elements per tap, a phase detector that locks C0 and C360 signals in a single adjustment, and a duty cycle distortion tolerance delay element to ensure accurate phase detection and compensation, allowing for adaptive wide range and timing delay resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional multi-phase clock signal generator is used, then the system can generate multi-phase clock signals, but duty cycle distortion in incoming clock signals causes inaccurate phase relationships and limited delay line range
Solution Approach 1:
The delay line is segmented into multiple individual delay elements (first delay element, second delay element, etc.) that can be independently controlled. This segmentation allows each element to be adjusted separately to compensate for duty cycle distortion while maintaining the overall delay function, thereby improving phase relationship accuracy without sacrificing delay line range.
Solution Approach 2:
The delay elements are made dynamically adjustable through individual control signals that can be modified in real-time based on the incoming clock signal characteristics. This dynamic control enables the system to adapt to varying duty cycle conditions and maintain accurate phase relationships across different operating conditions, resolving the contradiction between precision and adaptability.
2Measurement precision
If the locking process is made more complex to achieve accurate phase relationships, then phase detection accuracy improves, but initialization time increases
Solution Approach 1:
The system performs preliminary adjustment of the delay elements based on expected duty cycle distortion characteristics before the actual locking process begins. This preliminary action prepares the delay line in advance, reducing the number of iterations needed during the locking process and thereby achieving accurate phase detection faster, which resolves the contradiction between precision and initialization time.
Solution Approach 2:
The phase detector provides feedback about the actual phase relationships to the control logic, which then adjusts the delay elements accordingly. This feedback mechanism enables the system to converge to the correct phase relationships more efficiently by learning from each measurement, achieving high accuracy without excessive initialization time.
3Adaptability or versatility
If delay elements are added to increase delay line range, then adaptability improves, but device complexity increases
Solution Approach 1:
Each delay element is designed to be multi-functional, serving both as a variable delay component and as a compensator for duty cycle distortion. By making each element universal in its function, the system achieves extended delay range and improved adaptability without needing to add excessive numbers of specialized components, thereby managing device complexity while meeting performance requirements.
Data Source
AI summary
Multi-phase signal generators and methods for generating multi-phase signals are described. In one embodiment, the clock generator generates quadrature clock signals including those having 90, 180, 270 and 360 degrees phase difference with a first clock signal. One of the intermediate clock signals may be used as an enable signal to guide locking of all signals. For example, the 180 degree clock signal may be inverted and used as an enable signal to guide locking of the initial and 360 degree signals in a single phase adjustment procedure. The 0 and 360 degree signals may be delayed before their phase is compared to compensate for duty cycle error in the clock signals.